Clinical Characteristics, Electrodiagnostic, and Imaging Findings of Atypical Forms of Motor Neuron Disease

ABSTRACT

OBJECTIVE: To describe the clinical characteristics, electrodiagnostic, and imaging findings of Hirayama disease (HD), late onset monomelic amyotrophy (LMA), and brachial amyotrophic diplegia (BAD). METHOD: A retrospective analysis of the medical records, electrodiagnostic, and imaging findings of 12 patients (4 HD, 2 LMA, 6 BAD) was done. For patients whose last clinic follow-up exceeded 6 months a telephone survey was done to see if there were any symptom changes. RESULTS: The clinical, electrodiagnostic, and imaging findings of the HD and BAD patients were similar to previous studies. Except for a later onset, age disease duration was too short to distinguish LMA from HD or other motor neuron diseases. One patient in the BAD group progressed to amyotrophic lateral sclerosis (ALS) and another died due to undetermined respiratory failure. These two patients showed abnormalities in their lower extremities, thoracic paraspinal, and craniocervical muscles on needle electromyography. Except for another patient, none of the other three patients showed abnormalities in their lower extremities, thoracic paraspinals, or craniocervical muscles on needle electromyography. CONCLUSION: HD and BAD can be considered as separate disease entities. However, a longer follow-up period than previously recommended is necessary to differentiate BAD from ALS. Follow-up period was too short to determine whether LMA can also be considered as a separate disease entity.