Juvenile muscular atrophy of the distal upper limb (Hirayama disease) associated with atopy.

Juvenile muscular atrophy of the distal upper limb (Hirayama disease) is a rare disease predominantly affecting the anterior horn cells of the cervical spinal cord in young men. Although the disease is considered to be a type of cervical myelopathy, the mechanism remains unknown. An immunological study of five consecutive patients with this disorder who were examined in the neurology clinic at Kyushu University Hospital during the past 2 years were performed. All developed distal muscular atrophy and weakness of one or both upper limbs in the second decade, and showed forward displacement of the dural sac and passive dilatation of the posterior venus plexus at the lower cervical portion on MRI during neck flexion. Four of the five patients had one or more coexistent airway allergies, such as allergic rhinitis, pollinosis, and asthma, and all five patients had a family history of atopic or allergic disorders in close relatives. Four of the five patients had mild eosinophilia. All five patients commonly had IgE specific to two mite antigens, Dermatophagoides pteronyssinus and Dermatophagoides farinae, whereas three of them also showed a raised total serum IgE concentration. The frequency of mite antigen specific IgE was significantly higher in the present patients with Hirayama disease than in 82 healthy controls (26/82, p<0.005). These findings suggest that atopy may be one of the contributing factors for Hirayama disease.