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BioMed Research International
Volume 2013, Article ID 478516, 12 pages
Review Article

Nosology of Juvenile Muscular Atrophy of Distal Upper Extremity: From Monomelic Amyotrophy to Hirayama Disease—Indian Perspective

1Division of Neurology, Department of Internal Medicine, Command Hospital, Alipore, West Bengal University of Health Sciences, Kolkata 700 027, India
2Department of Neuroradiology & Interventional Radiology, Command Hospital (Air Force), Bangalore 560007, India

Received 30 April 2013; Accepted 12 July 2013

Academic Editor: Jessica Mandrioli

Copyright © 2013 Kaukab Maqbool Hassan and Hirdesh Sahni. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Since its original description by Keizo Hirayama in 1959, “juvenile muscular atrophy of the unilateral upper extremity” has been described under many nomenclatures from the east. Hirayama disease (HD), also interchangeably referred to as monomelic amyotrophy, has been more frequently recognised in the west only in the last two decades. HD presents in adolescence and young adulthood with insidious onset unilateral or bilateral asymmetric atrophy of hand and forearm with sparing of brachioradialis giving the characteristic appearance of oblique amyotrophy. Symmetrically bilateral disease has also been recognized. Believed to be a cervical flexion myelopathy, HD differs from motor neuron diseases because of its nonprogressive course and pathologic findings of chronic microcirculatory changes in the lower cervical cord. Electromyography shows features of acute and/or chronic denervation in C7, C8, and T1 myotomes in clinically affected limb and sometimes also in clinically unaffected contralateral limb. Dynamic forward displacement of dura in flexion causes asymmetric flattening of lower cervical cord. While dynamic contrast magnetic resonance imaging is diagnostic, routine study has high predictive value. There is a need to lump all the nomenclatures under the rubric of HD as prognosis in this condition is benign and prompt diagnosis is important to institute early collar therapy.