What is Cauda Equina Syndrome?
Cauda Equina Syndrome is a condition wherein there is loss of function of the lumbar plexus, nerve roots and spinal canal below the termination of the spinal cord. This condition is a serious, acute neurologic condition.
The spinal cord is the continuation of the central nervous system from the brain. It extends from the brain stem up to the lumbar area. It is safely contained inside the vertebral column, where it is protected from trauma. Nerve roots are nerves that extend off from the spinal cord responsible for nerve impulse transmission to and from the other parts of the body. The end of the spinal cord is located adjacent to the 1st lumbar vertebra. The termination of the spinal cord is known as the Conus medullaris. Below the conus medialis, there is a bundle of nerve root referred to as the cauda equina. Cauda equina contains the nerve roots from L1 to L5 and S1 to S5.
The Cauda Equina Located At the Terminal End of the Spinal Cord
The presence of any injury to the nerve roots, such as inflammation and compression, causes pain, decreased muscle strength, decreased reflexes and diminished sensations. This condition may be self-limiting and will not cause permanent damage. However, a more severe form of nerve root compression, called cauda equina syndrome may arise below the conus medullaris. This condition is an acute surgical emergency because cauda equina syndrome can cause permanent damage and may lead to paralysis of the legs, and loss of bladder and bowel control.
Cauda Equina Syndrome Symptoms
The compression of the nerve roots causes symptoms and signs below the level of the cauda equina such as:
- Paraplegia or paralysis and weakness on the lower extremities
- Loss of sensation in the lower extremities
- Urinary retention because of the weakness of the bladder sphincter
- Post-void residual incontinence
- Fecal Incontinence because of anal sphincter weakness or loss of tone
- Loss of sensation in the anal area
- Saddle anesthesia or diminished sensation in the groin when sitting
- Sexual dysfunction
- Bilateral pain in the legs, but may be absent in other people
- Low back pain that can be subdivided into:
- Bilateral absence of leg reflexes
Cauda Equina Syndrome Causes
The primary cause of cauda equina syndrome is the narrowing of the spinal canal especially in the level of the lumbar spine, which causes significant compression of the nerve bundles in the area. Several conditions cause this phenomenon, which include:
1. Spinal Lesions and Tumors
The presence of tumors in the area causes compression of the nerve roots. Lesions and tumors may arise from primary cancer or from a metastatic condition.
Trauma to the lumbar spine such as fracture, dislocation or subluxation, trauma from lumbar puncture, spinal anesthesia, high levels of anesthesia as well as penetrating and blunt trauma may cause cauda equina syndrome.
3. Disc Herniation
Herniations in the lumbar disc also cause compression of the underlying nerves. Because of herniation, large segments of the disc separate and takes up to 1/3 of the diameter of the spinal canal compressing the nerve roots in that area.
Compression of the Cauda Equina by a Disc Herniation
4. Spinal stenosis
Spinal stenosis is the narrowing of the spinal canal. This can result from osteoarthritis, congenital defects or spondylolisthesis.
Inflammatory conditions in the spinal area as in the case of ankylosing spondylitis, polyneuropathy, Paget disease and chronic tuberculosis can cause compression on the cauda equina.
The presence of spinal epidural abscess causes damage to the spinal column and subsequently to the nerve roots.
7. Iatrogenic causes
The presence of badly positioned screws in the spine as a result of orthopedic surgery can impede the nerve roots. When patients taking anticoagulant therapy undergo lumbar puncture, this may cause hematoma formation in the spinal canal causing compression.
Cauda Equina Syndrome Diagnosis
Diagnosis of cauda equina syndrome is dependent on physical examination and imaging tests.
- Physical examination
The examiner usually performs pinprick on the legs to assess for diminished pain sensations in the area. The absence of pain sensation with no other conditions or with no anesthesia may indicate nerve root compression. Other assessments such as testing the muscle strength of the lower extremities, assessing the leg reflexes, and assessing the anal sphincter tone are done.
- Imaging Studies
CT scan and MRI scan usually confirms the diagnosis of cauda equina syndrome. The result of imaging tests allows the surgeon to determine the extent of compression and what structures cause it.
The absence of compression in the lumbar spine with the presence of symptoms may indicate other conditions such as urinary tract infection and diabetes that causes problems on the urination.
Cauda Equina Syndrome Treatment
The primary treatment for cauda equina syndrome is surgical management. This condition is a surgical emergency because it can cause permanent loss of function of the structures below the compression. Other medical managements are also done as adjunct therapy.
Surgical decompression of the spinal canal is the best option to relieve tension inside the spinal cavity. It is done through laminectomy or other approaches within 48 hours of diagnosis and symptoms. This approach prevents permanent nerve damage and may return patient to previous physical condition. Removal of hematoma or blood clots, tumor, bone fragments and repair of herniated disc is also done depending on the cause of the syndrome.
Pain resulting from the condition is managed using anti-inflammatory medications such as ibuprofen. Presence of inflammatory conditions in the spine also requires the administration of methylprednisolone, a corticosteroid, to relieve inflammation. Cauda equina syndrome that is caused by infectious conditions must also be treated using antibiotics. Malignant neoplasm must also be treated with radiation and chemotherapy to totally eradicate the cancer.
Cauda Equina Syndrome Prognosis
The prognosis of cauda equina depends on the duration of symptoms and the time interval of managements. Lesser recovery chances happen in patients with long interval from the appearance of symptoms and the implementation of surgical management. Basically, patients with bilateral pain and complete groin numbness have higher risk of developing permanent bladder paralysis and lesser recovery. Life expectancy is usually not affected, although it can cause permanent paralysis. When complications arise from bladder and bowel problems as well as paralysis, it can significantly reduce the life expectancy.
Untreated conditions and those who have longer duration of the condition may experience complications such as permanent paralysis of the lower extremities, and loss of bladder and bowel function.
The prevention of this condition depends on early diagnosis and early treatment. Preventing infections and trauma is very essential to avoid these causes of cauda equina syndrome.