Simultaneous intracerebral microdialysis and positron emission tomography in the detection of ischemia in patients with subarachnoid hemorrhage

J Cereb Blood Flow Metab. 1996 Jul;16(4):637-44. doi: 10.1097/00004647-199607000-00014.


Intracerebral microdialysis (MD) was applied in patients with subarachnoid hemorrhage. The regional CBF, the CMRO2, and oxygen extraction ratio (OER) were measured with simultaneous positron emission tomography (PET). The aim was to directly correlate alterations in dialysate levels of energy-related metabolites (lactate, lactate/pyruvate ratio, hypoxanthine) and excitatory amino acids (EAAs) (glutamate and aspartate) to the energy state in the MD probe region as determined by PET. Regional ischemia was defined according to Heiss et al. and Lassen (Heiss et al., 1992; Lassen, 1966). Whole-brain ischemia was considered present when the OER for the whole brain exceeded the mean whole-brain OER + 2 SD of six reference patients. In general, the presence of whole-brain ischemia and/or regional ischemia within the region of the MD probe was associated with increased levels of energy-related metabolites and EAAs retrieved by MD. Increased levels of energy-related metabolites and EAAs were only occasionally seen when PET did not show any signs of ischemia or when signs of regional ischemia were found remote from the MD probe region. Thus, the energy-related metabolites and EAAs may be used as extracellular "markers" of ischemia. PET may be of use in defining critical ischemic regions (tissue at risk) where the MD probe can be inserted for chemical monitoring.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Brain / diagnostic imaging*
  • Brain / metabolism*
  • Brain Ischemia / diagnostic imaging
  • Brain Ischemia / metabolism*
  • Brain Ischemia / physiopathology
  • Cerebrovascular Circulation
  • Energy Metabolism
  • Excitatory Amino Acids / metabolism
  • Female
  • Humans
  • Male
  • Microdialysis
  • Middle Aged
  • Oxygen Consumption
  • Subarachnoid Hemorrhage / diagnostic imaging
  • Subarachnoid Hemorrhage / metabolism*
  • Subarachnoid Hemorrhage / physiopathology
  • Tomography, Emission-Computed*


  • Excitatory Amino Acids