Cauda equina syndrome is not a spinal cord syndrome. However, it mimics conus medullaris syndrome, causing similar symptoms.
Cauda equina syndrome most commonly results from a herniated disk in the lumbar spine. Other causes include congenital neurologic anomalies (eg, spina bifida), spinal cord infection, spinal epidural abscess, spinal cord tumor, spinal cord trauma, spinal stenosis, arteriovenous malformation, and complications after spinal surgery. Many of these conditions cause swelling, which contributes to compression of the nerves.
Cauda equina syndrome (like conus medullaris syndrome) causes distal leg paresis and sensory loss in and around the perineum and anus (saddle anesthesia), as well as bladder, bowel, and pudendal dysfunction (eg, urinary retention, urinary frequency, urinary or fecal incontinence, erectile dysfunction, loss of rectal tone, abnormal bulbocavernosus and anal wink reflexes). Urinary retention or incontinence results from loss of sphincter function.
In cauda equina syndrome (unlike in spinal cord injury), muscle tone and deep tendon reflexes are decreased in the legs.
Without treatment, cauda equina syndrome can cause complete paralysis of the lower extremities.
If symptoms suggest cauda equina syndrome, MRI should be done immediately if available. If MRI is unavailable, CT myelography should be done.
If traumatic bone abnormalities (eg, fracture, dislocation, subluxation) that require immediate spinal immobilization are suspected and advanced imaging is not immediately available, plain spinal x-rays can be done. However, CT detects bone abnormalities better.
Usually, treatment focuses on the disorder causing cauda equina syndrome, usually by relieving compression.
If cauda equina syndrome is causing sphincter dysfunction (eg, causing urine retention or incontinence), immediate surgery (eg, diskectomy, laminectomy) is required.
Analgesics should be used as needed to relieve pain. If symptoms are not relieved with nonopioid analgesics, corticosteroids can be given systemically or as an epidural injection; however, analgesia tends to be modest and temporary. Corticosteroids can also reduce swelling.
The most common cause of cauda equina syndrome is a herniated disk.
If cauda equina syndrome is possible, immediately do MRI, or if it is not available, do CT myelography.
Surgically evaluate patients with symptoms of cauda equina syndrome (eg, urinary retention, frequency, or incontinence) immediately.