Clinical Development and Implementation of an Institutional Guideline for Prospective EEG Monitoring and Reporting of Delayed Cerebral Ischemia.

Delayed cerebral ischemia (DCI) is the most common and disabling complication among patients admitted to the hospital for subarachnoid hemorrhage (SAH). Clinical and radiographic methods often fail to detect DCI early enough to avert irreversible injury. We assessed the clinical feasibility of implementing a continuous EEG (cEEG) ischemia monitoring service for early DCI detection as part of an institutional guideline. An institutional neuromonitoring guideline was designed by an interdisciplinary team of neurocritical care, clinical neurophysiology, and neurosurgery physicians and nursing staff and cEEG technologists. The interdisciplinary team focused on (1) selection criteria of high-risk patients, (2) minimization of safety concerns related to prolonged monitoring, (3) technical selection of quantitative and qualitative neurophysiologic parameters based on expert consensus and review of the literature, (4) a structured interpretation and reporting methodology, prompting direct patient evaluation and iterative neurocritical care, and (5) a two-layered quality assurance process including structured clinician interviews assessing events of neurologic worsening and an adjudicated consensus review of neuroimaging and medical records. The resulting guideline's clinical feasibility was then prospectively evaluated. The institutional SAH monitoring guideline used transcranial Doppler ultrasound and cEEG monitoring for vasospasm and ischemia monitoring in patients with either Fisher group 3 or Hunt-Hess grade IV or V SAH. Safety criteria focused on prevention of skin breakdown and agitation. Technical components included monitoring of transcranial Doppler ultrasound velocities and cEEG features, including quantitative alpha:delta ratio and percent alpha variability, qualitative evidence of new focal slowing, late-onset epileptiform activity, or overall worsening of background. Structured cEEG reports were introduced including verbal communication for findings concerning neurologic decline. The guideline was successfully implemented over 27 months, during which neurocritical care physicians referred 71 SAH patients for combined transcranial Doppler ultrasound and cEEG monitoring. The quality assurance process determined a DCI rate of 48% among the monitored population, more than 90% of which occurred during the duration of cEEG monitoring (mean 6.9 days) beginning 2.7 days after symptom onset. An institutional guideline implementing cEEG for SAH ischemia monitoring and reporting is feasible to implement and efficiently identify patients at high baseline risk of DCI during the period of monitoring.

Interrater Agreement for Consensus Definitions of Delayed Ischemic Events After Aneurysmal Subarachnoid Hemorrhage.

BACKGROUND: Thirty percent of patients with subarachnoid hemorrhage experience delayed cerebral ischemia or delayed ischemic neurologic decline (DIND). Variability in the definitions of delayed ischemia makes outcome studies difficult to compare. A recent consensus statement advocates standardized definitions for delayed ischemia in clinical trials of subarachnoid hemorrhage. We sought to evaluate the interrater agreement of these definitions. METHODS: Based on consensus definitions, we assessed for: (1) delayed cerebral infarction, defined as radiographic cerebral infarction; (2) DIND type 1 (DIND1), defined as focal neurologic decline; and (3) DIND2, defined as a global decline in arousal. Five neurologists retrospectively reviewed electronic records of 58 patients with subarachnoid hemorrhage. Three reviewers had access to and reviewed neuroradiology imaging. We assessed interrater agreement using the Gwet kappa statistic. RESULTS: Interrater agreement statistics were excellent (95.83%) for overall agreement on the presence or absence of any delayed ischemic event (DIND1, DIND2, or delayed cerebral infarction). Agreement was "moderate" for specifically identifying DIND1 (56.58%) and DIND2 (48.66%) events. We observed greater agreement for DIND1 when there was a significant focal motor decline of at least 1 point in the motor score. There was fair agreement (39.20%) for identifying delayed cerebral infarction; CT imaging was the predominant modality. CONCLUSIONS: Consensus definitions for delayed cerebral ischemia yielded near-perfect overall agreement and can thus be applied in future large-scale studies. However, a strict process of adjudication, explicit thresholds for determining focal neurologic decline, and MRI techniques that better discriminate edema from infarction seem critical for reproducibility of determination of specific outcome phenotypes, and will be important for successful clinical trials.