Use of single photon emission computed tomography (SPECT) in the follow-up of carbon monoxide poisoned patients treated with HBO therapy: a case report

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It is widely known that carbon monoxide (CO) has the toxic effects of tissue hypoxia and produces acute neurologic deficits and a severe neurologic reaction may be delayed for days or week after anoxic exposure. The prediction of outcome during the acute stages or the latest period is difficult in most cases because of variations in age, previous state of health, duration and severity of exposure, individual susceptibility and manner of treatment.

The initial laboratory findings do not provide any prognostic clues and attempts at further predicting the clinical outcome of acute CO poisoning by means of brain CT scan or other tests have remained unsuccessful. SPECT provides tomographic images of cerebral perfusion and it has been used in clinical practice.

We experienced two cases of CO poisoning in which SPECT was performed 1 month later from acute poisoning; they had different outcome and the clinical situation was directly related to SPECT imaging results.

The patients were a mother and her son, age 55 and 25 years, who were accidentally poisoned by a domestic bath heater. They were found unconscious at home and their GCS (Glasgow Coma Score) upon their arrival in the hospital was 3. Both patients were referred to our facility and improved greatly after HBO treatment (90 min at 2.8 ATA and 30 min at 1.9 ATA); the younger was almost totally awake and the older took a little bit longer period for regaining consciousness. The MRI in both cases showed edema and necrosis in both pallidi globi. Clinically, the younger recovered fully and the older had mild neurologic sequelae as ataxic walking and light dizziness, the last one disappeared in few days. They were treated for a total of 20 sessions of HBO at 2 ATA for 60 min.

The SPECT brain imaging was totally negative for the younger and showed a bilateral decrease of blood flow in the subcortical motor nuclei in the older patient.

We can conclude that SPECT imaging is more sensitive and more directly related with the clinical picture of the patient than MRI and we are strongly convinced to use this diagnostic test in all cases of severe carbon monoxide poisoning.