title: A rare anterior spinal epidural cyst mimicking Hirayama disease.
abstract: BACKGROUND
  Hirayama disease is a rare focal motor neuron disorder that manifests as slowly progressive unilateral or bilateral hand weakness and atrophy.
  
  
  METHODS
  The case report of a young man who presented with the phenotype of Hirayama disease indicated an extensive anterior cervical epidural arachnoid cyst.
  
  
  RESULTS
  A 34-year-old man presented with a 5-year history of slowly progressive hand and forearm weakness and atrophy. Nerve conduction studies demonstrated low median and ulnar motor amplitudes, and EMG demonstrated fibrillation potentials and long-duration, high-amplitude motor unit potentials in C6-T4-innervated muscles. MRI demonstrated a longitudinally extensive anterior spinal epidural cyst extending from C2 to L1. The patient had improved hand strength after surgery.
  
  
  CONCLUSIONS
  Anterior cervical epidural spinal cysts should be considered in the differential diagnosis in patients who present with slowly progressive hand weakness.
authors.affiliation: Department of Neurology and Neurosurgery, Mayo Clinic, 4500 San Pablo Road South, Jacksonville, Florida 32224, USA.
authors.forename: Megan R
authors.initials: MR
authors.lastname: Rahmlow
authors.forename: Stephen
authors.initials: S
authors.lastname: Pirris
authors.forename: Devon I
authors.initials: DI
authors.lastname: Rubin
mesh_terms: D000328:Adult; D003560:Cysts / Q000175:diagnosis* / Q000601:surgery; D004824:Epidural Space; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009431:Neural Conduction / Q000502:physiology; D013120:Spinal Cord Neoplasms / Q000175:diagnosis* / Q000503:physiopathology; D014897:Spinal Muscular Atrophies of Childhood / Q000503:physiopathology*