LAUSR

BACKGROUND Hirayama disease (HD), or monomelic amyotrophy, is a benign neurological disorder mostly affecting young Asian males. It usually presents with unilateral or bilateral muscular atrophy and weakening of the upper limbs. We treated an HD patient with bilateral hand paresthesia and weakness in one hand and both legs. This is the first HD case including lower extremity weakness and sensory abnormalities. We improved the patient's symptoms by administering steroids in parallel with conservative treatment. CASE DESCRIPTION A 22-year-old male visited our clinic with bilateral hand paresthesia and weakness in the right hand and both legs. He had been affected 40 days. Results of blood and cerebrospinal fluid tests were normal. Evoked potential study and brain magnetic resonance imaging (MRI) were normal. In cervical MRI, however, a lesion with high signal intensity of C6 level on T2-weighted images was confirmed, and gray and white matter were extensively invaded. We performed empirical steroid pulse therapy before the results of blood tests to differentiate spinal demyelinating disease. MRI with neck flexion showed HD-related findings, and autoantibody tests showed no specific findings. After steroid pulse therapy, his neurological symptoms improved within seven days, leaving only paresthesia of both toes when discharged. CONCLUSIONS HD occurs at a young age, so can damage the quality of life. Although our patient had unusual symptoms, the condition was diagnosed quickly, and his symptoms improved with steroid therapy. If HD is suspected, additional tests such as MRI with neck flexion should be performed and early steroid treatment might be considered.