Hereditary neuralgic amyotrophy

Hereditary neuralgic amyotrophy is an inherited nerve disorder marked by episodes of severe pain followed by nerve damage and muscle wasting, most often affecting the brachial plexus, the network of nerves serving the arm and shoulder. About half of cases involve a mutation in the SEPT9 gene, and the condition is inherited in an autosomal dominant pattern; episodes typically last one to six weeks and are thought to involve the immune system attacking nerves of the brachial plexus, sometimes also affecting the phrenic or recurrent laryngeal nerves. Symptoms include pain in the back, neck, arms or shoulders along with muscle wasting and weakness, and while nerves often regenerate with full recovery possible in milder cases, permanent damage can occur in more severe ones; the condition follows a course similar to the related Parsonage-Turner syndrome.