Cauda Equina Syndrome Symptoms and Causes

Cauda equina syndrome is a rare condition in which exposed nerve fibers located at the bottom of the spinal cord become irritated. The irritation is caused by something with which the exposed nerves come into contact. 

The term cauda equina means “horse's tail”; it is so named because of the resemblance.

Generally, the sensitive nerve tissue that comprises the spinal cord and nerve roots is encased in the center of the spinal column in an area known as the spinal canal. In this way, the highly responsive nervous tissue is protected from structures that may put pressure on it (which will likely cause symptoms such as pain and/or altered functionality). 

Most of the time, cauda equina syndrome is caused by a large, centralized herniated disc between the areas of L4/5 and L5/S1. According to research reviewed by the British Medical Journal, only about 0.12% of all herniated discs in the U.S. likely cause cauda equina.

Other, less common causes include trauma or injury to the spine that leads to fractures and/or subluxations. Tumors or infections that compress the cauda equina may also cause this syndrome. Bone spurs in the spinal canal are another possible cause. Tuberculosis, Potts' paralysis and iatrogenic causes (for example spinal manipulation while you're under anesthesia or postoperative complications) are also implicated, as are things may that occupy spinal spaces, such as cysts.

You may be predisposed to cauda equina syndrome if you have spinal stenosis (either congenital or acquired). If acquired stenosis underlies your cauda equina syndrome, most likely the stenosis comes from disc degeneration and degeneration of your facet joints. You may also have a thickened ligamentum flavum and a narrowing of your spinal canal.

Cauda equina syndrome is roughly categorized into 2 basic types, according to the defining symptom of urinary retention.

Complete cauda equina is accompanied by urinary retention while incomplete is not. With complete cauda equina syndrome, urinary retention has already been diagnosed. With incomplete cauda equina syndrome, you may experience reduced urinary sensation, have a small stream, or similar symptoms, but you're still able to urinate.

Urinary retention can be serious and that's why it's very important to get checked if you notice any changes in this functionality.

Other symptoms of cauda equina syndrome include sexual dysfunction, dysfunction of the bowel and/or numbness or other sensory changes around your anus. (Numbness around the anus is called "saddle anesthesia.") Of course, back pain is a symptom, as are sensory or motor changes in your lower limbs (including weakness and/or loss of reflexes and more.) Back pain is a symptom, as are sensory or motor changes in your lower limbs (including weakness and/or loss of reflexes and more.)

Cauda equnia syndrome symptoms may present themselves in one of three general patterns, which are labeled as “types.” They are: 

• Type 1: Symptoms are acute and come on very suddenly and intensely. Symptoms of cauda equina syndrome caused by a herniated disc present in this way. 
• Type 2: As the final destination after a long journey of chronic back pain, with or without sciatica. 
• Type 3: Insidiously, where you've slowly been experiencing more and more numbness, as well as urinary symptoms. 

Cauda equina syndrome is a result of an interruption or dysfunction of the nerves associated with the lumbar and sacral vertebrae. However, such disruption is only diagnosed as cauda equina when your bladder, bowel and/or sexual function is impaired. This includes the symptom of saddle numbness or saddle anesthesia, discussed briefly earlier, which is loss of feeling around the anus.

Cauda equina syndrome is diagnosed with MRI, myelogram, specialized nerve testing such as nerve conduction velocity tests and/or electromyography, CT scans.

If your doctor suspects you have cauda equina, you'll be subjected to a physical exam that uses palpation (touch) to determine the degree of feeling and response around your anus and rectum.​

Most of the time, cauda equina syndrome is due to a herniated disc; therefore, the treatment of choice will likely be spinal decompression surgery, probably a discectomy.

Once your cauda equina syndrome diagnosis is confirmed by your doctor, and if your MRI shows that the cause of the pressure on the cauda equina is reversible, at that point, surgery may make the most sense as an immediate treatment option.

With that said, sometimes emergency surgery is required to enable you to avoid permanent dysfunction of your lower extremity (or extremities) as well as your bladder, bowel or sexual functioning. 

The effects of untreated cauda equina syndrome can be devastating; the same is true for cauda equina syndrome that is treated too late. Do not delay in speaking with your doctor about your treatment options.

If something other than a herniated disc is creating the pressure on your cauda equina, you'll likely need to work with a specialist or team of specialists to address that problem, as well.

The controversies around diagnosis and treatment of cauda equina syndrome can easily complicate decision making. However, this condition is potentially life-threatening, especially so if you do not heed your symptoms. If you notice symptoms, speak with your doctor as soon as you can.

When it comes to cauda equina syndrome, it's only natural to feel embarrassed about discussing what you notice, or apprehensive about getting checked. But remember, doing so in a timely way may save your life—or at the very least, your quality of life.