Urgent warning signs
Cauda equina syndrome compresses the nerves at the base of the spinal cord
Cauda equina syndrome is a rare surgical emergency in which the bundle of nerve roots at the lower end of the spinal cord is squeezed [1]. Bladder or bowel changes and numbness between the legs are among the warning signs that need immediate attention [1].
Key points
- Leg and back pain are common and usually go away without surgery, but cauda equina syndrome is a surgical emergency [1].
- The nerve roots that control the bladder and bowel are especially vulnerable to damage [1].
- Earlier treatment offers the best outcomes, although some people do not recover complete function even with immediate treatment [1].
- A single normal bedside test does not rule the condition out, and rapid emergency MRI is recommended when it is suspected [2].
- Recovery often involves bladder, bowel, sexual and emotional support [2][3].
The cauda equina carries nerve signals to the pelvis and legs
The cauda equina is a bundle of nerve roots at the lumbar (lower) end of the spinal cord. The name is Latin for "horse's tail" [1]. These nerve roots send and receive messages to and from the pelvic organs and the lower limbs [1].
Cauda equina syndrome happens when those nerve roots are compressed, which cuts off sensation and movement [1]. A herniated disk pressing on the nerve bundle is one example that appears on MRI scans [1]. Fewer than 2% of all lumbar disc herniations lead to this syndrome [4].
The lowest nerve roots supply the bladder, the bowel and the sexual organs. That is why the typical problems involve those functions and the skin between the legs [4]. Squeezing and reduced blood supply to the nerve roots together can injure them [4].
When to get care
Cauda equina syndrome warning signs need emergency care
These signs need emergency care right away, because cauda equina syndrome is a surgical emergency [1]. Early treatment is what protects the nerves from permanent damage [1].
- Trouble with the bladder: you cannot urinate, or you leak urine and cannot hold it [1].
- Bowel dysfunction, which sits alongside bladder dysfunction in the list of warning signs [1].
- Numbness, tingling or burning between the legs, in the area between the anus and the genitals [1].
- Saddle numbness: reduced feeling around the buttocks, the area between the legs and the inner thighs, where a saddle would touch [1].
- Severe or worsening problems in the legs, including changed sensation [1].
- Pain that runs down both legs from the nerve roots, and weakness or lost reflexes in the legs [4].
Common mistake
Waiting for every sign to appear can cost time, because symptoms vary in intensity and may develop slowly [1]. In one review of older adults with diabetes, saddle numbness was absent at first in 38.7% of patients [5].
If you think you may have a medical emergency in the United States, call 911 or go to the nearest emergency room.
Doctors diagnose cauda equina syndrome with an exam and imaging
Diagnosis can be hard because symptoms vary and may change slowly over time [1]. Doctors usually work through several steps [1].
- Your doctor asks about your overall health, when the symptoms began and how they affect your activities [1].
- Your doctor checks stability, sensation, strength, reflexes, alignment and motion. You may be asked to stand, walk on your heels and toes, bend, and lift your legs while lying down [1].
- Your doctor may check the tone and numbness of the anal muscles with a gloved finger exam [1].
- Your doctor may use an ultrasound scan to measure how much urine stays in your bladder after you urinate [1].
- Your doctor may order X-rays, MRI scans and CT scans to assess the problem [1].
Speed matters once the syndrome is suspected. A recent review of national guidance recommends an emergency MRI at the hospital where you first present, as soon as possible and within four hours of the request [2]. A high leftover-urine reading raises suspicion, but a lower reading does not rule the syndrome out [2]. The review warns against false reassurance from any single bedside test [2].
The same review says the syndrome is defined by nerve dysfunction at the base of the spine, not by an MRI picture alone [2]. When MRI confirms compression, an immediate referral to a spine team is needed [2].
Emergency surgery relieves pressure on the compressed nerves
Immediate surgery is usually recommended to take pressure off the nerves [1]. The goal is to act before the pressure reaches the point where damage cannot be reversed [1]. The exact operation depends on what is causing the compression [1].
Delay matters. Waiting to decompress the nerves substantially increases the risk of permanent damage to automatic body functions such as bladder control [4]. The evidence on exact timing is still debated, as the table shows [6][4].
| Situation | Timing described |
|---|---|
| Incomplete cauda equina syndrome | Decompress as quickly as possible [2] |
| Syndrome with urinary retention (unable to urinate) | Within 24 hours of MRI under one national pathway [2] |
| Older adults with diabetes | Surgery within 48 hours improved bladder recovery [5] |
| Long-term bladder results by timing | Evidence was mixed and inconclusive [6] |
Cauda equina syndrome can leave lasting bladder and sexual problems
Even with immediate treatment, some people do not recover complete function [1]. Nerves heal at different speeds, and surgery may not repair permanent nerve damage [1].
- Bladder: about one third of people operated on for this syndrome caused by wear in the lower spine still had bladder problems at long-term follow-up [6].
- Bladder risk factor: studies consistently reported worse bladder outcomes in people who arrived unable to urinate than in those with incomplete syndrome [6].
- Sexual function: long-term sexual problems were reported in 58.4% of patients in a pooled estimate [3].
- Who is affected: sexual problems affect both men and women, and include trouble with arousal, orgasm and satisfaction, not only erections [3].
- Mood: an international group of patients and health professionals ranked social functioning, low mood and depression as outcomes of maximal importance [3].
Rehabilitation teams help people manage nerve damage after cauda equina syndrome
Rehabilitation after this syndrome is described as structured care covering the bladder, bowel, sexual health and emotional wellbeing [2]. You may want help from an occupational therapist, a social worker, a continence advisor or a sex therapist [1]. A support group lets you talk with people who have lived through it [1].
Some bladder and bowel control is automatic, but the voluntary parts may be lost. You may not know when you need to urinate or move your bowels [1]. General recommendations for managing bladder and bowel problems include the following. They are general suggestions, not a personal plan [1]:
- Emptying the bladder completely with a catheter 3 to 4 times each day is listed as a general recommendation [1].
- Drinking plenty of fluids and keeping up regular personal hygiene may help prevent urinary tract infections [1].
- Checking regularly for waste and clearing the bowels with gloved hands is also listed [1].
- You may want to use glycerin suppositories or enemas to help empty the bowels [1].
- Protective pads and pants can help prevent leaks [1].
Sources
- Cauda Equina Syndrome orthoinfo.org
- Cauda equina syndrome: a structured approach for the higher orthopaedic examination European journal of orthopaedic surgery & traumatology : orthopedie traumatologie
- Sexual dysfunction after cauda equina syndrome: a systematic review of long-term outcomes European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society
- Cauda Equina Syndrome: A Narrative Review Exploring the Pathophysiology, Clinical Spectrum, Diagnostic Strategies, and Time-Critical Management Cureus
- Diagnostic and Surgical Challenges of Cauda Equina Syndrome in Elderly Patients with Diabetes Mellitus: A Systematic Review and Meta-Analysis of Clinical, Radiological, and Surgical Outcomes La Clinica terapeutica
- Reassessing bladder recovery in cauda equina syndrome: long-term outcomes after surgical decompression:a systematic review and meta-analysis The spine journal : official journal of the North American Spine Society
Not medical advice. This page is general education written from the sources above. It cannot diagnose a condition or replace a licensed clinician who knows your history. If you may be having an emergency, call your local emergency number or go to the nearest emergency department.