Several spinal cord problems may cause typical sciatica signs and symptoms, and while rare, these conditions may cause paralysis or become life-threatening if not treated immediately.

The following are a few examples of spinal-cord-related serious medical conditions that may cause typical sciatica symptoms, highlighting several differentiating symptoms.

Cauda Equina Syndrome

Watch this Cauda Equina Syndrome Video in our Video Center.

Cauda equina syndrome occurs when the cauda equina, a bundle of nerve fibers at the bottom of the spinal cord, becomes irritated by pressure or inflammation.

The spinal cord runs from the base of the skull to the top of the lumbar spine, where it splits into a bundle of nerve root branches called the cauda equina.

The individual nerves in this part of the spinal cord exit through small holes in the lumbar spine called foramina, and run downward through the sacrum, to the legs and feet.

The nerve fibers of the cauda equina communicate sensory and motor nerve messages between the central nervous system and the pelvis and lower limbs. They are responsible for control and sensory function of the bowel and bladder, genitals and saddle area, and the nerves that run down the legs.

Any lumbar spine condition that compresses the nerves of the cauda equina can cause cauda equina syndrome.

Often, it is a massive disc herniation that causes the syndrome. Other causes include spinal stenosis, inflammation or infection within the spinal canal, tumors, or injury to the spine.

The symptoms of cauda equina syndrome will vary depending on which nerves are affected and the degree of nerve compression and subsequent irritation.

These symptoms include severe low back pain, and neurological problems in the saddle region and lower limbs that may include urinary or bowel incontinence, loss of feeling, motor weakness, or loss of motor function in the legs such as difficulty walking.

Though rare, acute cauda equina syndrome is a serious medical emergency. It usually requires decompression surgery on the spine within 24 hours, in order to remove pressure from the nerves.

Acute cauda equina syndrome that results in nerve damage is rare. However, if left untreated, cauda equina syndrome can result in paralysis, loss of sensation below the lumbar spine, and permanent loss of bladder and bowel control.

This syndrome is caused by the compression of the cauda equina, a group of nerves at the bottom of the spine. The cauda equina extends over part of the lower lumbar spine and the sacrum (triangle-shaped bone at the bottom of the spine). A primary symptom of cauda equina syndrome is sharp, stabbing pain in the legs as in sciatica. ¹ Gardner A, Gardner E, Morley T. Cauda equina syndrome: a review of the current clinical and medico-legal position. Eur Spine J. 2010;20(5):690–697. doi:10.1007/s00586-010-1668-3

A few differentiating signs and symptoms include some combination of:

Severe low back pain
Severe weakness and numbness in the legs making it difficult to stand or walk
Numbness, tingling, and/or weakness in the groin, genital, and/or anal region
Partial or complete loss of bowel and/or bladder control or retention of urine
Sexual dysfunction (often due to numbness in the perineal area)

Cauda equina syndrome may progress suddenly. It is important to treat this syndrome as soon as possible to prevent paralysis of the lower body.

Spinal Epidural Abscess

An illustration showing epidural space in the lower back.

Abscesses containing fluid or pus can collect in the epidural space and cause sciatica-like symptoms.

A spinal epidural abscess is the collection of pus in the epidural space. This abscess may develop as a result of cells that are carried through the blood from other locations, such as skin or urinary tract infections. The abscess compresses the spinal cord, causing sciatica-like symptoms, usually in both legs. ² Alerhand S, Wood S, Long B, Koyfman A. The time-sensitive challenge of diagnosing spinal epidural abscess in the emergency department. Internal and Emergency Medicine. 2017;12(8):1179-1183. doi:10.1007/s11739-017-1718-5

Apart from low back pain with radiating pain in the legs, other signs and symptoms of a spinal epidural abscess may include:

Fever
Increased pain when lying down or gently pressing the lower back
Loss of bladder control

Epidural abscess pain typically worsens with time. The abscess may become larger and spread to other areas if left untreated. Patients with immune deficiency, diabetes, and intravenous drug use may be at an increased risk for spinal epidural abscesses.

Hemorrhagic Lumbar Synovial Cyst

An illustration showing facet joint in the vertebrae.

Facet joint degeneration may lead to the formation of hemorrhagic lumbar synovial cysts.

A lumbar synovial cyst is a fluid-filled cavity that usually develops from degenerated facet joints and compresses the spinal cord. They usually develop from abnormal motion within a vertebral segment. In most cases, these cysts are not a medical emergency and may be treated non-surgically. However, if bleeding occurs into the cyst, it is called a hemorrhagic lumbar synovial cyst and is considered a medical emergency.

A hemorrhagic lumbar synovial cyst may cause acute, intolerable pain, numbness, and/or tingling in the lower back and legs, similar to sciatica. If sciatica symptoms become acute or severe, it is advised to visit a doctor. ³ Park HS, Sim HB, Kwon SC, Park JB. Hemorrhagic lumbar synovial cyst. J Korean Neurosurg Soc. 2012;52(6):567–569. doi:10.3340/jkns.2012.52.6.567 ^, ⁴ Cicuendez M, Alen JF, Ramos A, Lobato RD, Lagares A. Spontaneous hemorrhage into a lumbar synovial cyst. Eur Spine J. 2010;19 Suppl 2(Suppl 2):S190–S192. doi:10.1007/s00586-010-1332-y

See Synovial Cyst Symptoms and Diagnosis

The above list is not comprehensive; anyone with severe or concerning sciatica signs and symptoms is advised to consult a doctor.

View this Sciatica: Symptoms, Causes, and Treatment Infographic in our Infographic Center.

What is sciatica?

Sciatica is a set of symptoms that occurs when nerve roots between L4 to S3 on either side of the lower spine become irritated or pinched.

Sciatica symptoms originate in the lower back, radiate deep into the buttock, and travel down the leg.

Sciatica occurs due to an underlying medical condition; it is not a medical diagnosis.

What are the common causes of sciatica?

Lower back conditions that may cause sciatica include:

Lumbar Herniated Disc
Spondylolisthesis
Degenerated Disc Disease

What are the common symptoms of sciatica?

PAIN. Sciatica pain may be constant or intermittent and is usually described as a burning sensation or a sharp, shooting pain that extends from the lower back into the buttock, leg, and possibly the foot.
ALTERED SENSATION. Numbness, tingling, and/or a pins-and-needles sensation may be felt at the back of the leg.
WEAKNESS. Weakness may be felt in the leg and foot. A feeling of heaviness in the affected leg may make it difficult to lift the foot off the floor.

How is sciatica treated?

Nonsurgical Treatments

While treating sciatica, it is essential to obtain an accurate diagnosis of the underlying cause, since the treatment of each condition may be unique and different from the others.

Nonsurgical methods are typically tried first and may include one or a combination of the following:

Physical Therapy
Massage
Lumbar Therapeutic Injections
Medication
Manual Therapy

Surgical Treatments

Surgery may be indicated when progressive neurological deficits occur.

Microdiscectomy
Lumbar Decompression

This information is not intended or implied as a substitute for medical advice, diagnosis or treatment. All content, including text, graphics, images or other information provided is intended for general information purposes only. Always consult with your physician for diagnosis or treatment.

Dr. Jay Jagannathan is a neurosurgeon specializing in spine surgery, and he is the Founder and President of a Michigan-based multidisciplinary practice offering neurosurgery, neurology, and pain management services.

1 Gardner A, Gardner E, Morley T. Cauda equina syndrome: a review of the current clinical and medico-legal position. Eur Spine J. 2010;20(5):690–697. doi:10.1007/s00586-010-1668-3
2 Alerhand S, Wood S, Long B, Koyfman A. The time-sensitive challenge of diagnosing spinal epidural abscess in the emergency department. Internal and Emergency Medicine. 2017;12(8):1179-1183. doi:10.1007/s11739-017-1718-5
3 Park HS, Sim HB, Kwon SC, Park JB. Hemorrhagic lumbar synovial cyst. J Korean Neurosurg Soc. 2012;52(6):567–569. doi:10.3340/jkns.2012.52.6.567
4 Cicuendez M, Alen JF, Ramos A, Lobato RD, Lagares A. Spontaneous hemorrhage into a lumbar synovial cyst. Eur Spine J. 2010;19 Suppl 2(Suppl 2):S190–S192. doi:10.1007/s00586-010-1332-y