Cauda Equina Syndrome Causes
Cauda equina syndrome is caused by significant narrowing of the spinal canal that compresses the nerve roots below the level of the spinal cord. Numerous causes of cauda equina syndrome have been reported, including traumatic injury, disk herniation, spinal stenosis, spinal tumors (neoplasms), such as metastatic tumors, meningiomas, schwannomas, and ependymomas, inflammatory conditions, infectious conditions, and accidental causes by medical intervention (iatrogenic causes).
Trauma
Traumatic events leading to fracture or partial dislocation (subluxation) of the low back (lumbar spine) result in compression of the cauda equina.
A collection of blood surrounding the nerves following trauma (epidural hematoma) in the low back area can lead to compression of the cauda equina.
Penetrating trauma (gunshot or stab wounds) can cause damage or compression of the cauda equina.
A rare complication of spinal manipulation is partial dislocation (subluxation) of the low back (lumbar spine) that can cause cauda equina syndrome.
Herniated Disk
Most disk herniations will improve on their own (are self-limiting) and respond well to conservative treatment, including antiinflammatory medications, physical therapy, and short periods of rest (one to two days).
Cauda equina syndrome results from a herniated lumbar disk in 1-15% of cases.
Of lumbar disk herniations, 90% occur either at the vertebral levels L4-L5 or L5-S1.
Seventy percent of cases of herniated disks leading to cauda equina syndrome occur in people with a history of chronic low back pain, and 30% develop cauda equina syndrome as the first symptom of lumbar disk herniation.
Males in their 30s and 40s are most prone to cauda equina syndrome caused by disk herniation.
Most cases of cauda equina syndrome caused by disk herniation involve large particles of disk material that have completely separated from the normal disk and compress the nerves (extruded disk herniations). In most cases, the disk material takes up at least one-third of the canal diameter.
Spinal Stenosis
Spinal stenosis is any narrowing of the normal front to back distance (diameter) of the spinal canal.
Narrowing of the spinal canal can be caused by a developmental abnormality or degenerative process.
The abnormal forward slip of one vertebral body on another is called spondylolisthesis. Severe cases can cause a narrowing of the spinal canal and lead to cauda equina syndrome (see Multimedia File 3).
Tumors (Neoplasms)
Cauda equina syndrome can be caused by isolated tumors (primary neoplasms) or from tumors that have spread to the spine from other parts of the body (metastatic spinal neoplasms). Metastatic spine tumors are most commonly from the prostate or lung in males and from the lung and breast in females.
The most common initial symptom of people with cauda equina syndrome caused by a tumor (spinal neoplasm) is severe low back and leg pain.
Later findings include lower extremity weakness.
Loss of feeling in the legs (sensory loss) and loss of bowel or bladder control (sphincter dysfunction) are also common.
Inflammatory Conditions
Long-lasting inflammatory conditions of the spine, including Paget's disease and ankylosing spondylitis, can cause a narrowing of the spinal canal and lead to cauda equina syndrome.
Infectious Conditions
Infections in the spinal canal (spinal epidural abscess) can cause deformity of the nerve roots and spinal column.
Symptoms generally include severe back pain and rapidly worsening muscle weakness.
Accidental Medical Causes (Iatrogenic Causes)
Poorly positioned screws placed in the spine can compress and injure nerves and cause cauda equina syndrome.
Continuous spinal anesthesia has been linked to cases of cauda equina syndrome.
Lumbar puncture (spinal tap) can cause a collection of blood in the spinal canal (spontaneous spinal epidural hematoma) in patients receiving medication to thin the blood (anticoagulation therapy). This collection of blood can compress the nerves and cause cauda equina syndrome.
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