Bilateral Foot Drop Without Cauda Equinae Syndrome Due To L4-L5 Disc Prolapse: A Case Report

摘要

Aims: Lumbar disc prolapse in elderly patients at L4-L5 level presenting as bilateral foot drop without other features of cauda equine syndrome has been rarely reported. Methods: This is a report of an elderly lady with presenting with sudden backache and radiating pain to both legs with bilateral foot drop. There was no urinary or bowel involvement. Clinical examination showed a bilateral L5 radiculopathy with normal perianal sensation. Investigations excluded other causes of bilateral foot drop. MRI revealed a L4 - L5 central disc prolapse causing severe canal stenosis at that level. Results: Patient underwent L4 - L5 laminectomy and discectomy. At follow up a month later her bilateral foot drop had improved to normal and she was independent. Conclusion: This case highlights the fact that though very rare, L4 -L5 disc prolapse can manifest with bilateral foot drop and surgery can produce a good result. Introduction Unilateral foot drop due to lumbar disc prolapse is seen occasionally. Cauda equine features with associated bilateral foot drop due to lumbar degenerative and disc pathology is also seen occasionally. But bilateral foot drop due to a L4-L5 disc prolapse is very uncommon and almost impossible theoretically. This case had only bilateral foot drop without any cauda equine features due to a L4-L5 disc prolapse. Case report A 72 year old lady presented with sudden onset severe backache and bilateral foot drop when she was sweeping the floor. She gave no history of back pain or pain in the legs previously. She was on treatment for dyslipidaemia and had a past history of right cerebellar infarction for which she is on antiplatelet medication Clinical examination revealed a positive leg raising test at 45°, bilateral foot drop (Gr 1-2/5) with 50% sensory loss to pinprick both L5 dermatomes. Position sense was intact. Bilateral knee jerks, ankle jerks and plantar reflexes on both sides were normal. She had no other neurological deficits in the limbs and no cerebellar signs. Perianal sensation was intact with normal bladder function. Investigations to rule out medical causes of bilateral foot drop were all negative. MRI showed significant prolapse of the L45 intervertebral disc with ligamentum flavum hypertrophy and canal stenosis with evidence of compression of L5 foramina bilaterally (fig 1, 2, 3).