gms | German Medical Science

Objective: The current definition of delayed cerebral ischemia (DCI) is based on clinical characteristics and limited to awake patients. This largely precludes the use in poor-grade SAH patients, creating the need for additional parameters to evaluate the unconscious patient. Invasive neuromonitoring (INM) allows for continuous registration of brain metabolic functioning and may enable timely detection of metabolic crises in high-grade SAH patients.

Methods: We performed a retrospective two group cohort analysis of all SAH patients referred to a single tertiary care center from 2010 till 2018. Starting in 2014, invasive neuromonitoring was introduced to our institutional treatment algorithm to include functional DCI assessment for poor-grade and unconscious SAH patients. Eighty-six patients were monitored for DCI events since 2014 using parenchymal oxygen saturation measurement and cerebral microdialysis. These patients were compared to a historical cohort of 105 high grade SAH patients managed by limited neurological examination and intermittent radiological assessment. Groups were matched for all relevant baseline characteristics. We compared the timing of first DCI detection (clinical, metabolic or radiographic) requiring initiation of first-tier therapy (induced hypertension)

Results: In the pre-INM group, the first DCI event triggering first tier therapy was detected on average 8.08 days after ictus. With INM, the first DCI event triggering first tier therapy was detected after an average of 6.04 days (p=0.002; CI 0.792–3.277). The introduction of invasive monitoring was associated with an overall decrease in use of CT perfusion imaging and diagnostic cerebral angiographies by approximately 11%. Although no differences in the use of first tier therapy was observed between groups, there was a significant difference in the use of second tier endovascular treatment, precluding an unbiased comparison of neurological outcome between both groups.

Conclusion: In this retrospective cohort analysis, the introduction of invasive neuromonitoring resulted in an earlier initiation of first tier therapy. Data acquisition will continue to determine whether our expansion of the current DCI definition towards a functional aspect and a more timely initiation of treatment will result in better neurological outcome.