Role of bedside microdialysis in the diagnosis of cerebral vasospasm following aneurysmal subarachnoid hemorrhage

Object. Ischemia due to vasospasm is a feared complication in patients foll owing aneurysmal subarachnoid hemorrhage (SAH). Cerebral online microdialys is monitoring may detect the metabolic changes in the extracellular fluid a ssociated with ischemia. The aims of the present study were to correlate cl inical course. microdialysis-recorded data, trans cranial Doppler (TCD) ult rasonography findings. and angiographic findings in patients with SAH. Methods. In 60 patients a microdialysis catheter nas inserted into the brai n parenchyma that is most likely to be affected by vasospasm directly after aneurysm clipping. Hourly analyses of glucose, pyruvate, lactate, and glut amate levels were perfirmed using a bedside device. Blood-flow velocities w ere obtained using serial TCD measurements. Cerebral angiography was routin ely performed on Day 7 after aneurysm clipping or earlier in cases of clini cal deterioration (30 patients). In all patients the results of microdialys is monitoring. TCD ultrasonography, and angiography were correlated. The mean duration of monitoring was 7.3 +/- 2.5 days. In patients with acut e ischemic neurological deficits (18 patients) immediate microdialysis-reco rded alterations were observed if the probe was placed close to the malperf used region. In 13 of 15 patients with symptomatic vasospasm (delayed ische mic neurological deficit [DIND]), the microdialysis-recorded values reveale d secondary deterioration. In terms of confirming DIND. microdialysis had t he highest specificity (0.89, 95% confidence interval [CI] 0.78-1) compared with TCD ultrasonography (0.63, 95% CI 0.46-0.8) and angiography (0.53, 95 % CI 0.35-0.7). For microdialysis, the positive likelihood ratio was 7.8, w hereas this was significantly lower for TCD ultrasonography (1.7) and angio graphy (2.1). Conclusions. Although angiography also demonstrates vessel narrowing in asy mptomatic patients, online microdialysis reveals characteristic metabolic c hanges that occur during vasospasm. Thus, online microdialysis may be used to confirm the diagnosis of vasospasm.