PROXIMAL BRACHIAL MONOMELIC AMYOTROPHY OR HIRAYAMA DISEASE: NO LONGER AN ALIAS? (case report)

Abstract

Background. Brachial Monomelic Amyotrophy (BMMA) has been called as Hirayama disease (HD) when it is characterized by unilateral distal upper limb weakness and atrophy that shows progression for a limited period and is associated with typical features on MRI of cervical spine in flexion. Objective was to explore the differences when BMMA affects the proximal upper limb muscles with the help of case report. Methods. A case report of BMMA in an adult Indian male is represented. Results. A 30-year-old man presented to us with a history of weakness in the proximal aspect of his left upper limb that began four years ago. The weakness was progressive up until 6 months prior to his presentation since when the weakness had neither worsened nor improved. Cervical spine contrast enhanced MRI revealed mild loss of cervical lordosis, but no features of HD like localized cord atrophy, loss of attachment of dura from subjacent lamina on neutral position axial T2WI MRI, nor any presence of posterior epidural crescentic enhancing mass on flexion contrast sagittal T1WI MRI. The patient was managed with supportive therapy and has been under regular follow up ever since. His clinical status has been stable. Conclusions. We support the suggestion to consider proximal Brachial Monomelic Amyotrophy to be a separate entity and to be distinguished from Hirayama disease that should be reserved for patients with distal upper limb involvement with cervical MRI findings on flexion studies.

Keywords

• Brachial Monomelic Amyotrophy
• Hirayama disease
• cervical spine flexion MRI