Safety and potential benefits of acute intermittent hypoxia in people with chronic traumatic brain injury

BackgroundAcute intermittent hypoxia (AIH) was recently demonstrated to improve motor and cognitive function in several patient populations, including incomplete spinal cord injury, stroke, multiple sclerosis and mild cognitive impairment. ObjectiveOur clinical trial aimed to establish if AIH can be safely administered in patients with traumatic brain injury (TBI) and to collect preliminary data about its potential efficacy for treating motor, cognitive and affective sequelae of TBI. MethodsTwelve volunteers with chronic TBI underwent four AIH sessions conducted on separate days, in which they were exposed to fifteen 30-60-s hypoxic episodes interspersed with 60-90 s of breathing ambient air. Inspired oxygen (O2) concentration during hypoxic episodes was gradually reduced from 21% (equal to ambient air, sham), to 17%, 13%, and 9%, over the course of four sessions. Neuropsychological and motor tests were administered on days before and after AIH, as well as 60 min after each AIH session. In addition, transcranial magnetic stimulation (TMS) was applied to the hand motor area 45 min after the first (21% O2) and last (9% O2) AIH session. ResultsAll participants tolerated the AIH sessions well and were able to complete the entire protocol. No significant improvement in cognition or mood was noted after the AIH intervention. Motor performance gradually improved over the course of the study, but no significant changes in response to TMS were found in corticospinal excitability. ConclusionsAIH dosage as low as 9% O2 appears safe to use in chronic TBI, but its potential benefits remain to be investigated.