title: Role of bedside microdialysis in the diagnosis of cerebral vasospasm following aneurysmal subarachnoid hemorrhage.
abstract: OBJECTIVE
  Ischemia due to vasospasm is a feared complication in patients following aneurysmal subarachnoid hemorrhage (SAH). Cerebral online microdialysis monitoring may detect the metabolic changes in the extracellular fluid associated with ischemia. The aims of the present study were to correlate clinical course, microdialysis-recorded data, transcranial Doppler (TCD) ultrasonography findings, and angiographic findings in patients with SAH.
  
  
  METHODS
  In 60 patients a microdialysis catheter was inserted into the brain parenchyma that is most likely to be affected by vasospasm directly after aneurysm clipping. Hourly analyses of glucose, pyruvate, lactate, and glutamate levels were performed using a bedside device. Blood-flow velocities were obtained using serial TCD measurements. Cerebral angiography was routinely performed on Day 7 after aneurysm clipping or earlier in cases of clinical deterioration (30 patients). In all patients the results of microdialysis monitoring, TCD ultrasonography, and angiography were correlated. The mean duration of monitoring was 7.3+/-2.5 days. In patients with acute ischemic neurological deficits (18 patients) immediate microdialysis-recorded alterations were observed if the probe was placed close to the malperfused region. In 13 of 15 patients with symptomatic vasospasm (delayed ischemic neurological deficit [DIND]), the microdialysis-recorded values revealed secondary deterioration. In terms of confirming DIND, microdialysis had the 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, whereas this was significantly lower for TCD ultrasonography (1.7) and angiography (2.1).
  
  
  CONCLUSIONS
  Although angiography also demonstrates vessel narrowing in asymptomatic patients, online microdialysis reveals characteristic metabolic changes that occur during vasospasm. Thus, online microdialysis may be used to confirm the diagnosis of vasospasm.
authors.affiliation: Department of Neurosurgery and Radiology, Charité, Humboldt University, Berlin, Germany. andreas.unterberg@charite.de
authors.forename: A W
authors.initials: AW
authors.lastname: Unterberg
authors.forename: O W
authors.initials: OW
authors.lastname: Sakowitz
authors.forename: A S
authors.initials: AS
authors.lastname: Sarrafzadeh
authors.forename: G
authors.initials: G
authors.lastname: Benndorf
authors.forename: W R
authors.initials: WR
authors.lastname: Lanksch
mesh_terms: D000328:Adult; D000368:Aged; D001921:Brain / Q000098:blood supply / Q000378:metabolism; D002533:Cerebral Angiography; D002560:Cerebrovascular Circulation; D003422:Critical Care / Q000379:methods; D005260:Female; D005947:Glucose / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism; D006801:Humans; D002532:Intracranial Aneurysm / Q000150:complications* / Q000000981:diagnostic imaging / Q000601:surgery; D019344:Lactic Acid / Q000378:metabolism; D008297:Male; D017551:Microdialysis; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods / Q000592:standards; D019095:Point-of-Care Systems; D011183:Postoperative Complications / Q000000981:diagnostic imaging / Q000378:metabolism; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D013345:Subarachnoid Hemorrhage / Q000150:complications* / Q000000981:diagnostic imaging / Q000601:surgery; D017585:Ultrasonography, Doppler, Transcranial; D020301:Vasospasm, Intracranial / Q000000981:diagnostic imaging* / Q000209:etiology / Q000378:metabolism
chemical_list: D019344:Lactic Acid; D018698:Glutamic Acid; D005947:Glucose