title: MRI findings in Hirayama's disease: flexion-induced cervical myelopathy or intrinsic motor neuron disease?
abstract: Hirayama's disease is a benign juvenile form of focal amyotrophy affecting the upper limbs. Previous studies have suggested that the disorder is a neck flexion induced cervical myelopathy. We report clinical and magnetic resonance imaging findings in nine patients with Hirayama's disease. Cervical imaging of seven patients revealed spinal cord changes consisting of focal atrophy and foci of signal alterations. On neck flexion a forward movement and mild reduction in the anteroposterior diameter of the lower cervical cord against the vertebral bodies was noted in affected individuals as well as in five normal controls. In contrast to earlier reports, none of our patients showed complete obliteration of the posterior subarachnoid space. Measurement of the anteroposterior spinal cord diameter in each vertebral segment (C4-C7) revealed no significant differences in the degree of spinal cord flattening between the two groups. Furthermore, two of our patients had significant degenerative changes in the cervical spine (disc herniation, retrospondylosis) contralateral to the clinically affected side. These degenerative changes resulted in a marked cord compression on neck flexion but were not associated with ipsilateral clinical abnormalities or spinal cord alterations. Our results argue against a flexion-induced cervical myelopathy and support the view that Hirayama's disease is an intrinsic motor neuron disease.
authors.affiliation: Neurologische Klinik und Poliklinik, Universität Bonn, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Schröder
authors.forename: E
authors.initials: E
authors.lastname: Keller
authors.forename: S
authors.initials: S
authors.lastname: Flacke
authors.forename: S
authors.initials: S
authors.lastname: Schmidt
authors.forename: C
authors.initials: C
authors.lastname: Pohl
authors.forename: T
authors.initials: T
authors.lastname: Klockgether
authors.forename: U
authors.initials: U
authors.lastname: Schlegel
mesh_terms: D000293:Adolescent; D000328:Adult; D001132:Arm; D004576:Electromyography; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D016472:Motor Neuron Disease / Q000145:classification; D009119:Muscle Contraction / Q000502:physiology; D009134:Muscular Atrophy, Spinal / Q000145:classification / Q000175:diagnosis* / Q000503:physiopathology; D009334:Neck Muscles / Q000502:physiology; D012016:Reference Values; D013116:Spinal Cord / Q000503:physiopathology; D013117:Spinal Cord Compression / Q000209:etiology; D013118:Spinal Cord Diseases / Q000145:classification / Q000209:etiology; D013122:Spinal Diseases / Q000150:complications