Hirayama disease in a 17-year-old Chinese man

Re-evaluation of the symptoms of Hirayama disease through anatomical perspective

Hirayama disease is a rare disease of the anterior horn motor neuron caused by compression of the cervical spinal cord when the neck is flexed. Cervical myelopathy may accompany the disease. It is characterized by symmetrical or asymmetrical muscle weakness and atrophy of muscles innervated by lower cervical and upper thoracic motor neurons. We recorded two male cases of Hirayama disease between the ages of 15 and 21 based on magnetic resonance imaging (MRI) features obtained from the cervical neutral state and from the flexion position which appeared in the right upper extremity. Loss of strength and atrophy in the right upper extremities was existent in clinical findings of these patients. When MRI was taken in the flexion position, there were dilated veins as hypointense signal void on T2 weighted series in posterior epidural area. The contrast enhancement was seen on these veins. It was observed that the posterior dura was displaced anteriorly and the anterior subarachnoid space was narrow. In cases which show clinical findings such as atrophy and loss of strength, having normal MRI results obtained in the neutral position makes it difficult to diagnose Hirayama Disease. In case of a suspicion of Hirayama disease the diagnosis can be made more easily by MRI taken in the flexion position. These case reports aim to bring Hirayama disease to mind and optimize the management of affected individuals.

Hirayama Disease: A Rare Disease with Unusual Features

Hirayama disease, also known as monomelic amyotrophy (MMA), is a rare cervical myelopathy that manifests itself as a self-limited, asymmetrical, slowly progressive atrophic weakness of the forearms and hands predominantly in young males. The forward displacement of the posterior dura of the lower cervical dural canal during neck flexion has been postulated to lead to lower cervical cord atrophy with asymmetric flattening. We report a case of Hirayama disease in a 25-year-old Indian man presenting with gradually progressive asymmetrical weakness and wasting of both hands and forearms along with unusual features of autonomic dysfunction and upper motor neuron lesion.