Spine Surgery
Spine Surgery
What You'll Learn
- ACDF is the workhorse for 1–2 level cervical disc herniation causing radiculopathy or myelopathy; posterior approaches (laminectomy/laminoplasty) are preferred for ≥3 levels
- Cauda equina syndrome is a surgical emergency — bilateral leg pain/weakness, saddle anesthesia, urinary retention; decompression ideally within 24 hours
- Cervical myelopathy: surgery indicated for moderate-severe disease (mJOA <15) or progressive deficits; approach dictated by number of levels and alignment
- Fusion indications: instability, spondylolisthesis, deformity correction, post-tumor resection; avoid unnecessary fusion (risk of adjacent segment disease)
- Metastatic cord compression: NOMS framework guides management; Patchell trial showed surgery + RT superior to RT alone for single-level compression
- SPORT trial: surgery for lumbar disc herniation provides faster improvement but long-term outcomes converge with conservative treatment
HighYield Pearls
- Cauda equina syndrome: bilateral LE weakness + saddle anesthesia + urinary retention/incontinence + bowel dysfunction → EMERGENT MRI + decompression within 24–48h; central disc herniation at L4–L5 / L5–S1 most common culprit
- Metastatic epidural cord compression: give dexamethasone 16 mg/day promptly (oral or equivalent IV) for suspected MSCC with neurologic symptoms/signs (NICE NG234); avoid steroids before tissue diagnosis when lymphoma is suspected unless urgent neurologic compromise requires treatment; urgent MRI whole spine + neurosurgery and rad-onc consult for decompression and/or radiation (Patchell — surgery + RT > RT alone)
- Spinal epidural abscess: back pain + fever + neuro deficit in IV drug use / diabetes / recent procedure → urgent contrast MRI and antibiotics required; surgical drainage plus antibiotics is standard when there is neurologic deficit, progression, spinal instability, sepsis, or failure of medical therapy; carefully selected neurologically intact patients with an identified organism and close monitoring may be treated medically
- Cervical myelopathy: progressive gait/balance loss + hand clumsiness + Hoffmann/Babinski + hyperreflexia + Lhermitte; T2 cord hyperintensity at compression level → surgical decompression (ACDF for 1–2 levels, laminoplasty/laminectomy + fusion for ≥3 levels)
- Anterior spinal cord infarction: abdominal aortic dissection / cross-clamp / atherosclerosis → paraplegia + bilateral pain/temperature loss + sphincter dysfunction with PRESERVED proprioception/vibration (dorsal columns spared)
- Lumbar stenosis: neurogenic claudication worse with standing/walking, better with FLEXION/sitting (shopping-cart sign); MRI confirms; conservative first, laminectomy ± fusion if recalcitrant
- Chiari I: cerebellar tonsils >5 mm below foramen magnum + tussive (Valsalva-induced) occipital headache + neck pain + ataxia ± syrinx → suboccipital decompression (duraplasty vs not is controversial)
- Syringomyelia: central cord cavity → suspended bilateral UE dissociated sensory loss (pain/temp lost, vibration/proprioception spared) + LMN weakness ± Charcot joints; address underlying Chiari / tethered cord / post-traumatic etiology
- Spinal dural AVF: progressive myelopathy from venous hypertension → conus medullaris T2 hyperintensity + serpiginous dorsal flow voids; surgical clipping or endovascular embolization
- Spondylolisthesis: degenerative (older, L4–L5) vs isthmic (young, pars defect at L5–S1) → FUSION if neurologic deficit + significant slip / instability
🔍 Quick ReferenceClinical · Imaging / decision · Surgical approach
Clinical clues
- Saddle anesthesia + urinary retention + bilateral LE weakness → Cauda equina syndrome
- Hand clumsiness + gait imbalance + Hoffmann/Babinski + Lhermitte → Cervical myelopathy
- Shopping-cart sign / better with flexion-sitting, worse with standing-walking → Neurogenic claudication from lumbar stenosis
- Tussive (Valsalva-induced) occipital headache + neck pain ± ataxia → Chiari malformation type I
- Suspended bilateral UE dissociated sensory loss + LMN weakness ± Charcot joints → Syringomyelia
- Paraplegia + bilateral pain/temp loss with preserved proprioception/vibration after aortic surgery → Anterior spinal cord infarction
- Back pain + fever + neuro deficit in IVDU/diabetic → Spinal epidural abscess
- Progressive lower-extremity myelopathy in older man, often misdiagnosed as stenosis → Spinal dural AVF
Imaging / decision
- Cerebellar tonsils >5 mm below foramen magnum on sagittal MRI → Chiari I (consider suboccipital decompression)
- T2 cord hyperintensity at compression level → Cervical myelopathy — surgical indication
- Serpiginous dorsal flow voids + conus T2 hyperintensity → Spinal dural AVF
- Central canal expansion with fluid-filled cavity / cyst within cord → Intramedullary tumor (ependymoma, astrocytoma) vs syrinx
- Eccentric dural-based extramedullary mass → Meningioma / schwannoma (intradural extramedullary)
- Vertebral body destruction / pedicle erosion with epidural soft tissue → Extradural metastasis — STAT dexamethasone + MRI whole spine
- Pars interarticularis defect on oblique X-ray (“Scotty dog collar”) → Isthmic spondylolisthesis
- Rim-enhancing dorsal epidural collection on MRI with contrast → Spinal epidural abscess
Surgical approach / pearls
- ACDF (Smith-Robinson) → 1–2 level anterior cervical disc/myelopathy — workhorse cervical operation
- Laminoplasty → ≥3 level cervical stenosis with PRESERVED lordosis (fails in kyphosis — cord can’t drift back)
- Laminectomy + posterior fusion → Multilevel cervical stenosis with kyphosis or instability
- TLIF vs PLIF → TLIF (unilateral, less neural retraction) is the most popular lumbar fusion; PLIF for central pathology
- ALIF → Best access to L5–S1 (LLIF/XLIF blocked by iliac crest); watch for vascular injury and retrograde ejaculation
- Suboccipital decompression ± duraplasty → Chiari I with symptoms or syrinx
- Surgical clipping or endovascular embolization → Spinal dural AVF
- Pedicle screws + rods (instrumentation) → Fusion construct — watch for pseudarthrosis, hardware failure, adjacent segment disease, infection
Anterior vs. Posterior Approach
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
| Approach | Procedure | Indications | Key Points |
|---|---|---|---|
| Anterior | ACDF (Anterior Cervical Discectomy & Fusion) | 1–2 level disc herniation, cervical radiculopathy/myelopathy from anterior compression | Most commonly performed cervical spine surgery; removes disc + fuses adjacent vertebrae with graft/plate; Smith-Robinson approach |
| Anterior | Cervical corpectomy | Vertebral body pathology, retrovertebral disc, OPLL spanning disc space, tumor | Removes entire vertebral body + adjacent discs; higher pseudarthrosis rate than ACDF |
| Anterior | Cervical disc replacement (arthroplasty) | Single/two-level cervical disease in appropriate candidate | Preserves motion; may reduce adjacent segment disease; contraindicated if facet arthropathy, instability, or ossification |
| Posterior | Laminectomy + fusion | ≥3 level cervical stenosis; any alignment | Wide decompression; requires fusion with lateral mass or pedicle screws to prevent post-laminectomy kyphosis |
| Posterior | Laminoplasty | ≥3 level cervical stenosis; preserved lordosis required | Expands canal without removing lamina (open-door or French-door technique); preserves motion; NOT for kyphotic spines |
Lumbar Spine Approaches
| Approach | Procedure | Key Features |
|---|---|---|
| Posterior | PLIF (Posterior Lumbar Interbody Fusion) | Bilateral approach through the spinal canal; higher retraction of neural elements; good for central pathology |
| Posterior | TLIF (Transforaminal Lumbar Interbody Fusion) | Unilateral approach through the foramen; less neural retraction than PLIF; most popular lumbar fusion technique |
| Lateral | LLIF/XLIF (Lateral/Extreme Lateral Interbody Fusion) | Traverses psoas muscle; risk of lumbar plexus injury; cannot access L5–S1 (iliac crest blocks access); good for coronal deformity correction |
| Anterior | ALIF (Anterior Lumbar Interbody Fusion) | Retroperitoneal or transperitoneal approach; best access to L5–S1; risk of vascular injury (iliac vessels), retrograde ejaculation in males |
ACDF Complications
- Recurrent laryngeal nerve injury: hoarseness; historically taught to be more common with right-sided approach due to RLN course variability, but current evidence shows no significant difference between sides. Surgeon preference and prior neck surgery typically dictate side. Transient in most cases.
- Dysphagia: most common complication — early postoperative dysphagia up to 50% (most resolves over weeks to months); persistent dysphagia at 1 year ~5–15%
- Esophageal perforation: rare but serious
- Vertebral artery injury: rare; risk with far-lateral dissection
- Adjacent segment disease: long-term degeneration above/below the fusion
💎 Board Pearl
- ACDF is the most commonly performed cervical spine surgery and the first-line surgical option for 1–2 level anterior cervical pathology
- Laminoplasty requires preserved cervical lordosis — it will not work in kyphotic spines because the cord cannot drift posteriorly away from anterior compression
- LLIF/XLIF cannot access L5–S1 due to the iliac crest; ALIF is preferred for this level
- Recurrent laryngeal nerve palsy was historically taught to be more common with right-sided ACDF due to RLN course variability, but current evidence shows no significant difference between sides — side selection is now driven by surgeon preference and prior neck surgery
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