Hirayama's Disease - A Rare Case Report with Review of Literature

Abstract

Introduction: Hirayama's disease is a rare benign disorder, also referred to as monomelic amyotrophy (MMA), Juvenile non progressive amyotrophy, Sobue disease. It is a focal, lower motor neuron type of disease. Mainly young males in their second and third decades of age are most commonly affected. It is seen most commonly in Asian countries like India and Japan. In majority of people cause of this disease is unknown. MRI of cervical spine in flexion will reveal the cardinal features of Hirayama disease.

Case report: A 22 year gentleman came with a history of insidious onset of weakness in both the hands begenning with left side followed by right of 4 years duration. On examination he had clawing of both hands with wasting of forearm muscles. Lower limbs had no abnormality with normal deep tendon reflexes. MRI showed thinning of cord from C4 to C7 level suggestive of cord atrophy. Based on these features a diagnosis of focal amyotrophy was made. A cervical collar was prescribed and patient is under regular follow up.

Conclusion: Hirayama disease is a rare self-limiting disease. Early diagnosis is necessary as the use of a simple cervical collar which will prevent neck flexion, has been shown to stop the progression.

Keywords: Hirayama's disease; Juvenile non-progressive amyotrophy; Sobue disease; monomelic amyotrophy.

Fig 1

Both forearms showing wasting of muscles

Fig 2

Both forearms showing wasting of muscles and sparing of Brachioradialis

Fig 3

X ray Cervical Spine showing loss of lordosis

Fig 4

MRI C spine Neutral position T2 images showing thinning of cervical cord from C4 to C7 level, suggestive of cord atrophy

Fig 5

MRI C spine Flexion T2 images showing anterior displacement of the posterior dura from C4 to T1 levels with maximal shift at C6 and C7