REGIONAL CEREBRAL BLOOD-FLOW IN PERITUMORAL BRAIN EDEMA DURING DEXAMETHASONE TREATMENT - A XENON-ENHANCED COMPUTED TOMOGRAPHIC STUDY

OBJECTIVE: Regional cerebral flood flow (rCBF) in peritumoral brain ed ema is assumed to be decreased because of increased interstitial press ure. Impaired blood flow might lead to local hypoxia, altered metaboli sm, and disturbed ion homeostasis, thus causing neurological sequelae. Steroid treatment is thought to positively influence the sequelae of brain edema. We aimed to determine the rCBF in peritumoral edema in hu mans receiving dexamethasone treatment and the relationship of rCBF to global CBF. METHODS: We measured rCBF in 11 patients with untreated a naplastic gliomas or glioblastomas that were World Health Organization Grade III or IV restricted to one hemisphere with significant peritum oral edema who were receiving a standard dose of dexamethasone. rCBF w as determined using stable xenon-enhanced computed tomography in a ste reotactic frame. Edema was defined both by means of actual histology ( stereotactic biopsies) and by imaging criteria. RESULTS: rCBF in perit umoral edema was decreased by 32% as compared with contralateral norma l white matter. In each patient, this reduction was linearly related t o blood flow in nonaffected white matter and cortex. The flow ratio in the different compartments was 1 (edema):1.5 (contralateral white mat ter):2.7 (contralateral cortex). Absolute perfusion values in contrala teral cortex (means +/- standard deviations) (29.9 +/- 7.1 ml/100 g/mi n) and contralateral white matter (16.1 +/- 3.7 ml/100 g/min) were sig nificantly decreased as well. CONCLUSION: Our study demonstrated that rCBF in peritumoral brain edema during steroid treatment is still decr eased and is in a range in which it may cause neurological sequelae. A lso, global CBF was decreased in all patients.