NORD gratefully acknowledges Nens van Alfen, MD, PhD, Department of Neurology, Radboud University Medical Center, The Netherlands, for assistance in the preparation of this report.
Hereditary neuralgic amyotrophy (HNA) is a rare genetic disorder characterized by recurrent episodes of severe pain in the shoulder and arm. In most cases, pain may persist for a few hours to a few weeks and is followed by wasting and weakness of the muscles (amyotrophy) in the affected areas. Additional symptoms including distinct facial features and skeletal abnormalities may also be present. HNA involves the brachial plexus, the interweaving network of nerves that extend from the spine through the neck, into each armpit and down the arms. These nerves control movements and sensations in the shoulders, arms, elbows, wrists and hands. They also control the opening and closing of small blood vessels in the skin, as in response to outside temperature. The number and frequency of episodes can vary greatly from one person to another. Approximately, 75% of affected individuals will have recurrent episodes. The severity of the disorder can also vary greatly due, in part, to the specific nerves involved. HNA may result in residual pain even between episodes and some individuals may develop significant disability to the shoulder and affected areas. In some cases, HNA is caused by mutations or duplications in the SEPT9 gene. The disorder is inherited in an autosomal dominant manner.
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