Hirayama Disease MRI

A rare variety of cervical myelopathy related to flexion movements of the neck.

MRI Cervical spine sagittal T2w images
Focal lower cervical cord atrophy with anterior shifting of posterior dura on flexion MR studies is pathognomonic.

Similar case: http://www.neuroradiologycases.com/2012/11/hirayama-disease-mri.html

Hirayama et al first reported this disease in 1959.

Hirayama disease occurs mainly in young males between the ages of 15 and 25 years. The clinical features include insidious onset, predominantly unilateral upper extremity weakness and atrophy, cold paresis, and no sensory or pyramidal tract involvement.

Pathologic studies have shown the lesions only in the anterior horns of the spinal cord from C-5 to T-1, particularly marked at C-7 and C-8.

Current neuroradiologic techniques have shown forward displacement of the posterior wall of the lower cervical dural canal in neck flexion, which is presumed to be a primary

pathogenetic mechanism of Hirayama disease. The mechanism of this anteriorly displaced dural canal has been explained by Kikuchi et al as a tight dural canal in flexion, caused by a disproportional length between the vertebrae and the dural canal.

Early diagnosis of disease is necessary, because placement of a cervical collar will prevent neck flexion, which has been shown to stop disease progression.
Atrophy on routine nonflexion MR studies especially at the lower cervical cord, should raise the suspicion of Hirayama disease. When this sign is seen, a flexion MR study should be performed to confirm the diagnosis.