Plexopathies
Definition
Plexopathies are a form of peripheral neuropathy (i.e., a form of damage to peripheral nerves).
Common plexopathies include brachial plexopathy affecting the upper thorax (chest and upper back), arm, and shoulder region, cervical plexopathy affecting the neck and head, and lumbosacral plexopathy affecting the lower back and legs.
Description
A branching network of nerves in which individual nerve fibers can pass from one peripheral nerve to another is termed a nerve plexus. Within the peripheral nervous system, there are several such plexi (e.g., the cervical plexus, brachial plexus, lumbar plexus, sacral plexus, etc.) that are often associated with neuropathy and pain. These neuropathies are termed plexopathies.
Neural plexi
Neural plexi are branching and interwoven connections among peripheral nerves that allow a redistribution of nerve fibers among the peripheral nerves. As nerves are traced through the peripheral nervous system, they divide into branches that then communicate with branches of nearby nerves. Because peripheral nerves are composed of aggregates or collections of individual nerve fibers, individual fibers are able to pass through the branching connections (e.g., the individual nerve fiber that controls a specific muscle in a distant appendage) to then continue their course within a new peripheral nerve. Although the branching between nerves can be complex, in most cases the nerve fibers pass intact without branching and individual fibers remain separate and distinct.
For example, the brachial plexus is a neural plexus (a grouping and branching of nerves) located deep in the neck, shoulder, and maxilla region that is responsible for the proper innervation and control of the muscles of the shoulder, upper chest, and arms (upper limbs). Because of the complexities of branching nerve roots, trunks, and cords of the brachial plexus, injuries to the brachial plexus region often cause loss or impairments of function at distant muscle groups.
Injury to the median nerve of the brachial plexus can cause a loss of flexion of the fingers. This loss of flexion results in a loss of the critical ability to oppose the thumb with individual fingers. Median nerve impairment can also result in a loss of range of motion of the arm. Individuals who sustain median nerve injury causing loss of index finger flexion may develop an index finger that "points" or remains extended. Because the median nerve ultimately passes through the carpal tunnel of the wrist, injuries or inflammation of the wrist (e.g., carpal tunnel syndrome) can result in pain and loss of feeling far away from the wrist itself.
