title: Misinterpretation of parahippocampal herniation for a posterior fossa tumor: imaging and intraoperative findings.
abstract: Tumors of the hippocampal and parahippocampal gyrus are not uncommon, nor are lesions of the cerebellopontine and ambient cisterns. Lesions in these areas include astrocytomas, meningiomas, gangliogliomas, hamartomas, neurilemomas, epidermoids, and dermoids. Preoperative imaging is an important tool that can help distinguish lesions, making surgical therapy more targeted and appropriate. The authors report a case of a 41-year-old man with right-sided atypical trigeminal neuralgia and a left ambient cistern abnormality that was radiologically interpreted as a mesial temporal lobe or extramedullary ambient cistern mass lesion. Surgical exploration for biopsy revealed an abnormal posterior fossa anatomy and a parahippocampal herniation into the perimesencephalic cistern. Biopsy confirmed the finding of normal brain.
authors.affiliation: Department of Neurosurgery, University of Pittsburgh Medical Center, Suite B 400, 200 Lothrop Street, Pittsburgh, PA 15213, USA. horowitz@neuronet.pitt.edu
authors.forename: Michael
authors.initials: M
authors.lastname: Horowitz
authors.forename: Amin
authors.initials: A
authors.lastname: Kassam
authors.forename: Elad
authors.initials: E
authors.lastname: Levy
authors.forename: L Dade
authors.initials: LD
authors.lastname: Lunsford
mesh_terms: D000328:Adult; D001706:Biopsy; D001932:Brain Neoplasms / Q000175:diagnosis; D003937:Diagnosis, Differential; D006624:Hippocampus / Q000473:pathology* / Q000601:surgery; D006801:Humans; D007430:Intraoperative Care; D008279:Magnetic Resonance Imaging; D008297:Male; D019564:Unnecessary Procedures