Electroencephalographic findings in acute carbon monoxide poisoning

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

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 ([1HIMRS) to evaluate their usefulness as prognostic predictors. A hyperintense area on MRI T2-weighted images and a hypointense area on T1-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 reflectclinical 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.

[Cerebral anoxia in near-drowning of children. The prognostic value of EEG]

The retrospective electroclinical evaluation of anoxia by near-drowning in 23 children observed between 1985 and 1989 revealed 2 groups, each with a distinct evolution: the first group, with good prognosis of 17 children, which recovered consciousness without neurological complications between 2 d and 1 wk after the accident. The second group of 6 children with a poor outcome--either i), death; or ii), state of permanent injury; or iii), a high level of clinical deficits. The gravity of the early clinical state, the estimated duration of cardiorespiratory arrest, the severity of the hypothermia, the seizures and the paroxysmic activity, do not determine the severity of near-drowning encephalopathy. The EEG patterns described in correlation with the group and the clinical outcome permitted determination of prognostic criteria. A good prognostic consisted of the following: moderate background activity, sleep patterns, response to auditory and painful stimulations, and numerous beta rhythms. A bad outcome was defined by: high voltage, rhythmic delta waves; biphasic sharp waves; monotonous EEG, "burst-suppression" pattern, absence of beta rhythms. The importance of EEG recordings is emphasized performed as early as possible and until 3 or 7 d after the near-drowning. Any modification in the EEG, with attenuation or disappearance of fast frequencies and painful reactivity, appearance or enhancement of slow and biphasic sharp waves, are ominous signs and may be accompanied by the appearance of cerebral oedema and decerebration.

A case of cortical blindness due to carbon monoxide poisoning

We report a case of cortical blindness occurring 7 days after acute CO poisoning with no other neurological or psychic deficits apart from denial of the blindness with visual confabulation and slight loss of retentive memory. There was scant correlation between the course of the clinical pattern, which cleared completely within 6 days, and the electroencephalographic pattern with marked and diffuse slowing, which did not recede completely during 3 months observation. CT scanning of the skull, initially within normal limits, displayed 2 weeks later a faint but diffuse hypodensity of the white substance, more marked in the occipital region, which was no longer present 80 days after the first scan.