Delayed neuropsychiatric sequelae with improvement of decreased cerebral bold flow by single‐photon emission computed tomography during hyperbaric oxygen therapy: A case report with a 10‐year follow‐up

Abstract Background Delayed neuropsychiatric sequelae (DNS) occurs in 10%–30% of acute carbon monoxide poisoning cases. Patients with this condition present higher brain dysfunction. Hyperbaric oxygen (HBO) therapy was reportedly an effective treatment for DNS in the acute phase. Favorable predictive factors affecting the prognosis of patients with DNS after HBO therapy include younger age and longer interictal periods. However, the relationship between these factors and neuroimaging findings remains unclear. Case Presentation The patient was a 59‐year‐old man with DNS, who developed major depressive disorder and attempted suicide with charcoal briquettes. He was diagnosed with carbon monoxide poisoning and underwent acute HBO therapy. After a 1‐month lucid period, the patient developed intermittent carbon monoxide poisoning with cognitive dysfunction, following which HBO therapy was re‐initiated. Following treatment, the patient returned to work for 10 years. Frontal lobe hypoperfusion, measured by single‐photon emission computed tomography and cognitive impairment, improved with HBO therapy. However, magnetic resonance imaging revealed brain volume atrophy over time. Conclusion This study reported a case of DNS that completely resolved within a 10‐year follow‐up period. Cerebral blood flow reduction, mainly in the frontal lobe, improved along with cognitive recovery during HBO therapy. Despite gradually progressive brain atrophy over the past decade, no noted deficits in cerebral blood flow were observed in the frontal lobes. These findings suggest that improvement in cerebral blood flow during HBO therapy and its retention may be factors associated with a favorable prognosis in patients with DNS.