What it is
The cauda equina (Latin for "horse's tail") is the bundle of nerve roots that descend below the end of the spinal cord, transmitting motor and sensory signals to the legs, bladder, bowel, and genitals. Cauda equina syndrome occurs when these nerve roots are severely compressed — most commonly by a large central lumbar disc herniation.
This is a neurosurgical emergency. The time from onset of bowel or bladder dysfunction to surgical decompression directly affects the chance of meaningful recovery.
Recognizing it
The hallmark symptoms are:
- Urinary retention or incontinence — the most common and reliable indicator
- Saddle anesthesia — numbness in the areas that would contact a saddle when riding
- Bilateral leg weakness or pain — though this can be asymmetric
- Bowel dysfunction
Any combination of these symptoms, particularly in the setting of acute back or leg pain, requires urgent evaluation — the same day. MRI is the appropriate imaging study. Waiting to see if things improve is not appropriate when these symptoms are present.
Treatment
Emergency surgical decompression is the treatment. The extent of recovery depends on:
- How quickly surgery is performed after symptom onset
- The severity and completeness of neurological injury at presentation
Partial cauda equina syndrome (with urinary urgency or some preserved function) may recover better than complete syndrome (with true retention and absent perianal sensation). Recovery of bladder and bowel function is possible but not guaranteed, and many patients require rehabilitation after surgery regardless of outcome.