Hyperbaric oxygen therapy improves neurocognitive functions of post-stroke patients - a retrospective analysis

Abstract

Background: Previous studies have shown that hyperbaric oxygen therapy (HBOT) can improve the motor functions and memory of post-stroke patients in the chronic stage.

Objective: The aim of this study is to evaluate the effects of HBOT on overall cognitive functions of post-stroke patients in the chronic stage. The nature, type and location of the stroke were investigated as possible modifiers.

Methods: A retrospective analysis was conducted on patients who were treated with HBOT for chronic stroke (>3 months) between 2008-2018. Participants were treated in a multi-place hyperbaric chamber with the following protocols: 40 to 60 daily sessions, 5 days per week, each session included 90 min of 100% oxygen at 2 ATA with 5 min air brakes every 20 minutes. Clinically significant improvements (CSI) were defined as > 0.5 standard deviation (SD).

Results: The study included 162 patients (75.3% males) with a mean age of 60.75±12.91. Of them, 77(47.53%) had cortical strokes, 87(53.7%) strokes were located in the left hemisphere and 121 suffered ischemic strokes (74.6%).HBOT induced a significant increase in all the cognitive function domains (p < 0.05), with 86% of the stroke victims achieving CSI. There were no significant differences post-HBOT of cortical strokes compared to sub-cortical strokes (p > 0.05). Hemorrhagic strokes had a significantly higher improvement in information processing speed post-HBOT (p < 0.05). Left hemisphere strokes had a higher increase in the motor domain (p < 0.05). In all cognitive domains, the baseline cognitive function was a significant predictor of CSI (p < 0.05), while stroke type, location and side were not significant predictors.

Conclusions: HBOT induces significant improvements in all cognitive domains even in the late chronic stage. The selection of post-stroke patients for HBOT should be based on functional analysis and baseline cognitive scores rather than the stroke type, location or side of lesion.

Keywords: HBOT; cognitive function; hyperbaric oxygen; stroke.

Fig. 1

Flowchart of the patients included in the study.

Fig. 2

Hemorrhagic/ischemic stroke MAC comparison of cognitive scores post-HBOT. Only the IPS domain was significantly increased after HBOT for the hemorrhagic stroke patients compared to ischemic strokes. Statistical significance (p < 0.05) is marked by *. Bars represent means+standard deviation. Abbreviations: MAC – mean absolute change, HBOT – hyperbaric oxygen treatment, GCS – global cognitive scale, EF – executive function, IPS – information processing speed, MS – motor skills.

Fig. 3

Dominant/non-dominant MAC comparison of cognitive scores post-HBOT. The motor domain was significantly increased after HBOT at the dominant (i.e. left sided) stroke patients compared to non-dominant strokes. Statistical significance (p < 0.05) is marked by *. Bars represent means+standard deviation. Abbreviations: MAC – mean absolute change, HBOT – hyperbaric oxygen treatment, GCS – global cognitive scale, EF – executive function, IPS – information processing speed, MS – motor skills.

Fig. 4

Clinically significant improvement comparisons of hemorrhagic vs. ischemic, cortical vs. sub-cortical and dominant vs. non-dominant stroke patients. Scores were not significantly different in all the domains (p > 0.05). Bars represent percentages.

Fig. 5

Cortical/subcortical (i.e. BG) MAC comparison of cognitive scores post HBOT. Scores MAC were not significantly different in all the domains (p > 0.05). Bars represent means+standard deviation. Abbreviations: MAC – mean absolute change, HBOT – hyperbaric oxygen treatment, GCS – global cognitive scale, EF – executive function, IPS – information processing speed, MS – motor skills.