Clinical studies on three cases of the interval form of carbon monoxide poisoning: serial proton magnetic resonance spectroscopy as a prognostic predictor

Abstract

Three patients with the interval form of carbon monoxide (CO) poisoning were studied for associations between their clinical courses and serial changes on: (1) MRI; (2) EEG; (3) single photon emission computed tomography with N-isopropyl- p-[ 123I]iodoamphetamine ([ 123I]IMP SPECT); and (4) proton magnetic resonance spectroscopy ([ 1H]MRS) to evaluate their usefulness as prognostic predictors. A hyperintense area on MRI T 2-weighted images and a hypointense area on T 1-weighted images, appearing in the deep white matter, persisted for a prolonged period even after improvement of the clinical symptoms, and did not become an accurate indicator of clinical evaluation or prognosis. [ 1H]MRS studies with the volume of interest set in the frontal lobe white matter revealed increases in choline-containing compounds, and reductions of N-acetylaspartate in all cases. These findings normalized in one subclinical case over time. Distinctive findings in the severe cases included increased lactate in two cases showing akinetic mutism, with a difference in prognosis noted according to the degree and period of persistence of this increase. EEG findings were relatively well correlated with clinical symptoms in the early period, with a good correlation no longer consistent after a certain period was exceeded. [ 123I]IMP SPECT findings did not always reflect clinical symptomatology either. These results indicate that [ 1H]MRS is the most useful indicator in the clinical evaluation of patients with the interval form of CO poisoning.