Herniated disc on the lumbar spine may compress the spinal nerve that supplies the leg and foot its motor function. Such condition may produce symptoms of pain, muscle weakness and drop foot that results to the inability to raise the ankle and toes upward.

Significance

Herniated disc along the lumbar area or the lower back cause significant risk to drop foot, which is also called foot drop. This is because the sciatic nerve which is the spinal nerve that supplies for the motor and sensory functions to the leg passes through the lumbar spine. Compression on this nerve along the spinal canal results to muscle weakness and loss of motor function to the leg and foot.

Features

Disc herniation occurs in stages namely degenerative, prolapse, extrusion and sequestration. Nerve impingement occurs during the sequestration stage when the disc breaks and moves outside the spinal canal to compress the sciatic nerve passing through it.

Causes

Lumbar disc herniation may be due to aging, injury, trauma, improper body mechanics and other degenerative spinal conditions.

Manifestation

Nerve compression of the sciatic nerve by a bulging or herniated disc may result in muscle weakness loss of function to the legs. The sciatic nerve supplies the motor function of the anterior tibalis which is the muscle responsible for the upward movement of the ankle. Compression of the sciatic nerve may weaken this muscles that may cause drop foot.

Risks

Drop foot may become a permanent disability if left untreated. It may progress to contractures and gait deviations as well as the development of the combination of muscular and neurological dysfunction.

Source:

Spine Universe: Causes of Herniated Disc

Eorthopod: Foot Drop With Degenerative Spine Conditions

eMedicine: Foot Drop

More Information:

Mayfield Clinic: Herniated Lumbar Disc