Date of Award

January 2026

Document Type

Open Access Thesis

Degree Name

Medical Doctor (MD)

Department

Medicine

First Advisor

Jennifer A. Kim

Abstract

Background/Scientific Premise: Delayed cerebral ischemia (DCI) continues to be a leading cause of poor outcomes in hospitalized aneurysmal subarachnoid hemorrhage (aSAH) patients. In addition to cerebral vasospasm, a growing constellation of pathophysiologic processes has been implicated in the development of DCI, including impaired autoregulation, micro-thrombosis, inflammation, and cortical spreading depolarizations. However, management options for patients showing signs of emerging DCI have largely remained spasmolytic in nature, and it remains unclear if reversing cerebral vasospasm in patients with signs of emerging DCI will reliably improve underlying neurophysiology. To our knowledge, no group has reliably shown postprocedural improvements in quantitative EEG metrics associated with the development of DCI following endovascular interventions with intra-arterial vasodilators or angioplasty.

Research Aim and Hypothesis: Our primary aim was to investigate neurophysiologic responses to endovascular interventions with intra-arterial vasodilators and angioplasty across a large cohort. We predicted that following these interventions, patients would reliably show rapid, sustained postprocedural improvements in EEG metrics associated with the development of DCI.

Methods: We conducted a retrospective review of aSAH patients admitted to the YNHH Neuro-ICU between January 1st, 2020, and May 1st, 2025, who received intra-arterial verapamil or angioplasty for treatment of emerging DCI. Neurosurgical imaging reports were qualitatively reviewed for vasospasm severities observed on DSA as well as the relative verapamil doses administered and angioplasties performed across vascular territories. EEG recordings were analyzed for postprocedural improvements in alpha-delta ratios, relative alpha variabilities, and the incidence of EA.

Results: 62 patients underwent 112 endovascular procedures with adequate periprocedural EEG for inclusion in our cohort. The mean total dose of verapamil administered in each procedure was 23.6 +/- 11.7 mg, and 12 procedures also involved angioplasty of at least one artery. Patients demonstrated significant postprocedural median decreases in global ADR (-0.030 +/- 0.110, p < 0.01) and RAV (-0.001 +/- 0.008, p < 0.05). In addition, a postprocedural trend towards decreased lateralization was observed in the incidence of EA. Linear mixed modeling across vascular territories demonstrated a significant negative association between vasospasm severities and preprocedural ADRs (β = −0.027, SE = 0.005, p < 0.001) and a significant positive association between relative verapamil doses administered and postprocedural ADR changes (β = 0.007, SE = 0.002, p < 0.01). ADR and RAV did not vary significantly over time within the periprocedural periods, and no significant differences in MAP or ICP were observed between the periprocedural periods.

Scientific Impact and Relevance: Endovascular interventions to relieve cerebral vasospasm and prevent the development of DCI may lead to consistent, targeted neurophysiologic benefits that are detectable using continuous EEG monitoring. Future prospective work may be better able to isolate an independent treatment effect and determine in which patients these interventions may have longer-term clinical benefits. More broadly, it will continue to deepen our understanding of the relationship between cerebral vasospasm and the altered neurophysiology observed in aSAH patients developing DCI.

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This is an Open Access Thesis.

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