P-31 MAGNETIC-RESONANCE SPECTRA REVEAL PROLONGED INTRACELLULAR ACIDOSIS IN THE BRAIN FOLLOWING SUBARACHNOID HEMORRHAGE

Subarachnoid hemorrhage may be complicated by cerebral ischemia which, though reversible initially, can progress to an irreversible neurolog ical deficit. P-31 magnetic resonance spectroscopy, which can determin e intracellular pH and thus detect areas of ischemia noninvasively, wa s applied to 10 patients on 30 occasions, at various times after subar achnoid hemorrhage. In 5 of them, there were focal areas of the brain in which the intracellular pH was reduced to <6.8 compared with the no rmal range of 7.05 +/- 0.05. Consciousness was impaired in 4 of these patients. Repeat studies in these 4 patients showed that intracellular pH remained abnormally low for several days but eventually returned t oward normal. The return of intracellular pH to normal paralleled an i mprovement in clinical condition in each case. In the fifth patient wi th lowered regions of intracellular pH, there had been an impaired lev el of consciousness and a transient focal deficit prior to the single study. In the other 5 patients there were no areas of reduced pH(i) ev en though in 3 of them there was intraventricular or cisternal blood s hown on brain computerized tomography. In 2 of these 3 patients there were no abnormal neurological signs at the time of the magnetic resona nce study. The third patient had a dense and persistent hemiparesis. T he remaining two patients had no abnormal neurological signs at any st age. We suggest that the areas of acidosis may reflect ischemia which is potentially reversible. Since the technique is noninvasive, sequent ial P-31 magnetic resonance spectroscopy of the brain offers a method of detecting cerebral ischemia and, more importantly, of assessing met hods of treatment.