Peripheral nerve entrapment occurs when a nerve suffers from chronic compression along its normal anatomical course. Nerves normally are found within smooth channels or hollow spaces between bones, muscles, or ligaments. These spaces can become narrowed due to a variety of causes. For example, ligamentous scarring from trauma, bony enlargement due to arthritis, or muscle enlargement from overuse can all narrow the space available for nerves, compressing them. When nerves are compressed, their blood supply is reduced, a condition called ischemia. To illustrate, sometimes a person will fall asleep on their arm, impairing the circulation to the extremity. When the blood supply drops, the nerves stop working properly. When the person wakes up, the arm may feel “asleep.” There may be “pins-and-needles” sensations, or even weakness. These sensations go away once the circulation is reestablished. Similarly, when a nerve is chronically compressed (“peripheral nerve entrapment”), the resultant ischemia may cause abnormal sensations and weakness as well.
Peripheral nerve entrapments are typically treated conservatively at first. Physical therapy and splinting are attempted for several weeks. If no improvement occurs, the nerves undergo decompression. This is a surgical procedure in which the structures that are compressing the nerves are divided or even removed, thus relieving the compression. Commonly patients experience an immediate partial relief of symptoms, followed by a more delayed recovery phase that can require several weeks, months, or even years, depending upon both the location as well as the severity of the injury.