Cauda Equina Syndrome

Cauda Equina Syndrome Overview

The spinal cord extends from the brain down through the spinal canal inside the vertebral column. The spinal cord is surrounded by dural sacs, which are extensions of the brain-covering membranes. The brain-covering membranes are dura matter; arachnoid, which contains cerebrospinal fluid; and pia matter. Nerves that branch off of the spinal cord (also called nerve roots) are an extension of the spinal cord and are responsible for sending signals to and from the muscles and other structures throughout the body. These signals allow the brain to interpret information from the body including pain, touch, and sense of position. Outgoing signals allow the brain to control actions of the organs and muscle movements.

The spinal cord ends near the first lumbar vertebra in the lower back, forming the conus medullaris. The fibrous extension of the spinal cord is the filum terminale. The bundle of nerve roots below the conus medullaris is named the cauda equina (see Multimedia File 1). 

Compression or inflammation of the nerves roots can cause symptoms of pain, altered reflexes, decreased strength, and decreased sensation. Although these symptoms can become severe, and in some cases disabling, most are self-limiting and respond to conservative care. 

An extreme version of nerve compression or inflammation is cauda equina syndrome. Cauda equina syndrome is a serious condition caused by compression of the nerves in the lower portion of the spinal canal (see Multimedia File 2). Cauda equina syndrome is considered a surgical emergency because if left untreated it can lead to permanent loss of bowel and bladder control and paralysis of the lower extremities.

Cauda Equina Syndrome Causes

Cauda Equina Syndrome Symptoms

Symptoms of cauda equina syndrome include the following:

• Low back pain
  
  
• Unilateral (single leg) or bilateral (both legs) sciatica (pain originating in the buttocks and traveling down the back of the thigh and legs)
  
  
• Saddle and perineal hypoesthesia or anesthesia (numbness in the groin or area of contact if sitting on a saddle)
  
  
• Bowel and bladder disturbances
  
  
• Lower extremity motor weakness and loss of sensations
  
  
• Reduced or absent lower extremity reflexes

Low back pain can be divided into local and radicular pain.

• Local pain is generally a deep, aching pain resulting from soft tissue and vertebral body irritation.
  
  
• Radicular pain is generally a sharp, stabbing pain resulting from compression of the nerve roots. Radicular pain projects in dermatomal distributions (along the specific areas controlled by the compressed nerve).

Urinary manifestations of cauda equina syndrome include the following:

• Retention
  
  
• Difficulty initiating urination
  
  
• Decreased urethral sensation

Bowel disturbances may include the following:

• Incontinence
  
  
• Constipation
  
  
• Loss of anal tone and sensation

When to Seek Medical Care

Cauda equina syndrome is a surgical emergency. Persons should seek immediate medical care or go to the emergency department if they believe they have symptoms of cauda equina syndrome. Some of the early symptoms related to cauda equina syndrome, including low back pain and muscle weakness, are more often caused by simple disk herniation, which does not require urgent attention.

Clinical studies have determined that the likelihood of regaining function and having a positive outcome is directly related to the duration of symptoms of cauda equina syndrome. Within 48 hours of symptom onset, people with cauda equina syndrome should undergo surgical decompression (surgery to remove a portion of the bone in the vertebrae or to remove the offending lesions, such as the herniated disk, to make more space for the nerves).