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Abstract
Introduction The Windkessel phenomenon and normal perfusion pressure breakthrough (NPPB) represent distinct vascular physiologic processes. The windkessel phenomenon refers to the pressure-dampening effect of compliant or dilated blood vessels, while NPPB involves cerebrovascular autoregulation loss due to chronic low-pressure flow and subsequent intolerance of physiological pressures. We report a case of a patient with a long-standing giant vertebrobasilar fusiform aneurysm successfully reconstructed using flow diversion, followed by unexpected distal parenchymal hemorrhage. We analyze and summarize the pathomechanism of the combined effects of windkessel phenomenon and NPPB of this vascular lesion.
Methods A retrospective review of the patient’s medical record was performed.
Results A 60-year-old female with a pulsatile neck mass was diagnosed with dolichoectasia of the right cervical internal carotid artery and two large, irregular vertebrobasilar aneurysms. After 10 years of conservative management and the development of gait ataxia, new imaging showed growth of the more distal giant aneurysm. Flow diversion with partial coiling was pursued. Following successful flow diverter reconstruction, DynaCT revealed catastrophic thalamic and midbrain hemorrhage with intraventricular extension. Time stamped intra-operative intra-aneurysmal pressure measurements, angiography, MRI, and neuromonitoring data were retrospectively analyzed. They demonstrate aneurysmal pulse-pressure suppression prior to flow diversion and subsequent rupture of multiple deep perforators and simultaneous loss of somatosensory and motor evoked potential within the minute after finalizing the flow diverting construct.
Conclusions These findings support the theory that giant fusiform aneurysms function as a windkessel reservoir, chronically reducing distal pulse pressure which predisposes the brain vasculature to experience NPPG and potentially disastrous hemorrhage. This report is the first in the literature, to our knowledge, to identify the windkessel phenomenon and subsequent NPPB in vivo in the context of treating giant aneurysms with flow diversion. Despite an unfavorable outcome, understanding these mechanisms and employing careful intra-operative blood pressure management could mitigate or avert complications.
Disclosures A. Brake: None. L. Fry: None. F. De-Stefano: None. C. Lei: None. C. Heskett: None. K. Ebersole: None.