Cauda Equina Syndrome

Houston Methodist spine specialists diagnose and treat cauda equina syndrome, a rare but serious condition caused by severe compression of the cauda equina — the bundle of nerve roots at the base of the spinal canal. Cauda equina syndrome is a medical and surgical emergency, and prompt diagnosis and treatment are critical to help prevent permanent nerve damage.

If you experience new bladder or bowel changes, saddle anesthesia (numbness in the groin area), or worsening leg weakness, seek emergency medical care immediately. If symptoms are severe or worsening, call 911 or go to the nearest emergency department immediately rather than waiting for an appointment.

Our spine specialists work together to identify the cause of compression and recommend treatment based on your symptoms and clinical findings. When appropriate, eligible patients may also have access to clinical trials studying promising new approaches to spine care.

What Is Cauda Equina Syndrome?

Cauda equina syndrome is a condition that occurs when the bundle of nerve roots at the lower end of the spinal canal becomes severely compressed, which can quickly disrupt bladder, bowel, sexual and lower limb function. “Cauda equina" is Latin for "horse's tail," describing how the nerve bundle appears within the spinal canal.

Common Causes of Cauda Equina Syndrome

Cauda equina syndrome can result from conditions that significantly narrow the spinal canal in the lumbar (lower back) region. Common causes include:

• Large or severe lumbar disk herniation
• Spinal stenosis
• Spinal tumors or metastatic cancer
• Trauma or injury to the lower spine
• Spinal infection or abscess
• Inflammatory conditions, such as ankylosing spondylitis
• Complications from spinal surgery

Signs & Symptoms of Cauda Equina Syndrome

The symptoms outlined below are considered red flags. If these symptoms appear — especially suddenly — seek emergency evaluation immediately.

Delayed treatment significantly increases the risk of permanent paralysis, bladder and bowel dysfunction, and loss of sexual function. Symptoms may appear suddenly or develop over hours to days, and both patterns require urgent medical evaluation.

Saddle Anesthesia

Loss of sensation in the inner thighs, groin/perineum and buttocks (the areas that would contact a saddle) may occur. This symptom alone warrants urgent medical evaluation.

Bladder & Bowel Dysfunction

Sudden difficulty urinating, urinary retention, loss of bladder control or loss of bowel control can signal serious disruption of the nerve roots that control these functions.

Severe Lower Back Pain

Sudden, severe lower back pain, often with radiating pain down one or both legs may occur.

Lower Limb Weakness

Progressive weakness, numbness or heaviness in one or both legs is a serious sign of nerve root compression. This is a warning sign that requires immediate medical evaluation.

How Cauda Equina Syndrome Is Diagnosed

Fast and accurate diagnosis is essential because nerve damage can progress quickly without treatment. If cauda equina syndrome is suspected, imaging tests should be performed as quickly as possible to assess nerve compression and guide urgent treatment decisions.

Your care team may use one or more of the following:

• Magnetic resonance imaging (MRI) – primary diagnostic tool; visualizes nerve roots, soft tissues and the degree of compression
• Computed tomography (CT) scan or CT myelogram – helpful when MRI isn’t an option; provides detailed cross‑sectional imaging of the spinal canal
• Neurological examination – assessment of reflexes, strength and sensation to evaluate nerve involvement