Significance of inflammatory changes in the brainstem in forensic autopsy cases

Brain stem encephalitis is an uncommon disease. In order to assess the significance of inflammatory changes in the brain stem in a forensic autopsy material we reviewed the findings over a 12-year period. Between January 1st 1982-December 31st 1993, neuropathological examination of the brain was carried out in 29% of the autopsy cases from the Institute of Forensic Medicine, University of Oslo. Out of 4546 brains, 110 (2.2%) showed microglial nodules and perivascular lymphocytic cuffing in the lower brain stem. In 66 of the cases (60%), the abnormalities were limited to the nucleus and/or the spinal tract of the fifth cranial nerve. Only 16 of the 39 cases with more widespread changes, diagnosed as brain stem encephalitis, had a serious underlying or concomitant disease. Three particular cases of brain stem encephalitis are reported in more detail. In all three cases we suggest that the brain stem inflammatory changes may be either the direct or a contributory cause of death.