Hirayama disease in children from North America.

Hirayama disease has been mainly reported from Asia; only a few cases are from the Western hemisphere, particularly North America. This is a retrospective chart review of patients < 18 years, diagnosed with Hirayama disease from a single center over 10 years. We diagnosed 6 children (4 boys), 15.1 ± 1.2 years of age. Symptom onset was 3 months to 3 years before presentation. All had unilateral or bilateral asymmetric distal upper extremity weakness without objective sensory loss. Oblique amyotrophy and cold paresis were noted in 5. On electromyography, acute-on-chronic denervation was most frequently noted in cervical-8 (C8) and thoracic-1 (T1) myotomes followed by cervical-7 (C7) myotome in both upper limbs, sparing C5-C6 myotomes. Cervical magnetic resonance imaging (MRI) was abnormal in 3. Symptoms progressed over a mean of 16.5 months. Treatment consisted of placement of cervical collar. Heightened awareness of this entity among pediatric neurologists in North America will lead to early diagnosis and intervention, avoiding unnecessary investigations.