Download M2 segment middle cerebral artery aneurysms

M2 segment middle cerebral artery aneurysms:
Retrospective analysis of clinical and radiological
features and surgical outcome
Thesis submitted in fulfillment of the rules and
regulations for MCh Degree Examination of Sree Chitra
Tirunal Institute for Medical Sciences and Technology,
Thiruvananthapuram
By
Dr. Sathia Prabhu
Resident in Neurosurgery
Month and Year of Submission: October 2011
1 M2 segment middle cerebral artery aneurysms:
Retrospective analysis of clinical and radiological
features and surgical outcome
Submitted by
:
Dr. Sathia Prabhu
Programme
:
MCh Neurosurgery
Month & year of submission :
2 October, 2011
CERTIFICATE
This is to certify that the thesis entitled “M2 segment middle cerebral artery
aneurysms: Retrospective analysis of clinical and radiological features and surgical
outcome ” is a bonafide work of Dr. Sathia Prabhu and was conducted in the
Department of Neurosurgery, Sree Chitra Tirunal Institute for Medical Sciences &
Technology, Thiruvananthapuram (SCTIMST), under my guidance and
supervision.
Date
Dr. Suresh Nair
Place
Professor and Head of Department,
Department of Neurosurgery,
SCTIMST, Thiruvananthapuram
3 DECLARATION
This thesis titled
“M2 segment middle cerebral artery aneurysms: Retrospective
analysis of clinical and radiological features and surgical outcome ” is a
consolidated report based on a bonafide study done by me during the period from
January 2009 to September 2011, under the Department of Neurosurgery, Sree
Chitra Tirunal Institute for Medical Sciences & Technology (SCTIMST),
Thiruvananthapuram.
This thesis is submitted to SCTIMST in partial fulfillment of rules and regulations
of MCh Neurosurgery examination.
Place
Dr. Sathia Prabhu
Date
Department of Neurosurgery,
SCTIMST, Thiruvananthapuram.
4 ACKNOWLEDGEMENT
The guidance of Dr. Suresh Nair, Professor and Head of the Department of
Neurosurgery, has been invaluable and I am extremely grateful and indebted for
his contributions and suggestions, which were of invaluable help during the entire
work. He will always be a constant source of inspiration to me.
I owe a deep sense of gratitude to Dr. Girish Menon for his invaluable advice,
encouragement and guidance, without which this work would not have been
possible.
The critical remarks, suggestions of Dr. Jayanand Sudhir, helped me in achieving
a high standard of work.
I am deeply indebted to Dr. Mathew Abraham, Dr. Easwer H. V, Dr.
Krishnakumar K, Dr. George Vilanilam, Dr. Gopalakrishnan C. V and thank
them for their constant encouragement and support.
I wish to sincerely thank all my colleagues for their support at every step.
Last but not the least, I owe a deep sense of gratitude to all my patients without
whom this work would not have been possible.
5 INDEX
INTRODUCTION
7
REVIEW OF LITERATURE
8-81
AIMS AND OBJECTIVES
82
MATERIALS AND METHODS
83
RESULTS
84-86
DISCUSSION
87-97
CONCLUSIONS
98-99
ABBREVIATIONS
100-101
REFERENCES
102-115
PROFORMA
116-118
6 INTRODUCTION Middle cerebral artery (MCA) aneurysms are commonly encountered in neurosurgical practice. Due to the complex arterial and aneurysmal anatomy operative procedures for these aneurysms still remains a challenging task for the neurosurgeons. Most available literature on MCA aneurysms are on proximal and early branch MCA aneurysms. Only few studies are available on distal MCA aneurysms. In our experience with MCA aneurysms, we found that the distal aneurysms particularly the M2 segment aneurysms demanded special attention due to its peculiar clinical characteristics and challenging surgical management required when compared to aneurysms arising from other sites. Driven by its uniqueness and paucity of available literature we undertook the present study to further define and categorize these aneurysms. 7 REVIEW OF LITERATURE MICROANATOMY: Middle cerebral artery(MCA) is the largest and most direct branch of the internal cerebral artery(ICA). It courses laterally and slightly forward below the anterior perforated substance and approximately 1 cm posterior to the sphenoid wing. Within the Sylvian fissure, it makes a sharp posterosuperior turn at the limen insula to reach the surface of the insula. At the periphery of the insula, the branches of the MCA pass to the medial surface of the opercula of the frontal, temporal, and parietal lobes. Finally it runs over the brain surface as cortical branches. The MCA is classically divided into 4 segments. These are the M1 or sphenoidal segment, the M2 or insular segment, the M3 or opercular segment, and the M4 or cortical segment. The M1 (sphenoidal) segment 8 begins at the ICA bifurcation and extends laterally within the deep part of the Sylvian fissure to terminate at the genu around the limen insula. According to Gibo et al(1) and Yasargil(2), in most anatomical dissections or operations (86%), the bifurcation of the MCA occurs proximal to this genu. In contrast to this, Ture et al(3) found that the main bifurcation is located at the genu in 57.5% of the hemispheres,distal to the genu in 27.5%, and proximal to the genu in 15%. The M2 (insular) segment begins at the genu or the MCA bifurcation and terminates at the circular sulcus. As mentioned earlier the termination of M1 segment and the origin of M2 segment remains controversial. Though classically M2 segment origin has been defined from the genu of MCA at the limen insula, some authors consider the point of MCA bifurcation as the origin(1,2,3,4). The MCA divides into superior and inferior trunks at the level of the limen insula, and these trunks course over the insula as the M2 segment. The 9 superior and inferior trunks may be equal in diameter, or one of them may be larger than the other. According to Umansky et al(4), there are 4 types of branching patterns: 1) cortical branches arise as collateral vessels from a single trunk that terminates in the angular artery (6%); 2) the MCA divides into the superior (frontal) and inferior (temporal) trunks (64%); 3)the MCA divides into the superior, middle, and inferior trunks (29%); and 4) the MCA divides into 4 trunks (1%). In the study reported by Gibo et al(1), 78% of the MCAs divided into a bifurcation, 12% divided into a trifurcation, and 10% divided into multiple trunks. Yasargil(2) states that when a large branch arises from the superior or inferior trunk just after the bifurcation, a false impression or ‘‘pseudotrifurcation’’ or ‘‘pseudoquadrification’’ takes place. According to him even a dominant early branch from M1 segment can give a false impression of early bifurcation of MCA. M2 segment give rise to 8 to 12 branches, mainly arising from the superior trunk, before becoming M3 segment. The superior (frontal) M2 branch is the origin of the prefrontal, precentral, and central arteries. In 22.5% of 10 hemispheres dissected by Ture et al (3), the anterior and posterior parietal arteries have their origin in the superior M2 segment branch. They mainly supply the inferior frontal cortex, the frontal opercular cortex, and also the cortex in parietal and central sulcus areas. The inferior (temporal) M2 segment branch is the main origin of the posterior and middle temporal arteries, supplying mainly the middle and posterior temporal cortex and temporo‐occipital, angular, and posterior parietal regions . M3 (opercular) segments start at the peri‐insular sulci and end at the lateral surface of the brain. They mainly supply the medial opercular surface and, to a lesser extent (25%)(3), the superior or inferior peri‐insular sulcus.M4(cortical) segments are the distal branches over the cortical surface. In a recent article(3) addition of the M5 segment has been proposed, with the M4 segment being the parasylvian segment and the M5 segment being the terminal segment. M4 and M5 segments give rise to orbitofrontal, prefrontal,precentral, central, anterior parietal, posterior 11 parietal,angular, temporo‐occipital, posterior temporal, temporal,anterior temporal, and temporal polar arteries. 12 middle Fig.1:Divisions of MCA-schematic diagram
13 Fig.2:MCA branches 14 Fig.3:Distal MCA branches 15 The perforating branches of the MCA enter the anterior perforated substance and are called the lenticulostriate arteries. There is an average of 10 (range, 1–21) lenticulostriate arteries per hemisphere (1,2,3). Lenticulostriate branches arise from the prebifurcation part of the M1 in every case and from the postbifurcation part of the M1 segment in half of the hemispheres. Of the total number of lenticulostriate branches,approximately 80% arise from the prebifurcation part of the M1. Most of the remainder arise from the postbifurcation part of the M1, but a few arise from the proximal part of the M2 near the genu. The lenticulostriate arteries are divided into medial, intermediate,and lateral groups, each of which has a unique origin,composition, morphology, and characteristic distribution in the anterior perforated substance. The medial group is the least constant of the three groups and is present in only half of the hemispheres . Branching before entering the anterior perforated substance is less common than in the intermediate or lateral groups. The intermediate lenticulostriate arteries form a complex 16 array of branches before entering the anterior perforated substance between the medial and lateral lenticulostriate arteries.They are present in more than 90% of hemispheres(1). They arise predominantly from the main or prebifurcation part of the M1 or an early branch.The lateral lenticulostriate arteries are present in almost all hemispheres. They originate predominantly on the lateral part of the M1, pursue an S‐shaped course, and enter the posterolateral part of the anterior perforated substance. They may also arise from the early branches of the M1 or from the M2. 17 Fig.4:Perforators of MCA 18 CLINICAL FEATURES: MCA aneurysms account for approximately 20% of all intracranial aneurysms(5,6).There are 3 categories according to their origin: main trunk (M1 segment‐M1As) aneurysms arising at the origin of the temporopolar or anterior temporal arteries (lateral wall) or in relation to the lenticulostriate arteries (medial wall), bifurcation aneurysms(MbifAs) located at the first major bifurcation, and distal aneurysms(MdistAs) located beyond the major bifurcation. MCA aneurysms has certain special features which are not seen with aneurysms at other sites. Giant MCA aneurysms are more common than giant aneurysms in other locations, with the possible exception of the paraclinoid region of the ICA(7). This observation might relate to the fact that MCA aneurysms can reach massive proportions without producing symptoms from encroachment on vital structures. When large enough, unruptured MCA aneurysms can produce clinical symptoms from mass 19 effect(8).Headaches associated with signs of increased intracranial pressure, including papilledema, occur rarely with the larger aneurysms. Temporal lobe epilepsy is another symptom that occurs rarely as a result of MCA aneurysms but only exceptionally as a result of aneurysms in other locations. Ischemic symptoms such as transient ischemic attacks and small strokes, although rarely caused by aneurysms, occur more frequently with aneurysms of the MCA than with aneurysms in other locations. These symptoms are thought to result from intra‐aneurysmal thrombosis with subsequent embolism (9). Rupture of an aneurysm usually results in a syndrome indistinguishable from that associated with subarachnoid hemorrhage (SAH) from rupture of an aneurysm in any other location. Certain clinical characteristics, however, favor the diagnosis of a ruptured MCA aneurysm. These characteristics were first described by Hook and Norlen(8). Approximately 60% of patients with an MCA aneurysm lose consciousness at the onset of rupture (a higher proportion than with aneurysms at other locations). 20 Approximately one third of patients with a ruptured MCA aneurysm have primarily unilateral headache, which is much less commonly seen after rupture of aneurysms elsewhere. When such unilateral headache is present, it is almost always on the side of the aneurysm. Approximately 80% of the patients in the series of Hook and Norlen(8) had focal neurologic deficits when first seen. Such deficits usually consisted of hemiparesis, aphasia, visual field deficits,and central facial weakness, out of which half had severe deficits.. Only 34% of patients with ruptured aneurysms in other locations had such findings when first seen, and only 7% had severe deficits. When a patient with a ruptured aneurysm is first seen awake but with severe hemiparesis, the most likely location of the aneurysm by far is the MCA. These aneurysms are also slightly more likely to result in seizures after rupture than aneurysms in other locations. The propensity of MCA aneurysms to cause focal symptoms and signs is attributable to their tendency to bleed at least partially into the brain parenchyma as well as into the subarachnoid space. 21 The incidence of intracerebral hematoma in patients with ruptured MCA aneurysms is between 30% and 50%(10), which is considerably higher than with aneurysms in other locations. These intracerebral hematomas are frequently of great diagnostic value when identified by computed tomography (CT). A hematoma extending into the frontal opercula and the temporal opercula,bridging the sphenoid ridge, is virtually pathognomic of a ruptured MCA aneurysm. Dashti et al(11) reviewed patients treated from Kuopio university from 1997 to 2005 and studied the features of MCA aneurysms. All MCA aneurysms were divided into either M1 segment aneurysms, MCA bifurcation aneurysms or distal MCA aneurysms(distal to bifurcation). 3005 patients with 4253 aneurysms were studied. 48% of patients had MCA aneurysms. Among MCA aneurysms 15%were M1 segment, 80%were bifurcation and 5%were distal aneurysms. Median size of M1 anuerysm was 4mm(6mm for ruptured aneurysm).5%were giant aneurysm. Among patients with M1 aneurysms 33% presented with SAH, 36% had 22 intracerebral hematoma and 32% had preoperative hydrocephalus. Median size of bifurcation anuerysm was 8mm(10mm for ruptured aneurysm). Among patients with bifurcation aneurysms ,61% presented with SAH, 45% had intracerebral hematoma and 29% had preoperative hydrocephalus. 4%were giant aneurysm. In this series, 6% of M1As, 4% of MbifAs and 2.5% of all MCA aneurysms were giant (>25mm in diameter) . Distal MCA aneurysms (MdistAs): Occurrence of MdistAs: Distal middle cerebral artery aneurysms are the least frequent of the MCA aneurysms reported to form 1.1% to 5% (12‐17). Dashti et al reported a total of 78 MdistAs in his series(69 patients). Most of MdistAs are located in the sylvian cistern, on the cisternal branches of the MCA, but rare cases on perforating or penetrating branches have been reported. 23 Ogilvy et al(19) reviewed 65 middle cerebral aneurysms in 62 patients operated on over a 5‐year interval with 5 MdistAs. Fig.5:Incidence of various MCA aneurysms in Ogilvy et al study
24 Out of 791 patients studied by Horiuchi et al(12) there were 23 (2.9%) in the M1 segment, 759 (96%)at the bifurcation or trifurcation, and nine (1.1%) in distal MCA branches Fig.6: Incidence of various MCA aneurysms in Horiuchi et al study
25 Size of MdistAs: The aneurysm sizes ranged from 2 to 10 mm (mean 4.9 +/‐ 3 mm) in the study conducted by Horiuchi et al(12).Dashti et al(17) reported median size of 3mm for unruptured and 8mm for ruptured MdistAs.71%(44% among ruptured) were <7mm.3% were >25mm. Shape of MdistAs: Most distal cerebral artery aneurysms are saccular,few are fusiform, dissecting, or mycotic with longitudinal dilations of the parent cerebral arteries(17). Ruptured and unruptured MdistAs: Of the 1456 patients with MCA aneurysms studied by Dashti et al(17), only 18 (23%) of the 78 MdistAs presented with SAH, less than M1As (73/241 or 33%) or MbifAs (711/1385 or 51%). 44% of ruptured MdistAs were smaller than 7 mm in contrast to the results of the study of the International Study of Unruptured Intracranial Aneurysms. 26 Associated aneurysms with MdistAs: Distal middle cerebral artery aneurysms are often associated with other aneurysms. In Dashti et al (17)study, 1456 patients with MCA aneurysms carried altogether 1704 aneurysms . Associated aneurysms occurred in 51 (74%) of the 69 patients with MdistA. Intracerebral hematoma with MdistAs: Distal middle cerebral artery aneurysms bleed frequently into the adjacent brain . The incidence of intracerebral hematoma in patients with ruptured MCA aneurysms is between 30% and 50%, which is considerably higher than with aneurysms in other locations(10). Intracerebral hematoma was present with 9 (50%) of the 18 ruptured MdistAs in Dashti et al(17). Eight of the nine patients suffered cerebral hematomas with subarachnoid hemorrhage in Horiuchi et al study(12). Intracerebral hematoma is thought to affect the outcome mainly by the initial brain damage and distorting the 27 anatomy of MCA,which has been described by Yasargil and several others(19‐22). Preoperative hydrocephalus: Dashti et al (17) reported a incidence of 22% of preoperative hydrocephalus with MdistAs.
28 IMAGING: CT scan is essential to establish the diagnosis of SAH, to localize and quantitate the amount of blood in the cisterns and to predict the likelihood and location of vasospasm, and to determine whether an intracerebral hematoma is present. Hematomas attributable to ruptured MCA aneurysms may occur in the temporal lobe, frontal lobe, within the Sylvian fissure, or in combination. Digital subtraction angiography of cerebral vessels is the gold standard investigation. Preoperative cross circulation tests with BOT (balloon occlusion tests) are required in giant and complex aneurysms. Multislice helical CTA is the primary modality in many centers for several reasons: noninvasive and quick imaging, comparable sensitivity and specificity to DSA in aneurysms larger than 2 mm , disclosure of calcifications in the walls of arteries and aneurysm, and quick reconstruction of 3‐dimensional (3D) images(23‐29).The timing of angiography is related to each surgeon’s particular bias about the timing of 29 surgery. The angiogram can differentiate intrasylvian hematomas from temporal hematomas in which angiography shows an elevation of the M1 segment and increased distance between the M2 segment and the inner table(30). Another reason for early angiography is that vasospasm is not likely to be present; thus, the aneurysm and its surrounding anatomy can be demonstrated optimally. For intraoperative navigation toward MdistAs, 3D CTA or DSA reconstruction should be evaluated for the 3D localization of the main bifurcation of MCA in the sylvian fissure(17). In the work station, 3D CTA images can be rotated accordingly to evaluate the surgeon’s view, and a suitable bony exposure can be performed with virtual tools. Determination of the parent artery, distance of the aneurysm from the main bifurcation, and, finally, the exact location of the aneurysm dome in the sylvian and sulcal space are of utmost importance. 30 Besides DSA and CTA, magnetic resonance imaging T2 (coronal, axial) images may be helpful in preoperative planning(31). MRI is useful in assessing the thrombus and areas of diffusion restriction. 31 Fig.7:Plain CT showing SAH and temporal hematoma
32 Fig.8:Contrast CT and DSA image
33 Fig.9:Left M2 aneurysm CT angiogram
Fig.10:Right
M2
aneurysm
34 MRI
image
Fig.11:MCA
branches-angiographic
35 image
ANEURYSM PATHOPHYSIOLOGY: Because cerebral aneurysms usually arise along the main trunks of the circle of Willis due to hemodynamic stress and/or congenital factors, distal aneurysms are uncommon. Infection caused by mycotic emboli and trauma can lead to aneurysm formation at the distal cerebral artery(32).Although it remains unclear what kind of factors facilitate distal MCA aneurysm formation, congenitally fragile portions of the distal MCA may be the main feature responsible. Flow dynamics in intracranial aneurysms and their adjacent parent vessels are believed to play an important role in the development and rupture of intracranial aneurysms(33). The ideal method for visualizing intracranial hemodynamics would be in vivo blood flow analysis in which we can quickly and inexpensively acquire accurate blood flow information from each patient. Phase contrast MR imaging might be a promising noninvasive method for analyzing in vivo intracranial aneurysmal hemodynamics for living human beings in the future. 36 Tateshima et al(34) reported that the phase contrast MR imaging method was able to depict the complex 3D intraaneurysmal flow in an acrylic aneurysm model. Isoda et al(35,35) performed time‐resolved 3D phase‐
contrast MR imaging by using a 1.5T MR scanner to visualize hemodynamics in a silicon vascular model with a middle cerebral aneurysm.They ran an aqueous solution of glycerol as a flowing fluid with a pulsatile pump. Time‐resolved images of 3D streamlines and 2D velocity vector fields clearly demonstrated that the aneurysm had 3D complex vortex flows within it during systolic phase. Blood flow from the M1 segment of Middle cerebral artery (MCA) struck the posterior wall of the intracranial aneurysm. Blood flow followed the wall of the intracranial aneurysm (highest flow rate, 15 cm/s) and diverged into the 2 M2 segments near the inlet of the aneurysm. A helical flow at the left aspect of the aneurysm was seen along the aneurysmal wall. Where the helical flow reversed direction was coincident with the bleb. Flow rate of the bleb was low(less than 5 cm/s). Helical flow continued to flow into the center of the aneurysm from the bleb. Flow rate was less than 5cm/s. Two 37 blood flows flow out from the anterior trunk of MCA peripheral to the central incoming jet of the M1 segment. One of these flows, flowing at the posterior aspect of the aneurysm with slow flow of around 5 cm/s, corresponded with the irregular surface of the aneurysmal wall. 38 Fig.12:3D angiogram
a.Anterior-oblique view
b.Posterior-anterior view
39 Fig.13:3D streamline view
a.Anterior-oblique view
b.Posterior-anterior view
Numbers and colors correspond with flow rate in
the legend at the right side of the figure regarding 3D streamlines.Units are meters per second.
Arrows indicate flow schematically
40 MANAGEMENT OPTIONS: With the exception of fusiform, serpentine, and dissecting aneurysms, almost all MCA aneurysms have a neck. Though the branches may take off at some distance from the entrance of the MCA, which may make clipping difficult and sometimes impossible, it is exceptional to have branches coming off the dome of the aneurysm (9). Microsugery remains the treatment of choice. Endovascular treatment presents a viable alternative to open microsurgery in selected cases. To make this selection properly, an accurate assessment of the anatomy of the aneurysm, particularly the size of the neck in relation to the height of the fundus, is necessary. Most literature on management of MCA aneurysms includes both proximal and distal aneurysms. There is a paucity of literature specifically on distal aneurysms. All patients with ruptured aneurysms are treated early. The discussion now centers on whether to treat a particular patient with a particular aneurysm by open microsurgery or by an endovascular approach. Clearly, 41 patients who present with symptoms from the mass effect of an intratemporal hematoma should be treated with open surgery to evacuate the hematoma and, at the same time, clip the aneurysm (9). This is particularly true when the patient is rapidly deteriorating, and in these cases, it has become reasonable to take the patient directly to the operating room after the CT scan has demonstrated a large intratemporal hematoma. Endovascular treatment: Endovascular coil embolization of intracranial aneurysms was introduced in the early 1990s. During its initial use, the technique was primarily used to treat aneurysms in the posterior circulation, where surgical access is particularly technically challenging. Currently, the technique is widely accepted as a valid alternative to surgical clipping in the treatment of anterior circulation aneurysms. Regli et al.(37) reported the treatment of 30 consecutive patients with 34 unruptured MCA aneurysms. Thirteen patients were taken up for 42 endovascular embolization, and 21 patients underwent surgical clipping of their aneurysms.11 of 13 aneurysms (32%) showed an unfavorable configuration for endovascular treatment, and these patients underwent clipping procedures along with the 21 surgically treated patients. Only 2 aneurysms (6%) were successfully treated with endovascular coiling. Factors contraindicating endovascular treatment in Regli et al series: Neck width>4mm Dome/neck ratio<1.5mm Inadequate access Unstable intraluminal thrombus Arterial branch origin at neck These criteria are becoming relative contraindications with improving skills and technology in endovascular treatment.
In a larger MCA aneurysm series, Iijima et al.(38) reported endovascular embolization in 154 ruptured or unruptured MCA berry aneurysms. The 43 authors successfully occluded 149 of the aneurysms with detachable coils and attempted embolization in 5 aneurysms (3%). The majority of aneurysms were small (7 +/‐ 3 mm), and no giant aneurysm was treated in this series. The authors excluded from their study group patients who required STA‐ MCA bypass surgery. They used a balloon assisted technique to treat 66 aneurysms (44%). There were 27 Procedure‐related complications (18%): 20 patients (13%) had thromboembolic complications, and 7 patients (5%) had an aneurysm perforation, which was found on computed tomography after the procedure Most of the patients had a good clinical outcome, with an mRS score of 3 or less, except for 3patients who remained with severe disability. Ten deaths were reported: 9 patients with a ruptured aneurysm and 1 patient with an unruptured aneurysm. In that series, aneurysm recanalization was observed in 20 of the 105 available follow‐up angiograms (20%) at an average of 15 months after the procedure. One aneurysm reruptured between staging procedures in an acute phase of SAH. 44 Doerfler et al.(39) presented a series of 38 ruptured and unruptured MCA aneurysms in 36 patients. In 5 aneurysms (13%), coil embolization was not done because the aneurysm had a wide neck or because there was arterial incorporation in the body of the aneurysm, an insecure coil position, or vasospasm. These patients underwent surgical clipping instead. Eighteen percent of the aneurysms were large, most of the aneurysms were small, and no giant aneurysm was treated. Complications occurred in 6 patients (16%), but no aneurysm perforation was reported. The authors noted 3 instances of aneurysm recanalization at the 6‐month angiographic follow‐ up examination. A prospective evaluation of 26 endovascularly treated MCA aneurysms was reported by Lubicz et al.(40) .The majority of the patients (76%) in that study had unruptured aneurysms, and patients with ruptured aneurysms presented with Hunt and Hess grade I or II SAH. Sixteen patients were treated with balloon‐ assisted coil embolization, and 2 were treated with a stent alone. Complete occlusion was achieved in 15 patients (57%). An 45 aneurysm perforation and a thromboembolic complication were reported. All patients showed good clinical outcomes (mRS score <2). On 6‐month follow‐ up angiograms, 6 recanalizations (24%) were seen, 1 of which required retreatment.
Suzuki et al(41) reported their results for endovascular coiling with 115 patients. One hundred fifteen MCA aneurysms in 115 patients (mean age, 55.1years) were treated by an endovascular technique from April 1990 to March 2007.Forty‐ eight patients (42%) presented with acute subarachnoid hemorrhage, and 67patients (58%) had unruptured aneurysms. Fifty‐ three aneurysms (46%) were small with a small neck, 28 (24%) were small with a wide neck, 22 (19%) were large, and 12(11%) were giant. Angiographic results immediately after embolization showed complete occlusion in 53 aneurysms (46%), a neck remnant in 51 (44%), and incomplete occlusion in 3 (3%). Because of anatomic difficulties, they could not embolize 8 aneurysms (7%).Thirteen patients underwent combined treatment that included endovascular and extracranial‐ intracranial bypass surgery. Morbidity and mortality rates were 6.9% (8patients) and 3% (3 46 patients), respectively. Procedure‐ related complications were encountered in 10 patients (9%). Seventy patients had long‐ term follow‐ up angiograms. Seven aneurysms (10%) were recanalized; all were large or giant. One partially embolized large aneurysm ruptured 13 months after embolization. 47 Fig.14:Pre and post procedure images in Suzuki et al study
48 SURGICAL APPROACHES: Three surgical approaches are commonly practiced all over the world.These approaches were reviewed in detail by Ogilvy et al(18) and Baskaya et al(9). Sylvian fissure approach: The basic approach to MCA aneurysms using the sylvian fissure technique involves minimal modifications of the standard frontotemporal (pterional) craniotomy.The patient is placed in the supine position with the head turned approximately 45 degrees and tilted slightly backward. A standard pterional scalp flap is used. Once the bone is removed and dura opened, the sylvian fissure can be opened in one of two ways.The fissure can be opened medially(proximal Sylvian fissure approach), following the MCA distally from the carotid bifurcation until the aneurysm is encountered. Alternatively, the sylvian fissure can be opened peripherally (distal Sylvian fissure approach)while following the distal MCA branches proximally to the aneurysm. 49 The medial transsylvian approach: This approach initially involves a true subfrontal angle of dissection. Once the olfactory tract is identified, the arachnoid over the optic nerve is usually visible. At this point, cerebrospinal fluid can be removed from the optic cistern after the arachnoid is opened. Once a subfrontal retractor is in place, the arachnoid over the optic and proximal carotid artery can be opened widely under the microscope. The sylvian fissure is opened widely from medial to lateral. The self‐retaining retractors on the frontal and temporal lobes are gradually advanced deeper and the angle between the retractors is made gradually more acute as the fissure is opened. Dissection proceeds distally on the internal carotid artery until a point where the bifurcation between anterior and middle cerebral artery is identified. As this point is reached, the Ml segment is dissected free by continued opening of the medial Sylvian fissure. Initial dissection is usually carried out on the inferior aspect of the Ml segment. Aneurysms of the Ml segment usually arise from the posterior superior surface of the MCA in relation to lenticulostriate vessels. As many as 19 small‐caliber lenticulostriate vessels 50 can arise from the Ml or proximal M2 segments of vessels. These vessels supply the deep basal ganglia and internal capsule and must be preserved. Aneurysms of the Ml segment often occur in relation to two or more lenticulostriate vessels. For this reason, the aneurysm neck must be thoroughly dissected with small vessels separated sharply in order to completely clip these lesions. Aneurysms arising on Ml are usually small. Once the perforating vessels are dissected free at the aneurysm neck, the clip blades can be inserted in this space. At times, small aneurysms on the Ml segment can be obliterated using bipolar coagulation or tiny aneurysm clips. It is preferable to place a temporary clip on the MCA prior to the use of cautery in order to reduce the pressure in the aneurysm dome As the sylvian fissure is opened, the middle cerebral artery bifurcation (or trifurcation) will be encountered. For aneurysms at this location a segment of the MCA stem for temporary clipping is prepared in an area where no perforators are present. Using the medial transsylvian approach, care must be taken to not over‐retract the frontal or temporal lobes as the aneurysm is 51 encountered. Excessive retraction can induce aneurysm rupture or cause postoperative swelling of the retracted lobe. With larger middle cerebral aneurysms, the dome may be encountered prior to visualizing the middle cerebral bifurcation region. The dome should be left alone until the Ml segment and distal M2 branches are dissected free. Distal trans sylvian approach: This approach has the advantage of facilitating exposure of the distal anatomy of the aneurysmal complex, which is usually the difficult aspect of the case. The major disadvantage is that the surgeon reaches the aneurysm before achieving proximal control. In some cases, once proximal control of the Ml segment is secured, a distal‐to‐proximal dissection can be used to isolate the M2 vessels. Superior temporal gyrus approach: The patient’s head is turned about 60 degrees and tilted slightly backward. The incision starts at the level of the zygoma just in front of the tragus and curves slightly backward above the ear before swinging forward to the edge of the hairline about 2‐3 cm lateral to the midline. The scalp and skin 52 flap are reflected anteriorly as described for the transsylvian approach. The bony removal of the pterion and lateral aspect of the sphenoid ridge is performed in the same manner as described for the pterional approach. The dura is opened and an incision about 2‐3 cm long made in the superior temporal gyrus. The cortisectomy is initiated about 1 cm behind the front of the sylvian fissure and is parallel to the fissure. Once the cortisectomy is complete, the selfretaining retractors can be placed on either side of the cortisectomy. Using suction and bipolar coagulation the cortisectomy is extended medially into the vertical segment of the sylvian fissure over the insula. The sylvian veins are left intact. The branches of the MCA are then identified and followed proximally toward the region of the aneurysm. By avoiding the dome of the aneurysm, one of the two major divisions of the MCA can usually be identified and followed proximally on the side away from the aneurysm to the main stem of the MCA. Only enough of the main trunk of the MCA is exposed to allow the application of a temporary clip, if necessary. Once the distal part of the MCA and origin of the main divisions 53 are identified, the entire aneurysm neck and the surrounding vessels can be fully dissected. Small perforators may be stuck to the neck or part of the dome and must be sharply dissected free from the aneurysm neck in order to provide a space for clip placement in the neck region. This is particularly true in cases of giant aneurysms when the anatomy may not be entirely clear until all of the aneurysm neck is exposed. Often a third major middle cerebral branch is encountered and must be dissected away from the neck. Recurrent lenticulostriate vessels arising from the origin of the main divisions must be identified and separated from the neck. As with the sylvian fissure approach, final preparation of the aneurysm neck is often facilitated by the use of temporary occlusion 54 of the MCA.
Fig.15:Sylvian approach for shorter M1 segment
55 Fig.16:Superior temporal approach for longer M1 segment
Fig.17: Superior temporal gyrus approach-Schematic diagram
56 By using the preoperative radiological studies to define the characteristics of a MCA aneurysm, the choice of surgical approach can be made to maximize safety of aneurysmal dissection and clipping. Strong consideration should be given to the presence or absence of intraparenchymal hematoma, the length of the Ml segment, as well as the direction and size of the aneurysm (9,18). The presence of a parenchyma hematoma within the temporal lobe is one indication to consider the superior temporal gyrus approach (9,18). One shortcoming of this approach in the setting of a hematoma would be the possibility of operating through the clot and entering the aneurysm dome; by review of the angiogram, this event can be avoided. The superior temporal gyrus approach can be thought of as a form of lateral (from peripheral to proximal) transsylvian approach since in fact the sylvian fissure is entered peripherally usually at a depth of 1.5‐3 cm. 57 Review of preoperative angiograms should include an observation of the length of the MCA trunk segment and the relationship of the aneurysm to this segment (9,18). When a long Ml is present two strategies can be used to reach and dissect the aneurysm. A peripheral‐to‐central opening of the sylvian fissure may be performed to expose the lesion. Alternatively, the use of the superior temporal gyrus approach can be used. To approach MCA bifurcation lesions that occur at the end of a long Ml segment, use of a standard central‐to‐peripheral sylvian fissure opening can be difficult. When the Ml segment is short, opening the sylvian fissure from medial to lateral provides excellent access to the aneurysm. The direction that the aneurysm “points” should also influence the decision of surgical approach(9,18).This is particularly true for larger lesions. For inferiorly and laterally directed lesions, the MCA Ml segment and major divisions can be isolated using either a sylvian fissure or a superior temporal gyrus approach. Although isolation and control of the proximal MCA is more readily obtained using the sylvian fissure approach, dissection of the aneurysm neck can be easier from the superior temporal 58 gyrus approach. For superiorly directed lesions, the sylvian fissure approach with proximal‐to‐distal exposure of the arterial anatomy can be ideal. As the Ml segment is dissected free, the neck of the lesion is encountered. If a superior temporal gyrus approach is used for such a lesion, the dome may well be encountered before the neck and middle cerebral bifurcation can be isolated. Ogilvy et al(18) reviewed 65 middle cerebral aneurysms in 62 patients operated on over a 5‐year interval where ,a choice of operative approach was made based on preoperative evaluation of available radiological studies. The superior temporal gyrus was used when intraparenchymal hematoma was present in the temporal lobe or when the length of the middle cerebral artery trunk was long (average length 2.44 +/‐ 0.41 cm). This approach was used in 20 operations on 22 aneurysms. The sylvian fissure approach was used in cases where the middle cerebral artery main trunk was short (1.32 +/‐ 0.41 cm) or the direction of the aneurysm was favorable. This approach was used in 38 operations. In 4 operations (5aneurysms) they combined the 59 two approaches to remove clot, obtain adequate exposure, and secure control of the proximal MCA. The postoperative outcome was scored as good (no deficits ,returning to preoperative lifestyle),fair(minimal deficits, living at home) and poor(dependent on health care centres). Majority of patients were Hunt and Hess grade 0 and 1.31 out of 38 patients operated by sylvian fissure approach had good outcome with 1 death. 17 out of 20 patients operated by superior temporal approach had good outcome with 2 deaths.3 out of 4 patients operated by combined approach had good outcome with no deaths. Baskaya et al (9) with a total cases of 108 cases reported fair or good outcome in 87% of cases. Preoperative Hunt and Hess grade was 0‐II in 71% of patients.7 patients died.(Good‐no deficits,fair‐independent with minimal deficits,poor‐dependent with severe deficits) 60 Table.1: Reports of outcome from various other series on MCA aneurysms: Author
No
Good
Fair/poor
Mortality(%)
outcome(%) outcome(%)
Yasargil et al(42)
184 83.7
Fein and Flamm et al 114 87
11.4
4.9
7
6
25
13
(43)
Rinne at al(13)
457 62
61 Distal MCA aneurysms: There is a paucity of literature regarding approaches specifically for distal aneurysms, almost nil considering M2 aneurysms as a separate entity. The standard distal transslvian/superior temporal gyrus approach is preferred for cases with space occupying ICH. Intracerebral hematoma associated with ruptured MdistAs usually is a combination of intraparenchymal and intrasylvian hematomas. Evacuation of ICH before clipping brings the risk of premature rupture , which is difficult to handle, and forced dissection might result in injury to distal MCA branches(12). Dashti et al(17) suggested to secure the aneurysm first and then partially evacuate the hematoma.They also mentioned that minor force should be applied as not to sever perforating arteries and most of the clot should remain because the extremely complicated arterial tree in the area of the distal sylvian fissure does not allow safe evacuation. The lateral supraorbital approach, a less invasive modification of the pterional 62 approach was proposed by Dashti et al(17) for surgery of MbifAs if uncomplicated by the presence of hematoma. In Horiuchi et al(12) study of nine patients with distal MCA aneurysms eight lesions were saccular aneurysms that were clipped and the remaining one was a mycotic aneurysm that was trapped. All patients had good outcomes after obliteration of their aneurysm, although their preoperative condition was not good. 63 Difficult aneurysms: Presence of large hematoma: Evacuation of an intrasylvian hematoma is difficult because of the presence of small perforating vessels in the subarachnoid space and fibrous adhesion of the clot. Here superior temporal gyrus approach is preferred(9,18). By working on the medial side of the clot cavity in the subpial plane, the sylvian arteries can be identified and followed proximally. The majority of the hematoma can be left in place until after the aneurysm is clipped, at which time an aggressive hematoma resection is undertaken. In cases of recent hemorrhage, the limits of the sylvian fissure may be difficult to define, and by removing a small amount of anterior superior temporal gyrus, the depth of the fissure can be entered and further dissection can be made. 64 Rupture before clipping: Aneurysm may rupture while opening the sylvian fissure or dissecting the aneurysm base. The rupture site is rather at the dome than at the base. Control should be first attempted via suction and/or compressing the bleeding site with cottonoids. Sudden and short hypotension by cardiac arrest, induced by intravenous adenosine , can be used to facilitate quick dissection and clipping in case of uncontrolled bleeding(44). A pilot clip may be inserted to the ruptured secondary pouch if it is visible(17). Otherwise, a temporary clip proximally or clips on both sides are inserted for further dissection of the base and final clipping. A small and thin walled aneurysm may rupture at its neck during dissection. Under temporary clipping of arteries, reconstruction of the base by involving a part of M1 trunk in the clip should be attempted. One option, hindered by the deep location of aneurysm, is to suture the rupture site with 8/0 or 9/0 running sutures, followed by clipping augmented by glue(11). 65 Wada et al(45) reported a method of detecting the probable site of rupture preoperatively by combining 3D CTA and 2D CT images(nonshaded volume‐rendering image) by identifying the relation of the maximal thickness of hematoma around the aneurysm fundus .This helps the surgeon to guess the potential site of rupture introperatively and to take adequate precautions. Fig.18:Combined 3D CTA and 2D CT images(Black arrow‐maximal hematoma,white arrow head‐probable site of rupture)
66 Very small aneurysm: In very small (2‐3 mm) aneurysm, clipping is difficult because the wall is fragile. Temporary clipping of M1 reduces intraluminal pressure and softens the dome (18).With minimal reduction of the M1 lumen, a thin portion of the healthy M1 wall is taken inside the clip for safe closure of the neck(11). If the first clip slides exposing some of the neck, double clipping may be applied. Coagulation and wrapping under temporary clipping of M1 provides another option. Fusiform aneurysms: Fusiform aneurysms are commonly due to arterial dissections. Mycotic fusiform aneurysms are common in distal MCA. In the Dashti et al(11,17) series, fusiform M1As were rare, only 0.6% all MCA aneurysms . Wrapping, proximal occlusion, excision, trapping, and reconstruction are techniques to be considered for fusiform MCA aneurysms(46‐49) . M1 lumen may be reconstructed by placing multiple fenestrated clips in a row, either right‐angled or straight ones. Large fusiform aneurysms may also be 67 treated by arteriotomy, followed by reconstruction of the M1 lumen by suturing alone or by clips and running sutures. In giant fusiform aneurysms,parent artery occlusion with preoperative bypass should also be considered(50). Intraluminal thrombus: In case of intraluminal thrombus temporary clips are placed proximally and the aneurysm dome is incised with a knife for internal decompression, usually by suction or, in case of major thrombus, by ultrasonic aspirator(51). Intraluminal thrombus is carefully removed, and the decompressed dome is clamped between the neck and the incision by a mosquito‐like vascular clamp, used in vascular surgery. The vascular clamp softens the base for aneurysm clips and also prevents slipping of intraluminal thrombus inside M1. The lumen is irrigated copiously by saline. Then, the dome is usually reduced enough to allow final dissection of the neck anatomy before deciding how to perform the final clipping. 68 Giant /multilobulated aneurysms: Giant aneurysms merit special consideration. . When choosing the approach, the surgeon should be sure that adequate visualization of the aneurysm neck anatomy will be available. The same decision‐making process as for a simple aneurysm should apply if a direct clipping of the lesion is anticipated. If the lesion points laterally into the temporal lobe, a combined approach using the sylvian fissure exposure to identify the Ml vessel and the superior temporal gyrus approach to dissect out the M2 branches can be used. In Yasargil’s(42) original series of 184 MCA aneurysms, 83(45%) were multilobed. The orientation of MCA aneurysms is frequently with the long axis along the axis of the parent vessel. This can create difficulty establishing line of sight that allows optimal visualization. The proximal M1 vessel is often deep and out of the surgeon’s view. Maintaining visualization for proximal control may not be easily attainable. The necks of MCA aneurysms are frequently broad‐based and circular, and this feature makes endovascular coiling techniques less effective. 69 Multiple technical maneuvers can be used in the treatment of complex MCA aneurysms, including temporary arterial occlusion, coagulation of the fundus, reconstruction with multiple clips, suction decompres sion, circulatory arrest with hypothermia, partial clipping followed by coil embolization, and wrapping. The fenestrated clip was first introduced and used by Dr.Charles Drake(52) in 1969 as a solution to the treatment of complex basilar aneurysms .Sugita et al.(53)reported a series of 18 aneurysms (eight internal carotid and 10 vertebral) treated with fenestrated aneurysm clips. They illustrated examples of interlocking fenestrated clip placements for complex internal carotid artery aneurysms. They did not use the fenestration to allow placement of clips at orthogonal or near orthogonal angles.Tanaka et al. (54)published a larger series that incorporated some of these patients. In this expanded series, they emphasized the use of a “multiple clipping technique” using combinations of fenestrated and nonfenestrated clips. To treat 25 large and giant aneurysms of the internal carotid artery, they applied a total of 58 clips, 31 of which had fenestrations. Six aneurysms required “perpendicular” 70 placements. In both reports, the authors emphasized the preference for “parallel”clip placements over “perpendicular” placements for internal carotid artery aneurysms to prevent “dog ear” remnants. Fifteen patients with complex MCA aneurysms were treated using an interlocking tandem clipping technique by Clatterbuck et al(55).All patients recovered completely with GOS of 5. 71 Fig.19:Interlocking tandem clipping technique: Example 1
72 Example
2
73 Bypass operations: In published series, direct clipping was possible in the majority of cases (38%‐71%)(18,56‐60) .Combined 3D DSA, CTA, and MRI data are necessary for a complete view on the vascular anatomy, intraluminal thrombus, and thickness and calcifications of the wall(6,51,61). When giant M1A protrudes toward the frontal lobe and involve lateral lenticulostriate arteries(LLA), clipping is not advocated, but parent artery occlusion with preoperative bypass operation should be considered. This also applies to aneurysms with massively calcified wall. Giant M1As often protrude to the middle fossa, distorting the intrasylvian anatomy, shifting M1 superiorly and medially, and not involving LLAs. In these cases, clipping is considered, supported by a preoperative bypass if necessary(12,48,62,63). Preoperative high‐flow EC‐IC bypass using the ELANA (excimer laser–
assisted non‐occlusive anastomosis) or SELANA (Sutureles excimer laser–
assisted non‐occlusive anastomosis) techniques needs to be considered if the MCA or one of its major branches will be sacrificed to treat unclippable 74 giant MCA aneurysms(64). The excimer laser‐assisted nonocclusive anastomosis technique for a high‐flow bypass is an innovative cerebrovascular surgical tool. The use of excimer laser‐assisted nonocclusive anastomosis helps to create a vein graftartery anastomosis without temporarily occluding the recipient artery. The adequate choice of donor vessels, which are the STA or occipital artery for a low‐flow bypass and the radial artery or saphenous vein graft for a high‐flow bypass, can deliver different amounts of flow into the MCA territory. The selection of the ideal conduit for a high‐flow bypass depends on physiology and the neurosurgeon’s preference. When one places an anastomosis to an artery smaller than 2 mm, a saphenous vein graft is not recommended(48,65). Compared with high‐flow bypasses, STA‐MCA bypasses are simpler to achieve and remain an effective technique for favorable long‐term patency and significantly lower procedural morbidity(66). 75 Combined endovascular and revascularisation procedures: This combination approach offers the advantage of avoiding a deep perianeurysmal dissection when surgical exposure is especially difficult secondary to severe brain swelling or mass effect. Furthermore, endovascular treatment can be performed hours or days after bypass construction, which permits assessment of the bypass and distal MCA territorial patency in anticipation of permanent MCA bifurcation and/or M1 segment sacrifice just distal to the origin of the lenticulostriate arteries, using superselective BTO in the awake patient. Shi et al(66) reported a series of 9 patients with this technique with 90‐99% occlusion in all patients. 76 Fig.20:a.Preoperative imaging following combined approach
b.Postoperative
imaging
following
77 combined
approach
Complex reconstruction procedures: Sekhar et al(48) published various reconstruction procedures in 7 patients with giant and complex MCA aneurysms. The operative techniques used included saphenous vein graft bypass (n ‐1), radial artery graft interposition (n ‐2), radial artery patch (n ‐ 1), superficial temporal artery interposition graft (n ‐1), superior thyroid artery interposition graft (n‐ 1), direct reimplantation of branch (n‐ 1), and reconstruction of trifurcation (n‐1). There was no mortality. Six patients had excellent outcomes with Glasgow Outcome Scale scores of 5, and one patient had a good outcome with a Glasgow Outcome Scale score of 4. 78 Fig.21:Illustrations of operative techniques by Sekhar et al:
79 80 81 AIMS AND OBJECTIVES To study retrospectively: ‐the demographic pattern, the clinical features and the radiological findings of patients treated for aneurysms arising from M2 segment of middle cerebral artery ‐the various surgical options available and the final outcome following these procedures 82 METHODS All patients with M2 segment MCA aneurysms treated at Sree Chitra Tirunal institute for medical sciences and technology (SCTIMST), Trivandrum, India over the past 10 years were included in the study. A retrospective analysis of the demographic characteristics, clinical presentations, preoperative functional status, radiological findings, type of operative procedures, complications and postoperative outcome was done from the available medical records. Follow up status was assessed with Glasgow outcome scale (GOS) during their visit to the outpatient department clinics . 83 RESULTS A total number of 16 patients were treated for M2 segment MCA aneurysms from Feb.1991 to Jan.2011.7 were males and 9 were females. Average age at presentation was 45(11‐63) years. 3 patients were under the age of 30years.4 patients had other associated aneurysms among which 1patient had multiple aneurysms. Aneurysm was found in right side in 10 patients and in left side in 6 patients. 6 patients had aneurysm from the superior trunk and 10 patients from the inferior trunk. Right inferior trunk was the commonest site for M2 segment MCA aneurysms in our study. 15 patients presented with SAH and 1 patient presented with hemiparesis. Headache was the commonest symptom which was present in all patients with SAH. Hemiparesis was noted in 4 patients and dysphasia in 2 patients at the time of admission. Only 2 patients had a history of seizures at presentation. 2 among the patients were smokers and 3 were known 84 hypertensives. No family history of SAH/intracranial aneurysms was noted in any of the patients. No history of significant head injury noted in any of the patients. At admission 11 patients were in WFNS grade 1,1 in grade 2 and 3 in grade 3. Preoperative CT revealed Fisher grade 3 SAH in 11 patients, grade 4 in 4 patients and grade 1 in 1 patient.3 patients had intracerebral hematoma and 1 patient had intraventricular hemorrhage. Intraluminal thrombus was noted in 5 patients with 2 patients having established MCA territory infarct preoperatively. 3 patients had hydrocephalus preoperatively. Mean size of the aneurysm was 12.7mm(3‐43mm). Aneurysm was <7mm in 7 patients(6 aneurysms <5mm) and >25mm in 2 patients. 50% of the aneurysms had wide neck and 3 aneurysms were fusiform. 15 patients were operated whereas 1 patient refused for surgery and lost follow up. All patient underwent elective surgery by pterional /frontotemporal craniotomy. 8 patients underwent clipping alone, either single or multiple. 3 patients underwent clipping with muscle wrapping. In 2 patients only coagulation and muscle wrapping was done. 1 patient 85 underwent clipping with reconstruction and an another excision of aneurysm with end to end anastomosis. Temporary clipping was used during dissection and clipping in 9 patients.1 patient had premature aneurysm rupture during dissection. None of the patients developed rebleed during follow up. No significant residual aneurysm or recurrence was noted in follow up images.1 patient developed fresh massive MCA infarct following surgery who underwent emergency decompressive craniectomy. Out of 2 patients with preoperative hemiparesis, one patient recovered to normal power following surgery whereas the other continued to have residual paresis. 13(87%) patients had a GOS of 5 at last follow up. 1 had a GOS of 4 and an other of 3 during their last follow up. 86 DISCUSSION Demographical features: Aneurysms usually present in 4th and 5th decades, more commonly in females. The average age at presentation in our study was 45(11‐63)years.3 among the 16 patients were below 30 years (19%) which is higher than the usual incidence of other aneurysms in young patients. A slight female preponderance (57%) was noted similar to Horiuchi series(12). Since the total number of patients studied is less it is difficult to comment that M2 aneurysms are more common in young and in females, but a definite trend is noted which has to be confirmed with larger series. Pathogenesis: Being remote to the circle of Willis the pathogenesis of distal MCA aneurysms seems to be different from the aneurysms arising from the circle of Willis. Increased hemodynamic stress especially at the branching sites is considered as a major factor for higher incidence of aneurysms arising from 87 the circle of Willis. This factor is implicated for the higher incidence of these aneurysms in hypertensives. Weakening of the distal MCA vessels due to atherosclerosis, infective emboli and connective tissue disorder is considered to be the commonly attributable factors for distal MCA aneurysms (46,67‐72). Among our patients only 2(12%) smokers and 3(19%) hypertensives were identified. None of our patients had any connective tissue disorder or a family history of intracranial aneurysms. No documented infective pathology at the site of aneurysms or any cardiac source of infective emboli could be established in any of the patients. These findings are in contradiction to the presumed pathogenesis suggested by the other studies on distal MCA aneurysms. 4 patients had another associated aneurysm at other site and 1 patient had multiple aneurysms accounting for 31% of patients having more than one aneurysm. Though this incidence is much less than the reported incidence(74%) by Dashti et al.(17) for distal MCA aneurysms, it is significantly higher when compared to the incidence reported with other 88 aneurysms. Considering the significant number of patients with multiple aneurysms and a slight preponderance in females and young patients , we tend to implicate a congenital abnormality predominantly affecting the intracranial vessels rather than a systemic abnormality as the cause for M2 segment aneurysms. Clinical and radiological features: Among the 15 patients who had SAH, all of them presented with holocranial headache with no specific laterality as reported by Hook and Norlen(8) for MCA aneurysms. Hook and Norlen reported that 80% of the patients in his series of MCA aneurysms presented with focal deficits like hemiparesis, aphasia, facial weakness and visual field deficits. This high incidence of focal deficits with MCA aneurysms were considered to be due to the larger size, presence of thrombi causing embolic infarcts and higher incidence of parenchymal hematoma causing mass effect.37.5% of our patients had focal deficits at the time of presentation which is considerably less than the incidence reported by Hook and Norlen. Only 2 patients 89 presented with seizures which is also less than the expected incidence with MCA aneurysms. Majority of our patients(73%) had Fisher grade 3 SAH at presentation. Only 3(19%) patients had intracerebral hematoma. The reported overall incidence for hematoma with MCA aneurysms ranges from 30‐50%.Dashti et al(17) reported 50% incidence of hematoma in distal MCA aneurysms. In our study we noted that just the presence of hematoma alone doesnot cause any focal deficits, rather patients with well established MCA infarcts always had deficits. This indicates that infarcts due to emboli from intraluminal thrombi which was commonly seen in our patients is the probable cause for focal deficits rather the mass effect due to hematoma or mere gaint size of the aneurysm. Mean size of the M2 aneurysms in our study was 12.7(3‐43)mm which is more than the reported size for distal MCA aneurysms by Horiuchi et al(12) and Dashti et al(17).It is also more than the mean size of proximal MCA aneurysms reported by Dashti et al(11).12% of our patients had giant aneurysms(>25mm) which is also higher than the reported incidence of 90 giant aneurysms by the same authors. Among our patients who bled ,47% of patients had aneurysm size <7mm which is similar to the results of Dashti et al(44%)(17).In both the studies significant number of patients bled with aneurysm size <7mm contradicting the conclusions of international study of unruptured intracranial aneurysms(73).Though these aneurysms can attain larger size before rupture or causing clinical symptoms,the risk of rupture still remains high even when the size is <5mm. The anatomy of these aneurysms are complex due to larger size, mutilobed fundus, wide neck or fusiform shape and origin of distal branches from the fundus. 91 Table.2: Clinical and radiological features of Distal MCA aneurysms compared with other studies : Dashti et al(17) No. of cases 69(78 Horiuchi et Our al(12) study 9 16 aneurysms) Age NA 58(40‐78)yrs 45(11‐63) Age below 30 years NA 0 3(19%) Sex(M:F) NA 2:7 7:9 66% 47% Aneurysm <7mm with 44% rupture Giant aneurysms 3% 0 12.5% Intracerebral hematoma 11(50*)% 88% 19% Multiple aneurysms 74% 55% 31% *Among ruptured aneurysms,NA‐Details not available in the article 92 Surgical options: The anatomy of these aneurysms are complex due to larger size, mutilobed fundus, wide neck ,fusiform shape and origin of distal branches from the fundus. Presence of hematoma further complicated the anatomy. These factors make the management of these aneurysms difficult. A case by case consideration of the intraoperative findings should be done to decide the type of surgical procedure which can be provided for that patient. In our study, simple clipping was always tried whenever feasible reserving complex procedures only if obsolutely necessary. All our patients underwent pterional/frontotemporal craniotomy with trans‐sylvian approach. 53%(8 patients) of the patients could be managed by clipping alone, either with a single clip or multiple clips. Patients with multilobulated aneurysms with distal branches arising from fundus of one of the lobe underwent partial clipping and muscle wrapping over the residual neck(20%‐3 patients). 2 patients with small aneurysms having 93 wide neck were coagulated and wrapped with muscle. 1 patient with giant aneurysm underwent partial excision and aneurysmorrhaphy of the residual neck.1 patient with fusiform dilatation of the trunk underwent excision with end to end anastomosis. Almost all giant aneurysms had intraluminal thrombus requiring incision and evacuation under temporary clipping of proximal and distal segments. Temporary clipping of proximal vessels was required in 9 patients. Other indications for temporary clipping were the presence of adherent hematoma, thin walled blebs and large tense neck .Hematomas were evacuated first before clipping if they had already surfaced along temporal gyrus or along distal sylvian fissure. Partial evacuation of the hematoma over the neck alone may be adequate to apply the clips. Further decompression of hematoma can be made once the final clipping has been done. Probably due to low threshold for temporary clipping during dissection of aneurysm only one patient had early rupture before clipping. 94 Endovascular management is usually not considered for MCA aneurysms. Though encouraging results were reported by various recent series by Iijima et al(38), Lubicz et al(40) and Susuki et al(41), most of these aneurysms were small with narrow neck. Due to reasons like wide neck, complicated anatomy and origin of distal branches from the neck, which was noted in most of our patients, none of our patients were considered for endovascular management. Outcome: 87% of our patients had a GOS of 5 during follow up which is comparable to the results of series by Baskaya et al(22),Yasargil et al(42) and Fein and Flamm et al(43) on MCA aneurysms. All patients who presented with WFNS grade 1 had a GOS of 5 at followup. 3 patients had a GOS of 3 during follow up among which 2 patients had preoperative established MCA infarct and the other 1 patient developed MCA infarct postoperatively. Thus WFNS grade at presentation and presence of established MCA infarcts were the 2 factors with prognostic value noted in our study. Other factors including age, sex, presence of hematoma, 95 morphology of the aneurysm and the surgical options undertaken did not correlate with the outcome. Even older patients with good preoperative status did well with surgery. Table.3: Details of 16 patients studied in our study No. Age Sex WFNS Fisher Size grade of MCA grade Aneurysm infarcts in CT (mm) Surgical procedure* at follow Pre‐ Post‐
scan op op GOS up 1 11 m 1 3 17 ‐ ‐ CR 5 2 60 m 1 3 4.2 ‐ ‐ Not opt. ‐ 3 62 f 1 4 5 ‐ ‐ C 5 4 44 m 1 3 7 ‐ ‐ C 5 5 50 f 3 3 4.2 + + C 4 6 38 f 3 3 35 ‐ ‐ EA 5 7 57 f 1 4 8.4 ‐ ‐ C 5 8 52 f 1 3 3 ‐ ‐ CGW 5 96 9 36 m 1 3 14 ‐ ‐ C 5 10 48 m 2 3 20 ‐ ‐ CGW 5 11 53 m 1 3 4.6 ‐ ‐ C 5 12 51 m 1 3 3 ‐ ‐ C 5 13 60 f 3 3 9 ‐ + CLW 3 14 63 f 1 4 3.7 ‐ ‐ CLW 5 15 14 m unbled 1 43 + + C 5 16 21 f 1 23 ‐ ‐ CLW 5 4 *Clipping‐C, Clipping and wrapping‐CLW, Coagulation and wrapping‐
CGW, Clipping‐reconstruction‐CR, Excision and anastomosis‐EA 97 CONCLUSIONS M2 segment aneurysms are rarely encountered in our clinical practice. Though M2 aneurysms are classified among distal MCA aneurysms, their clinical characteristics are unique in exhibiting partially both the features of proximal and distal aneurysms, thus deserving a separate catogery in classification of MCA aneurysms. These aneurysms are difficult to treat due to their location within the sylvian fissure, associated hematoma, larger size and complex anatomy with frequent branching arteries arising from the aneurysm. Inspite of these factors ,clipping and reconstruction still remains the best surgical option in majority of cases, though other options like coagulation or wrapping and excision with revascularisation has to be considered in some cases. 98 Overall outcome for surgical treatment is good. Preoperative WFNS grade and presence of established MCA infarcts were the factors found to be strongly associated with the final outcome. Our series of 16 cases is probably the first study about these complex aneurysms. 99 ABBREVIATIONS ICA‐Internal carotid artery MCA‐Middle cerebral artery STA‐Superficial temporal artery M1As‐M1 segment aneurysm MbifAs‐MCA bifurcation aneurysm MdistAs‐Distal MCA aneurysms EC‐IC‐Extracranial‐intracranial SAH‐Subarachnoid hemorrhage GOS‐Glasgow outcome score mRS‐Modified Rankin scale 100 WFNS‐World federation of neurosurgeons BOT‐Balloon occlusion test CT‐Computed tomography CTA‐CT angiography DSA‐Digital subtraction angiography MRI‐Magnetic resonance imaging 101 REFERENCES 1. Gibo H, Carver CC, Rhoton AL. Microsurgical anatomy of the middle cerebral artery. J Neurosurg. 1981;54:151–169. 2. Yasxargil MG. Operative anatomy of the middle cerebral artery. In: Yasxargil MG, ed. Microneurosurgery. Vol. I. New York: Thieme Verlag; 1984:72–91. 3. Ture U, Yasxargil MG, Al‐Mefty O, et al. Arteries of the insula. J Neurosurg. 2000;92:676–687. 4. Umansky F, Juarez SM, Dujovny M. Microsurgical anatomy of the proximal segments of the middle cerebral artery. J Neurosurg. 1984;61: 458–467. 5. Robinson RG. Ruptured aneurysms of the middle cerebral artery. J Neurosurg. 1971;35:25–33. 102 6. Sundt TM, Kobayashi S, Fode NC, et al. Results and complications of surgical management of 809 intracranial aneurysms in 722 cases: related and unrelated to grade of patient, type of aneurysm, and timing of surgery. J Neurosurg. 1982;56:753–765. 7. Heros RC, Kolluri S. Giant intracranial aneurysms presenting with massive cerebral edema. Neurosurgery. 1984;15:572–577. 8. Hook O, Norlen G. Aneurysms of the middle cerebral artery. Acta Chir Scand Suppl. 1958;235:1–39. 9.Baskaya.K,Coscarella,Surgical management of middle cerebral artery aneurysms.Neurosurg Q,2005;15:201‐210. 10. Graf CJ, Nibbelink DW. Cooperative study of intracranial aneurysms and subarachnoid hemorrhage: report on a randomized treatment study. III.Intracranial surgery. Stroke. 1974;5:559–601. 11.Dashti.R,Hernesniemi.J.Microneurosurgical management of proximal middle cerebral artery aneurysms.Surg Neurol 2007;67:6‐14. 12. Horiuchi T, Tanaka Y, Takasawa H, et al. Ruptured distal middle 103 cerebral artery aneurysm. J Neurosurg 2004;100(3):384 ‐ 8. 13. Rinne J, Hernesniemi J, Niskanen M, et al. Analysis of 561 patients with 690 middle cerebral artery aneurysms anatomic and clinical features as correlated to management outcome. Neurosurgery 1996;38(1):2 ‐11. 14. Rinne J, Ishii K, Shen H, et al. Surgical management of aneurysms of the middle cerebral artery. In: Schmideck HH, Roberts DW, editors. Schmideck & Sweet operative neurosurgical techniques: indications, methods, and results. Philadelphia, PA7 Saunders Elsevier; 2006. p. 1144‐ 66. 15. Stoodley M, Weir B. Surgical treatment of middle cerebral artery aneurysms. In: LeRoux P, Winn H, Newell D, editors. Management of cerebral aneurysms. Philadelphia, PA7 Elsevier Inc; 2004. p. 795‐ 807. 16. YasSargil MG. Microneurosurgery, vol 2. Stuttgart‐New York7 Georg Thieme Verlag; 1984. p. 124‐ 64. 104 17.Dashti.R ,Hernesniemi.J.Microneurosurgical management of distal middle cerebral artery aneurysms.Surg Neurol 2007;67:553‐563. 18.Ogilvy.C,Heros.R.C.Surgical management of middle cerebral artery aneurysms.Surg neurol,1995;43:15‐24. 19. Yoshimoto Y, Wakai S, Satoh A, et al. Intraparenchymal and intrasylvian haematomas secondary to ruptured middle cerebral artery aneurysms: prognostic factors and therapeutic considerations. Br J Neurosurg 1999;13(1):18 ‐ 24. 20. Papo I, Bodosi M, Doczi T. Intracerebral haematomas from aneurysm rupture: their clinical significance. Acta Neurochir (Wien) 1987; 89(3‐4):100 ‐ 5. 21. Pasqualin A, Bazzan A, Cavazzani P, et al. Intracranial hematomas following aneurysmal rupture: experience with 309 cases. Surg Neurol 1986;25(1):6 ‐ 17. 22. BasSkaya M, Menendez J, Yqceer N, et al. Results of surgical treatment of intrasylvian hematomas due to ruptured intracranial aneurysms. 105 Clin Neurol Neurosurg 2001;103(1):23 ‐ 8. 23. Dillon E, van Leeuwen M, Fernandez M, et al. Spiral CT angiography. Am J Radiol 1993;160:1273 ‐ 8. 24. Harbaugh R, Schlusselberg D, Jeffery R, et al. Three‐dimensional computerized tomography angiography in the diagnosis cerebrovascular disease. J Neurosurg 1992;76(3):408 ‐ 14. 25. Kangasniemi M, M7kel7 T, Koskinen S, et al. Detection of intracranial aneurysms with two‐dimensional and three‐dimensional multislice helical computed tomographic angiography. Neurosurgery 2004; 54(2):336 ‐ 40. 26. Ogawa T, Okudera T, Noguchi K, et al. Cerebral aneurysms: evaluation with three‐dimensional CT angiography. AJNR Am J Neuroradiol 1996;17(3):447‐ 54. 27. Tampieri D, Leblanc R, Oleszek J, et al. Three‐dimensional computed tomographic angiography of cerebral aneurysms. Neurosurgery 1995; 36(4):749 ‐ 54. 106 of 28. Villablanca J, Hooshi P, Martin N, et al. Three‐dimensional helical computerized tomography angiography in the diagnosis, characterization, and management of middle cerebral artery aneurysms:comparison with conventional angiography and intraoperative findings. J Neurosurg 2002;97(6):1322 ‐ 32. 29.Wintermark M, Uske A, Chalaron M, et al. Multislice computerized tomography angiography in the evaluation of intracranial aneurysms: a comparison with intraarterial digital subtraction angiography. J Neurosurg 2003;98(4):828‐ 36. 30. Shimoda M, Oda S, Mamata Y, et al. Surgical indications in patients with an intracerebral hemorrhage due to ruptured middle cerebral artery aneurysm. J Neurosurg. 1997;87:170–175. 31.Nagasawa S, Ohta T, Tsuda E. Magnetic resonance angiographic source images for depicting topography and surgical planning for middle cerebral artery aneurysms: technique application. Surg Neurol 1998;50(1):62 ‐ 4. 107 32. Bohmfalk GL, Story JL, Wissinger JP, et al: Bacterial intracranial aneurysm. J Neurosurg 48:369–382, 1978 33. Imbesi SG, Kerber CW. Analysis of slipstream flow in two ruptured intracranial cerebral aneurysms. AJNR Am J Neuroradiol 1999;20:1703–05 34. Tateshima S, Grinstead J, Sinha S, et al. Intraaneurysmal flow visualization by using phase‐contrast magnetic resonance imaging: feasibility study based on a geometrically realistic in vitro aneurysm model. J Neurosurg 2004;100:1041–48 35. Isoda H, Inagawa S, Takeda H, et al. Preliminary study of tagged MR image velocimetry in a replica of an intracranial aneurysm. AJNR Am J Neuroradiol 2003;24:604–07 36.Isoda.H,Hirano.M.Visualisation of hemodynamics in a silicon aneurysm model using time resolved ,3D,phase contrast MRI.AJNR Am J Neuroradiol,2006;27:1119‐22. 37.Regli.L,Uske.AEndovascular coil placement compared with surgical clipping for the treatment of unruptured middle cerebral artery aneurysms,J Neurosurg,1999;90:1025‐1030 108 38. Iijima A, Piotin M, Mounayer C, Spelle L, Weill A, Moret J: Endovascular treatment with coils of 149 middle cerebral artery berry aneurysms.Radiology 237:611–619, 2005. 39. Doerfler A, Wanke I, Goericke SL, Wiedemayer H, Engelhorn T, Gizewski ER,Stolke D, Forsting M: Endovascular treatment of middle cerebral artery aneurysms with electrolytically detachable coils. AJNR Am J Neuroradiol27:513–520, 2006. 40. Lubicz B, Graca J, Levivier M, Lefranc F, Dewitte O, Pirotte B, Brotchi J, Balériaux D: Endovascular treatment of middle cerebral artery aneurysms. Neurocrit Care 5:93–101, 2006. 41.Suzuki.S,Tateshima.S,Jahan.R.Endovascular treatment of middle cerebral artery aneurysms with detachable coils:Angiographic and clinical outcomes in 115 consecutive patients.Neurosurgery,2009;64:876‐889. 42. YasSargil MG. Microneurosurgery, vol 2. Stuttgart‐New York7 Georg Thieme Verlag; 1984. p.124‐164 43. Flamm ES, Fein JM. Middle cerebral artery aneurysms. In: Flamm ES, 109 Fein JM, eds. Cerebrovascular Surgery. Vol. III. New York: Springer‐ Verlag; 1985:861–877. 44. Randell T, Niemel7 M, Kytt7 J, et al. Principles of neuroanesthesia in aneurysmal SAH—the Helsinki experience. Surg Neurol 2006;4:382‐8. 45.Wada.K,Arimoto.H.Usefulness of preoperative three dimensional computed tomographic angiography with two dimensional computed tomographic imaging for rupture point detection of middle cerebral artery aneurysms.Neurosurgery,2008;62(1suppl):126‐133. 46. Day A, Gaposchkin C, Rivet DJ, et al. Spontaneous fusiform middle cerebral artery aneurysms: characteristics and a proposed mechanism of formation. J Neurosurg 2003;99(2):228‐ 40. 47. Drake C, Peerless S. Giant fusiform intracranial aneurysms: review of 120 patients treated surgically from 1965 to 1992. J Neurosurg 1997; 87(2):141 ‐ 62. 48. Sekhar L, Stimac D, Bakir A, et al. Reconstruction options for complex middle cerebral artery aneurysms. Neurosurgery 2005; 110 56(1 Suppl):66 ‐ 74. 49. Sadasivan B, Ma S, Dujovny M, et al. Use of experimental aneurysms to evaluate wrapping materials. Surg Neurol 1990;34:3 ‐7. 50. Ausman J, Diaz FG, Malik GM, et al. A new microsurgical approach to cerebrovascular lesions of the sylvian point. Surg Neurol 1990;34:48‐ 51. 51. Heros R, Fritsch M. Surgical management of middle cerebral artery aneurysms. Neurosurgery 2001;48(4):780‐ 5. 52. Del Maestro RF: Origin of the Drake fenestrated clip. J Neurosurg 92:1056–1064, 2000. 53. Sugita K, Kobayashi S, Kyoshima K, Nakagawa F: Fenestrated clips for unusual aneurysms of the carotid artery. J Neurosurg 57:240–246, 1982. 54. Tanaka Y, Kobayashi S, Kyoshima K, Sugita K: Multiple clipping technique for large and giant internal carotid artery aneurysms: Angiographic analysis.J Neurosurg 80:635–642, 1994. 111 55.Clatterbuck.R.E.,Galler.R.M.,Chalif.D.J.Orthogonal interlocking tandem clipping technique for the reconstruction of complex middle cerebral artery aneurysms.Neurosurgery,2006;59(4supp):347‐352. 56. Gewirtz R, Awad I. Giant aneurysms of the anterior circle of Willis: management outcome of open microsurgical treatment. Surg Neurol 1996;45(5):409‐ 20. 57. Lawton M, Spetzler R. Surgical management of giant intracranial aneurysms: experience with 171 patients. Clin Neurosurg 1995; 42:245 ‐ 66. 58.Lawton M, Spetzler R. Surgical strategies for giant intracranial aneurysms. Neurosurg Clin N Am 1998;9(4):725 ‐ 42. 59.Lawton M, Spetzler R. Surgical strategies for giant intracranial aneurysms. Acta Neurochir 1999;(Suppl 72):141 ‐ 56. 60. Piepgras D, Khurana V, Whisnant J. Ruptured giant intracranial aneurysms: Part II. A retrospective analysis of timing and outcome of surgical treatment. J Neurosurg 1998;88(3):430 ‐5. 112 61. Symon L, Vajda J. Surgical experiences with giant intracranial aneurysms. J Neurosurg 1984;61(6):1009 ‐ 28. 62. Piepgras D, McGrail K, Tazelaar H. Intracranial dissection of the distal middle cerebral artery as an uncommon cause of distal cerebral artery aneurysm. Case report. J Neurosurg 1994;80(5):909‐ 13. 63. Sakamoto S, Ikawa F, Kawamoto H, et al. Acute surgery for ruptured dissecting aneurysm of the M3 portion of the middle cerebral artery. Neurol Med Chir (Tokyo) 2003;43(4):188‐ 91. 64. Streefkerk H, Wolfs J, Sorteberg W, et al. The ELANA technique: constructing a high flow bypass using a non‐occlusive anastomosis on the ICA and a conventional anastomosis on the SCA in the treatment of a fusiform giant basilar trunk aneurysm. Acta Neurochir 2004;146(9):1009 ‐ 19. 65. Jafar JJ, Russell SM, Woo HH: Treatment of giant intracranial aneurysms with saphenous vein extracranial‐to‐intracranial bypass 113 grafting: Indications, operative technique, and results in 29 patients. Neurosurgery 51:138–146, 2002. 66.Shi.Z.,Zeigler.J.Duckwiler.G.R.Management of giant cerebral artery aneurysms with incorporated branches:Partial endovascular coiling or combined extracranial‐intracranial bypass‐a team approach.Neurosurgery,2009;65(1suppl):121‐128. 67. Bohmfalk GL, Story JL, Wissinger JP, et al: Bacterial intracranial aneurysm. J Neurosurg 48:369–382, 1978 68. Chun JY, Smith W, Halbach VV, Higashida RT, Wilson CB,Lawton MT: Current multimodality management of infectious intracranial aneurysms. Neurosurgery 48:1203–1214, 2001 69. Mizutani T, Kojima H, Asamoto S, Miki Y: Pathological mechanism and three‐dimensional structure of cerebral dissecting aneurysms. J Neurosurg 94:712–717, 2001 70. Nakasu S, Kaneko M, Matsuda M: Cerebral aneurysms associated with Behcet’s disease: a case report. J Neurol Neurosurg Psychiatry 70:682–684, 2001 114 71. Nakatomi H, Segawa H, Kurata A, Shiokawa Y, Nagata K,Kamiyama H, et al: Clinicopathological study of intracranial fusiform and dolichoectatic aneurysms: insight on the mechanism of growth. Stroke 31:896–900, 2000 72. Olmsted WW, McGee TP: The pathogenesis of peripheral aneurysms of the central nervous system: a subject review from the AFIP. Radiology 123:661–666, 1977 73. International Study of Unruptured Intracranial Aneurysms Investigators. Unruptured intracranial aneurysms—risk of rupture and risks of surgical intervention. International Study of Unruptured Intracranial Aneurysms Investigators. N Engl J Med 1998;339(24):1725‐ 33. 115 PROFORMA Name: Age: Sex: Hospital No.: Address: Contact No.: PRESENTING SYPTOMS: Headache‐onset,severity,Side,type,associated symptoms Seizures‐type,frequency,past history of seizures Loss of consciousness‐onset,duration Altered sensorium Limb weakness‐onset,progression,Side,severity,recovery TIA‐type,frequency Dyspasia/aphasia‐onset,progression,duration Others PERSONAL AND FAMILY HISTORY: Smoking Hypertension 116 Family history of intracranial bleed History of /suggestive of connective tissue disorder History of significant head injury in the past CLINICAL EXAMINATION: GCS Focal deficits WFNS grade Any significant systemic findings‐cardiac Any foci of infection Any features of connective tissue disorder Others RADIOLOGICAL FINDINGS: CT‐SAH pattern,Fisher grade,hematoma,IVH,hydrocephalus,infarcts CT Angiogram‐side,site,trunck,size,shape,aneurysm morphology,neck,thrombus,blebs,vasospasm,vascular anamoly MR angiogram‐ side,site,trunck,size,shape,aneurysm morphology,neck,thrombus,blebs,vasospasm,vascular anamoly DSA‐ side,site,trunck,size,shape,aneurysm morphology,neck,thrombus,blebs,vasospasm,cross circulation,vascular anamoly Other significant investigations if any 117 SURGICAL DETAILS: Approach‐ Intraop findings‐ Duration‐ Mode of intervention‐
clipping/wrapping/coagulation/reconstruction/excision and anastomosis/combined Additional procedures‐Thrombus removal/hematoma evacuation Intraoperative difficulty‐ Intraoperative rupture‐ Temporary clipping‐Total duration Intraoperative complications‐ Immediate postop complications‐ FOLLOW UP: Postop CT‐new infarcts/rebleed/residual hematoma Check angiogram‐Residual neck/distal flow Postoperative fresh deficits‐ GOS at discharge‐ GOS during follow up at ‐ 6 weeks, 6 months, 1 year, 2 years, 5 years, last follow up
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