Download Operative approaches to lateral and third ventricular

Operative approaches to lateral and third ventricular tumors
Presented By : Nilesh S. Kurwale
6/20/2009
1
Velum interpositum
• Located in the roof of third ventricle
• Formed by two membranous layers • Contains two paired internal cerebral veins and its tributaries
6/20/2009
2
Lateral ventricular tumors
• Confined to ventricles
– Neurocytoma
– Colloid cyst
– Choroid plexus papilloma
• Extending into the parenchyma
– Astrocytoma
– Ependymoma
– ODG
6/20/2009
3
Key features
• Craniotomy flap placed so as to minimize brain retraction.
• Self retaining rather than handheld retractor
• Minimum Neural incision
6/20/2009
4
• Internal debulking of tumor before separation.
• Preservation of arteries
• Minimal sacrifice of veins
• CSF diversion
6/20/2009
5
Frontal horn tumors
• Interhemispheric transcallosal approach
• Transcortical approach
6/20/2009
6
Transcallosal approach • Indications:
– Frontal horn tumors located mainly in the ventricle.
– Minimal hydrocephalus
– Tumor extending to both frontal horns and to third ventricle
6/20/2009
7
Positioning and craniotomy
• Supine position
• Lateral position
– Ipsilateral approach
– Contralateral approach
• Craniotomy – Cross midline
– 2/3rd anterior and 1/3rd posterior to coronal suture
6/20/2009
8
Surgical technique
• Reflect dura based on sinus
• Identify bridging veins and preserve
• Identify corpus callosum and ACAs
• Callosotomy
6/20/2009
9
Intraventricular orientation
• Choroid plexus and thalamostriate veins
• Foramen of monro
• Tumor identification
• Resection of tumor as internal debulking followed by dissection.
6/20/2009
10
Complications •
Vascular injury
–
–
–
•
Arachanoid granulations
Bridging veins
ACAs
Corpus callosal syndrome
–
–
6/20/2009
Reduced spontaneity of speech to frank mutism.
Interhemispheric transfer syndromes
11
Advantages • Less chances of Neural injury
• Access to both ventricles
• Less chances of epilepsy (?)
• Entry to third ventricle easy if required
6/20/2009
12
Disadvantages
• More chances of Vascular injury
• Theoretical risks of callosotomy
• Superiorly located tumors are generally can not be tackled.
6/20/2009
13
Transcortical approach
• Indication: – Tumor growing outside the ventricle
– Tumor located mainly in anterio‐superiorly in frontal horn
– Non‐dominant hemisphere
– Surgeons preference
6/20/2009
14
Positioning and craniotomy
• Principles followed are same
• Corticectomy in middle frontal gyrus
• Entry in ventricle • Tumor debulking and dissection
6/20/2009
15
Complications • Epilepsy
– Direct cortical incision and damage
• Memory loss
– Retraction of caudate nucleus. • Hemiplegia
– Retraction of centralis semiovalis
6/20/2009
16
Disadvantages • More chances of epilepsy and porencephalic cysts
• Limited entry to opposite ventricles
• Small ventricles‐ chances of missing
6/20/2009
17
Tumors involving the body
• Transcallosal approach is better • Combined transcallosal and transcortical approach is needed for large tumors involving both ventricles
6/20/2009
18
Atrial tumors
• Transcortical approach is favored.
• Lateral decubitus position with face turned towards the floor
• Superior lobule is identified
• 1‐2 cm corticectomy 6/20/2009
19
Why transcortical approach preferred? • Ventricles diverge posteriorly
• Splenium sacrifice has physiological risks
• PCA injury is more common
6/20/2009
20
Complications • Speech problems
– Acalculia, apraxia
• Visual field deficits
– Homonymous hemianopia
– Visual spatial processing
• Splenium syndrome
– Interhemisphere disconnection syndrome
6/20/2009
21
Additional approaches
• Approach through occipital pole incision
• Occipital lobectomy
– Cortical incision placed in sup. occipital gyrus
– Invariably lead to visual field deficits
6/20/2009
22
Temporal horn tumors
• Supine with head turned almost laterally.
• Small temporal craniotomy
• Dura opened based on base
6/20/2009
23
Entry corridors to ventricle
• Middle gyrus approach
• Temporal tip resection
• Occipitotemporal gyrus resection
• Temporo‐parietal junction
6/20/2009
24
Complications – Visual field deficits
• Superior quadrantonopia
– Language deficits – Others
• Dyslexia
• Agraphia
• Acalculia
6/20/2009
25
Third ventricular tumors
– Tumors growing inside out
– Tumors growing outside in
6/20/2009
26
diagram
6/20/2009
27
Approach to Ant. TV tumors
• Subfrontal • Frontotemporal • Anterior transcallosal
• Anterior transcortical • Transsphenoidal 6/20/2009
28
Subfrontal approach
• Supine position with head extension
• Coronal flap incision
• Quadrangular craniotomy flush with
•
orbital margins
• Frontal sinus exteriorized and packed
• Olfactory nerve divided if necessary
6/20/2009
29
Corridors • Interoptic • Opticocarotid
• Lamina terminalis
• Transfrontal‐ transsphenoidal
• Lamina terminalis‐rostrum of callosum approach
6/20/2009
30
Frontotemporal or subtemporal approach
• Frontotemporal craniotomy
• Dura reflected on sphenoid ridge • Tumor approached through corridor between third nerve and carotid.
• Temporal pole can be elevated or resected.
6/20/2009
31
Anterior transcallosal approach
• Advantages
– Short trajectory to third ventricle
– Can access posterior and basal TV
– Bilateral exposure of foramina of monro
– No requirement of ventriculomegaly
6/20/2009
32
Maneuvers for TV entry
• transforaminal
• Transchoroidal
• Transfornicial
6/20/2009
33
Transforaminal • Gives access to anterior TV • Foramen of monro identified • Initial dilatation can be tried • Incision is made through one column of fornix at anteriosuperior edge.
6/20/2009
34
Transchoroidal • Entry into the middle of TV
• Opening through the velum interpositum
• Two approaches: – Suprachoroidal • Incision in tinea fornicia
– Subchoroidal
• Incision in teniea choroidea
6/20/2009
35
Transfornicial • Identify the septum pellucidum • Develop a plane between septa.
• Incision is given in the body of fornix not exceeding 2 cm behind the FM. 6/20/2009
36
• In both the approaches velum interpositum is opened.
• The interval between two internal cerebral veins is separated and entered.
• Minor veins can be sacrificed.
6/20/2009
37
• Tumors can be decompressed as stated earlier
• Complete hemostasis is mandatory
• Post operative cavity drain can be kept
6/20/2009
38
Complications • Fornicial injury
– Recent memory disturbances
• Vascular compromise
– Basal ganglia infarcts
– Thalamic infarcts
– Limbic system ischemia
• Hippocampal syndrome
6/20/2009
39
Approaches to the post TV tumors
• Transventricular • Interhemispheric transcallosal • Occipital transtentorial
• Infratentorial supracerebellar
6/20/2009
40
Indications • Transventricular (Wegen’s)
– Tumors arising in corpus callosum and extending to third ventricle
• Transcallosal (Dandy’s)
– Tumor extending to splenium
6/20/2009
41
• Occipital‐ transtentorial ( Popen’s)
– Tumor extending to medial wall of ventricle and in occipital lobe
• Supracerebellar infratentorial (krause’s) – Pineal region tumors
6/20/2009
42
Endoscopy • Treatement of choice for malignant third ventricular tumors
• Biopsy of lesion • Post operative radiotherapy
6/20/2009
43
Technique
• Selection of burr hole point
• Advancement of scope
• Biopsy using endoscopic instrument
6/20/2009
44
Disadvantages
• Two dimensional vision
• Less freedom of movements
6/20/2009
45
Complications
• Inadequacy of hemostasis
• Conversion of procedure to open
6/20/2009
46
Image guidance
• Recent development • Useful for biopsy
• Anatomical orientation
6/20/2009
47
6/20/2009
48