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Spine Interventions: Different Goals Similar Techniques eEdE-228 Sepand Salehian Victor Lopez James Fernandez Justin Tran Lon Hoang Jonathan Cross Neuroradiology Fellows at: T h e au th o r s h ave no f ina nc ia l d is c lo s u r es . Lumbar Puncture Intrathecal Sampling Lumbar Puncture: Patient Selection • Indications: meningitis, cytology, pseudotumor cerebri, etc. • Risks include bleeding, infection, pain, post-LP headache, and rarely subdural hemorrhage. • Anti-coagulant medication should be held • Labs: platelets and PT/INR • Patient must be able to lie prone without difficulty • Patient must be able to assume a lateral decubitus position if intrathecal pressure measurements are necessary • Other methods are available if patient cannot rotate to a lateral decubitus position 1 Lumbar puncture: Procedure • Needle Selection/Equipment • 22g spinal needle, easier and faster CSF collection than 25g • Quincke (A) -- beveled tip, easy skin penetration, easy to steer • Whitacre (B) – non-cutting needle, theoretical lower risk of CSF leak • 3.5 inches (9 cm) sufficient for most patients; 5 inches (13 cm) required for obese patients • Standard lumbar puncture kit Fluoroscopic image demonstrates proper positioning of 22g spinal needle through the right interlaminar space 2 Lumbar Puncture: Technique • Technique • Interlaminar space at L1-L2 or below, with patient prone, or slightly oblique. Oblique positioning opens the interlaminar space. • CSF Collection • Typically 3-4 cc in each tube, depending on orders. Cytology requires more fluid volume; larger volumes reduce false negatives • Opening pressure • Measure in left lateral decubitus if possible • Alternatively, in the prone position, add length of needle to pressure measurement with manometer at level of needle hub. • Studies have demonstrated the accuracy of this technique, which merely overestimate by ~2-3 cm H20 • In patients who cannot rotate, this metric may be used to the operator’s advantage • Replace the stylet prior to removal of the needle to reduce the chance of CSF leak and to reduce risk of possible nerve root injury • Pitfalls • Osteoporotic bone – may require formal radiographic spot images for needle guidance • Excessive lumbar lordosis – needle may inadvertently contact upper or lower lamina • Can increase lumbar flexion by placing pillow under abdomen • Post-Procedure • Lie flat on back for 1 hour then discharge 3 Myelograms Intrathecal Injections Myelography vs MRI Myelography: Indications • Evaluation of local anatomic topography which may serve to contact, displace, or impinge the thecal sac and/or thecal sac contents (i.e., nerve roots, cord, etc.) • Offers dynamic and functional • • Degenerative causes • Disk disease • Vertebral bodies—endplates • Facets • Ligamentum flavum • • • Abnormal vessels (Spinal AVM, spinal dural AVF) • Arachnoid cysts • Arachnoiditis • Perineural cysts • evaluation of the CSF space as compared to MRI Allows for opening pressure measurements and collection of CSF, if indicated Superior osseous detail as compared to MRI Useful in post-operative spine, where hardware may result in artifact on MRI MRI is superior for evaluation of intramedullary or extramedullary lesions 4 Myelography: Myelography: Patient selection and pre-procedure workup Technique • Pre-medication for patients with contrast allergy • Certain medications reduce the seizure threshold and should be discontinued prior to procedure: phenothiazines, MAO inhibitors, Flexeril, Demoral, Antidepressants, Antipsychotics, Amphetamines • Risks • Approach and access is identical to lumbar puncture • 22g-26g needles • Decreased chance of post-procedure headache with smaller bore needles • Contrast • Nonionic contrast should be used, as ionic contrast may result in potentially fatal neurotoxicity • Ascending tonic clonic seizure syndrome with • Fever/infection ionic contrast • Positional headache and CSF leak requiring autologous blood patch • Seizure • Headache due to irritation caused by contrast • 15 mL of Isovue M200 sufficient for whole spine • Attachment of contrast syringe/tubing to the needle done in “wet-to-wet” fashion to avoid air bubbles • Test injection of 1-2 mL contrast under fluoroscopy to demonstrate free flow of contrast in the subarachnoid space • Exclude subdural or epidural injection 5 Myelography: Subdural injection CSF block CSF block indicates inability of intrathecal contrast to migrate further due to local extrinsic factors. Consider a lateral decubitus position to potentially aid further migration of contrast. If a subdural injection is suspected, replace the stylet and reposition the needle A) Fluoroscopic image demonstrates a globular collection of contrast signifying a subdural injection. AV fistula B) Abrupt tapering of contrast column indicates CSF block due to extrinsic factors. C) CT myelography demonstrates a serpiginous filling defect in the thecal sac consistent with a dilated venous structure in a patient later determined to have a dural AVF. 6 Myelography: CT evaluation • Roll patient 360 degrees 2-3 times before placing patient onto CT scanner to ensure adequate distribution of contrast • Data is acquired at 0.5-0.625 mm and multiplanar reconstructions at 2 mm axial, sagittal, and coronal planes with both bone and soft tissue algorithms • Post myelography care similar to lumbar puncture • • • Lie flat for 1 hour Hydration Rarely, contrast may irritate the meninges, but this typically resolves on its own CT myelography 7 Fluoroscopic Guided Intrathecal Injection Indications • Intrathecal injection of Risks • IT Chemotherapy • Risks associated with chemotherapy medication– bone marrow suppression, nausea/vomiting, pulmonary toxicity, renal toxicity, seizures • Some chemotherapeutic agents, such as methotrexate, can be toxic to the skin should direct contact occur • Therapeutic: leptomeningeal involvement/meningitis • Prophylactic: leukemia/lymphoma with high predilection for CNS involvement • Intrathecal baclofen injection as • Baclofen • Hypotonia, headache, nausea/vomiting, seizures, respiratory depression, urinary frequency or retention trial for baclofen pump to alleviate spasticity • • • • CSF leak Bleeding Infection Pain 8 Fluoroscopic Guided Intrathecal Injection Technique: IT Chemo Technique: IT Baclofen (trial) • Similar approach as a lumbar puncture with • Note: Trial is done only when there is an • • • • patient prone Upon entering the thecal sac, tubing attached to the chemotherapy syringe is connected to the needle Chemotherapeutic agent injected slowly over 2 minutes Small volume of air or autologous CSF is administered to inject remaining medication beyond the connector tubing through the needle Tubing/syringe combination detached, and the inner stylet of the needle quickly replaced before removing the needle completely so as to avoid backflow of chemotherapeutic agent onto the skin understanding that patient will receive a baclofen pump implant if baclofen trial is successful • Standard dose of 50 mcg/1mL administered; and this can be titrated upward to 100 mcg/2mL if further testing is required • Patient’s response monitored for an 8-hour period following the procedure • To ensure that baclofen will ablate problematic spasticity • Trial typically more potent than actual titrated pump apparatus • Ashworth scores; Spasm Frequence Scale; and Visual Analogue Scales are measured pre-test and post-test at ½ hrs, 1, 2, 4, and 6 hours post injection • A positive response to an IT baclofen test is defined as 2 point drop on the Ashworth scoring system 9 Lumbar Drains Lumbar Drains: Introduction • Often performed with the assistance of neurosurgery after failed placement at bedside • Indications: • Iatrogenic CSF leak • Post-operative iatrogenic injury to thecal sac resulting in CSF leak • Treatment of shunt infections • Improvement of spinal cord perfusion before or after thoraco-abdominal aortic aneurysm repair • Concern for cord ischemia • Theoretical goal is to relieve pressure and enhance arterial perfusion to cord • Evaluation of normal pressure hydrocephalus • Reduction of ICP • Equipment – Standard lumbar drain kit • 14g Tuohy needle with a cutting bevel and curved end • 16g kink-resistant silicone drainage catheter and hydrophilic guidewire 10 Lumbar Drains: Technique • Interlaminar space at L2-L3 or below, with the patient prone or slightly oblique (depending on location of conus medullaris) • Image intensifier is positioned to allow for a cranially angled entry, typically around 40-45 degrees • If performed on a fluoroscopy table, skin entry site will be approximately one vertebral body below the target interlaminar space • Cranial angulation allows for easier insertion of the catheter and less kinking • Once CSF is returned from Tuohy needle and access into the subarachnoid space is confirmed, neurosurgery proceeds with catheter insertion; and connects to drainage bag apparatus • The procedure is typically a highly collaborative endeavor with neurosurgery Sagittal pictorial of lumbar spine demonstrating 14 gauge needle advanced into the thecal compartment via a L2-3 interlaminar approach. 11 Lumbar Drains: Technique Lateral fluoroscopic view of lumbar spine demonstrating 14-gauge needle advanced into the thecal compartment via a L3-4 interlaminar approach. This particular patient was s/p transphenoidal surgery and had incurred a CSF leak. Neurosurgery requested that patient not remain in prone position for an extended period of time in order to avoid unnecessary CSF leakage; highlighting the collaborative nature of the procedure 12 Epidural Injections Epidural Injection Introduction Equipment • Therapeutic procedure performed in • Fluoroscopy exam table with rotating C-arm fluoroscopy suite • Most common clinical indications: • Epidural blood patch • • Post dural puncture headache Spontaneous intracranial hypotension • Epidural steroid injection • Symptomatic degenerative disease, refractory to conservative treatment options • Lidocaine, 25g 1.5-inch needle • 22g Quincke spinal needle • Lymphangiography connector tubing • Contrast – Isovue-M200 • Sterile 5 mL syringes • Can be performed at any level of the spine, but most often lumbar 13 Epidural Injection - Technique • Patient positioned prone on exam table • Standard prep and drape of the skin surface, site marking, and application of local anesthesia • Fluoroscopy views • Initial AP view should be used to visualize anatomy and confirm presence of normal lumbar segmentation • 15 degree RAO projection will best visualize the apex of the interlaminar space • The opposite 20-35 degrees LAO projection should be saved as the 2nd detector position to best visualize the lamina en face RAO projection demonstrating the L2-3 interlaminar space. The apex of the interlaminar space is well seen on this image. The needle is positioned parallel to the x-ray beam over this space 14 Epidural Injection - Technique Needle placement • Spinal needle should be parallel to • • • • xray beam directed toward superior interlaminar space in the first RAO projection Advance approximately 2 cm into the soft tissues In the LAO projection, needle tip can be safely advanced until the tip is just inferior to the lamina. Needle stylet should be removed and small 3 mL syringe with connector tubing should be connected, with air gap removed Small amount of contrast can be injected to confirm position outside the spinal canal Needle should be advanced slowly under continuous fluoroscopy with slight forward pressure on the syringe applied Needle placement (cont.) • While the needle tip is within the ligamentum flavum, there will be significant resistance to contrast injection • As needle passes into epidural space, there will be loss of resistance and contrast pooling around the needle tip • Ensure that contrast remains stagnant in the epidural space by reimaging with fluoroscopy after a few seconds delay • Syringe can be detached from connector tubing when proper needle position is confirmed 15 1) Needle tip is placed just underneath left L2 lamina, as viewed en face from 25-30 degree LAO. 2) Small amount of contrast test injection is performed outside spinal canal. Needle is then advanced into ligamentum flavum, where contrast injection is not possible. 3) There is loss of resistance as the needle passes through ligament. Injected contrast pools at the needle tip. Recheck after few seconds delay to confirm epidural, rather than intrathecal placement. 16 Epidural Blood Patch Technique Risks • Procedure assistant should slowly aspirate blood • from sterilized peripheral IV • Inject autologous blood to the epidural space • The patient should be informed that a pressure • • • • sensation in the lower back, that may radiate to the ventral abdomen, buttocks or legs can be expected Inject up to 5 mL of blood and reassess the patient at each interval Volume of injected blood should be titrated to patient’s tolerance Up to 30 mL can be administered in a single treatment, though a target of 20 mL is used at our institution for first treatment Volume can be increased if patient requires repeat treatment • Needle can be removed after completion of blood patch injection • Routine observation for 1 hour in a monitored recovery area • • Bed rest with bed flat, or slight Trendelenberg position is recommended during recovery period Outpatients can be discharged home after the short recovery time • General procedure risks related to needle placement: • Infection, including meningitis • Hemorrhage • Pain • Unintended dural puncture, which will often require needle removal and access at a different interlaminar level • Patient should be informed that in select cases, they may experience worsening of headache related to rebound intracranial hypertension Other symptoms post-procedure: • Nausea • Radicular pain/paresthesia • Dizziness 17 Epidural Blood Patch Sagittal pictorial demonstrates an interlaminar approach epidural blood patch. Red column of autologous blood is demonstrated lining the epidural space. 18 Epidural Steroid Injection Technique: Risks: • Needle placement is identical to technique • applied for an epidural blood patch injection • Prior imaging should be reviewed to target level above that possessing the greatest degenerative disease or neural impingement • After the needle position is confirmed in the epidural space, total of 2 mL betamethasone (6mg/mL) can be administered and followed by 2 mL injection of preservative-free 0.5-1% lidocaine • It is critical to avoid advancing needle into the subarachnoid space, causing chemical arachnoiditis due to steroid injection or spinal anesthesia related to lidocaine If unintended dural puncture occurs, the needle should be removed with stylet in place and a new site should be chosen at a different interlaminar space on the contralateral side 19 Epidural Steroid Injection Sagittal view pictorial demonstrates an interlaminar approach epidural steroid injection. Grey steroid injection is seen lining the epidural space and partially covering the affected nerve. 20 Transforaminal Epidural Steroid Injection • Introduction • Alternative approach for therapeutic steroid injection can be used for selective treatment of a specific symptomatic nerve root • Prior MRI or CT should be reviewed to confirm impingement of the target nerve root • Fluoroscopy views: • Initial AP view to survey anatomy and confirm trajectory • C-arm should be rotated to an oblique projection where the “scotty dog” appearance of posterior elements is well visualized • The site of skin entry should be marked just inferior to the pedicle above targeted neural foramen • Needle should be parallel to x-ray beam on the oblique projection; then C-arm can be rotated to direct AP for further needle advancement until needle tip is just below pedicle • Small injection of contrast should confirm that the needle tip is not within a vascular structure or thecal sac • Ideally, the small amount of injected contrast should be visualized flowing underneath the pedicle and into the epidural space Proper projection for localization of the left L5-S1 neural foramen, with RAO and slight cranial angulation of the xray beam. Needle placement should be targeted immediately inferior to the ipsilateral L5 pedicle. 21 Transforaminal Injection Transforaminal Epidural Steroid Injection • Alternatively, if performing a selective nerve root block, the needle can be positioned distal to the dorsal nerve root ganglion (slightly more lateral) in the neural foramen, with contrast seen only surrounding a single nerve root sleeve AP projection demonstrates needle tip positioned inferior to the pedicle, with injected contrast flowing medial to the pedicle into the epidural space of the spinal canal 22 Disc Interrogation: Disc Aspiration/Biopsy Provocative Discography Posterolateral approach (lumbar) Anterolateral approach (cervical) Disc Aspiration Introduction Equipment Recovery and Risks • • • Lay flat for 1 hour and no heavy lifting At our institution, the most common indication for a disc aspiration is suspicion of infection (discitis/osteomyelitis). • • Isolates/cultures requested for targeted antibiotic therapy Infective discitis has an incidence of 0.4-2.4 per 100,000 each year in the western world with a bimodal age distribution (childhood and 6th decade). The lumbar spine is most commonly affected (up to 60%), followed by thoracic and cervical spine. Biplane Fluoroscopy system or CT • Local Anesthetic • Sterilizing solution • Needle kit or strenuous activity for 24 hours • Risks: • Risks associated with the procedure are similar to any biopsy including, damage to any of the surrounding structures including the spinal cord, and lack of a final diagnosis requiring a repeat aspiration • Fever, severe pain, neuropathic pain, and bleeding 23 Disc Aspiration (Lumbar) – Posterolateral Technique Technique • Prep and drape in usual sterile fashion • Image intensifier is positioned such that the endplates are in profile and the superior articular process projects over the midportion of the intervertebral disc. The anterior margin of the superior articular process serves as a landmark for Chiba needle entry • 18-22g Chiba needle is advanced via the far lateral approach to the outer annulus of the disc. The inner stylet is removed and aspiration is performed from this location. If there is no fluid return, the stylet can be replaced and further advanced (with confirmation of position on AP imaging) and aspiration reattempted. • The stylet is replaced and the introducer needle is then removed. Example: L3-4 discitis T1 weighted fat saturated contrast enhanced sagittal image demonstrating post contrast enhancement and irregularity of the L3-4 disc space and adjacent endplates The II is positioned so that the facet bisects the intervertebral disc space. The needle is advanced parallel to the x-ray beam, anterior to the facet. AP view should be obtained to confirm needle position. Needle is then carefully advanced to the desired location within the disc. 24 CT guided C-spine disc/body aspiration: Case example of a cervical CT guided aspiration via an anterolateral approach 33 year old IV drug user presents with fever and neck pain T2 weighted sagittal image: There is focal kyphosis of the C-spine at C5-6, with associated anterior loss of height of the C5 and C6 vertebral bodies. There is accompanying significant edema at C5 and C6, and high signal intensity in the disc. T1 sagittal image: There is hypointensity in the C5 and C6 vertebral bodies T1 post-contrast sagittal image: There is enhancement throughout C5, C6, C5-6 disc, and along the prevertebral soft tissues 24 Percutaneous anterolateral cervical spine approach • Peri-operative • Consent and labs obtained • General anesthesia • CT guided anterolateral cervical technique • Via manual compression, the carotid artery and internal jugular vein are displaced inferiorly relative to the operator (posteriorly relative to patient). This creates a soft tissue plane devoid of any critical structures and provides maximal displacement of such structures to avoid untoward complications. The rebounding pulse of the carotid artery is felt on the palmar aspect of the operator’s digits, indicating that the vessel will not be in the trajectory of biopsy needle • 22g spinal needle is positioned on the skin surface just 1-2 mm above the dorsal aspect of the operator’s digits. • 22g needle is advanced beyond the medial boundary of the carotid space (per a distance determined to be safe by pre-operative imaging), beyond the circum-periphery of the vascular structures • Sequential CT images are obtained as needle is advanced to ensure safe guidance to target site. Hypopharynx (airway) and laryngeal structures are avoided • Sample aspirations are obtained • Similar approach may be used for cervical CT guided aspiration at C5-6 level: Sequential CT images demonstrate progressive advancement of spinal needle until target is reached at the C5-6 disc space vertebroplasty targeting the mid-body. 25 Percutaneous anterolateral cervical spine approach Graphical pictorial depicts the anterolateral approach to the cervical disc aspiration. CT guided aspiration at C5-6 level: Sequential CT images demonstrate progressive advancement of spinal needle until target is reached at the C5-6 disc space 26 Provocative discography - Introduction • Used as an adjunct to identify cause of back pain due to an unsuspected annular fissure • Useful in cases of clinical discordance between chronic pain and lack of imaging findings. Enables identification of the true symptomatic level in the setting of multiple disc herniations • Indications from North American Spine Society • ALL must be present • If surgical management is a viable option • Pain is not responsive to conservative treatment measures • Pain persists for an extended period of time • No evidence of contraindications such as severe spinal stenosis resulting in intraspinal obstruction, infection or predominantly psychogenic pain • At least ONE of the following is present • A high index of suspicion for discogenic pain where the pain is severe enough to consider surgical intervention • Failed back surgery 27 Provocative discography - Procedure • Prep and drape in usual sterile fashion • Image intensifier is positioned such that the endplates are in profile and the superior articular process projects over the mid-portion of the intervertebral disc • The anterior margin of the superior articular process serves as a landmark for 22g Chiba needle entry • Typically three levels are studied; at least one “normal” level serves as an internal control • Place all needles prior to contrast injection and confirm correct needle tip position with AP and lateral views L5-S1 right oblique approach. Note the triangular window for entry formed by the superior articular process medially, iliac crest laterally, and L5 inferior endplate superiorly 28 Provocative discography - Procedure • • • • • • Patient is blinded to level of injection Controlled hand injection of 1-2 mL of Omnipaque 240 Nurse observes the patient response with direct questioning Identify extension of contrast beyond the confines of the nucleus pulposus Injection may elicit pain, characterized as concordant or discordant to baseline pain profile Post-discography CT Normal L4-L5 nucleogram. The patient did not experience pain at any point during injection L5-S1 nucleogram showing diffuse broadening of contrast consistent with diffuse internal fissuring. 29 Provocative discography - CT Axial and sagittal CT lumbar discogram (axial slice at the L2-3 level): At L2-3: Anterior radial fissure with associated extravasation anteriorly, with a circumannular fissure. At L3-4: (Anterior fissure not well seen) At L4-5: Diffuse internal fissuring Axial and sagittal CT lumbar discogram (axial slice at the L4-5 level): At L3-4: Normal appearing nucleogram. At L4-5: Normal appearing nucleogram At L5-S1: Diffuse internal fissuring and diffuse internal derangement Of note: In this case, there was sacralization of the L5 vertebral body. As this represents a non-mobile segment, it was unnecessary to include L5-S1 as part of provocative discographic study. 30 Disc Sampling Disc sampling (aspiration or provocative discography): pictorial demonstrates the similar posterolateral technique employed by both procedures. 31 Vertebral Body Biopsy Radiofrequency Ablation Vertebral Augmentation The Vertebral Body Biopsy Introduction Equipment • • Image guided spinal bone biopsies are conducted for histopathological diagnosis of indeterminate sclerotic/lytic lesions, often found incidentally on MR/CT imaging • Spinal biopsies are either performed on a biplane fluoroscopy system in an interventional suite or on a CT scanner (CT guidance is usually preferred for cervical, upper thoracic, and sacral lesions as overlying soft tissues may result in difficulty localizing the lesion using fluoroscopy in these regions) • • • • Biplane fluoroscopy/CT Sterilizing solution Local Anesthetic Mallet Osteo-Site Murphy Coaxial Bone Biopsy Needle Set (11G coaxial with an inner 14G biopsy needle or 13G/16G set, 10 or 15cm length) Recovery • 2 hour observation • Patient lay flat for 1 hour • No heavy lifting or strenuous activity for 24 hours Risks • • • • • Infection Pain Bleeding (i.e. epidural hematoma) Damage to any of the surrounding structures including the spinal cord Lack of a final diagnosis requiring a repeat biopsy 32 The Vertebral Body Biopsy: Technique • • • Skin overlying the desired vertebra is prepped and draped in usual sterile fashion with the patient prone on the fluoroscopy table. Skin entry site overlying the desired pedicle is marked once the image intensifier is in position (pedicle is viewed parallel to the x-ray beam). Local lidocaine anesthetic is administered to the subcutaneous tissues and periosteum overlying the pedicle and a small skin incision is made. • Biplane fluoroscopy • Superior and inferior endplates are lined up on AP and lateral view perfectly • Bilateral pedicles and ribs are aligned and perfectly superimposed on lateral view, with minimal redundant shadows • Pedicles are well visualized • If pedicles are not adequately visualized: consider aborting procedure; consider CT guidance measures; consider parapedicular approach • Using a transpedicular approach, a 11-13 gauge Osteo-site vertebral biopsy introducer needle is situated upon the pedicle • • • • • • Obtain purchase in pedicle (tactile texture differences between osteoporotic vs. neoplastic vs. osteosclerotic bone) Adjust hand to tripod position for superior control and maneuverability Needle trajectory should be parallel to x-ray beam (such that needle appears as a dot) The introducer needle is carefully advanced through the pedicle by continuous manual pressure or with a mallet The needle tip is positioned proximal to the lesion under fluoroscopic guidance. Using co-axial technique: the inner stylet is removed and biopsy needle is advanced • This is done with a twisting motion under pressure, or small mallet may be used to gently tap if the lesion is sclerotic. • The biopsy needle is then removed with application of gentle aspiration. The specimen is placed on a slide and given to onsite cytopathology for immediate review. • The inner stylet is then replaced and the introducer needle is removed under fluoroscopic guidance with direct manual compression applied. • Once hemostasis is achieved and there are no immediate complications, the patient can be transferred to the PACU by anesthesia. 33 L1 Vertebral Body Biopsy: Example Case of L1 lesion T1 weighted fat saturated contrast enhanced sagittal and axial images demonstrate an enhancing lesion in the L1 vertebral body. Pedicle is oriented in a trajectory parallel to the x-ray beam; as is the biopsy needle. The pedicles above and below the target vertebral body can be used as landmarks to orient the operator. The medial margin of the pedicle must be respected. Confirm needle placement on both AP and lateral projections immediately before and during the biopsies 34 Image-guided Radiofrequency Ablation of Spinal Tumors Technique, Indications, Risks: • Employs radiofrequency as a source of thermal energy • High frequency alternating current is passed through needle, which causes local frictional heating and tissue necrosis • Ellipsoid ablation volume at marker = 30 x 20 mm @ 50 C • Typically done after vertebral body biopsy in patients with osseous metastatic disease confirmed by on-site cytopathology. • The setup, approach, and preparation are identical to vertebral body biopsy. • • The identical outer cannula used for the biopsy/vertebroplasty is used first to advance the RF probe directly into the lesion Ablation occurs under real time imaging guidance to ensure steadfast location of RF ablation needle tip/marker • • Equipment: • MetaSTAR Generator • SpineSTAR ablation instrument • AE cable • Hand Switch cable Risk of thermal ablation of neural tissue needs to be minimized If pathologic fracturing is present, then vertebral augmentation follows RF ablation • Necrotic tissue may theoretically improve cement distribution • Indications include: • Radio/chemotherapy-resistant tumors • Patients who have received maximum doses of radiation • Persistent pain • • Palliative endeavor Patients at risk of myelosuppression • Risks • Heating of tissue to 45 C is cytotoxic to spinal cord and peripheral nerves • • • Care should be taken in vertebral lesions when tumor invades posterior cortex, as there is a higher risk of thermal damage to nerves and cord High risk lesion is defined as a tumor within 1 cm of a neural structure Radicular pain 35 Vertebral Augmentation Osteoporosis • World Health Organization (WHO) defines osteoporosis as a bone mineral density at the hip or lumbar spine of greater 2.5 standard deviations below the young normal adult reference population • Aging population is increasing in size • 55% of Americans over the Age of 50 suffer from osteopenia or osteoporosis • Women make up 80% of the population affected with osteoporosis • Expected to affect 14 million people by 2020 • Economic burden: costs the United States 20.3 billion dollars; actual cost likely higher as it is difficult to account for the indirect costs of disability, time off work, pain, diminished mobility, insomnia, and depression • Hallmark of osteoporosis is lack of ultrastructural integrity within bone architecture • Compromised bone strength • Low bone mass • Disruption of bone architecture • Fractures of fragility or insufficiency fractures • May result from standing height • Common sites include the vertebra, hip, and wrist • Vertebral compression fractures quite simply interferes with the activities of daily living 36 Vertebral Augmentation: Osteoporotic compression fractures • Substantial acute and chronic pain—substantial morbidity • Severe thoracic kyphosis due to a compression fracture can cause up to a 10% diminished pulmonary forced vital capacity • Increased kyphosis of abdominal cavity can also result in reduced satiety • 5-year survival of a patient who sustains a compression fracture is lower than a similar patient with a hip fracture • Mainstay of conservative management: oral narcotic analgesia, NSAIDS, bed rest, orthosis, physical therapy/exercise, and medical treatment of osteoporosis • Spinal orthoses reduce pain by reducing motion, decreasing postural flexion, and providing axial support • Exercise promotes muscle growth which in turn provides columnar support to the spine • Basics of imaging diagnosis • Lateral and AP of the spine to detect degree of height loss • MRI can differentiate between acute, subacute, or healed osteoporotic compression fractures (edema on T2 weighted imaging) • CT would allow for evaluation of the integrity of the posterior wall of the vertebral body CT L Spine sagittal view: There is a L2 compression fracture deformity with mild loss of height. There is no associated retropulsion. Posterior wall is intact. 37 Treatment for compression fractures: Vertebroplasty, Kyphoplasty, Vertebral Augmentation Vertebroplasty Kyphoplasty Vertebral Augmentation Once the needle is advanced to the middle of the vertebral body, PMMA is directly injected. No other maneuver is entertained. Theoretical intent is height restoration of vertebral body height by directing a balloon into the mid-body to restore height in a craniocaudad dimension; then injecting PMMA. Vertebral augmentation implies the creation of cavity prior to the delivery of PMMA. Certain kits provide a needle osteotome to create an excavation in the mid vertebral body, after which PMMA is injected. 38 PMMA: Postulated Biomechanisms of Action • Vertebroplasty, kyphoplasty, and vertebral augmentation all have a similar underlying basis, approach, and goal; with slightly different technical aspects pertaining to the delivery of the PMMA cement • Vertebral augmentation implies the creation of a cavity by way of an osteotome device, and then depositing cement • Kyphoplasty implies the attempt at height restoration by using a balloon to expand the fracture site, and then depositing cement • Vertebroplasty implies reaching the target fracture line, then depositing the cement • PMMA cement confers stability to the vertebral body fracture line, thereby reducing friction and internal dynamic instability which creates the sensation of pain • Initially, polymethylmethacrylate (PMMA) was implemented to treat aggressive variants of vertebral hemangiomas • Thereafter, its use evolved as a means to treat painful metastatic lesions to the spine • Explanations and potential biomechanisms of action • Thermal necrosis; chemotoxicity upon intraosseous pain receptors • Cement monomer itself may be a neurotoxic compound disabling pain receptors locally • Polymerization reaction of PMMA is exothermic reaching temperatures of up to 122 C • Clinically efficacious in reducing pain • Controversy surrounds whether or not height restoration in kyphoplasty occurs 39 Indications/Patient selection • Characterization of pain • Pain is at the level of the fracture; and is exacerbated with bending, prolonged standing or sitting, and improves with rest • Focal tenderness over the site of the fractured vertebrae on physical examination • Timing of intervention is poorly defined: treatment may be pursued in as early as 2-6 days; others wait until patient has failed 2-6 weeks of conservative therapy on oral/opiate analgesia, and supportive orthosis • Advocates of early treatment argue that kyphotic deformity results in maldistribution of load on the spine increasing the risk of future fractures • Acute or subacute fracture on MRI • Patient mobility is a very important issue • If patient is mobile, patients who still have pain after 4-6 weeks are considered candidates • If patient is non-mobile, patients with pain are offered an earlier percutaneous vertebral augmentation • Intervention more like to improve symptomology with the following fractures as they are less likely to improve with conservative treatment: • • • • Thoracolumbar junction (T11-L2) Osteoporotic burst fractures Wedge anterior compression fracture > 30 degrees angulation Continued collapse on follow up imaging 40 Contraindications • Absolute contraindication • Active local infection: osteomyelitis, discitis, epidural abscess, fever, sepsis • Bleeding diathesis • Relative contraindications • Cortical disruption makes cement containment difficult • Only after careful pre-operative consideration may patient undergo percutaneous vertebral augmentation • Posterior wall destruction and/or tumor extension into spinal canal • Increased risk of neural compression with injection of cement • Vertebra plana—renders procedures more technically difficult • Radiculopathy obscures the true nature and origin of the back pain • Retropulsion; or other sinister epidural pathology that may cause canal obliteration • Osteoblastic lesion • Lack of immediate decompressive surgery capability 41 Vertebral Augmentation: Peri-procedural Proper pre-procedure imaging: • CT, MR • Confirm the spinal level with patient and room staff • Prophylactic antibiotics • IV Ancef • Tobramycin (powder formintermixed with cement) • Anesthesia • Local anesthesia • Local is injected in the skin, subcutaneous tissues, and periosteum of the vertebra • Conscious sedation/Moderate sedation • General anesthesia • In cases involving CT guided needle localization, general anesthesia will provide optimum situational control • Also ideal for multilevel vertebroplasty Equipment: • Biplane fluoroscopy/CT • Mallet • StabiliT Kit • Hydraulic Master Syringe Assembly • Activation element • DFINE introducer • Locking delivery canula • VertecoR Straightline Osteotome/midline osteotome • StabiliT ER2 bone cement and saturate mixing system Risks: • Transverse process fractures • Hemorrhage with cortical breeches • Epidural hematoma • Infectious osteomyelitis • Sterility within operating field must be maintained • Cement leak • Can occur in the epidural veins • Leading to pulmonary embolism • Epidural space • Overflow of PMMA into epidural space can cause spinal cord compression • Neural foramina • Pain • Due to injecting at high pressure • Osseous ischemia • Inflammatory reaction to PMMA cement 42 Anatomy Inferior vena cava Aorta Lumbar vein Basivertebral vein 3D conception of vertebral anatomy is important in order to discriminate local topography with internal landmarks. Note: 1) Medial border of the pedicle 2) Epidural space 3) Vascular structures Anterior internal epidural venous plexus Transverse process Pedicle Cord Spinous process 43 Common Approaches Transpedicular Parapedicular • Most common approach • Pedicle serves as a clear anatomic landmark • Respect the medial boundary to avoid transgressing the epidural space •Allows operator to pass along lateral to the pedicle, rather than through it •Indications: pedicle is too thin; not visualized; or destroyed by tumor burden rendering it inaccessible •Risks: greater risk of paraspinous hematoma; decreased ability to control post-procedural bleeding by local tamponade 44 Anatomy and Guidance Axial and sagittal pictorials of a lumbar vertebral body demonstrating needle position at varying angulations, which affects height and laterality of distal tip. The pictorials demonstrate the import of needle positioning and obeying structural landmarks: medial margin of the pedicle, anterior margin of vertebral body, and endplates. Red zones: 1) Beyond the anterior margin of the vertebral body rests the aorta/IVC; 2) Medial to the pedicle is the epidural space/thecal sac; 3) inferior to the pedicle is the neural foramen 45 Vertebral Augmentation Technique • • • • Biplane fluoroscopy • Superior and inferior endplates are lined up on AP and lateral view perfectly • Bilateral pedicles and ribs are aligned and perfectly superimposed on lateral view, with minimal redundant shadows • Pedicles are adequately visualized • If pedicles are not adequately visualized, consider aborting procedure; consider CT guidance measures; consider parapedicular approach Local anesthetic/skin incision Guide 11-13 gauge needle (trocar+canula) into the pedicle or target site • Transpedicular: Obtain purchase in pedicle (tactile texture differences between osteoporotic vs. neoplastic vs. osteosclerotic bone) • Adjust hand to tripod position for superior control and maneuverability • Needle trajectory should be parallel to x-ray beam (such that needle appears as a dot) • Use mallet to guide needle through bone • Advance needle tip to the anterior border of the middle portion of the vertebral body proper on lateral view • Remove trocar and co-axially advance the osteotome needle • Rotate osteotome to cross the midline and create a cavity into which cement will be posited Inject PMMA • Under realtime fluoroscopic guidance, visualize delivery of PMMA in two planes • Different admixtures have different hardening times and operator should be aware of time limitations to administer cement • Important to have the PMMA enter through the fracture line • • • Ending the procedure • Reinsert the trochar • Rotate canula several times • Slowly remove needle Apply manual pressure to incision site Post-operative care and monitoring • Recovery and monitoring for 2-3 hours • Supine position • PMMA cement usually hardens to 90% in 1 hour • Evaluate for neurological and hemodynamic changes • IF there are any undesirable clinical changes obtain CT or MRI • NSAIDS and oral narcotic analgesia initially only if necessary • Monitor pain level 46 Vertebral Augmentation Technique C E A B G D F L3 compression fracture: A) Pictorial demonstrates importance of establishing an obliquity parallel to the pedicle such that it can be viewed “en face”. B) Utilizing tripod technique with hand, the 13g introducer needle is positioned over the pedicle; adjusted parallel to the x-ray beam; and advanced with a mallet, intermittently repositioning as it is directed through the pedicle. C,D) Note the perfect alignment of the superior endplates on both the lateral and the AP projection; and note the near perfect anatomic alignment of bilateral pedicles on the lateral. Once the 13g needle is positioned through the midbody, the osteotome is inserted co-axially through the canula; rotated ideally to create a cavity which extends through the midline of the vertebral body. E,F) If a larger cavity is desired, the osteotome can be maneuvered in different ways to excavate other parts of the vertebral body. G) Finally, once a cavity is established, the osteotome is removed, and the engineered cavity may be filled with PMMA, here seen on the AP view. Ideally, the introduction of cement is viewed in real-time under fluoroscopic guidance in both AP and lateral projections. 47 Vertebral Augmentation Technique C B E A D L1 compression fracture: A) STIR sagittal MRI demonstrates acute compression fracture of the L1 vertebral body with edema and retropulsion. B) The endplates, the pedicles, and the ribs are perfectly aligned by rotating the C-Arm. Fluoroscopic image demonstrates the L1 compression fracture. C, D) After having placed the 13g needle through the pedicle and into the body, the osteotome is positioned and is rotated to cross the midline. E) The lateral view demonstrates PMMA within the L1 vertebral body. The posterior border of the body is well respected; the anterior margin demonstrates no evidence of leakage. 48 References Van der Leede H., Jorens P.G., Parizel P., et al: Inadvertent intrathecal use of ionic contrast agent. Eur Radiol 2002; 12: pp. S86-S93 Silbergleit R., Mehta BA, Sanders WP, Talati SJ. 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