Hereditary neuralgic amyotrophy (HNA)
Incidence
It is an autosomal dominant condition.
Clinical Characteristics
This condition is an autosomal dominant form of recurrent focal neuropathy. It is characterized clinically by episodes of brachial plexus neuropathy with muscle weakness and atrophy, as well as sensory disturbances. In almost all cases, the onset of muscle weakness is preceded by severe pain in the affected arm. The age of onset of the disease is in the second and third decade of life, although children in the first decade may be affected. Recovery is usually complete and begins weeks to months after the onset of symptoms. Recurrent episodes affect the same as well as the opposite arm. From electrophysiologic studies there is no evidence for a generalized neuropathy in HNA. Histologically minor signs of axonal degeneration distal to the affected brachial plexus have been described. Several minor dysmorphic features are associated with HNA, including short stature, hypotelorism, epicanthal folds, and cleft palate, but clear segregation of the dysmorphism with the neuropathy has not been proved. In the hereditary form, as in the sporadic form, individual episodes of symptoms may be preceded by infections or immunization.
Precipitants
In the hereditary form, as in the sporadic form, individual episodes of symptoms may be preceded by infections or immunization.
Provocation Tests
no
Diagnostic Procedures
Clinical diagnosis. is characterized by painful episodes of brachial palsy.