II. Pathophysiology
- Massive Central DIsc protrusion
 - Compression of lumbar spinal nerve roots
 
III. Precautions
- Maintain a high index of suspicion
 - Delayed diagnosis or misdiagnosis is not uncommon (even by neurosurgical senior residents)
 
IV. Causes
- Large Central DIsc Herniation
 - Lumbar Spinal Stenosis
 - Lumbar Spine Trauma
 - Spinal Neoplasm
 - Lumbar Spondylosis with cauda equina compression
 - Post-procedure (iatrogenic)
 
V. Symptoms
- Bilateral Sciatica
- See also Lumbar Stenosis for extensive description
 - Dull aching pain in perineum, Bladder or Sacrum
 - Radiation to Buttock and leg
 - Provoked by Exercise or prolonged standing
 - Relieved with rest or forward bending
 
 - Neurologic Changes
- Saddle Anesthesia
- Change in Sensation when wiping with toilet paper
 
 - Bowel Incontinence or Constipation
 - Urinary BladderIncontinence or acute Urinary Retention
 - Acute Erectile Dysfunction
 
 - Saddle Anesthesia
 
VI. Signs
- Loss of perineal Sensation or perineal reflex (or Anal Wink)
- May best correlate with cauda equina findings on MRI
 
 - Loss of Rectal Tone
- Resting tone applies pressure to inserted finger without patient bearing down
 - Patient tries to resist Defecation
- Puborectalis Muscle contracts and applies pressure to the anterior inserted finger
 - External anal sphincter contracts and applies pressure circumferentially around the inserted finger
 
 - Patient bears down
- Pressure on inserted finger increases
 
 - Overall poor efficacy of Rectal Tone to diagnose S2-S4 neurologic deficit
 
 - Loss of Bulbocavernosus Reflex
 - Increased post-void residual Urine Volume
 - 
                          Foot Drop
                          
- Ankle dorsiflexion bilateral weakness
 - Absent Ankle Jerk
 
 
VII. Imaging (See Lumbar Stenosis)
- L-Spine MRI (preferred)
 - CT Myelography
- Indicated if MRI contraindicated
 
 
VIII. Lab (Indicated if Epidural Abscess or other infection suspected)
IX. Diagnosis: High yield exam findings
- Altered perineal Sensation
 - Increased post-void residual
 - Abnormal Rectal Tone
- More recent evidence (see above) suggests Rectal Tone is an unreliable test for cauda equina
 
 
X. Differential Diagnosis: Back Pain with Acute Neurologic Symptoms (e.g. Cord Syndrome, Peripheral Neuropathy)
- Central Spinal Stenosis (including cauda equina)
 - Spinal Infection (e.g. Spinal Epidural Abscess, Discitis)
 - Aortic emergencies (Aortic Dissection, Abdominal Aortic Aneurysm, Claudication)
 - Neurologic Syndromes (Multiple Sclerosis, Guillain-Barre, Transverse Myelitis)
 
XI. Management
- Neurologic Deficits suggest Cauda Equina Syndrome
 - Immediate Neurosurgery Consultation
 
XII. Prognosis
- Delay >72 hours risks permanent neurologic deficit
 
XIII. References
- Cali and Bond (2022) Crit Dec Emerg Med 36(7): 4-11
 - Swaminathan, Shoenberger and Long in Swadron (2023) EM:Rap 23(3): 19-21
 - Balasubramanian (2010) Br J Neurosurg 24(4): 383-6 [PubMed]