Treatment of Delayed Cerebral Ischemia in Good-Grade Subarachnoid Hemorrhage: Any Role for Invasive Neuromonitoring?

Background Good-grade aneurysmal subarachnoid hemorrhage (Hunt and Hess 1-2) is generally associated with a favorable prognosis. Nonetheless, patients may still experience secondary deterioration due to delayed cerebral ischemia (DCI), contributing to poor outcome. In those patients, neurological assessment is challenging and invasive neuromonitoring (INM) may help guide DCI treatment. Methods An observational analysis of 135 good-grade SAH patients referred to a single tertiary care center between 2010 and 2018 was performed. In total, 54 good-grade SAH patients with secondary deterioration evading further neurological assessment, were prospectively enrolled for this analysis. The cohort was separated into two groups: before and after introduction of INM in 2014 (pre-INMSecD: n = 28; post-INMSecD: n = 26). INM included either parenchymal oxygen saturation measurement (p(ti)O(2)), cerebral microdialysis or both. Episodes of DCI (p(ti)O(2) <10 mmHg or lactate/pyruvate > 40) were treated via induced hypertension or in refractory cases by endovascular means. The primary outcome was defined as the extended Glasgow outcome scale after 12 months. In addition, we recorded the amount of imaging studies performed and the occurrence of silent and overall DCI-related infarction. Results Secondary deterioration, impeding neurological assessment, occurred in 54 (40.0%) of all good-grade SAH patients. In those patients, a comparable rate of favorable outcome at 12 months was observed before and after the introduction of INM (pre-INMSecD 14 (50.0%) vs. post-INMSecD 16, (61.6%); p = 0.253). A significant increase in good recovery (pre-INMSecD 6 (50.0%) vs. post-INMSecD 14, (61.6%); p = 0.014) was observed alongside a reduction in the incidence of silent infarctions (pre-INMSecD 8 (28.6%) vs. post-INMSecD 2 (7.7%); p = 0.048) and of overall DCI-related infarction (pre-INMSecD 12 (42.8%) vs. post-INMSecD 4 (23.1%); p = 0.027). The number of CT investigations performed during the DCI time frame decreased from 9.8 +/- 5.2 scans in the pre-INMSecD group to 6.1 +/- 4.0 (p = 0.003) in the post-INMSecD group. Conclusions A considerable number of patients with good-grade SAH experiences secondary deterioration rendering them neurologically not assessable. In our cohort, the introduction of INM to guide DCI treatment in patients with secondary deterioration increased the rate of good recovery after 12 months. Additionally, a significant reduction of CT scans and infarction load was recorded, which may have an underestimated impact on quality of life and more subtle neuropsychological deficits common after SAH.