OR6.1 | Degenerative Spine Disorders — Practice Quiz

Correct. L5 root compression (typically by L4–L5 disc) causes weakness of extensor hallucis longus, foot drop, and sensory loss over the dorsum of the foot and first web space.

L4–L5 disc prolapse compresses the L5 nerve root causing weakness of extensor hallucis longus (great toe dorsiflexion) and sensory loss over the dorsum of the foot and first web space. L5 dermatome covers the dorsum of the foot and big toe.

Recall the L4–L5–S1 dermatomes: L4 covers the medial leg and foot; L5 covers the dorsum of the foot/big toe and first web space; S1 covers the lateral foot, sole, and little toe. Weakness of great toe dorsiflexion points to L5.

Correct. Cauda equina syndrome (saddle anaesthesia + bladder/bowel dysfunction + bilateral weakness) is a surgical emergency. Urgent MRI confirms the diagnosis and emergency decompression should follow without delay.

Saddle anaesthesia, bilateral leg weakness, and bladder/bowel dysfunction together constitute cauda equina syndrome — a surgical emergency requiring urgent MRI and decompressive surgery within hours to prevent permanent neurological damage.

This presentation — saddle anaesthesia, urinary retention, and bilateral leg weakness — is cauda equina syndrome, one of the absolute red flags in low back pain requiring emergency treatment. Delay risks permanent incontinence and paralysis.

Correct. Cervical spondylotic myelopathy presents with progressive myelopathic features — spastic gait, UMN signs (hyperreflexia, Hoffman's sign), fine motor impairment, and bilateral hand symptoms — with structural cord compression on MRI.

Cervical spondylotic myelopathy presents with upper motor neuron (UMN) signs below the level of compression (hyperreflexia, spasticity, Hoffman's sign, clonus, Babinski) combined with cervical pain. Fine motor loss (inability to button) is characteristic. MRI is diagnostic.

Radiculopathy affects a single nerve root with dermatomal sensory loss and lower motor neuron signs. Myelopathy causes UMN signs below the level (hyperreflexia, spasticity, Hoffman's) plus bilateral hand incoordination. MRI cord signal change confirms myelopathy.

Correct. When the knee is flexed during hip flexion, both hamstring tension and hip joint stress are relieved. Pain abolition confirms sciatic nerve root tension as the cause, distinguishing true sciatica from hamstring tightness and hip arthritis.

The SLR test stretches the sciatic nerve and its roots. When SLR is positive, bending the knee (releasing tension on the nerve) abolishes the pain — confirming neurogenic origin. Hip pathology pain persists regardless of knee position. A positive SLR at <70° with pain below the knee (not just buttock) is significant for disc prolapse.

SLR flexes the hip with knee extended (stretching sciatic nerve + hamstrings). Flexing the knee eliminates hamstring tension and reduces hip stress. If pain disappears, it was sciatic nerve root tension — not hamstring or hip joint origin.

Correct. In the absence of cauda equina syndrome, conservative management (analgesics, NSAIDs, physiotherapy, core strengthening) for 4–6 weeks is the standard first-line approach. Close neurological monitoring for cauda equina red flags is essential for central disc prolapse.

Lumbar disc prolapse without cauda equina involvement is managed conservatively initially (4–6 weeks of analgesics, physiotherapy, activity modification). Surgery is indicated for failed conservative management (>6 weeks), progressive neurological deficit, or cauda equina syndrome. Central disc prolapse requires close monitoring for cauda equina red flags.

Immediate surgery is reserved for cauda equina syndrome or progressive neurological deficit. Normal bladder/bowel function allows a trial of conservative management. Extended strict bed rest is outdated — early mobilisation with physiotherapy gives better outcomes.

Correct. C6 radiculopathy classically presents with thumb and index finger pain/numbness, decreased biceps and brachioradialis reflexes, and forearm lateral sensory disturbance — from C5–C6 disc prolapse.

C6 radiculopathy presents with pain radiating to the thumb and index finger (C6 dermatome), weakness of wrist extension (extensor carpi radialis), decreased biceps and brachioradialis reflexes, and sensory disturbance in the thumb/index finger. C5–C6 disc is the most common cervical disc prolapse level.

Key cervical root localisation: C5 = lateral arm/deltoid (deltoid weakness, biceps reflex); C6 = lateral forearm/thumb/index (biceps/brachioradialis reflex); C7 = middle finger/triceps reflex; C8 = ring/little finger/medial forearm. Thumb + index + decreased biceps jerk = C6.

Correct. MRI is the investigation of choice for degenerative spine disease when neurological involvement is suspected. It clearly delineates disc prolapse, nerve root compression, canal stenosis, and cord signal changes without radiation.

MRI is the gold-standard investigation for evaluating disc prolapse, nerve root compression, spinal cord pathology, and soft tissue structures in degenerative spine disease. X-ray shows bony changes but not neural structures. CT myelography is an alternative when MRI is contraindicated.

Plain X-rays demonstrate bony changes (osteophytes, disc space narrowing) but cannot show nerve roots, discs, or spinal cord. MRI is required to assess soft tissue and neural structures.

Correct. S1 root compression produces: absent ankle jerk (most reliable sign), weakness of plantar flexion (cannot stand on tiptoe), and sensory loss over the lateral foot, sole, and little toe.

S1 root compression causes: weakness of plantar flexion (gastrocnemius/soleus — unable to stand on tiptoe), absent ankle jerk (Achilles reflex), and sensory loss over the lateral foot, sole, and little toe (S1 dermatome). L5–S1 disc is the most common level for lumbar disc prolapse.

Remember: L4 = medial leg + knee jerk; L5 = dorsum foot/big toe + no reflex change (L5 has no reliable reflex); S1 = lateral foot/little toe + absent ankle jerk + plantar flexion weakness. Absent ankle jerk with lateral foot numbness = S1.