Intracranial pressure dynamics, cerebral autoregulation, and brain perfusion after decompressive craniectomy in malignant middle cerebral artery infarction: is there a role for invasive monitoring?

Abstract

Objective: Malignant middle cerebral artery infarction (MMI) is a severe neurological condition. Decompressive craniectomy (DC) is an established lifesaving surgical treatment. However, the role of neurocritical care with monitoring and management of the intracranial pressure (ICP), pressure reactivity index (PRx), cerebral perfusion pressure (CPP), and optimal perfusion pressure (CPPopt) remain unclear. This study aims to examine the dynamics of these variables post-DC in relation to clinical outcome.

Methods: This retrospective study included 70 MMI patients who underwent DC with ICP monitoring of at least 12 hours and available data of clinical outcome (modified Rankin Scale [mRS] at 6 months). The associations between mRS and cerebral physiology (ICP, PRx, CPP, and ∆CPPopt) was analysed and presented in different outcome heatmaps over the first 7 days following DC.

Results: ICP above 15 mmHg was associated with unfavourable outcome, particularly for longer durations. As PRx exceeded zero, outcome worsened progressively, and values above 0.5 correlated to poor outcome regardless of duration. As CPP dropped below 80 mmHg, there was a transition from favourable to unfavourable outcome. Negative ∆CPPopt, particularly below -20 mmHg, corresponded to unfavourable outcome. In two-variable heatmaps, elevated PRx combined with high ICP, low CPP or negative ∆CPPopt correlated with worse outcome.

Conclusion: Invasive ICP-monitoring may provide prognostic information for long-term recovery in MMI patients post-DC. The study highlighted disease-specific optimal physiological intervals for ICP, PRx, CPP, and ΔCPPopt. Of particular interest, the autoregulatory variable, PRx, influenced the safe and dangerous ICP, CPP, and ∆CPPopt intervals.

Keywords: Cerebral autoregulation; Decompressive craniectomy; Intracranial pressure; Malignant media infarction; Neurointensive care; Pressure reactivity index.

Fig. 1

Cerebral physiological variables post-DC vs. predisposed and surgical factors. Grid heat map illustrating age (years), GCS M pre-DC (scale), midline shift post-DC (mm), DC size (cm²), and infarct volume (cm³) correlated to ICP, PRx, CPP, ∆CPPopt using Spearman analysis. Colours represent Spearman correlation coefficient. Blue refers to 0.3, and red to −0.3. No correlation coefficients were found to be outside this range. The symbol * refers to statistically significant P-value, below 0.05. As indicated, midline shift post-DC correlated significantly to higher ICP and PRx, while larger DC size correlated significantly to lower ∆CPPopt. GCS M = Glasgow Coma Scale Motor score. DC = decompressive hemicraniectomy. ICP = intracranial pressure. PRx = pressure reactivity index. CPP = cerebral perfusion pressure. ∆CPPopt = CPP – optimal CPP

Fig. 2

Insult duration and intensity of ICP and PRx in relation to clinical outcome. Figure A illustrates correlation between insult intensity and duration of ICP and mRS. The colour scale shows that red represents unfavourable outcome, blue favourable outcome, and white insufficient amount of data. ICP and PRx were analysed on above threshold basis. Figure B illustrates a similar plot for PRx. As indicated, there was a transition from better towards worse outcome for higher ICP and PRx for longer durations. ICP = intracranial pressure. PRx = pressure reactivity index. mRS = modified Rankin Scale

Fig. 3

ICP, PRx, CPP, and ∆CPPopt in relation to clinical outcome. Figure A illustrates correlation between ICP level and mRS. The colour scale E indicates that red represents unfavourable outcome, and blue favourable outcome. The rest of the figures were created similarly, as figure B shows PRx, figure C CPP, and figure D ∆CPPopt. As the figures indicate, unfavourable outcome was associated with ICP above about 15 mmHg, PRx above around 0.5, CPP below about 70 mmHg, and ∆CPPopt below around −10 mmHg. ICP = intracranial pressure. PRx = pressure reactivity index. CPP = cerebral perfusion pressure. ∆CPPopt = CPP – optimal CPP. mRS = modified Rankin Scale

Fig. 4

ICP, PRx, CPP, and ∆CPPopt the first 7 days post DC in relation to clinical outcome. Figure A presents correlation over the first seven days after DC between ICP level and mRS. The colour scale indicates that red represents unfavourable outcome, blue favourable outcome, and white insufficient data amount. The rest of the figures were created similarly, as figure B presents PRx, figure C CPP, and figure D ∆CPPopt. As demonstrated, unfavourable outcome correlated to ICP over roughly 15 mmHg, PRx over around 0, particularly after day 2, CPP below about 70 mmHg, and ∆CPPopt below roughly 0, particularly towards the end of the observation period. ICP = intracranial pressure. PRx = pressure reactivity index. CPP = cerebral perfusion pressure. ∆CPPopt = CPP – optimal CPP. mRS = modified Rankin Scale. DC = decompressive hemicraniectomy

Fig. 5

Insult duration and intensity of CPP and ∆CPPopt in relation to clinical outcome. CPP and ∆CPPopt were analysed on both above and below threshold basis. Figure A illustrates correlation between insult intensity and duration of below threshold CPP and mRS. The colour scale shows that red represents unfavourable outcome, blue favourable outcome, and white insufficient amount of data. The rest of the figures were composed similarly, as figure B shows above threshold CPP, figure C below threshold ∆CPPopt, and figure D above threshold ∆CPPopt. As indicated, unfavourable outcome correlated to CPP below 60 mmHg, below 70 mmHg for longer durations, and above 80 mmHg for longer durations. Also, unfavourable outcome was associated to ∆CPPopt below −20 mmHg, and below 0 mmHg for longer durations. CPP = cerebral perfusion pressure. ∆CPPopt = CPP – optimal CPP. mRS = modified Rankin Scale

Fig. 6

ICP, CPP, and ∆CPPopt combined with PRx in relation to clinical outcome. Figure A presents association of the combination of ICP-PRx with mRS 6 months after decompressive hemicraniectomy. The colour scale to the right illustrates that red represents unfavourable outcome, and blue favourable. White cells express insufficient amount of data. The rest of the heatmaps were created similarly as figure B presents CPP-PRx, and figure C ∆CPPopt-PRx. As demonstrated, high PRx combined with high ICP, low CPP, and low ∆CPPopt correlated particularly to worse outcome. ICP = intracranial pressure. PRx = pressure reactivity index. CPP = cerebral perfusion pressure. ∆CPPopt = difference between CPP and optimal CPP. mRS = modified Rankin Scale