Hereditary neuropathy with liability to pressure palsy (HNPP) is a disorder that affects peripheral nerves. This condition 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. The most common problem sites involve nerves in wrists, elbows, and knees. 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. This condition is caused by the loss of one copy of the PMP22 gene or alterations within the gene. It is inherited in an autosomal dominant manner.
The Human Phenotype Ontology (HPO) provides the following list of features that have been reported in people with this condition. Much of the information in the HPO comes from Orphanet, a European rare disease database. If available, the list includes a rough estimate of how common a feature is (its frequency). Frequencies are based on a specific study and may not be representative of all studies. You can use the MedlinePlus Medical Dictionary for definitions of the terms below.
|Signs and Symptoms||Approximate number of patients (when available)|
|Decreased nerve conduction velocity||90%|
|Abnormality of the voice||7.5%|
|Cranial nerve paralysis||7.5%|
|Autosomal dominant inheritance||-|
|Segmental peripheral demyelination/remyelination||-|
|Vocal cord paralysis||-|
Making a diagnosis for a genetic or rare disease can often be challenging. Healthcare professionals typically look at a person’s medical history, symptoms, physical exam, and laboratory test results in order to make a diagnosis. The following resources provide information relating to diagnosis and testing for this condition. If you have questions about getting a diagnosis, you should contact a healthcare professional.
There is no specific treatment for hereditary neuropathy with liability to pressure palsy. Treatment is based on an individual's symptoms. Some people with this condition use braces, such as a wrist splint or ankle-foot orthosis (AFO). Protective pads worn at the elbows or knees may prevent pressure and trauma to local nerves. Activities to avoid include prolonged sitting with legs crossed, occupations requiring repetitive movements of the wrist, prolonged leaning on elbows, and rapid weight loss. Vincristine, commonly used in the treatment of lymphoma, has been reported to worsen the symptoms of hereditary neuropathy with liability to pressure palsy. Surgical decompression of nerves remains a controversial treament for this condition.
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What treatments are available for hereditary neuropathy with liability to pressure palsy? See answer