Neuromonitoring in the Decompressed Brain: Rethinking Physiology, Monitoring, and Thresholds After Decompressive Craniectomy.

Decompressive craniectomy (DC) is a life-saving intervention for refractory intracranial hypertension across traumatic, ischemic, and hemorrhagic etiologies. While its immediate hemodynamic benefits are well established, DC fundamentally disrupts intracranial physiology by abolishing the closed-box condition of the cranial vault, thereby altering the interpretation of all monitored parameters. Neuromonitoring (NM) after DC remains a largely unaddressed domain in current consensus statements and evidence-based guidelines. This viewpoint synthesizes available evidence to address five critical clinical questions: the pathophysiological changes induced by DC; the rationale for continued invasive monitoring; the optimal sensor placement site; the contribution of noninvasive monitoring modalities; and whether conventional ICP and CPP thresholds remain applicable in the decompressed brain. Observational data indicate that intracranial hypertension persists or recurs in 36-76% of patients post-DC, underscoring the continued value of monitoring. Emerging evidence challenges the universal applicability of standard ICP thresholds, with post-DC data suggesting clinically relevant outcomes at substantially lower values. These findings highlight a fundamental gap in the field and underscore the urgent need for prospective, standardized research in the decompressed brain.