The impact of hyperbaric therapy on cognitive functions in patients treated for idiopathic sudden hearing loss or hard-to-heal chronic wounds

Hyperbaric Oxygen Therapy (HBOT) may improve brain metabolism, synaptic plasticity and neurogenesis and modulate inflammatory processes, resulting in improvement of cognitive function in various neurological disorders. 53 individuals aged 26 to 83 years, 23 women and 30 men, 23 patients treated for idiopathic hearing loss (group I) and 30 patients treated for difficult-to-heal chronic wounds (group II) were included to the study. The Mini Mental State Examination (MMSE) Verbal Fluency Test (VF), Trail Making Test (TMT), Ray Auditory Verbal Learning Test (RAVLT) and Color Word Interference Stroop tests were applied for assessment of different cognitive domains. Cognitive assessment were performed before and after HBOT treatment. For statistical analysis non-parametric tests were applied. Significance of differences between groups were conducted using the U-Mann-Whitney test. The statistical significance of changes in neuropsychological test results before vs after hyperbaric oxygen therapy (HBOT) was assessed using the Wilcoxon signed-rank test for paired samples. For correlation analysis the R-Spearman test was used. Cognitive decline was found in both patients groups. Group II at baseline show worse performance on most cognitive tests compared to group I. After HBOT significant improvement was observed in most cognitive parameters in both groups. No significant difference between groups after HBOT were observed in seven parameters of verbal tests (VF and RAVLT). No significant changes were noted in the first learning trial and word recall after distraction in the RAVLT and VF (phonological) in patients from group I, and word recall after distraction in the RAVLT in the patients from group II. Before HBOT older age correlated with worse cognitive abilities in booth groups. After HBOT older age correlated with worse results of the TMT A and B in group II, no such correlations were found in the group I. In group I before and after HBOT worse performance on cognitive tests correlated with greater cognitive impairment measured by the MMSE. In group II before HBOT results of MMSE were associated with poorer results in the TMT A and TMT B and in the fifth trial of the RAVLT. After HBOT, worse MMSE results correlated with the worse performance on Stroop A and one parameter of the RAVLT. HBOT therapy showed positive influence on most cognitive domain in patients treated for chronic hard-to-treat wound and idiopatic hearing loss. Older age and general severity of cognitive decline is connected with worse cognitive improvement after HBOT.