Changes of cerebral blood flow following dexamethasone treatment in brain tumour patients. A Xe/CT study.
BACKGROUND
It is not exactly known how dexamethasone improves the function of brain that is affected by tumour. Whether and in what sense dexamethasone influences cerebral blood flow has rarely been addressed and previous investigations have yielded inconsistent results.


METHODS
Stable xenon-enhanced computed tomography (Xe/CT) was used to assess the regional cerebral blood flow (rCBF) in 67 patients with supratentorial primary and secondary brain tumours. rCBF studies were done at least once prior to resection or stereotactic biopsy of the tumours. In nine patients repeated studies before surgery and in 15 patients additional studies after resective surgery were obtained. Dexamethasone was administered according to the clinical needs before surgery and systematically after surgery. Of the preoperative studies 30 were obtained before and 47 during dexamethasone treatment. The rCBF data were analysed upon correlations with daily dose, cumulative dose, and duration of dexamethasone treatment. Moreover, individual courses before and after surgery were examined.


RESULTS
Mainly inverse correlations were found between the treatment parameters, particularly the daily dose of dexamethasone, and rCBF. Only in the subgroup of glioblastoma patients, a positive correlation was found of both duration and cumulative dose of dexamethasone with rCBF in oedema. Serial observations of individual patients confirmed the above findings, yet with possible exceptions. After tumour resection a clear improvement of rCBF was regularly observed.


CONCLUSIONS
The beneficial effect of dexamethasone is not attributed to an increase of cerebral blood flow, because rather decreases of rCBF are mostly observed.
Van Roost
D
D
Department of Neurosurgery, University of Bonn, Germany.
Hartmann
A
A
Quade
G
G
D000328:Adult; D000368:Aged; D001783:Blood Flow Velocity / Q000187:drug effects; D001921:Brain / Q000098:blood supply*; D001929:Brain Edema / Q000000981:diagnostic imaging / Q000188:drug therapy; D003907:Dexamethasone / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012039:Regional Blood Flow / Q000187:drug effects; D015173:Supratentorial Neoplasms / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000556:secondary; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D014978:Xenon
D014978:Xenon; D003907:Dexamethasone