Little evidence of improved cognitive indices or quality of life following hyperbaric oxygen for post-concussion syndrome compared to a no treatment group

Clinical bottom line:

1. No statistically significant improvement in cognitive indices or quality of life between patients receiving a course of HBOT and no treatment.
2. Intra-group improvements did show statistically significant improvements that may be due to a participation effect.
3. A highly controversial area with competing methods of interpreting the observed changes.

Citation/s:1. Boussi-Gross R, Golan H, Fishlev G, Bechor Y, Volkov O, Bergan J, Friedman M, Hoofien D, Shlamkovitch N, Ben-Jacob E, Efrati S. Hyperbaric oxygen therapy can improve post concussion syndrome years after mild traumatic brain injury-randomized prospective trial. PloS one. 2013 Nov 15;8(11):e79995.
Lead author's name: Corresponding author: Shai Efrati

Three-part Clinical Question:For adult patients with post-concussion syndrome following mild traumatic brain injury, does the addition of a course of hyperbaric oxygen therapy improve symptoms?
Search Terms: mild TBI; PTSD; post-concussion syndrome

The Study:Single-blinded randomised controlled trial without intention-to-treat.
The Study Patients: Mild TBI suffered between one and six years previously with persisting post-concussion syndrome and impaired cognitive function.
Control group (N = 45; 24 analysed): No treatment (later crossed over to active treatment).
Experimental group (N = 45; 32 analysed): 100% oxygen breathing at 1.5 ATA for 60 minutes daily, 5 days/week to a total of 40 treatments.

The Evidence:


Control Group

HBO Group


95% CI





Memory Index






-152.9 to 169.3

Information Processing Speed Index






-141.3 to 154.8

EQ-Visual Analogue Scale (0 to 10)






-2.4 to 2.8

1. Highly controversial study design because of the authors' position that sham is not possible in this area. The consequence is that the best design possible is randomisation to no treatment for comparison.
2. Method of randomisation not stated. Single blinding of outcome observers seems rather fragile given the subject is aware of allocation.
3. 34 patients were withdrawn due to withdrawal of consent (19), problems with cognitive testing (7), use of medication during treatment (4), personal reasons (3) or ear problems during treatment (1). Only 56/90 (62%) of randomised patients were included in results - high possibility of bias.
4. All results here are for the comparison between groups after treatment/no treatment initial period. Highly complex result reporting and only a small fraction of the data given here.
5. Intra-group comparisons suggest improvement in both groups after active HBOT. Authors report high individual variability in scores.
6. The authors report significant improvement in brain perfusion in both groups after treatment with HBO using SPECT.
7. Authors discuss potential for a placebo effect but argue that in the absence of a true sham then HBOT should be used based on these results. They do not discuss the implications of similar beneficial effects being apparent after a course of exposures to 1.3ATA breathing air in other studies. If this is truly efficacious it would be simpler, safer and cheaper to deliver than 'true' HBOT.
8. All results are assessed over the short term only.

Appraised by:Mike Bennett; Monday, 8 February 2021
Kill or Update By: Feb 2023