Flexion-Induced Cervical Cord Compression: Hirayama Disease

Hirayama disease is a rare condition causing muscle weakness and atrophy, primarily affecting the distal upper limbs and involving specific nerve root distributions (C7-T1 myotomes). The underlying cause involves circulatory changes in the lower cervical spinal cord, leading to ischemia in the anterior horn cells. Diagnosis relies on electrophysiological studies and magnetic resonance imaging, particularly when the neck is flexed.

• 1
  The patient presented with progressive weakness and atrophy in the right distal arm and hand muscles.
• 2
  MRI in flexion revealed dilation of the posterior internal vertebral venous plexus due to forward displacement of the posterior dura mater.
• 3
  Electromyography showed active denervation in the C7-T1 innervated muscles of the right arm.