Cauda Equina Syndrome: Symptoms & Warning Signs
Cauda equina syndrome symptoms include numbness in the “saddle” area, new bladder or bowel problems, sexual changes and weakness in the legs. Cauda equina syndrome (CES) is rare, but it is a surgical emergency [Source].
Quick Answer: What Is Cauda Equina Syndrome?
Call 911 or go to the nearest emergency room now if you have back or leg pain with any of these: new numbness in the groin, buttocks or inner thighs; new trouble passing urine or controlling your bladder or bowels; new sexual numbness or problems; or leg weakness that is getting worse. Do not book an office visit or wait to see if it passes.
- It happens when the bundle of nerve roots at the bottom of the spinal canal is badly squeezed, most often by a large herniated disc [Source].
- It is rare. Most back pain and sciatica is not cauda equina syndrome [Source].
- It needs an emergency MRI and, if confirmed, usually urgent surgery to take pressure off the nerves [Source].
What Is Cauda Equina Syndrome?
The spinal cord ends in the upper part of the lower back. Below that point, a bundle of nerve roots keeps running down the spinal canal. This bundle is the cauda equina, which is Latin for “horse’s tail” [Source].
The “Horse’s Tail” Nerve Roots
These nerve roots carry signals to and from the legs, the bladder, the bowel and the sexual organs [Source]. Cauda equina syndrome happens when many of these roots are pressed on at the same time.
CES is rare. A study that covered all of Scotland for one year found about 3 cases per 100,000 people caused by disc problems. It was most common in adults aged 30 to 49 and was more common in women [Source].
Cauda Equina Syndrome Symptoms: Go to the ER Now
Not everyone has every symptom. Symptoms depend on which nerve roots are pressed and how hard [Source]. Watch for these warning signs:
Warning signs checklist
- Saddle numbness: new numbness or tingling in the buttocks, the area between the legs or the inner thighs.
- Bladder changes: trouble starting to pass urine, a weak stream, not feeling when your bladder is full, or leaking urine.
- Bowel changes: new loss of bowel control or not feeling when you need to go.
- Sexual changes: new numbness of the genitals or new sexual problems.
- Leg problems: sciatica in both legs, or weakness or numbness that is spreading or getting worse.
If you notice any of these signs with back or leg pain, call 911 or go to the nearest emergency room. Tell the staff, “I am worried about cauda equina syndrome.” For other back pain emergencies, such as pain after a bad fall or back pain with fever, see our guide on when back pain is an emergency.
Early (Incomplete) vs Complete CES
Doctors often split CES into stages. In early or incomplete CES, the bladder still works, even if it feels different. In later CES, the bladder stops emptying, which is called retention, or urine leaks without warning [Source].
This matters because damage in the later stage is less likely to be reversed [Source]. One review warned that many listed “red flags” are really signs of late CES [Source]. That is why you should act on early signs, such as new saddle tingling or a change in how your bladder feels. Do not wait until you cannot pass urine at all.
Common Causes of Cauda Equina Syndrome
The most common cause is a large herniated disc in the lower back [Source]. If the spinal canal is already narrow, a smaller herniation can be enough [Source]. Other causes include:
- Narrowing of the spinal canal (lumbar spinal stenosis)
- Tumors or other growths in the spine
- Spinal infection or inflammation
- Serious injury, such as a fall or car crash
- Bleeding in the spinal canal
- Rarely, a problem after spine surgery or spinal anesthesia
Most people with a herniated disc never develop cauda equina syndrome. Still, if you have a known disc problem, it helps to know the warning signs.
Cauda Equina Syndrome vs Sciatica
The table shows key differences between sciatica and CES.
| Feature | Typical sciatica | Possible CES |
|---|---|---|
| Legs affected | Usually one leg | Often both legs |
| Saddle feeling | Normal | Numb, tingling or changed |
| Bladder and bowel | Normal | New trouble or loss of control |
| Sexual function | Normal | New numbness or problems |
| What to do | See a doctor if it is severe or not improving | Go to the emergency room now |
Severe pain alone does not mean you have CES. Pain from a pinched nerve can be very strong and still be ordinary sciatica. The changes in saddle feeling, bladder, bowel and sexual function are what set CES apart.
If You Have Sciatica: Know Your Red Flags
Most sciatica gets better over weeks with simple care, such as staying gently active, short-term pain relief and physical therapy. People with a known large disc herniation or a narrow spinal canal should know the CES warning signs well. So should anyone whose sciatica moves into both legs.
Check in with yourself each day. Can you feel the toilet paper when you wipe? Does your bladder empty as usual? Is any leg weakness getting worse? If anything changes, treat it as an emergency, not as something to mention at your next visit.
For ordinary back or leg pain without these warning signs, an office visit is the right next step.
Dr. Amit Sharma & our minimally invasive pain & spine team.
How Cauda Equina Syndrome Is Diagnosed
A careful history and physical exam come first [Source]. The doctor checks strength, feeling, reflexes and saddle feeling. A rectal exam may be done to check muscle tone and feeling [Source].
- Urgent MRI: the main test. It shows the nerve roots and what is pressing on them [Source].
- Bladder scan: an ultrasound after you pass urine shows how much urine is left behind [Source].
- CT or CT myelogram: used when MRI is not possible, or to look at bone after an injury [Source].
Many people checked for possible CES turn out not to have it. In one review, about 19% of adults who came in with suspected CES had it confirmed by both exam and scan [Source]. Getting checked is still the right choice.
Treatment and Recovery
When CES is confirmed, urgent surgery is usually the treatment of choice. A spine surgeon (a neurosurgeon or orthopedic spine surgeon) removes what is pressing on the nerves, such as the disc fragment [Source]. Injections and pain medicines do not treat CES.
Why Timing Matters
A review of 322 patients found better recovery of feeling, strength, bladder and bowel function when surgery was done within 48 hours of symptoms starting than when it was done later [Source]. Some people still improve after later surgery [Source].
Life After Surgery
Recovery is different for each person. Leg strength often comes back before bladder function, and bladder function may keep improving for years [Source]. Some people have lasting nerve pain, numbness, or bladder, bowel or sexual problems. Care may include physical therapy, bladder and bowel programs, and emotional support [Source].
Role of a Pain Specialist
Cauda equina syndrome is treated in the emergency room and by a spine surgeon, not in a pain management office. SpinePain Solutions does not provide emergency care for CES.
A pain specialist can help in two non-emergency ways. The first is care for ordinary back pain and sciatica without warning signs, starting with conservative options. The second is help with lasting nerve pain after CES surgery, working alongside your surgeon. Dr. Amit Sharma, Chief, Division of Pain Medicine at Good Samaritan University Hospital, sees patients at our Bay Shore, Commack and Farmingdale offices (see office locations). Call 631-310-0000. If you are weighing spine surgery that is not an emergency, see our guide to getting a second opinion.
Frequently Asked Questions
What are the first signs of cauda equina syndrome?
Early signs often include new back pain with sciatica in both legs, numbness or tingling in the saddle area, and changes in how your bladder feels or works. Some people notice they cannot feel the toilet paper when they wipe. These signs need emergency care right away.
What is saddle anesthesia?
Saddle anesthesia is numbness or reduced feeling in the parts of the body that would touch a saddle. This includes the buttocks, the area between the legs and the inner thighs. New saddle numbness with back or leg pain is a warning sign of cauda equina syndrome.
Is cauda equina syndrome an emergency?
Yes. Cauda equina syndrome is a surgical emergency. If you have warning signs, call 911 or go to the nearest emergency room now. Do not wait for an office visit.
Can a herniated disc cause cauda equina syndrome?
Yes. A large herniated disc in the lower back is the most common cause. A smaller disc herniation can also cause it if the spinal canal is already narrow. Most herniated discs never cause cauda equina syndrome.
How is cauda equina syndrome different from sciatica?
Sciatica usually affects one leg, and bladder, bowel and saddle feeling stay normal. Cauda equina syndrome affects many nerve roots at once. It can cause symptoms in both legs, saddle numbness and new bladder, bowel or sexual problems.
How is cauda equina syndrome diagnosed?
Doctors start with your history and a careful nerve exam. An urgent MRI of the lower spine is the main test. A bladder scan after you pass urine can show if urine is being left behind. CT, sometimes with a myelogram, is used if MRI is not possible.
Can you recover from cauda equina syndrome?
Many people improve after surgery, but recovery is different for each person. Some people have lasting numbness, pain, or bladder, bowel or sexual problems. Bladder function can keep improving for years after surgery. Treatment before bladder control is lost gives the best chance.
How fast does cauda equina syndrome need surgery?
As fast as possible. A large review found better results when surgery was done within 48 hours of symptoms starting than when it was done later. Some people still improve after later surgery, but no one should wait to see if symptoms pass.
Dr. Amit Sharma & our minimally invasive pain & spine team.
Medical References
- American Association of Neurological Surgeons. Cauda equina syndrome. Wiseman D. Updated April 5, 2024. AANS.
- American Academy of Orthopaedic Surgeons. Cauda equina syndrome. OrthoInfo. OrthoInfo.
- Ahn UM, Ahn NU, Buchowski JM, Garrett ES, Sieber AN, Kostuik JP. Cauda equina syndrome secondary to lumbar disc herniation: a meta-analysis of surgical outcomes. Spine (Phila Pa 1976). 2000;25(12):1515-1522. doi:10.1097/00007632-200006150-00010. PubMed.
- Hoeritzauer I, Wood M, Copley PC, Demetriades AK, Woodfield J. What is the incidence of cauda equina syndrome? A systematic review. J Neurosurg Spine. 2020;32(6):832-841. doi:10.3171/2019.12.SPINE19839. PubMed.
- Woodfield J, Lammy S, Jamjoom AAB, et al. Demographics of cauda equina syndrome: a population-based incidence study. Neuroepidemiology. 2022;56(6):460-468. doi:10.1159/000527727. PubMed.
- Todd NV. Guidelines for cauda equina syndrome. Red flags and white flags. Systematic review and implications for triage. Br J Neurosurg. 2017;31(3):336-339. doi:10.1080/02688697.2017.1297364. PubMed.
Related resources: when back pain is an emergency, herniated disc, spinal stenosis, sciatica pain gone but leg still numb, nerve pain, back pain.
