The study is a retrospective review of the author's experience treating chronic brain injury with HBOT, supplemented by cases communicated to the author, who developed untoward effects during or after their HBOT. The object of the study was to affirm or refute the author's general impression that there was an optimal dose of HBOT in chronic brain injury which was lower than the traditional dose applied in chronic non-central nervous system wounding. Furthermore, when this lower dosage range was exceeded and approached the traditional doses for non-CNS wounding oxygen toxicity would result. To address these impressions the study seeks to review the author's medical records and other patient/doctor communications to the author where side effects of HBOT occurred in the treatment of chronic brain injury and abstract signs, symptoms, and the dose of HBOT employed.