Case of the Week
Section Editors: Matylda Machnowska1 and Anvita Pauranik2
1University of Toronto, Toronto, Ontario, Canada
2BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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August 28, 2014
Hirayama Disease
- Hirayama disease, also termed juvenile unilateral muscular atrophy of the upper extremity, or monomelic atrophy, is a self-limiting cervical myelopathy due to spinal cord compression by forward displacement of the posterior dural sac during neck flexion.
- It occurs mainly in young adults between the ages of 15 and 25 years.
- Clinical Presentation: Insidious onset of slowly progressive muscle weakness and muscular atrophy of the distal upper limb with sparing of brachioradialis muscles
- Key Diagnostic Features:
- Localized cervical cord atrophy
- Abnormal cervical curvature
- Asymmetric cord flattening with parenchymal changes in lower cervical cord
- Loss of attachment between the posterior dural sac and subjacent lamina
- Anterior shifting of the posterior wall of the cervical dural canal
- Enhancing epidural component in lower cervical and thoracic region
- Prominent epidural flow voids suggestive of dilated venous plexus
- DDx:
- Syringomyelia
- Amyotrophic lateral sclerosis
- Cervical spondylotic myelopathy
- Spinal cord tumor
- Rx: Even though it is a self-limiting disease, early recognition and the use cervical collar to avoid neck flexion is important to prevent disease progression.