Decision Framework

• Key principle: approach from the direction of the compressive pathology
• Anterior compression (disc herniation, osteophyte, vertebral body pathology) → anterior approach
• Posterior compression (ligamentum flavum hypertrophy, facet overgrowth, multilevel stenosis) → posterior approach
• Circumferential compression: may require combined or staged approach
• Other factors: number of levels, sagittal alignment (lordosis vs. kyphosis), prior surgery, medical comorbidities

Cervical Spine Approaches

Lumbar Spine Approaches

ACDF Complications

• Recurrent laryngeal nerve injury: hoarseness; more common with right-sided approach (due to nerve course variability); transient in most cases
• Dysphagia: most common complication (up to 50% transient); usually resolves within weeks
• Esophageal perforation: rare but serious
• Vertebral artery injury: rare; risk with far-lateral dissection
• Adjacent segment disease: long-term degeneration above/below the fusion

When to Fuse

When NOT to Fuse

• Simple lumbar disc herniation: discectomy/microdiscectomy alone is sufficient
• Single-level lumbar laminectomy: no evidence of benefit from adding fusion if spine is stable
• No instability on flexion/extension imaging
• Laminoplasty: inherently motion-preserving; does not require fusion

Instrumentation

• Pedicle screws: strongest posterior fixation point; placed through vertebral pedicle into body; used with rods for posterior stabilization
• Lateral mass screws: used in subaxial cervical spine (C3–C6) where pedicles are too small for pedicle screws
• Interbody cages: structural spacer placed in disc space; filled with bone graft; restores disc height and provides anterior column support
• Bone graft options: autograft (iliac crest — gold standard), allograft, BMP-2 (bone morphogenetic protein); BMP-2 has complications including heterotopic ossification and swelling

Adjacent Segment Disease (ASD)

• Accelerated degeneration of levels adjacent to a fusion due to increased biomechanical stress
• Radiographic changes in up to 25–30% at 10 years; symptomatic ASD in ~10%
• More common with longer fusion constructs and multilevel fusions
• Motion preservation (disc arthroplasty, laminoplasty) may reduce ASD risk — theoretical benefit, long-term data still accumulating

Clinical Presentation

• Classic triad: bilateral lower extremity weakness/pain, saddle anesthesia (S2–S5), bladder dysfunction
• Red flags requiring urgent imaging:
  • Bilateral sciatica (especially new onset)
  • Saddle anesthesia or perineal numbness
  • Urinary retention (most consistent finding) with overflow incontinence
  • Decreased rectal tone / fecal incontinence
  • Progressive bilateral leg weakness
  • Sexual dysfunction (new onset)
• Most common cause: large central lumbar disc herniation (most often L4–L5 or L5–S1)
• Other causes: spinal epidural abscess, epidural hematoma, tumor, spinal stenosis, post-surgical

Incomplete vs. Complete CES

Diagnosis

• MRI is the study of choice — demonstrates level and cause of compression
• CT myelogram if MRI contraindicated
• Post-void residual >200 mL supports diagnosis in equivocal cases
• Do NOT delay imaging for urodynamics or EMG

Surgical Timing

• Surgical emergency: decompression ideally within 24 hours of symptom onset
• Earlier surgery (<24 hours) associated with better neurological and bladder outcomes in most studies
• Surgery within 24–48 hours is still beneficial; outcomes decline significantly after 48 hours
• CES-I → CES-R conversion can occur rapidly — argue for earliest possible decompression to prevent progression
• Standard procedure: wide laminectomy with discectomy at the affected level

Definition & Pathophysiology

• Cervical spondylotic myelopathy (CSM): most common cause of spinal cord dysfunction in adults >55 years
• Chronic compression of the cervical spinal cord from degenerative changes: disc herniation, osteophyte formation, ligamentum flavum hypertrophy, OPLL
• Cord compression → demyelination → axonal loss → gliosis; often irreversible once established
• Cord signal change on T2 MRI indicates myelomalacia/gliosis; T1 hypointensity = worse prognosis

Clinical Features

• Gait dysfunction (broad-based, spastic); often the earliest motor finding
• Hand clumsiness / loss of fine motor dexterity (myelopathy hand — grip-and-release test; finger escape sign)
• Upper motor neuron signs: hyperreflexia, Hoffman sign, clonus, Babinski, spastic tone
• Lhermitte sign (electric shock sensation with neck flexion)
• Sensory changes: numbness, paresthesias in hands; posterior column dysfunction
• Bowel/bladder dysfunction: late finding indicating severe myelopathy

Modified Japanese Orthopaedic Association (mJOA) Score

Surgical Approach Selection

Key Considerations

• Natural history: CSM is generally progressive; stepwise deterioration is the most common pattern; rarely improves spontaneously
• Earlier surgery = better outcomes: patients with shorter symptom duration and less cord damage have better surgical results
• Collar immobilization does not treat myelopathy; used only for temporary stabilization in trauma or post-operatively

Epidemiology & Presentation

• Metastatic epidural spinal cord compression (MESCC) occurs in 5–10% of cancer patients
• Most common primary tumors: lung, breast, prostate, renal cell, multiple myeloma
• Thoracic spine is the most common location (~60%), followed by lumbar and cervical
• Back pain is the earliest and most common symptom (>90%); precedes neurologic deficits by weeks to months
• Progressive weakness, sensory level, bowel/bladder dysfunction indicate cord compression

NOMS Decision Framework

SINS (Spinal Instability Neoplastic Score)

• SINS 0–6: stable — no surgical stabilization needed
• SINS 7–12: potentially unstable — surgical consultation
• SINS 13–18: unstable — surgical stabilization indicated

The Patchell Trial (2005)

• Design: RCT comparing direct decompressive surgery + postoperative RT vs. RT alone for single-level MESCC
• Key finding: surgery + RT group had significantly more patients who regained/retained ability to walk (84% vs. 57%)
• Surgery group also had: longer ambulatory duration, longer survival, reduced need for opioids and corticosteroids
• Inclusion: single area of cord compression, at least one neurologic sign, not totally paraplegic for >48 hours
• Exclusion: radiosensitive tumors (lymphoma, myeloma, leukemia, germ cell), multiple areas of cord compression
• Conclusion: surgery + RT is standard of care for single-level MESCC from radioresistant tumors in surgical candidates

Management Summary

Steroids in Metastatic Cord Compression

• Dexamethasone started immediately upon diagnosis (loading dose 10 mg IV, then 4 mg q6h)
• Reduces vasogenic edema, provides temporary neurologic improvement
• Bridge to definitive treatment (surgery or radiation)

Lumbar Disc Herniation

• Natural history: most improve with conservative treatment over 6–12 weeks; disc resorption occurs in up to 60–70% over time
• Surgical indications:
  • Refractory radiculopathy after ≥6 weeks of conservative management
  • Progressive motor deficit (e.g., foot drop)
  • Cauda equina syndrome (emergency)
  • Intractable pain significantly impairing function
• SPORT trial (Spine Patient Outcomes Research Trial):
  • Surgery provides faster pain relief and functional improvement at 3 months and 1 year
  • By 4–8 years, outcomes tend to converge between surgical and non-operative groups (intent-to-treat analysis)
  • High crossover rate (~40% non-operative crossed to surgery) complicated interpretation
  • As-treated analysis favored surgery at all time points

Surgical Techniques for Disc Herniation

• Recurrence rate: 5–15% after microdiscectomy; recurrent herniation at same level may eventually require fusion

Lumbar Spinal Stenosis

• Neurogenic claudication: bilateral leg pain/heaviness/numbness worsened by walking and standing, relieved by sitting or leaning forward (flexion opens the canal)
• Differentiate from vascular claudication: neurogenic relieved by sitting/flexion; vascular relieved by standing still (no need to sit)
• Conservative treatment: PT, epidural steroid injections, activity modification; reasonable for mild-moderate symptoms
• Surgical indication: neurogenic claudication refractory to ≥3 months conservative treatment with significant functional limitation
• SPORT trial for stenosis: surgery (decompressive laminectomy) associated with greater improvement in pain and function compared to non-operative care at all time points up to 8 years
• Procedure: lumbar laminectomy (decompression) at affected levels; fusion added only if concurrent instability or spondylolisthesis

Spondylolisthesis

• Definition: anterior slippage of one vertebral body on another
• Most common types:
  • Isthmic (Type II): pars interarticularis defect (spondylolysis); most common at L5–S1; typical in young athletes (gymnasts, football linemen)
  • Degenerative (Type III): facet joint arthropathy; most common at L4–L5; more common in women >50
• Meyerding classification: Grade I (<25% slip), Grade II (25–50%), Grade III (50–75%), Grade IV (75–100%), Grade V (spondyloptosis = complete slip)

Surgical Management by Grade

Spine Surgery Urgency