Overview
Cauda equina syndrome (CES) is a rare but potentially catastrophic neurological emergency resulting from compression of the cauda equina — the bundle of lumbar and sacral nerve roots that descend below the termination of the spinal cord at L1–L2. Compression of these roots can cause permanent bowel, bladder, and sexual dysfunction as well as lower extremity paralysis if not surgically decompressed on an emergent basis. CES demands immediate recognition, urgent imaging, and expeditious surgical intervention.
Pathophysiology
The cauda equina occupies the lumbar spinal canal below the conus medullaris. Acute compression — most commonly by a large central disc herniation at L4–L5 or L5–S1 — simultaneously affects multiple nerve roots supplying the perineum, bladder, rectum, and lower extremities. The ischemic component of nerve root compression may produce irreversible injury within hours of onset, underscoring the time-sensitive nature of the condition. Other causes include epidural hematoma, epidural abscess, spinal metastasis, and severe spinal stenosis.
Symptoms — Recognize These Signs Immediately
CES is a medical emergency. Seek immediate emergency evaluation if you experience any of the following:
- Urinary retention — inability to initiate urination or complete bladder emptying (most sensitive early sign)
- Urinary or fecal incontinence — loss of voluntary bowel or bladder control
- Bilateral leg weakness or paralysis
- Sexual dysfunction — loss of erection, ejaculation, or genital sensation
- Severe low back pain with acute onset
Saddle anesthesia — numbness in the perineum, inner thighs, and genitalia
CES incomplete (CES-I) — with altered but not absent sphincter function — carries a better prognosis than CES retention (CES-R) with complete urinary retention and is more amenable to functional recovery following decompression.
Diagnosis
MRI of the lumbar spine with sagittal and axial sequences is the diagnostic study of choice and should be obtained without delay. Post-void residual bladder volume on ultrasound provides objective assessment of bladder function. Urodynamic studies have a role in the post-operative period to characterize residual bladder dysfunction.
Surgical Treatment
Emergency surgical decompression — typically within 24–48 hours of symptom onset, and ideally within 6–12 hours for complete presentations — is the only treatment that can reverse or limit neurological injury. The standard procedure is emergent lumbar discectomy with wide decompression of the affected nerve roots. Prolonged delay to surgery is associated with persistent bladder dysfunction, permanent neurological deficits, and chronic pain syndromes.
Prognosis
Neurological recovery is highly variable and inversely correlated with the duration and completeness of compression. Bladder function is the most commonly affected and the slowest to recover. Many patients require post-operative urological rehabilitation and long-term follow-up.
Consult Dr. Kevin Kwan
If you or someone you know is experiencing symptoms consistent with cauda equina syndrome, go to the nearest emergency department immediately. For urgent surgical consultation, Dr. Kwan is available for rapid evaluation and intervention.
Emergency: Call 911 or go to the nearest emergency room immediately.