cord atrophy at the C6 –7 vertebral level (Fig 1A). Axial T1-
weighted and gradient-echo T2-weighted images showed evi-
dence of cord atrophy, more obvious on the left anterior aspect
(Fig 1B). Because the clinical presentation was reminiscent of
Hirayama disease, a flexion cervical MR study was obtained.
Sagittal and axial T1- and T2-weighted images showed anterior
displacement of the posterior wall of the cervical dural canal
below C-3, causing marked flattening of the cord (Fig 1C and
D). An epidural mass, isointense with the cord on T1-weighted
images and hyperintense on T2-weighted images, was noted at
the posterior aspect of the lower cervical canal with some small
flow void signals inside it (Fig 1C and D). After injection of
contrast material, the epidural mass displayed strong and ho-
mogeneous enhancement (Fig 1E). This mass disappeared af-
ter the patient returned to a nonflexion position, and it was
considered to be engorged venous plexus due to dural shifting.
The clinical presentation and the characteristic findings on
flexion MR images led to the diagnosis of Hirayama disease. A
neck collar was placed to prevent neck flexion, and the patient
was doing well, with no further progression of symptoms, at the
3-month follow-up study