Hereditary neuropathy with liability to pressure palsies

Hereditary neuropathy with liability to pressure palsies is a disorder that affects peripheral nerves. These nerves connect the brain and spinal cord to muscles as well as sensory cells that detect touch, pain, and temperature. In people with this disorder, the peripheral nerves are unusually sensitive to pressure.

Hereditary neuropathy with liability to pressure palsies causes recurrent episodes of numbness, tingling, and/or loss of muscle function (palsy). An episode can last from several minutes to several months, but recovery is usually complete. Repeated incidents, however, can cause permanent muscle weakness or loss of sensation. This disorder is also associated with pain in the limbs, especially the hands.

A pressure palsy episode results from problems in a single nerve, but any peripheral nerve can be affected. Episodes often recur, but not always at the same site. The most common problem sites involve nerves in wrists, elbows, and knees. Fingers, shoulders, hands, feet, and the scalp can also be affected. Many people with this disorder experience carpal tunnel syndrome when a nerve in the wrist (the median nerve) is involved. Carpal tunnel syndrome is characterized by numbness, tingling, and weakness in the hand and fingers. An episode in the hand may affect fine motor activities such as writing, opening jars, and fastening buttons. An episode in the leg can make walking, climbing stairs, or driving difficult or impossible.

Symptoms usually begin during adolescence or early adulthood but may develop anytime from childhood to late adulthood. Symptoms vary in severity; many people never realize they have the disorder, while some people experience prolonged disability. Hereditary neuropathy with liability to pressure palsies does not affect life expectancy.

Hereditary neuropathy with liability to pressure palsies is estimated to occur in 2 to 5 per 100,000 individuals.

Mutations in the PMP22 gene cause hereditary neuropathy with liability to pressure palsies.

Hereditary neuropathy with liability to pressure palsies is caused by the loss of one copy of the PMP22 gene or alterations within the gene. The consequences of PMP22 mutations are not clearly understood. Most likely, PMP22 mutations affect myelin, the protective substance that covers nerve cells. As a result of these mutations, some of the protective myelin covering may become unstable, which leads to increased sensitivity to pressure on the nerves.

Read more about the PMP22 gene.

This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder.