Intracerebral Microdialysis of Glutamate and Aspartate Two Vascular Territories after Aneurysmal Subarachnoid Hemorrhage

Abstract

Cerebral ischemia associated with subarachnoid hemorrhage may have severe consequences for neuronal functioning. The excitatory amino acid neurotransmitters glutamate and aspartate have been shown to be of particular importance for ischemia and ischemic neuronal damage. For seven patients who underwent early surgery for ruptured intracranial aneurysms, intracerebral microdialysis of glutamate and aspartate was performed to monitor local metabolic changes in the medial temporal (all seven patients) and subfrontal cortex (Patients 4 through 7). Samples were collected every 30 or 60 minutes, using an autosampler. The results show that extracellular glutamate and aspartate concentrations can rise to very high levels after surgery for subarachnoid hemorrhage and aneurysm. These increased levels of excitatory amino acids correlated well with the clinical course and neurological symptoms of the patients. Simultaneous sampling from two vascular territories (middle cerebral artery and anterior cerebral artery) also showed that a rise in extracellular glutamate and aspartate in one territory is not necessarily parallel with a rise in the other. The application of the microdialysis technique with an on-line assay system might be of value in the future for continuous monitoring of ischemic events to optimize treatment with, for example, blockers of glutamatergic neurotransmission.

NMDA Receptor Antagonist Felbamate Reduces Behavioral Deficits and Blood–Brain Barrier Permeability Changes after Experimental Subarachnoid Hemorrhage in the Rat

“…The neurotoxic effects of widespread subarachnoid blood associated with transient cerebral ischemia cause diffuse cortical damage that occurs immediately after the hemorrhage (Doczi, 1985;Doczi et al 1986;Enblad et al, 1996;Gotoh et al, 1984;Hutchinson et al, 2000;Jackowski et al, 1990;Nilsson et al, 1996Nilsson et al, , 1999Persson et al, 1996;Sarrafzadeh et al, 1998Sarrafzadeh et al, , 2002Saveland et al, 1996;Schulz et al, 2000;Staub et al, 2000;Untemberg et al, 2001). This damage results from the interaction of numerous pathophysiologic factors where presumably, the blood itself and/or active substances derived in part from the degradation of the extravasated blood are centrally involved.…”

“…Recently, bedside intracerebral microdialysis monitoring of patients with SAH exhibiting signs of delayed ischemia revealed dramatic changes in extracellular concentrations of excitatory amino acids, including glucose, piruvate, lactate, glycerol, and glutamate, confirming that these characteristic metabolic changes occur during vasospasm (Unterberg et al, 2001;Zouh et al, 1996). Moreover, a correlation between EAA concentrations and patient clinical status has been demonstrated Hutchinson et al, 2000;Inage et al, 2000;Nilsson et al, 1996Nilsson et al, , 1999Persson et al, 1996;Sarrafzadeh et al, 1998Sarrafzadeh et al, , 2002Saveland et al, 1996;Schulz et al, 2000;Staub et al, 2000).…”

“…Data collected in both clinical and experimental settings have reported remarkable changes in levels of lactate, glycerol, glutamate, and aspartate, in addition to changes in the lactate/piruvate ratio. These levels are in turn, affected by ischemic deterioration, with changes in metabolite levels varying with respect to substance, location, and time Hutchinson et al, 2000;Inage et al, 2000;Nilsson et al, 1996Nilsson et al, , 1999Persson et al, 1996;Sarrafzadeh et al, 1998Sarrafzadeh et al, , 2002Saveland et al, 1996;Schulz et al, 2000;Staub et al, 2000;Untemberg et al, 2001). …”

Clipping Versus Coiling for Ruptured Intracranial Aneurysms

“…However, there is no evidence that 1 method is more efficient and reliable than other methods. [37][38][39] Cumulative meta-analysis, including 1981 patients altogether, demonstrated that the frequency of shunt-dependent hydrocephalus was not significantly different between coiling and clipping. This result differs with the prior meta-analysis conducted in 2007, 40 which showed that the risk of shuntdependent hydrocephalus was significantly higher after coiling than clipping for ruptured intracranial aneurysms.…”

Middle Cerebral Artery Occlusion and Reperfusion in Primates Monitored by Microdialysis and Sequential Positron Emission Tomography

“…1 This approach was adopted to validate MD with the ultimate goal, which was to obtain a reliable monitoring instrument in neurosurgical intensive care. [2][3][4][5][6][7][8] The reliability of the interstitial substances as markers of ischemia, eg, the lactate/pyruvate (LP) ratio and glutamate, was substantiated when the ischemic state of the brain could be directly assessed by PET in the MD probe regions and compared with biochemical changes of the microdialysates sampled simultaneously. 1 To study focal ischemia followed by reperfusion under more standardized conditions, an experimental middle cerebral artery (MCA) occlusion (MCAO) model of transient focal ischemia with reperfusion was established in primates.…”