Complications of a Herniated Lumbar Disc

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i3rd lumbar vertebrae fracture image by Dr Cano from

Lumbar discs are plates of cartilage that separate the vertebrae of the lower back. When a lumbar disc ruptures, and its center, called the nucleus pulposus, herniates, it can bulge into the spinal canal. The spinal cord ends at the level of the first lumbar vertebrae. Below it, a bundle of spinal nerves called the cauda equina, or “horse’s tail,” descends from the spinal cord through the central canal of the vertebral column. A herniated lumbar discs can compress the cauda equina, a condition called cauda equina syndrome, and complications can ensue.

Excretory and Urinary Dysfunction

Nerves that are essential to the proper functioning of the urinary and excretory systems descend from the spinal cord as part of the cauda equina. These nerves can be damaged by lumbar disc herniation into the spinal canal. A number of disconcerting physical symptoms can result, such as bladder and bowel incontinence, or difficulty urinating.

The University of Maryland Medical Center warns that cauda equina syndrome can cause permanent damage to the nerves of the bowel and bladder, and that the incontinence may be irreversible.

Sensory Disturbances

Sensory nerves which detect feeling in the lower part of the body are also part of the cauda equina. Rather than in the back, damage from cauda equina syndrome most often causes pain in one or both legs. The precise location of this radiating pain varies depending on which lumbar disc has herniated. Sensory nerve damage can also cause numbness in the legs. warns that cauda equina syndrome is also associated with a progressively diminishing capacity to detect sensation in the inner thighs, back of the legs and area around the rectum.


The cauda equina contains motor nerves that supply voluntary muscle impulses from the brain, and involuntary, or autonomic, muscle impulses from the spinal cord. When compression from a lumbar disc herniation affects the motor nerves of the cauda equina, nerve impulses to the muscles in the thigh, leg and foot can be disrupted. Muscle weakness can result.

Muscle weakness from cauda equina syndrome may manifest as “foot drop,” a condition wherein an individual is unable to properly raise the foot while walking This causes a gait disturbance as the individual must raise the leg abnormally high while stepping in order to avoid dragging the foot on the ground.

If not treated, continued pressure on the nerves of the cauda equina could lead to paralysis, according to