Hirayama disease: Clinical article

Object. Controversy exists over the choice of surgical candidates and prognosis of Hirayama disease. The purpose of this study was to examine the outcomes of patients with cervical flexion myelopathy who received surgical treatment. Methods. A retrospective study was conducted. From May 2002 through December 2006, 6 young patients with cervical flexion myelopathy were seen in the Department of Neurosurgery at Chang Gung Memorial Hospital. The neurological and radiological findings in all 6 patients met the criteria for Hirayama disease. All patients had evidence of a tight dural canal or forward migration of the posterior wall of the dural canal in dynamic MR imaging studies. Five patients were treated with surgical decompressive procedures (4 anterior and 1 posterior) and 1 patient received conservative treatment. Duration of follow-up ranged from 13 months to 4 years. Results. Motor function improved in 3 of 5 surgically treated patients and sensory function improved in 2. Neurological symptoms were unchanged in the conservatively treated patient. During follow-up MR imaging in the surgical group, anterior effacement during neck flexion was noted in 1 patient treated with a posterior approach. Conclusions. Hirayama disease is so rare that it is easily misdiagnosed. Diagnosis is achieved via clinical presentation, neurophysiological examination, and neuroradiological imaging studies (dynamic MR imaging). The anterior decompressive approach may be better for patients showing anterior effacement and severe cervical kyphosis during neck flexion in MR imaging.