OBJECTIVE: Increased intracranial pressure (ICP) is most likely not being transmitted uniformly within the cranium. The ICP profiles in the supra- and infratentorial compartments remain largely unclear. Increased ICP in the cerebellum, however, is insufficiently captured by supratentorial ICP (ICPsup) monitoring due to compartmentalization through the tentorium. The authors hypothesized that additional infratentorial ICP (ICPinf) monitoring can be clinically valuable in selected patients. The aims of this study were to demonstrate the safety and feasibility of ICPinf monitoring and to investigate the influence of the ICPinf on clinical outcome in a real-world setting. METHODS: Fifteen consecutive patients with posterior fossa (PF) lesions requiring surgery and anticipated prolonged neurointensive care between June 2019 and December 2021 were included. Simultaneous ICPsup and ICPinf were recorded. ICP burden was defined as a 15-minute interval with a mean ICP > 22 mm Hg. The Glasgow Outcome Scale score was assessed after 3 months. RESULTS: The mean ICPinf was substantially higher compared with ICPsup throughout the entire period of ICP recording (16.08 ± 4.44 vs 10.74 ± 3.6 mm Hg, p < 0.01). ICPinf was significantly higher in patients with unfavorable outcome when compared with those with favorable outcome (mean 17.2 ± 4.1 vs 11.4 ± 3.5 mm Hg, p < 0.05). Patients with unfavorable outcome showed significantly higher ICPinf burden compared with those with favorable outcome (mean 40.6 ± 43.8 vs 0.3 ± 0.4 hours, p < 0.05). Neither absolute ICPsup nor ICPsup burden was significantly associated with unfavorable outcome (p = 0.13). No monitoring-associated complications occurred. CONCLUSIONS: Supplementary ICPinf monitoring is safe and reliable. There is a significant transtentorial pressure gradient within the cranium showing elevated ICPs in the PF. Elevated ICP levels in the PF were strongly associated with unfavorable neurological outcome irrespective of ICPsup values.
