Regional cerebral blood flow measurements with Xenon-CT in the prediction of delayed encephalopathy after carbon monoxide intoxication

Neurocognitive sequelae after carbon monoxide poisoning and hyperbaric oxygen therapy

Carbon monoxide (CO) has been the leading cause of poisoning mortality in many countries and hyperbaric oxygen (HBO) is a widely accepted treatment for CO poisoning. However, some patients with CO poisoning will still develop neurocognitive sequelae regardless of HBO therapy, which can persist since CO poisoning or be present days to weeks after a recovery from CO poisoning. HBO has been used in the prevention and treatment of neurocognitive sequelae after CO poisoning, and some mechanisms are also proposed for the potential neuroprotective effects of HBO on the neurocognitive impairment after CO poisoning, but there is still controversy on the effectiveness of HBO on neurocognitive sequelae after CO poisoning. In this paper, we briefly introduce the neurocognitive sequelae after CO poisoning, summarize the potential predictive factors of neurocognitive sequelae, and discuss the use of HBO in the treatment and prevention of neurocognitive sequelae after CO poisoning.

Neuroimaging, Cognitive, and Neurobehavioral Outcomes Following Carbon Monoxide Poisoning

Carbon monoxide is a colorless, odorless gas produced as a byproduct of combustion. Carbon monoxide is the leading cause of poisoning injury and death worldwide. Morbidity following CO poisoning includes neurologic sequelae, neuropathologic abnormalities on brain imaging, neurobehavioral changes, and cognitive impairments. It is estimated that as high as 50% of individuals with carbon monoxide poisoning will develop neurologic, neurobehavioral, or cognitive sequelae. Carbon monoxide related cognitive impairments included impaired memory, attention, executive function, motor, visual spatial, and slow mental processing speed. Given the high rate of brain related morbidity and the fact that the majority of carbon monoxide is avoidable, awareness and prevention of carbon monoxide poisoning is warranted.

Catatonia after cerebral hypoxia: do the usual treatments apply?

BACKGROUND

Neurologic deterioration occurring days to weeks after a cerebral hypoxic event accompanied by diffuse white matter demyelination is called delayed posthypoxic leukoencephalopathy (DPHL). Manifestations of DPHL are diverse and include dementia, gait disturbance, incontinence, pyramidal tract signs, parkinsonism, chorea, mood and thought disorders, akinetic mutism, and rarely catatonia.

METHODS

We report a case of malignant catatonia in a patient diagnosed with DPHL that was refractory to electroconvulsive therapy (ECT) and review the literature on catatonia in DPHL.

RESULTS

The patient was a 56-year-old woman with schizoaffective disorder who was admitted with catatonia 2 weeks after hospitalization for drug overdose and respiratory failure. Her catatonic symptoms did not respond to treatment of lorazepam, amantadine, methylphenidate, or 10 sessions of bilateral ECT at maximum energy. Repeat magnetic resonance imaging revealed extensive periventricular white matter lesions not present on admission scans, and she was diagnosed with DPHL.

DISCUSSION

No treatment for DPHL has been proven to be widely effective. Hyperbaric oxygen treatments may reduce the rate of development, and symptom improvement has been reported with stimulants and other psychotropic agents. Review of literature reveals rare success with GABAergic agents for catatonia after cerebral hypoxia and no cases successfully treated with ECT. There are 7 case reports of neurologic decompensation during ECT treatment after a cerebral hypoxic event.

CONCLUSION

Caution is advised when considering ECT for catatonia when delayed sequelae of cerebral hypoxia are on the differential diagnosis, as there is a dearth of evidence to support this treatment approach.

Carbon-monoxide poisoning, behavioural changes and suicide: an unusual industrial accident

We report a case of CO intoxication caused by a motor vehicle's faulty heating-system. A truck driver experienced severe mental deterioration, behavioural changes and delirium after acute CO intoxication and committed suicide 15 months later. This report examines the pathogenetic mechanism of CO, the immediate and delayed consequences of CO intoxication, diagnostic difficulties and current treatment options. The medical-legal aspects of the case are discussed.

Neurospect in neurotoxic chemical exposure demonstration of long-term functional abnormalities

Patients who had experienced well-documented neurotoxic exposure months or years earlier were evaluated. Seventy-two right-handed adults who claimed continuing abnormalities of cognitive and memory function were examined after Xenon-133 inhalation and i.v. HMPAO. Single photon emission computed tomography (SPECT) results were statistically compared with age-matched controls. Bilateral, often asymmetrical, impairment of perfusion was found, mostly in the frontal, temporal, and parietal lobes. This hypoperfusion was predominantly left-sided in young patients and predominantly right-sided in the elderly. Abnormalities were found months and years after neurotoxic exposure had ceased. Our findings suggest that NeuroSPECT can provide evidence of impaired cerebral function and may therefore help to further define neurotoxic exposure and its chronic effects.

Environmental emergencies

This article reviews the pearls and pitfalls of high-altitude sickness, decompression sickness, and barotrauma; new findings relevant to the near-drowning patient; continued controversies on hyperbaric oxygen for carbon monoxide poisoning; pitfalls in hypothermia management; and updates on the management of venomous snakebites.