Hi Hiriyama disease is a motor neuron disease which usually affects the young males in the age group 15 - 25 years old. It starts with sudden onset of muscular atrophy especially of hand and forearm and weakness of hands. Treatment mainly consists of physiotherapy focusing on hand coordination movements and muscle strengthening exercises. Please visit a Neurologist for further evaluation and management. In case of further queries, please feel free to write back to me. Regards Dr Prashik Meshram