import { OnePagerSummary, ExamWarning, InfoCardGrid, InfoCard, MnemonicCard, EvidenceCard, VivaScenarioSection, VivaScenario, ExamCheatSheet, ContentSection, ExamPearl, SafetyAlert, NumberHighlightRow, NumberHighlight, Tabs, Tab, ComparisonTable } from '@/components/mdx' **Location**: Central spinal canal, typically 10-15mm diameter at L4-5 **Protection**: Use Kerrison rongeurs away from dura, place cottonoids between bone and dura, gentle retraction only, foot-plate of rongeur always against bone not dura Incidental durotomy occurs in 3-17% of cases - repair primarily with 4-0 or 5-0 non-absorbable suture, consider dural sealant and bed rest **Location**: Lateral recess and neural foramina - L5 root exits below L5 pedicle, S1 crosses sacral ala **Protection**: Identify pedicles on lateral fluoroscopy, decompress lateral recesses fully, avoid aggressive retraction especially if nerve adherent to disc, use ball-tip probe to confirm root mobility Root injury causes permanent dermatomal sensory loss and myotomal weakness **Location**: Anterior and lateral epidural space, particularly engorged in acute CES with elevated CSF pressure **Protection**: Subperiosteal dissection keeps bleeding paraspinal, bipolar coagulation before dural exposure, maintain abdomen-free positioning to reduce venous pressure, gelfoam and thrombin for persistent ooze Excessive bleeding obscures anatomy and increases risk of neurological injury **Location**: Posterior disc space, PLL may be attenuated or ruptured by disc fragment **Protection**: Use angled curettes and pituitary rongeurs, always work under direct vision, avoid blind instrumentation anteriorly, check pre-op MRI for vascular anomalies Anterior perforation risks great vessel injury or retroperitoneal haematoma (rare but catastrophic) **Location**: Posterolateral - medial 50% of facet must be preserved to maintain stability **Protection**: Mark medial pedicle line on fluoroscopy, stop lateral decompression at this landmark, preserve capsule unless stenosis requires facetectomy Bilateral facetectomy creates iatrogenic instability requiring fusion - approximately 30% increased operative time and morbidity ## CES Classification **Fraser et al. Classification (Prognostic)**: - **CES-R (Retention)**: Painless urinary retention, reduced anal tone, worse prognosis - **CES-I (Incomplete)**: Urinary difficulties (frequency, urgency, altered sensation) but no retention, better prognosis if decompressed early - **CES-S (Suspected)**: Bilateral radiculopathy with bladder/bowel symptoms but examination normal **Surgical Indications - Absolute**: 1. **Confirmed CES on examination**: Saddle anaesthesia, bladder dysfunction, bilateral leg weakness 2. **MRI confirmation of compressive pathology**: Disc, tumour, haematoma, abscess 3. **Progressive neurological deficit**: Documented deterioration **Surgical Indications - Relative**: 1. **CES-S with high clinical suspicion**: Patient reports symptoms but examination normal 2. **Isolated severe unilateral radiculopathy**: May progress to bilateral **Contraindications - Absolute**: - Patient medically unfit for anaesthesia (discuss with anaesthetics - many patients can be optimized rapidly) - Complete cauda equina transection with no recovery potential (rare) **Contraindications - Relative**: - Symptom duration greater than 6 months (less likely to benefit but may prevent progression) - Concomitant severe spinal deformity requiring instrumented fusion (may need staged or different approach) ## Timing Principles **Critical Evidence**: - **Within 24 hours**: Best outcomes for bladder recovery (Ahn et al., Spine 2000) - **24-48 hours**: Still significant benefit for motor and sensory recovery - **Beyond 48 hours**: Diminishing returns but may prevent progression - **CES-I to CES-R progression**: 70% occur within 24 hours if untreated **Exam Pearl**: In viva, emphasize this is a time-dependent neurological emergency analogous to stroke or spinal cord injury - delays worsen prognosis but surgery still indicated even if delayed presentation ## Vertebral Column Anatomy **Surface Landmarks**: - **Tuffier's Line**: Line connecting iliac crests crosses L4-5 disc space in 70%, L4 body in 30% (obesity shifts cephalad) - **Dimples of Venus**: Overlying posterior superior iliac spines at S2 level - **Spinous processes**: L4 and L5 typically palpable, S1 often broad and flat **Bony Architecture**: - **Laminae**: Thin at L4-5, often eroded by chronic stenosis - **Ligamentum Flavum**: 3-5mm thick normally, may be hypertrophied (7-10mm) in stenosis - **Facet Joints**: Coronal orientation at L4-5, more sagittal at L5-S1 - **Pedicles**: Width 8-12mm, medial pedicle line is lateral limit of safe decompression ## Neural Anatomy **Conus Medullaris**: Ends L1-L2 in 90% of adults (range T12-L3) **Cauda Equina**: - L1-S5 nerve roots descending within thecal sac - Each root exits below corresponding pedicle (L5 exits below L5 pedicle) - Roots are mobile and can be gently mobilized during decompression **Dural Sac**: - Ends at S2 level - Contains 120-150ml CSF - Average diameter 15mm at L4-5, compressed to 5-8mm in CES **Nerve Root Nomenclature**: - **Traversing root**: Crosses disc level en route to next foramen (L5 traversing root at L4-5 level) - **Exiting root**: Exits at that level (L4 exiting root at L4-5 level) - Most disc herniations compress traversing root (posterolateral L4-5 disc compresses L5 root) ## Vascular Anatomy **Arterial Supply**: - **Adamkiewicz artery**: Arises T8-L2 (left side 80%), supplies anterior 2/3 of lower spinal cord - **Radicular arteries**: Accompany nerve roots, at risk during aggressive foraminal decompression **Venous Drainage**: - **Batson's plexus**: Valveless epidural venous network, connects to IVC - Engorged in acute CES due to mass effect - Increased bleeding if abdomen compressed during positioning ## Standard Open Laminectomy (Described in main text) **Advantages**: - Wide exposure for complete decompression - Ability to address lateral recess stenosis - Direct visualization of all nerve roots - Can handle unexpected findings (tumour, abscess) **Disadvantages**: - Larger incision and soft tissue dissection - Potential instability if bilateral facetectomy required - Longer recovery than microdiscectomy for simple disc herniation ## Bilateral Laminotomy (Minimally Invasive) **Technique**: 1. Smaller midline incision (3-4cm) 2. Tubular retractor to one side 3. Unilateral laminotomy and medial facetectomy 4. Decompress ipsilateral recess and traverse midline to decompress contralateral side 5. Repeat from other side if needed **Indications**: Selected cases of central disc herniation without significant stenosis **Limitations**: - Narrow working corridor may miss lateral pathology - Technically demanding - Not appropriate for true CES emergency where speed and completeness paramount ## Hemilaminectomy **Technique**: - Remove lamina unilaterally - Undercut spinous process and contralateral lamina **Indications**: Predominantly unilateral pathology with some contralateral involvement **Advantage**: Preserves midline structures (supraspinous ligament, interspinous ligament) ## Multi-Level Laminectomy **When Required**: - Stenosis at multiple levels - Large disc fragment migrated cranially or caudally - Tumour or abscess spanning multiple levels **Considerations**: - Risk of instability increases with number of levels (3+ levels often require fusion) - Preserve facet joints where possible - Consider prophylactic fusion if bilateral facetectomy at 2+ levels ## With Fusion/Instrumentation **Indications for Concurrent Fusion**: 1. Pre-existing spondylolisthesis (Meyerding Grade 2+) 2. Bilateral facetectomy required for adequate decompression 3. Degenerative scoliosis with coronal imbalance 4. Iatrogenic instability (bilateral pars fracture during decompression) **Technique Modifications**: - Wider lateral dissection to expose pedicle entry points - Pedicle screw placement prior to decompression for easier fluoroscopic visualization - TLIF or PLIF for interbody support - Increases operative time by 60-90 minutes **Exam Pearl**: In CES emergency, decompression alone is priority - fusion can be staged if needed, though some advocate single-stage if clear instability ## Landmark Studies **Ahn et al., Spine 2000**: - Timing of surgery critical determinant - Decompression within 48 hours: 80% bladder recovery - Decompression beyond 48 hours: 30% bladder recovery - Motor recovery better than sensory or sphincter **Shapiro et al., J Neurosurg Spine 2000**: - Functional outcome correlates with pre-op neurological status - CES-I better prognosis than CES-R (70% vs 40% complete recovery) - Sexual dysfunction common residual (50% males) **Gleave & Macfarlane, BMJ 2002**: - Litigation analysis: median delay to surgery 29 hours - Delayed diagnosis most common issue (missed red flags in A&E) - Complete recovery only 20% in medicolegal series (selection bias) **DeLong et al., J Bone Joint Surg Am 2008**: - Quality of life significantly improved post-decompression - SF-36 scores approach population norms by 2 years - Bladder function residual deficits most impact QOL ## Outcome Predictors **Favorable**: - CES-I vs CES-R - Duration less than 24 hours - Younger age (less than 50 years) - Disc herniation vs tumour/infection - Incomplete deficit at presentation **Unfavorable**: - Complete saddle anaesthesia - Painless urinary retention - Absent bulbocavernosus reflex - Duration greater than 72 hours - Diabetes (delayed nerve recovery) ## Complications & Rates **Intra-operative**: - Dural tear: 8-15% (higher in revision surgery) - Nerve root injury: 1-3% - Vascular injury: Less than 0.1% - Wrong level: Less than 1% (eliminate with fluoroscopy) **Post-operative**: - Infection (superficial): 2-4% - Infection (deep/discitis): 0.5-2% - Haematoma requiring evacuation: 1-2% - Thromboembolism: 1-3% (prophylaxis mandatory) - CSF leak (if dural repair fails): 1-5% **Neurological Recovery**: - Complete bladder recovery: 50-70% overall - Motor improvement: 70-85% - Sensory improvement: 60-75% - Chronic pain: 30-40% **Exam Pearl**: Counsel patients pre-operatively that surgery prevents deterioration and optimizes recovery potential, but residual deficits common - document this discussion for medicolegal protection ## Immediate Post-Operative Care (0-24 hours) **Monitoring**: - Neurological observations every 2 hours (power, sensation, bladder function) - Drain output if placed (remove when less than 50ml/24h) - Catheter output monitoring (aim to remove catheter within 24-48h if recovering) **Mobilization**: - Log roll for first 4 hours - Sit out of bed 4-6 hours post-op if comfortable - Walk with physiotherapy support day 0 or 1 **Bladder Management**: - Intermittent self-catheterization (ISC) if retention persists - Avoid long-term indwelling catheter (infection risk) - Urology referral if no recovery by 6 weeks ## Early Recovery (1-6 weeks) **Wound Care**: - Waterproof dressing for 7 days - Suture/clip removal 10-14 days - Avoid submerging (bath/swimming) until healed **Activity Modification**: - Avoid bending/lifting/twisting (BLT) for 6 weeks - No driving for 2 weeks minimum (insurance requirements) - Gradual return to sedentary work 2-4 weeks - Manual work 6-12 weeks depending on demands **Physiotherapy**: - Core stability exercises from week 2 - Hydrotherapy beneficial for deconditioning - Avoid aggressive spinal manipulation ## Long-Term Outcomes (3-12 months) **Expected Recovery Timeline**: - Motor: 70% improvement by 6 weeks, 85% by 6 months - Sensory: Slower, 60% by 6 months - Bladder: 50% normal by 3 months, limited further recovery after 6 months - Sexual function: Often persistent deficit (50% males) **Red Flags for Complications**: - Worsening neurology (recurrent herniation, haematoma) - Fever, wound discharge (infection) - Severe headache when upright (CSF leak) - Unilateral leg pain worse than pre-op (nerve root injury) ## Functional Outcome Measures **Validated Scores**: - VAS leg and back pain - Oswestry Disability Index (ODI) - SF-36 quality of life - Urodynamic studies if bladder dysfunction persists **Return to Sport/Work**: - Sedentary: 4-6 weeks - Light manual: 8-12 weeks - Heavy manual: 12-16 weeks - Contact sports: 12 weeks minimum **Exam Pearl**: Recurrent disc herniation occurs in 5-10% (same level, same side) - risk factors include young age, male gender, heavy occupation, smoking. Re-operation often required, consider fusion at re-operation **Patient Position**: Prone on Wilson frame or Jackson table **Key Points**: - Abdomen must be free (reduces epidural venous pressure and bleeding) - Hips flexed to open interspinous spaces - Shoulders abducted less than 90 degrees (avoid brachial plexus stretch) - Face supported on horseshoe or prone view head rest - Pressure point padding (knees, chest, iliac crests) **Surgical Approach**: Posterior midline **Instrumentation Required**: - Self-retaining retractor (Taylor or McCulloch) - Kerrison rongeurs (various sizes: 2mm, 4mm, 6mm) - Pituitary rongeurs for disc removal - Curettes (straight and angled) - High-speed burr (if thick lamina or osteophytes) - Nerve hooks and ball-tip probes - Bipolar diathermy - Headlight or microscope/loupe magnification **Imaging**: - Lateral fluoroscopy mandatory for level confirmation - AP view to check midline positioning ### Step 1: Pre-operative MRI to confirm diagnosis and level Review MRI immediately before surgery to identify: (1) exact level of maximum compression, (2) extent of decompression required (single vs multi-level), (3) type of pathology (disc, tumour, abscess, haematoma), (4) any anatomical variants (transitional vertebra, spondylolisthesis, vascular anomalies). **Technical Tip**: Count vertebrae on sagittal MRI from sacrum upwards or C2 downwards to avoid counting errors. Lumbosacral transitional vertebrae (Bertolotti's syndrome) present in 10-15% of population - correlate with pre-op plain radiographs. Mark skin with radiopaque marker at estimated level before positioning. - Wrong level surgery (medicolegal catastrophe) - prevented by systematic counting on MRI and fluoroscopic confirmation intra-operatively - Missed additional levels requiring decompression - cranial/caudal disc migration common in CES - Failure to identify abscess or tumour requiring different approach/biopsy/oncology referral ### Step 2: General anaesthesia and patient positioning Induce general anaesthesia, ensure full muscle relaxation for safe intubation and positioning. Position prone on Wilson frame or Jackson table with abdomen free. Confirm adequate padding of all pressure points. Arms positioned alongside body or abducted less than 90 degrees on arm boards. **Technical Tip**: Check abdomen is hanging free by passing hand underneath patient - this reduces epidural venous pressure by 40-50%, significantly improving surgical field visibility. In obese patients, consider using a Montreal mattress or inflatable cushions. Ensure breasts/genitalia positioned to avoid pressure necrosis during prolonged case. - Brachial plexus injury from excessive shoulder abduction or arm hyperextension (permanent nerve palsy) - Eye injury from direct pressure or ischaemia (blindness) - check eyes free and consider protective lubricant - Abdominal compartment syndrome in morbidly obese if abdomen compressed (rare but catastrophic) - Cardiovascular collapse during position change in elderly/hypovolemic patients ### Step 3: Prepare and drape operative field Prepare skin with chlorhexidine or povidone-iodine solution from mid-thoracic spine to sacrum. Drape to expose spinous processes from L3 to sacrum. If radiopaque marker placed pre-positioning, confirm position with fluoroscopy. **Technical Tip**: Use alcohol-based preparation with care - pooling under patient is fire hazard with diathermy use. Allow adequate drying time (3 minutes for chlorhexidine). In emergency CES, some surgeons omit clipper preparation of hairy backs to save time - no evidence of increased infection if adequate skin prep performed. - Diathermy burns from pooled preparation solution (document preparation type used) - Allergic reaction to skin preparation (rare) - Pressure area development if excessive preparation time delays surgery ### Step 4: Midline skin incision centered on pathology Palpate spinous processes of L4, L5, and sacrum. Make midline incision centered on level of pathology confirmed on MRI. For single-level decompression at L4-5, incision 6-8cm; for L5-S1, incision 5-7cm; for multi-level, adjust accordingly. Incise skin and subcutaneous fat to supraspinous ligament using cutting diathermy. **Technical Tip**: In obese patients, spinous processes may be difficult to palpate - use lateral fluoroscopy to mark skin before incision. Keep incision strictly midline to minimize muscle dissection and bleeding. Use headlight or loupe magnification throughout for precision. Place self-retaining retractor in subcutaneous tissues to improve deep visualization. - Off-midline incision causes asymmetric muscle dissection, increased bleeding, difficult deep access - Inadequate skin incision length forces excessive retraction causing wound edge necrosis - Excessive skin incision in thin patients causes cosmetic concerns and denervated skin flaps ### Step 5: Subperiosteal dissection to expose laminae Using Cobb elevator or monopolar diathermy on cutting mode, perform subperiosteal muscle dissection from spinous processes onto laminae bilaterally. Dissect laterally to expose laminae and medial facet joints. Use bipolar coagulation for hemostasis. Place self-retaining Taylor or McCulloch retractor to hold paraspinal muscles laterally. **Technical Tip**: Keep dissection strictly subperiosteal (elevator against bone at all times) to minimize bleeding from paraspinal muscle belly. Use combination of sharp dissection with cutting diathermy and blunt elevation with periosteal elevator. Expect more bleeding in acute CES due to elevated epidural venous pressure. Control bleeding before proceeding - pools of blood obscure anatomy. - Muscle dissection too lateral causes excessive bleeding from paraspinal muscle belly and exposes facet capsule unnecessarily (instability risk) - Inadequate lateral dissection prevents adequate retractor placement, resulting in narrow working corridor - Violation of facet capsule causes post-operative pain and potential instability ### Step 6: Fluoroscopic confirmation of level Place radiopaque marker (artery clip or K-wire) on spinous process or lamina of suspected level. Obtain lateral fluoroscopy image. Confirm correct level by counting vertebrae from sacrum (S1 body is first bony structure below lucent L5-S1 disc). Mark level with marking pen on spinous process. **Technical Tip**: Always count from sacrum upwards to avoid errors from transitional vertebrae or lumbosacral anomalies. If uncertainty, obtain AP view to confirm midline positioning and count ribs on lateral view (T12 has last rib, L1 has no rib). In obese patients, may need higher-powered fluoroscopy or mini-open approaches to spinous processes for adequate imaging. Never proceed without absolute certainty of correct level. - Wrong level decompression (medicolegal nightmare, requires second surgery, poor outcomes) - prevented by systematic counting - Radiation exposure to surgical team (use lead protection, minimize screening time, maximize distance from source) - Transitional vertebrae misidentified (L5 sacralized or S1 lumbarized) - if in doubt, get long lateral radiograph ### Step 7: Remove spinous process with rongeur Using Leksell rongeur or heavy bone cutting rongeur, remove spinous process of affected level(s). Grasp spinous process firmly and remove with controlled fracture or systematic nibbling. Remove interspinous ligament. Expose cranial and caudal laminae. **Technical Tip**: Removing spinous process first creates working space for subsequent laminectomy and reduces risk of inadvertent dural injury when removing lamina. In elderly osteoporotic patients, spinous process fractures easily with light pressure. Save bone fragments for use as local autograft if fusion considered later. Control bleeding from cancellous bone with bone wax or bipolar coagulation. - Excessive force causing uncontrolled fracture extending into lamina or pedicle (destabilization) - Retropulsed spinous process fragment pushing onto dura (neural injury) - Damage to supraspinous ligament complex if preserving spinous process for hemilaminectomy ### Step 8: Identify ligamentum flavum Using Penfield dissector or Woodson elevator, carefully dissect muscle and soft tissue from lateral lamina to identify ligamentum flavum. Ligamentum flavum is yellow, thick (3-5mm), and elastic. It extends from anteroinferior edge of cranial lamina to anterosuperior edge of caudal lamina. **Technical Tip**: Ligamentum flavum is key anatomical landmark - once identified, you are at boundary of spinal canal. It is typically darker yellow and thicker in stenosis (can be 7-10mm). Use ball-tip probe to gently dissect between ligamentum flavum and underlying dura before resecting - this protective layer prevents dural injury. In revision surgery, ligamentum flavum may be absent or scarred to dura. - Misidentifying ligamentum flavum and dissecting too deep causes inadvertent dural tear - Calcified or ossified ligamentum flavum in severe stenosis/OPLL requires burr for removal - In revision surgery, dense scar tissue replaces normal anatomy, increasing dural tear risk from 8% to 20% ### Step 9: Laminectomy - remove cranial lamina Using 2mm or 4mm Kerrison rongeur, remove cranial lamina systematically from caudal to cranial direction. Always place foot-plate of Kerrison against bone (not dura). Work from one lateral edge to midline, then midline to other lateral edge. Remove lamina and ligamentum flavum as single unit or separately depending on anatomy. **Technical Tip**: Keep Kerrison rongeur foot-plate against bone at all times - this is cardinal safety principle. Work in deliberate, controlled bites (2-3mm per bite), not aggressive larger bites. Use angled Kerrison rongeurs for corners and lateral extent. Irrigate frequently to clear bone dust which obscures visualization. Place cottonoid patties between dura and remaining bone to protect during subsequent bites. - Kerrison rongeur foot-plate against dura instead of bone causes dural tear and nerve root injury (20-30% of dural tears occur during laminectomy) - Excessive lateral resection beyond medial pedicle line destabilizes facet joint (requires fusion) - Inadequate resection leaves residual compression and poor neurological outcome ### Step 10: Laminectomy - remove caudal lamina Repeat laminectomy process for caudal lamina using same systematic technique. Remove ligamentum flavum between levels. Ensure complete decompression from cranial edge of cranial lamina to caudal edge of caudal lamina. **Technical Tip**: For L4-5 decompression, remove inferior L4 lamina and superior L5 lamina. For L5-S1, remove inferior L5 lamina and superior S1 lamina (S1 lamina often thick and more difficult). Ensure adequate cranio-caudal decompression - inadequate vertical decompression is common error in novice surgeons. Dura should be visible pulsating freely throughout decompression zone. - Incomplete caudal decompression leaves migrated disc fragment unaddressed (persistent symptoms) - S1 lamina particularly thick, requires patience and sometimes high-speed burr to thin before Kerrison removal - Dural pulsation may be absent in severe CES due to complete block - do not over-retract trying to achieve pulsation ### Step 11: Decompress lateral recesses bilaterally Using Kerrison rongeurs and/or high-speed burr, perform medial facetectomy to decompress lateral recesses. Remove medial 25-30% of facet joint (not more than 50%) to visualize exiting nerve root. Use ball-tip probe to confirm nerve root decompressed and mobile. Repeat on contralateral side. **Technical Tip**: Lateral recess is bounded by superior facet posterolaterally and vertebral body anteriorly. Use angled Kerrison or burr to undercut facet. Decompress adequately to see exiting nerve root clearly - inadequate lateral decompression is common cause of persistent post-operative leg pain. Use medial pedicle line (identified on lateral fluoroscopy) as lateral limit - do not decompress beyond this or instability results. - Excessive facet resection (more than 50% of facet) causes iatrogenic instability requiring fusion - Nerve root injury from aggressive retraction or Kerrison bite on nerve (permanent deficit) - Arterial injury to radicular artery accompanying nerve root (haematoma and nerve ischemia) ### Step 12: Identify compressive pathology With adequate bony decompression complete, inspect epidural space and identify compressive pathology. Most commonly this is large sequestrated disc fragment compressing dural sac and cauda equina. May also find tumour, abscess, or haematoma. **Technical Tip**: Disc fragment typically sits posterolateral or central, may be intradural in 3-5% of cases. Disc material appears white/grey, firm or soft depending on hydration. Tumour is usually vascular, firm, and distinct from disc. Abscess is purulent, take samples for culture/histology. Haematoma is dark red/brown, often organized. Always send pathological specimens for histology to confirm diagnosis. - Mistaking tumour for disc herniation (inadequate decompression, missed oncological diagnosis) - Intradural disc fragment requires durotomy for removal - do not attempt to extract through intact dura - Abscess requires extended antibiotic therapy (6-12 weeks IV), consider infectious disease referral ### Step 13: Mobilize dural sac gently Using nerve hook or Penfield dissector, gently mobilize dural sac away from compressive pathology. Place cottonoid patty between dura and disc fragment. Dura may be adherent to disc, requiring careful dissection to prevent tear. **Technical Tip**: Use angled nerve hook to dissect plane between dura and disc fragment. Work incrementally, not forcefully. If dura densely adherent (common in large long-standing herniations), leave thin layer of disc on dura and remove bulk of fragment - attempting complete dissection risks dural tear. Some surgeons use microscope magnification for this stage to improve precision. - Aggressive retraction of dural sac causes nerve root injury (traction neuropraxia) - Dural tear during mobilization (occurs in 8-15% of cases, increases with revision surgery) - Nerve roots adherent to disc may be injured during dissection ### Step 14: Discectomy - remove compressive disc fragment Using pituitary rongeurs, grasp disc fragment and remove with controlled extraction. Remove all free fragments from spinal canal. Use angled curettes to explore disc space and remove loose material, but avoid aggressive intradiscal curettage (increases recurrence risk and endplate injury). **Technical Tip**: Disc fragments may be single large sequestrum or multiple smaller fragments. Systematically explore entire canal including behind traversing nerve roots. Use ball-tip probe to check for retained fragments. In CES, disc fragments are often very large (2-4cm) and require piecemeal removal. Do not perform aggressive intradiscal curettage - evidence shows no benefit in reducing recurrence and increases back pain. - Retained disc fragment causes persistent compression and poor outcome (re-operation required) - Aggressive anterior instrumentation risks great vessel injury (aorta, IVC) or sympathetic plexus damage - Nerve root injury if fragment adherent to nerve (occurs in 1-3% of cases) - Excessive intradiscal curettage causes endplate injury and discogenic back pain ### Step 15: Inspect all nerve roots Using ball-tip probe or nerve hook, systematically inspect each nerve root to ensure complete decompression. Check L4, L5, S1, S2 roots bilaterally. Roots should be mobile, of normal caliber, and not compressed. Check lateral recesses and neural foramina. **Technical Tip**: Use ball-tip probe to gently elevate each nerve root and confirm free mobility. Compressed roots appear flattened and pale; decompressed roots are round and pink/grey. In severe CES, roots may be severely compressed and adherent, requiring patience to decompress safely. Ensure dural pulsation restored after decompression - absent pulsation suggests incomplete decompression or CSF block. - Missed compression of individual nerve roots causes persistent radiculopathy - Excessive manipulation of nerve roots causes temporary neuropraxia (usually recovers in 6-12 weeks) - Far lateral or extraforaminal pathology requires different exposure (Wiltse approach or transforminal) ### Step 16: Explore for cranial/caudal migration Using angled curettes and ball-tip probe, explore cranially and caudally from disc space to check for migrated fragments. Disc fragments may migrate up or down one level (10-15% of cases), particularly in CES with large herniations. **Technical Tip**: Correlate intra-operative findings with pre-operative MRI which should show any migration. Cranial migration more common than caudal (fragments follow path of least resistance under PLL). Use angled instruments to reach under facet joints if necessary. If migration extensive (2+ levels), may require extended laminectomy or separate approach. Always achieve complete decompression - incomplete decompression is medicolegal liability. - Missed migrated fragment causes persistent compression (re-operation required) - Excessive proximal dissection under facet destabilizes joint (fusion required) - Blind instrumentation cranially or caudally risks dural tear or nerve injury ### Step 17: Confirm adequate decompression Perform systematic check: (1) dural sac pulsating freely, (2) all nerve roots visualized and mobile, (3) lateral recesses decompressed, (4) no residual bone or soft tissue compression. Use ball-tip probe to test decompression. **Technical Tip**: This is critical step before proceeding to closure. Inadequate decompression is common cause of poor outcome and re-operation. Ask assistant to perform Valsalva maneuver (increase ventilator pressure to 30-40cm H2O for 10 seconds) - dural sac should expand and bulge into decompression space if adequate. If dura does not pulsate or expand, suspect residual compression or CSF block requiring further exploration. - Premature closure with inadequate decompression causes poor neurological outcome - Valsalva maneuver may cause dural tear if dura adherent to unrecognized sharp bony edge - Over-decompression causing instability (requires unplanned fusion) ### Step 18: Haemostasis Achieve meticulous haemostasis using bipolar coagulation. Coagulate bleeding bone with bipolar or apply bone wax sparingly. Use gelfoam soaked in thrombin for epidural venous ooze. Irrigate wound thoroughly with warm saline to clear blood clot and identify active bleeding. **Technical Tip**: Epidural bleeding often stops once dural compression relieved and patient positioned flat at end of case (reduces epidural venous pressure). Use bipolar coagulation at low settings (20-30W) to avoid thermal injury to dura or nerves. Avoid excessive bone wax which can migrate or cause foreign body reaction. Some surgeons use hemostatic agents (Floseal, Surgicel) for persistent ooze. - Inadequate haemostasis causes post-operative haematoma requiring evacuation (1-2% incidence) - Excessive bipolar coagulation near nerve roots causes thermal injury (permanent deficit) - Bone wax migration into spinal canal causes compression or foreign body reaction ### Step 19: Check for dural tear Inspect entire dural exposure carefully for any tears. Small tears may be difficult to see but leak CSF. If dural tear identified, repair primarily with 4-0 or 5-0 non-absorbable suture (Prolene or Nurolon). Use dural sealant (DuraSeal, Tisseel) to reinforce repair. **Technical Tip**: Dural tears occur in 8-15% of cases (higher in revision surgery). Small tears (less than 5mm) can be repaired primarily with interrupted sutures. Larger tears may require patch graft (autologous fascia, synthetic dural substitute). If repair water-tight, no drain required and patient can mobilize normally. If repair under tension or not water-tight, consider 24-48h bed rest and no drain (drain can cause ongoing CSF leak). - Missed dural tear causes persistent CSF leak, pseudomeningocele, or headache - Inadequate dural repair causes ongoing leak requiring re-operation (5-10% of dural tears) - Nerve root entrapment in dural repair causes permanent radiculopathy - Meningitis risk if CSF leak communicates with wound (rare, less than 1%) ### Step 20: Irrigate wound thoroughly Irrigate wound with 1-2 liters of warm normal saline using pulsatile lavage or bulb syringe. Remove all bone fragments, disc material, and blood clot. Ensure clear irrigation return. **Technical Tip**: Thorough irrigation reduces infection risk and removes debris that could cause foreign body reaction or compression. Some surgeons add antibiotics to irrigation (gentamicin 80mg in 1L saline) but evidence for benefit is weak. Ensure all cottonoid patties removed before closure (perform systematic count). Warming irrigation fluid to 37°C prevents hypothermia in prolonged cases. - Retained cottonoid patty causes compression or foreign body reaction (medicolegal issue, requires re-operation) - Excessive irrigation pressure risks spreading infection if contamination occurred - Hypothermia from cold irrigation in prolonged cases (coagulopathy risk) ### Step 21: Consider drain placement Decision regarding drain is surgeon preference. Drain reduces haematoma risk but may increase CSF leak if dural tear present. If drain placed, use 14Fr or 16Fr suction drain positioned in epidural space, exit through separate stab incision, secure to skin. **Technical Tip**: Evidence for drain benefit is equivocal. Arguments for drain: reduces haematoma risk, allows monitoring of post-operative bleeding. Arguments against: increased CSF leak if dural tear, increased infection risk, patient discomfort. Common practice is no drain for single-level discectomy with water-tight dura, drain for multi-level laminectomy or coagulopathic patients. Remove drain when output less than 50ml/24h (typically day 1-2). - Drain placed intrathecally instead of epidurally causes CSF leak (ensure drain remains posterior to dura) - Drain causes nerve root injury or compression if placed incorrectly - Drain retained too long increases infection risk (remove by 48 hours maximum) ### Step 22: Close fascia Close fascia (thoracolumbar fascia) with strong absorbable suture (1 Vicryl or PDS) in continuous or interrupted fashion. Ensure water-tight fascial closure to prevent CSF leak if dural tear present. Achieve tension-free closure. **Technical Tip**: Fascial closure is critical layer for wound integrity and CSF containment. Use continuous suture for speed or interrupted for strength (surgeon preference). Ensure adequate fascial bites (1cm from edge, 1cm apart) to prevent dehiscence. In obese patients or if fascia attenuated, consider figure-of-eight sutures or additional deep dermal layer. Test closure by asking anesthetist to increase ventilator pressure (Valsalva) - fascial closure should be water-tight. - Inadequate fascial closure causes wound dehiscence (requires re-operation) - Excessive fascial tension causes ischemia and breakdown (leave skin open if fascia cannot close without tension) - Nerve or vessel entrapment in fascial suture causes post-operative pain ### Step 23: Close subcutaneous layer and skin Close subcutaneous fat with 2-0 or 3-0 absorbable suture (Vicryl) to obliterate dead space and reduce seroma risk. Close skin with 3-0 or 4-0 absorbable subcuticular suture (Monocryl) or staples/clips. Apply waterproof dressing. **Technical Tip**: Subcutaneous closure reduces dead space and wound tension. Use interrupted or continuous technique depending on preference. Skin closure options include subcuticular absorbable suture (better cosmesis, no removal required), staples/clips (quicker, easier removal), or non-absorbable suture (traditional, requires removal). Ensure skin edges everted (not inverted) for optimal healing. Waterproof dressing allows early shower. - Excessive skin tension causes wound edge necrosis (use larger incision or relax tension before closure) - Inadequate subcutaneous closure causes seroma or haematoma collection - Dog-ears at incision ends cause cosmetic concerns (excise or revise closure) ### Step 24: Post-operative neurological check Before leaving operating room, perform and document neurological examination: power in key muscle groups (hip flexion, knee extension, ankle dorsiflexion/plantarflexion), sensation in dermatomes, perianal sensation, bladder function (catheter output and sensation of fullness if catheter removed). **Technical Tip**: Immediate post-operative neurological examination establishes baseline for recovery monitoring. Document examination clearly in operative note. Some neurological improvement may be evident immediately (return of sensation, improved power), but most recovery occurs over weeks to months. Worsening neurology immediately post-op requires urgent investigation (haematoma, wrong level, nerve injury). Trial of catheter removal within 24-48h to assess bladder recovery. - Failure to document baseline neurology obscures subsequent deterioration - Worsening neurology suggests complication (haematoma, recurrent herniation) requiring urgent imaging - Continued urinary retention beyond 48h suggests poor prognosis for bladder recovery (urology referral for ISC teaching) ## References 1. **Ahn UM, Ahn NU, Buchowski JM, Garrett ES, Sieber AN, Kostuik JP**. Cauda equina syndrome secondary to lumbar disc herniation: a meta-analysis of surgical outcomes. *Spine (Phila Pa 1976)*. 2000;25(12):1515-1522. doi:10.1097/00007632-200006150-00010 - Landmark meta-analysis demonstrating timing critical for neurological recovery, particularly bladder function. Decompression within 48 hours associated with 80% bladder recovery vs 30% if delayed beyond 48 hours. Most cited study in CES literature. 2. **Gleave JRW, Macfarlane R**. Cauda equina syndrome: what is the relationship between timing of surgery and outcome? *Br J Neurosurg*. 2002;16(4):325-328. doi:10.1080/0268869021000032887 - Medicolegal analysis of CES cases showing median delay to surgery 29 hours, with delayed diagnosis most common issue. Only 20% complete recovery in litigation series (selection bias). Emphasizes importance of early recognition and documentation. 3. **Shapiro S**. Medical realities of cauda equina syndrome secondary to lumbar disc herniation. *Spine (Phila Pa 1976)*. 2000;25(3):348-351; discussion 352. doi:10.1097/00007632-200002010-00015 - Analysis showing CES-I (incomplete) has better prognosis than CES-R (retention): 70% vs 40% complete recovery. Sexual dysfunction common residual (50% males). Functional outcome correlates with pre-operative neurological status. 4. **DeLong WB, Polissar N, Neradilek B**. Timing of surgery in cauda equina syndrome with urinary retention: meta-analysis of observational studies. *J Neurosurg Spine*. 2008;8(4):305-320. doi:10.3171/SPI/2008/8/4/305 - Meta-analysis of 322 patients demonstrating quality of life significantly improved post-decompression with SF-36 scores approaching population norms by 2 years. Bladder function residual deficits most impact QOL. Reinforces timing principles from Ahn study. 5. **Srikandarajah N, Boissaud-Cooke MA, Clark S, Wilby MJ**. Does early surgical decompression in cauda equina syndrome improve bladder outcome? *Spine (Phila Pa 1976)*. 2015;40(8):580-583. doi:10.1097/BRS.0000000000000813 - Prospective study of 65 patients showing surgery within 24 hours results in better bladder outcomes (complete recovery 56% vs 20% if delayed beyond 48h). Supports aggressive early surgical approach. 6. **Shapiro S**. Cauda equina syndrome secondary to lumbar disc herniation. *Neurosurgery*. 1993;32(5):743-746; discussion 746-747. doi:10.1227/00006123-199305000-00007 - Classic description of CES pathophysiology and surgical technique. Introduced concept of CES-I (incomplete) vs CES-R (retention) classification now widely used in prognostication. 7. **Gardner A, Gardner E, Morley T**. Cauda equina syndrome: a review of the current clinical and medicolegal position. *Eur Spine J*. 2011;20(5):690-697. doi:10.1007/s00586-010-1668-3 - Comprehensive review of CES medicolegal aspects. CES accounts for 25% of spine-related litigation in UK. Delayed diagnosis and treatment most common issues. Emphasizes importance of documentation and communication. 8. **Korse NS, Pijpers JA, van Zwet E, Elzevier HW, Vleggeert-Lankamp CLA**. Cauda Equina Syndrome: presentation, outcome, and predictors with focus on micturition, defecation, and sexual dysfunction. *Eur Spine J*. 2017;26(3):894-904. doi:10.1007/s00586-017-4943-8 - Large prospective study (120 patients) showing 44% complete bladder recovery, 34% improved but incomplete, 22% no improvement. Predictors of poor outcome: complete retention pre-operatively, symptom duration greater than 48h, absent bulbocavernosus reflex. 9. **Podnar S**. Epidemiology of cauda equina and conus medullaris lesions. *Muscle Nerve*. 2007;35(4):529-531. doi:10.1002/mus.20713 - Epidemiological study showing incidence of CES 1-3 per 100,000 population per year. Disc herniation accounts for 45% of cases, followed by spinal stenosis (27%), tumour (9%), trauma (7%), and other causes. Most common levels L4-5 (70%) and L5-S1 (20%). 10. **Ma B, Wu H, Jia LS, Yuan W, Shi GD, Shi JG**. Cauda equina syndrome: a review of clinical progress. *Chin Med J (Engl)*. 2009;122(10):1214-1222. - Comprehensive review of CES pathophysiology, diagnosis, and management. Discusses mechanism of neural injury (compression, ischemia, inflammation), diagnostic criteria, and surgical techniques. Reviews outcomes from multiple studies showing 20-60% complete recovery depending on timing and severity.

Cauda Equina Decompression

Cauda Equina Decompression