Analyzing Nimodipine-Associated Hemodynamic and Electrophysiologic Changes and Functional Outcomes in Aneurysmal Subarachnoid Hemorrhage
Sithmi Jayasundara1, Rachel Choi1, Amedeo Rapuano1, Yilun Chen1, Ilayda Top1, Madelynne Olexa1, Rafael Maarek1, Jennifer Yan1, David Vargas Estrella1, Jessica Magid-Bernstein1, Abdelaziz Amllay2, Lena O'Keefe1, Ryan Hebert2, Farhad Bahrassa2, Kevin Sheth1, Rachel Beekman1, Emily Gilmore1, Charles Matouk2, Jennifer Kim1, Nils Petersen1
1Neurology, 2Neurosurgery, Yale School of Medicine
Objective:
To characterize the effects of nimodipine administration on cerebral autoregulation, quantitative electroencephalography (qEEG), and functional outcomes.
Background:
Aneurysmal subarachnoid hemorrhage (aSAH) is a life-threatening condition after which patients are at risk for vasospasm and delayed cerebral ischemia (DCI). Nimodipine, a calcium channel blocker, is used to reduce the risk of DCI. However, its potentially harmful effects on cerebral physiology remain incompletely understood.
Design/Methods:
Nimodipine-associated blood pressure (BP) reductions were quantified as the difference between median BP in the hour before and minimum BP in the hour after nimodipine. Autoregulatory function was measured by analyzing changes in near-infrared spectroscopy-derived tissue oxygenation in response to changes in mean arterial pressure (MAP). The resulting autoregulatory index was used to determine the upper and lower limits of autoregulation (ULA, LLA) in each patient. Cortical activity was measured by computing percent changes in each qEEG frequency band in the anterior and middle cerebral vascular regions. Patients were dichotomized into good and poor outcome groups by modified Rankin Scale >3 at 3 months and compared using an independent samples t-test.
Results:
We identified 265 occurrences of nimodipine administration with simultaneous recording of continuous EEG and physiologic data among 21 aSAH patients with median (IQR) age 59 (51, 61) years, Hunt Hess 3 (2, 4), and modified Fisher 4 (3, 4). Patients with good outcome had a greater increase in alpha power after nimodipine compared to those with poor outcome (+4% vs. -0.9%, p = 0.02) and spent less time below LLA (7% vs. 19%, p < 0.001) despite having similar average BP reductions (15 mmHg vs. 14 mmHg, p = 0.488).
Conclusions:
Nimodipine-associated BP reductions are associated with changes in autoregulation and electrophysiology that differ based on patient outcomes. Prolonged hypoperfusion below the LLA with no alpha power improvement may contribute to adverse effects in these patients.
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