The spine is composed of small bones called vertebrae; between each vertebra is a "cushion" called a disc. With time, the jelly-like center of the disc may shift and leak out through a crack in the tougher, outer layer of the disc. This is called a disc herniation or "slipped disc." The North American Spine Society reports a common area for disc herniation to occur is in the lower, or lumbar, regions of the spine. While pain is the most common symptom of lumbar disc herniation, in rare cases, complications involving the bladder and the bowel may occur.
Urinary Retention
According to Dr. Michael Eisen, writing in the medical reference UpToDate, an especially common disc herniation is called an L2 herniation--herniation around the second lumbar vertebra. An L1/L2 herniation occurs at the disc between the first and second lumbar vertabrae; an L2/L3 herniation occurs between the second and third lumbar vertebrae. Herniations at L2 may result in two different, though related, syndromes. Conus medullaris syndrome is the name given to the collection of symptoms that occur when the nerve fibers at the end of the spinal cord--the conus medullaris--become damaged. Cauda equina syndrome occurs when the nerve fibers that hang below the spinal cord--the cauda equina--become injured or damaged. A possible complication of both of these syndromes is urinary retention, in which the bladder becomes paralyzed and cannot expand to hold more urine. The National Kidney and Urologic Diseases Information Clearinghouse website reports that severe discomfort or pain, as well as difficulty urinating, are all potential symptoms of urinary retention.
Urinary Incontinence
A lumbar disc herniation resulting in conus medullaris or cauda equina syndrome may also lead to urinary incontinence. This occurs because the bladder becomes overly full of urine, but the muscles within the bladder are paralyzed and limp, and so cannot contract to empty the bladder. The patient is not able to voluntarily empty the bladder, and so urine leaks out in a way that the patient is not able to control.
Sphincter Dysfunction
A sphincter is simply a medical term for a ring of muscles that controls the opening and closing of body passages. The anal sphincter, for instance, controls the exit of stool from the end of the bowel--the rectum. The urethral sphincter controls the exit of urine from the bladder. When a lumbar disc herniates, and causes conus medullaris or cauda equina damage, these sphincters may not function properly. If the anal sphincter is not working, fecal incontinence may occur--the patient will have no control over his bowel movement. If the urethral sphincter is dysfunctional, urine will leak out of the bladder, leading to another possible reason for urinary incontinence.
References
- North American Spine Society: Herniated Lumbar Disc
- "UpToDate;"; Anatomy and localization of spinal cord disorders; Michael Eisen; May 2009
- American Association of Neurological Surgeons: Cauda Equina Syndrome
- St. Joseph Hospital Glossary of Terms: Anal Sphincter
- Urinary Retention
