Neuroscience · Year 2 · from Neuroscience
Case 1: Cauda Equina Syndrome
Patient Presentation
Demographics: 52-year-old male
Chief Complaint: Severe low back pain, leg weakness, and urinary retention for 24 hours
History of Present Illness: A 52-year-old man with a history of chronic low back pain and lumbar disc disease presents with sudden worsening of back pain radiating to both legs that began 24 hours ago while lifting heavy furniture. Over the past 12 hours, he has developed progressive weakness in both legs and has been unable to urinate despite feeling the urge. He also reports numbness in his buttocks and inner thighs and decreased sensation around his anus. He denies fever, recent infection, or trauma besides the lifting event.
Physical Examination:
- Vital signs: BP 148/92, HR 88, T 37.0C
- General: In significant pain; cannot sit comfortably
- Neurological:
- Mental status: Normal
- Motor: Bilateral ankle dorsiflexion 3/5; knee extension 4/5; hip flexion 4/5
- Sensory: Saddle anesthesia (perineal and perianal numbness); decreased sensation posterior thighs bilaterally
- Reflexes: Absent ankle jerks bilaterally; knee jerks 1+
- Rectal examination: Markedly decreased rectal tone; absent anal wink reflex
- Bladder: Palpable distended bladder; post-void residual 650 mL on catheterization
Workup:
- MRI lumbar spine (emergent): Large central disc herniation at L4-L5 severely compressing the cauda equina; complete effacement of the thecal sac
- Urinalysis: Normal (no UTI)
Diagnosis: Cauda equina syndrome secondary to massive L4-L5 disc herniation
Treatment:
- EMERGENT neurosurgical consultation
- Foley catheter placement for urinary retention
- Emergency L4-L5 laminectomy and discectomy performed within 12 hours of presentation
- Post-operative gradual improvement in leg strength
- Bladder function slowly recovering but requiring intermittent catheterization at discharge
- Intensive physical therapy
- At 6-month follow-up: walking independently, partial recovery of bladder control, persistent mild sensory deficits in saddle area
Clinical Pearl: Cauda equina syndrome is a surgical emergency caused by compression of the nerve roots below the conus medullaris (typically below L1-L2). Unlike spinal cord compression, cauda equina is a lower motor neuron injury causing flaccid paralysis, areflexia, and LMN bladder dysfunction (urinary retention with overflow incontinence). The pathognomonic features are saddle anesthesia, bilateral leg weakness/sciatica, and bowel/bladder dysfunction. Surgical decompression within 24-48 hours correlates with better outcomes, though some advocate for even earlier intervention. Delayed surgery leads to permanent deficits, particularly bladder dysfunction.