Focal T2 Hyperintensity in the Dorsal Brain Stem in Patients with Vestibular Schwannoma
K. Okamotoa,
T. Furusawab,
K. Ishikawab,
K. Sasaib and
S. Tokiguchic
a Center for Integrated Human Brain Science, Brain Research Institute, Niigata University, Niigata, Japan
b Department of Radiology, Niigata University Hospital, Niigata, Japan
c Department of Neurology, Toi Clinic, Izu, Japan
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Fig 1. MR image of a 53-year-old man obtained 3 years and 1 month after surgery. A 3-mm-thick FSE T2-weighted image obtained at the level of the inferior cerebellar peduncle shows a tiny area of hyperintensity in the left dorsal portion in the brain stem (arrow).
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Fig 2. MR images of a 52-year-old man obtained 1 year and 3 months after surgery.
A, A 3-mm-thick FSE T2-weighted image obtained at the level of the middle cerebellar peduncle shows a focal hyperintensity at the right lateral angle of the fourth ventricle in the brain stem (arrow).
B–D, Alternate CISS MR images show that the hyperintensity is contiguous (arrows). The lower end of the hyperintense area is located more anteriorly and deeper on the fourth ventricle floor, and the upper end is more posteromedial.
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Fig 3. MR images of the patient in Fig 2 obtained before surgery.
A, FSE T2-weighted MR image shows a large cystic schwannoma. The fourth ventricle is compressed by the tumor, and the tiny area of hyperintensity can be seen at the same site (arrow).
B, A CISS MR image shows the hyperintense area more clearly (arrow).
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Fig 4. MR image, obtained 13 months after surgery, of a 46-year-old woman with a large cerebellopontine angle meningioma. A 3-mm-thick FSE T2-weighted image obtained at the level of the middle cerebellar peduncle shows atrophic change of the right middle cerebellar peduncle and right cerebellar hemisphere, with a dilated fourth ventricle secondary to infarction in the right anterior inferior cerebellar artery distribution (distal AICA syndrome). Most of the meningioma was removed, but a residual tumor is seen in the enlarged right internal auditory canal as an isointensity lesion (arrow). No focal hyperintensity lesion is observed in the dorsal brain stem.
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