• Asita S Sarrafzadeh, Daniel Haux, Lutz Lüdemann, Holger Amthauer, Michail Plotkin, Ingeborg Küchler, and Andreas W Unterberg.
• Charité Campus Virchow Medical Clinic, Humboldt University of Berlin, Augustenburger Platz 1, D-13353 Berlin, Germany. asita.sarrafzadeh@charite.de
• Stroke. 2004 Mar 1;35(3):638-43.

Background And PurposeCerebral microdialysis (MD) is discussed as a technique for detection of cerebral ischemia in subarachnoid hemorrhage; however, clinical data on cerebral blood flow (CBF) are limited in these patients. The main objective of this study was to investigate whether pathological MD parameters reflect a reduced regional CBF (rCBF) determined by 15O-H2O PET.MethodsThirteen subarachnoid hemorrhage patients (age, 48.7+/-15.0 years; World Federation of Neurological Surgeons grade 1 to 5) were studied. Extracellular glucose, lactate, lactate/pyruvate (L/P) ratio, glutamate, and glycerol levels were analyzed hourly. rCBF was determined in the volume of interest of the MD catheter and all vascular territories. MD values were correlated to rCBF on the day of PET. Then, MD concentrations of asymptomatic versus ischemic phases (3-day medians) were analyzed.ResultsIn symptomatic patients (n=10), rCBF was significantly lower compared with controls (n=3, P=0.048). Glutamate correlated best with rCBF (r=-0.66; P=0.014), followed by glycerol (r=-0.62; P=0.021). The L/P ratio was most sensitive (0.82) and specific (1.0) in indicating symptoms of ischemia, but only during longer periods of ischemia.ConclusionsrCBF correlates best with glutamate, followed by glycerol, whereas the L/P ratio is sensitive only after longer periods of ischemia. Clinically relevant regional metabolic derangements occur already above an rCBF of 20 mL x 100 g(-1).min(-1). Future research should focus on identifying alternative causes of metabolic derangement in subarachnoid hemorrhage patients and optimal treatment management in these patients.

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