title: [The usefulness of MRI around the tentorial incisura for determining the mechanism of brain stem injury: a case report].
abstract: We report a case of isolated brain stem injury caused by the tentorium cerebelli. A 17-year-old male was admitted to our hospital. Thirty minutes before admission, he was struck by another motorcycle while driving his own motorcycle. The Glasgow Coma Scale (GCS) was 10. He had no extremity weakness and his pupils were normal. CT scan showed no evidence of intracranial lesions except for facial bone fractures. His consciousness level improved to GCS 13 at 6 hours after admission. Follow-up CT scan was normal, however MRI 3 days after admission showed a contusion at the left lateral midbrain. He was discharged without any neurological deficits on 6 days after admission. Analysis of the distance between the brain stem and the tentorial margin using MR cisternography showed that the left side was shorter than the right side. We presumed that an isolated lateral brain stem injury was caused by the direct impact of the tentorium cerebelli. Typically the location of this type of lesion is present in the same side as that of impact. However in this case the orientation was opposite to that. We considered that the distance between the brain stem and the tentorial margin affected the mechanism of this lesion.
authors.affiliation: Department of Emergency and Critical Medicine, Tokai University School of Medicine, Bohseidai, Isehara-city, Kanagawa 259-1193, Japan. mshibata@is.icc.u-tokai.ac.jp
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Shibata
authors.forename: Seiji
authors.initials: S
authors.lastname: Morita
authors.forename: Hideo
authors.initials: H
authors.lastname: Ishizaka
authors.forename: Hideki
authors.initials: H
authors.lastname: Shiramizu
authors.forename: Kazuki
authors.initials: K
authors.lastname: Akieda
authors.forename: Yoshimori
authors.initials: Y
authors.lastname: Ikeya
authors.forename: Shinichi
authors.initials: S
authors.lastname: Iizuka
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Mamata
authors.forename: Mitsunori
authors.initials: M
authors.lastname: Matsumae
authors.forename: Sadaki
authors.initials: S
authors.lastname: Inokuchi
mesh_terms: D000293:Adolescent; D001933:Brain Stem / Q000293:injuries* / Q000473:pathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D014949:Wounds, Nonpenetrating