The pathologic findings in two adult patients with idiopathic intracranial hypertension (IIH) who died unexpectedly are reported from the University of Iowa College of Medicine, Iowa City. Patient 1 died of cardiac arrest during operation for duodenal ulcer, and patient 2 died in her sleep of unknown cause. No histologic evidence of either intracellular or interstitial brain edema was found at autopsy. Arachnoid granulations were not available for study. 
COMMENT. The absence of cerebral edema was in agreement with the report of 3 patients studied by Greer and in contrast to a finding of interstitial and intracellular edema in cortical biopsies of 10 patients reported by Sahs and Joynt. A review of tissue from 3 of the Sahs and Joynt cases, one a girl aged 17 years, showed artifactual changes and no convincing evidence of edema on re-examination of slides. The authors recommend measures of brain water content of frozen tissue and examination of arachnoid granulations when available, in future investigations of pathogenesis of pseudotumor cerebri.
The MRI has been used to clarify the pathophysiology of pseudotumor in 7 children, aged 6 months to 13 years. Normal signal intensity in the white matter was in keeping with absence of brain edema, as reported in the Iowa autopsy specimens. (Connolly MB et al. 1992; see Progress in Pediatric Neurology II, 1994, pp 336-7).