Spine and Spinal Cord Surgery
Questions here blend precise clinical localisation with emergency decision-making and classification systems.
Degenerative disease
- Disc herniation: a paracentral L4-5 disc compresses the traversing L5 root; L5-S1 compresses S1; a far lateral disc compresses the exiting root at that level.
- Cauda equina syndrome: saddle anaesthesia, urinary retention with overflow, bilateral leg weakness and reduced anal tone. This is an emergency: immediate MRI and decompression, generally within 24 to 48 hours.
- Lumbar stenosis causes neurogenic claudication relieved by flexion, with a positive shopping trolley sign and normal distal pulses.
- Cervical spondylotic myelopathy: clumsy hands, unsteady gait, Hoffmann sign, inverted radial reflex and T2 cord signal change; treat with anterior decompression and fusion, laminoplasty or laminectomy with fusion.
- Spondylolisthesis is graded by Meyerding; flexion-extension films assess instability.
Trauma
- Clear the spine clinically when there is no pain, no midline tenderness, no neurology, no distracting injury and the patient can move the neck, or radiologically with CT.
- Document the ASIA examination; classify with TLICS or AOSpine.
- Odontoid type II fractures are unstable; treat with halo immobilisation in the young or C1-C2 fusion, and consider a collar in frail elderly patients.
- Ankylosing spondylitis produces highly unstable hyperextension fractures that need long-segment fixation.
- Central cord syndrome with canal stenosis is safely decompressed early, within 24 hours, particularly when there is instability.
Neoplastic disease
- Extradural metastases are commonest; intradural extramedullary lesions are meningioma and schwannoma; intramedullary lesions are ependymoma and astrocytoma.
- Metastatic cord compression: dexamethasone, whole spine MRI, then surgery for a single level, radioresistant tumour or instability, otherwise radiotherapy or stereotactic body radiotherapy.
- Primary malignant bone tumours require en bloc resection rather than piecemeal removal.
Worked example
A 60-year-old with prostate cancer has back pain, urinary retention and bilateral leg weakness. This is cauda equina syndrome from metastatic compression; give dexamethasone, obtain urgent MRI of the whole spine and proceed to decompression and stabilisation.
Traps
- Waiting for imaging in cauda equina syndrome.
- Treating a normal plain film as a cleared spine.
- Delaying surgery while escalating steroids in progressive myelopathy.
- Failing to image the whole spine in metastatic disease.