Carbon Monoxide-Induced Cortical Visual Loss: Treatment with Hyperbaric Oxygen Four Years Later

Objective: We present a patient who developed visual loss after carbon monoxide (CO) poisoning and was treated with hyperbaric oxygen. Clinical Presentation and Intervention: A 21-year-old woman poisoned with CO (with coma lasting 4 h and carboxyhemoglobin level 46%) developed seizures and cortical blindness 3 days after poisoning. Four years later, her visual acuity was 0.2 in both eyes. An 18 F-fluorodeoxyglucose positron emission tomography (PET) scan showed reduced metabolism in the bilateral posterior temporal and occipital lobes. The patient received a total of 50 hyperbaric oxygen sessions over 3 months for visual loss and the visual acuity improved to 0.5 in both eyes. In addition, increased metabolism was detected in the brain in post-treatment PET scans. Conclusion: PET documented brain hypoperfusion 4 years after CO poisoning and hyperbaric oxygen therapy improved visual acuity. However, we cannot endorse routine use of hyperbaric oxygen for such patients, until results of further clinical trials demonstrate efficacy of hyperbaric oxygen in CO-induced chronic brain injury.