Cauda Equina Syndrome

Cauda equina (Latin) means horse tail. It is a name given to the nerve roots in the lumbosacral spinal canal as they look similar to horse tail on visualization. Cauda equina syndrome is the compression of the spinal nerve roots in the lumbar and sacral area of the spine Lesions above this level leads to compression of spinal cord and is not cauda equina syndrome, but the presentation is more dramatic and carries same or more urgency as of cauda equina syndrome.

Compression of the spine causes weakness of upper or lower extremities with increased reflexes and with or without involvement of the bowel or bladder. Cauda equina syndrome is essentially a clinical presentation of new onset or worsening weakness in one or both lower extremities, gait abnormality, involvement of the bladder and numbness in either lower extremity and peri genital area (sacral anesthesia).

These patient may also have sexual dysfunction. The patients usually have severe back pain. Cauda equina syndrome is usually associated with pain in the back and occasionally with radiculopathy. Rarely, patients with cauda equina syndrome may present without any complaints of pain.

This happens due to compression of the nerve roots in the lumbar spine and leading to dysfunction of the muscles as well as altered sensation that are taken care by the specific nerve roots. This is a severe form of presentation of nerve root compression in the lumbar spine.

It can present acutely or over many months or days. It may be caused due to degeneration of disk fragment, mass in the spinal canal, bleeding in the spinal canal, intraspinal mass like tumor, fracture, gunshot or rarely with a birth defect (usually an arteriovenous malformation). The presentation can be acute or chronic depending on the pathology.

Fractures or dislocations of the lumbosacral spine may lead to cauda equina syndrome. These are traumatic injuries and are associated with high velocity accidents like motor vehicle accident or fall from height. Traumatic disc herniation may also lead to cauda equina syndrome.

Acute cauda equina syndrome is usually treated under the care of a spine surgeon who can be of orthopedic or a neurosurgical background. A chronic cauda equina syndrome in which a surgery has been ruled out is usually under the care of neurologist and may also need care of oncologist or radiation oncologist in cases which are associated with malignancy or metastasis.

The rectal exam can be of diagnostic value in cauda equina syndrome lacks rectal sphincter is associated with cauda equina syndrome and should be checked in all patients. It may be the only sign of Cauda Equina Syndrome.

Cauda equina syndrome is diagnosed clinically due to its characteristic presentation of new onset or worsening of weakness, gait abnormality, bowel or bladder dysfunction, sexual dysfunction and sacral anesthesia. Confirmation of diagnosis is done with advanced imaging specifically. MRI which helps to find out the level of compression as well as helps in diagnosing the pathology.

In patients who have contraindications for MRI (Pacemaker, aneurysmal clip), CT scan and myelogram may be done. Confirmatory diagnosis of the pathology can only be done at the time of surgery and with the need of histopathologic examination of the tissue compressing on the nerve roots.

Causes of acute cauda equina syndrome can be a disk fragment (most common), fracture or dislocation of the spine, a hematoma caused by bleeding in the spinal canal, vascular insult to the nerve root due to underlying systemic or local pathology, infection, inflammation, gunshot or stabbing to spine, motor vehicle accident or fall, birth defect (arteriovenous malformation).

Cause of chronic cauda equina syndrome can be a slow growing mass or a degenerative spine with disk fragment or hypertrophied ligaments causing lumbar stenosis, birth defects etc. A mass can be in the form of tumor or metastasis or rarely a primary tumor of the nerve roots or the nerve elements.

Cauda equina syndrome is a disabling disease. It leads to weakness and usually with dysfunction of the bladder and sometimes bowels too. It leads to impaired gait due to the weakness of the muscles of the leg. Due to involvement of bladder, it may lead to retention or incontinence of urine leading to use of alternate methods for evacuation of the bladder. Patients may have gait problems too.

Patients with cauda equina syndrome usually have new onset or worsening weakness in one or both lower extremities, gait abnormality, involvement of the bladder and numbness in either lower extremity and peri genital area (sacral anesthesia). These patient may also have sexual dysfunction. The patients usually have severe back pain. These patients may have preexisting back pain and radiculopathy. Patients may have a history of cancer with or without metastasis to the spine and may have already undergone treatment for that in the past.

An acute onset cauda equina syndrome is a surgical emergency and the patient should go to the ER immediately. Advanced imaging should be performed as soon as possible to confirm the diagnosis after the physical examination of the patient. If a cauda equina syndrome is confirmed, a surgery may be needed to decompress the spine and allow the recovery of the nerve roots. Patients with chronic cauda equina syndrome who have insidious onset over many days or weeks, should seek medical attention to confirm the diagnosis as well as plan a possible treatment for their disease.

Cauda equina syndrome is a rare presentation of various pathologies of the spine. Most pathologies present with back pain or/and radiculopathy. They may also develop subtle weakness, but developing profound weakness with involvement of bladder and gait is rare. It is even rarer in degenerative disk disease and lumbar canal stenosis.

Patients with acute presentation of cauda equina syndrome with confirmatory diagnosis on an MRI showing mass effect on the nerve roots usually will need an urgent or emergent surgery to decompress the nerve roots. They will need to be admitted to the hospital and will need to undergo physical rehabilitation for optimization of the function as well as enhance their recovery.

Patients with chronic cauda equina syndrome may also need surgery depending on the pathology, but may also need adjuvant treatment especially in the cases of malignancy or metastasis in the form of chemo or radiotherapy. Occasionally these patients with chronic cauda equina syndrome can manage with adjuvant treatments only without the need for surgery. Patients with poor general condition and multiple comorbidities may have to be treated non-surgically so as to curtail the risk to their life due to the anesthesia as well as the surgery.

Recovery from cauda equina syndrome depends on the type of pathology, amount of compression, number of levels involved as well as the surgery performed. In most cases, the recovery will happen if their condition has been treated promptly but may not lead to full recovery of the functions. Patients will need to undergo physical rehabilitation to optimize their function as well as enhance their recovery.

Cauda equina syndrome usually causes bladder problems in the form of retention or incontinence. These patients need to be treated for their bladder problems separately so as to allow recovery and at the same time avoid complications due to the condition.

Cauda equina syndrome can occasionally cause involvement of bowels also which may lead to constipation in most cases.

Cauda equina syndrome causes disability in the form of weakness of the lower extremities and involvement of bowel or bladder, and problems with ambulation, but it cannot be a direct cause of death, though in patients with chronic sequelae of cauda equina complications like deep vein thrombosis causing pulmonary embolism, urinary tract infection causing sepsis pulmonary infection or respiratory failure may be secondary cause of death in such patients.

Cauda equina syndrome in itself is a rare entity and to get it twice is rarer, though not impossible. Patients who are predisposed to cauda equina syndrome like those with malignancy or metastasis or those with blood disorder and are on anticoagulants may rarely have cauda equina syndrome twice too.

An acute presentation of cauda equina syndrome if treated appropriately can lead to good recovery, but if not treated appropriately or in patients with chronic cauda equina, the sequelae of cauda equina syndrome may be long lasting or permanent too.

Any surgery on lumbar spine carries a risk of cauda equina syndrome. This can happen due to any bleeding at the surgical site, which leads to hematoma formation and compression of the nerve roots causing the presentation of cauda equina syndrome. These patients need to be treated urgently with decompression and need to be carefully followed up.

As the cauda equina syndrome and itself is a rare entity, there is no possible way to prevent a cauda equina syndrome. Patients who are on anticoagulants carry a higher risk of cauda equina syndrome, but the benefits of anticoagulant therapy far outweighs the risk of cauda equina syndrome or any other such bleeding complication. Similarly patient with metastases are at increased risk of cauda equina syndrome and their tumor is appropriately treated with chemo or radiotherapy, but prophylactic treatment with the surgery or radio or chemotherapy just to prevent cauda equina syndrome is not advisable.