Hyperbaric oxygen for late sequelae of carbon monoxide poisoning enhances neurological recovery: case report

Neuropsychiatric sequelae have been reported in 15%-45% of survivors of carbon monoxide (CO) poisoning. Hyperbaric oxygen (HBO₂) therapy reduces the incidence of cognitive and neurological a dysfunction. The efficacy of providing HBO₂ beyond the first one to two days after initial insult is unknown. However, some evidence exists for the benefit of this treatment. We report on treating a patient 14 months after CO injury, who responded with markedly improved neurologic status. A 27-year-old scholar was found comatose due to CO poisoning (carboxyhemoglobin = 31.7%). He received five acute HBO₂ treatments. After discharge, he developed chorea, Parkinsonism, dystonia, memory loss, slowed processing speed and verbal fluency, leaving him disabled. After the patient reached a clinical plateau, HBO₂ was tried again at 90 minutes at 2.4 ATA plus air breaks. Neuropsychological testing was performed at baseline and after each 20 HBO₂ cycles, five of which were performed during the period from 14-22 months after CO exposure. After the first 20 treatments, Parkinsonism and dystonia improved. After 40 sessions, further improvements were seen on mental speed, verbal fluency, and fine motor movements. The outcome following 100 treatments was that the patient regained independence, including the ability to drive and to become gainfully employed. Our case calls into question the concept that HBO₂ therapy has no role during the chronic phase of CO brain injury. Randomized clinical trials should be considered to evaluate the therapeutic efficacy of HBO₂ in patients with neurological sequelae following CO injury.