Electroencephalographic mapping and 99mTc HMPAO single-photon emission computed tomography in carbon monoxide poisoning.

STUDY OBJECTIVE: To investigate whether topographic analysis of EEG mapping and technetium-99m (99mTc) hexamethylpropylenamine oxide (HMPAO) brain single-photon emission computed tomography (SPECT) can detect cerebral anomalies in the acute phase of carbon monoxide poisoning. DESIGN: Twelve patients aged 18 to 55 years with severe carbon monoxide poisoning and no history of neurologic disorder were evaluated. Either nasal (5 patients) or hyperbaric (7 patients) oxygen therapy was administered. Criteria for hyperbaric oxygen therapy were blood CO of more than 20%, loss of consciousness, pregnancy, or signs of cardiac injury. After oxygen treatment, all patients had a blood CO value of 0% and no patient had persistent acute signs of toxicity. Patients then were investigated by confentional EEG, EEG mapping, and 99mTc HMPAO brain SPECT. These procedures were performed on the day of admission. PARTICIPANTS: After nasal (5 patients) or hyperbaric (7 patients) oxygen therapy was administered, 12 adults with severe carbon monoxide poisoning were evaluated. All studies were performed on the day of admission. MEASUREMENTS: Conventional EEG, EEG mapping, and 99mTc HMPAO brain SPECT. RESULTS: While classic EEG was normal in 9 of 12 patients and showed diffuse anomalies in 3, EEG mapping and 99mTc HMPAO brain SPECT demonstrated unilateral or bilateral regional anomalies in 8 of 12 patients. Anomalies were localized in temporo-parieto-occipital areas, the watershed areas of the major cerebral arteries, or in temporal cortex. CONCLUSION: These preliminary results suggest that EEG mapping and 99mTc HMPAO brain SPECT can be complementary tools to diagnose early regional cerebral anomalies in carbon monoxide-poisoned patients.

Bilateral cerebral mediofrontal hypoactivity in Tc-99m HMPAO SPECT imaging.

Fifteen patients who had bilateral mediofrontal hypoactivity and 30 control subjects without this SPECT anomaly underwent Tc-99m HMPAO brain SPECT imaging. Bilateral mediofrontal hypoactivity was found in various neurologic disorders, including subcortical arteriosclerotic encephalopathy, lacunar state, chronic alcoholism, progressive nonvascular dementia, carbon monoxide poisoning, and diabetes mellitus. This SPECT abnormality was, however, specifically associated with three clinical signs: motor disabilities predominating in the lower limbs, urinary incontinence, and akinetic mutism.

Prediction of cerebral palsy in high-risk neonates: a technetium-99m-HMPAO SPECT study.

In infants who have experienced prenatal or perinatal injury, it is often difficult, on the basis of clinical examination and conventional investigations (electroencephalogram, cranial ultrasound scan), to diagnose those with brain damage and to predict the type and the severity of subsequent neurological handicaps. We investigated the predictive value of 99mTc-HMPAO brain SPECT performed in the first weeks of life in high-risk neonates. Right-left asymmetries in tracer uptake had no predictive value, regardless of their localization or severity. On the other hand, a change in antero-posterior rCBF distribution was found in 7/10 of neonates with adverse outcome (death, major neurological sequelae) and in none of the 78 neonates with no major motor neurological sequelae. Compared to conventional investigations, 99mTc-HMPAO brain SPECT did not provide additional predictive information when neurological examination, electroencephalogram and cranial ultrasonography were all normal or all abnormal. Conversely, in the 30 patients with anomalies on one or two of the above investigations, SPECT showed an abnormal antero-posterior pattern in 4/6 neonates with major neurological sequelae and no change in the antero-posterior rCBF distribution in the 24 infants who developed normally. In conclusion, our results suggest that 99mTc-HMPAO brain SPECT, when performed in the first weeks of life, can be useful in high-risk neonates to predict occurrence of major neurological handicaps. Because of the relative invasive character of HMPAO scan in neonates and the overall accuracy of the noninvasive tests, radionuclide examination should not be performed in every high-risk neonate. According to our results, 99mTc-HMPAO brain SPECT might be indicated in those children where noncongruent results were obtained with conventional studies.

Metabolic changes in the rat brain after acute and chronic ethanol intoxication: a 31P NMR spectroscopy study.

In this work, 31P phosphorus NMR (31P NMR) studies of the brain have been conducted in rats acutely and chronically intoxicated with ethanol. In both groups, changes in levels of high-energy phosphates were observed: increase of phosphocreatinine (PCr)/beta AaTP and PCr/inorganic phosphate (Pi) in acute and long-term ethanol exposure, and decrease of Pi/beta ATP after acute ethanol administration. These changes in high-energy phosphates, indicative of a reduction of adenosine triphosphate (ATP) and PCr consumption (PCr+ ADP+ H+ ATP+ Cr; ATP ADP+ Pi), suggest a reduction of cerebral metabolism both in acute and chronic ethanol exposure. In addition, in the group of rats chronically intoxicated with ethanol, there were variations in phosphodiester peak intensities (decrease of phosphomonoester (PME)/phosphodiester (PDE), increase of PDE/beta ATP), suggesting increased breakdown of membrane phospholipids. These changes could provide a metabolic explanation for the development of cerebral atrophy in chronic alcoholism.

Detection of bilateral and symmetrical anomalies in technetium-99m-HMPAO brain SPECT studies.

The detection of bilateral and symmetrical regional cerebral blood flow (rCBF) abnormalities requires knowledge of the antero-posterior rCBF distribution in normal subjects of all age groups. These data are very difficult to obtain in children for ethical reasons and in older subjects because of the necessity of recruiting a large number of healthy volunteers from each age group. Therefore, to obtain normal values of antero-posterior rCBF distribution, we have retrospectively selected a group of patients with a low probability of having cerebral lesions, whose 99mTc-HMPAO brain SPECT studies were analyzed semiquantitatively. Cerebellum/mean cerebral cortex index when compared to young adults was higher in the neonatal period, slightly lower between 2 mo and 15 yr, and more or less identical after 15 yr. Cortico/occipital indexes exhibit considerable changes during the first year of life due to important differences in maturation timing of cerebral cortical areas. After 1 yr, all cerebral cortical areas approximately displayed a parallel evolution. A slight increase in fronto/occipital and temporo/occipital indexes was, however, still observed during childhood, while in elderly subjects there was a trend towards a decrease in all cortico/occipital indexes (particularly in prefrontal and motor areas). Changes that occurred after 1 yr were, however, usually smaller than interindividual variation. Despite the large range of "normal" values, the antero-posterior analysis could be useful in various neurologic disorders, because it allows detection of symmetrical rCBF anomalies undiagnosed by the right-left analysis.

Cerebral palsy: initial experience with Tc-99m HMPAO SPECT of the brain.

The outlook for children with cerebral palsy is determined by the severity of motor problems and the presence of associated disabilities, in which early detection remains a medical challenge. The authors studied 13 children (aged 13 months to 12 years) with cerebral palsy by means of single photon emission computed tomography (SPECT) of the brain with technetium-99m hexamethylpropyleneamineoxime (HMPAO). In all children with hemiplegia, SPECT demonstrated hypoperfusion in the hemisphere contralateral to the motor deficit. SPECT demonstrated normal findings in patients with mild diplegia; bilateral hypoperfusion in the superior motor cortex in patients with moderate di- or tetraplegia; and bilateral reduction of perfusion in the superior motor, inferior motor, prefrontal, and parietal cortices in patients with severe di- or tetraplegia. Results suggest that Tc-99m HMPAO SPECT of the brain is a valuable complementary tool for thorough neurologic assessment in cerebral palsy.

Functional imaging of brain maturation in humans using iodine-123 iodoamphetamine and SPECT.

The application of regional cerebral blood flow (rCBF) study by means of lipophilic radiotracers and single photon emission computed (SPECT) devices in very young infants is hampered by the considerable changes of rCBF pattern as a result of the cerebral maturation process. In an attempt to determine the normal evolution of [123I]IMP SPECT pattern as a function of age, we retrospectively selected the studies of 30 babies with normal clinical examination, EEG and CT or ultrasound scans at time of SPECT. There was a marked predominance of the thalamic perfusion over cortical areas until the end of the second month. The distribution of regional cortical activity followed a strict sequence. The perfusion of both parietal and occipital areas was well-visualized around the 40th week of gestational age and thereafter rapidly rose, always, however, with a slight predominance of the parietal activity. At the opposite, frontal activity which remained scarcely recognizable up to the second month tremendously rose to present the adult-like pattern at the beginning of the second year. The rCBF changes described above are well in agreement with the behavioral evolution occurring during prime infancy.

Regional brain blood flow in congenital dysphasia: studies with technetium-99m HM-PAO SPECT.

Congenital dysphasia is a developmental speech disorder not explained by deafness, phonation disorder, mental retardation, neurologic lesion, or psychiatric disease. The existence of brain lesions has often been postulated but conventional investigations fail to demonstrate any cerebral abnormality. By means of [99mTc]hexamethyl-propyleneamine oxime (HM-PAO) brain single photon emission computed tomography (SPECT) we have studied 14 children suffering from congenital dysphasia. The brain computed tomographic scan was normal in all cases. In two patients with expression impairment the SPECT study demonstrated a hypoperfusion in the inferior frontal convolution of the left hemisphere, involving the Broca's area. In nine of 12 patients with global dysphasia (deficits in both comprehension and expression), SPECT study showed two hypoperfused areas: an abnormality in the left temporoparietal region and a hypoactivity in the upper and middle areas of the right frontal lobe. These results suggest that congenital dysphasia could be due, like acquired aphasia, to specific impairment of the language cerebral areas and that brain SPECT studies with [99mTc]HM-PAO could be useful for a better comprehension of the physiopathology of these disorders.

Brain single photon emission computed tomography in neonates.

This study was designed to rate the clinical value of [123I]iodoamphetamine (IMP) or [99mTc] hexamethyl propylene amine oxyme (HM-PAO) brain single photon emission computed tomography (SPECT) in neonates, especially in those likely to develop cerebral palsy. The results showed that SPECT abnormalities were congruent in most cases with structural lesions demonstrated by ultrasonography. However, mild bilateral ventricular dilatation and bilateral subependymal porencephalic cysts diagnosed by ultrasound were not associated with an abnormal SPECT finding. In contrast, some cortical periventricular and sylvian lesions and all the parasagittal lesions well visualized in SPECT studies were not diagnosed by ultrasound scans. In neonates with subependymal and/or intraventricular hemorrhage the existence of a parenchymal abnormality was only diagnosed by SPECT. These results indicate that [123I]IMP or [99mTc]HM-PAO brain SPECT shows a potential clinical value as the neurodevelopmental outcome is clearly related to the site, the extent, and the number of cerebral lesions. Long-term clinical follow-up is, however, mandatory in order to define which SPECT abnormality is associated with neurologic deficit.

Single photon emission computed tomography in seizure disorders.

Fourteen children with various seizure disorders were studied using a cerebral blood flow tracer, 123I iodoamphetamine (0.05 mCi/kg), and single photon emission computed tomography (SPECT). In the five patients with radiological lesions, SPECT showed congruent or more extensive abnormalities. Five of the nine children with a normal scan on computed tomography had abnormal SPECT studies consisting of focal hypoperfusion, diffuse hemispheric hypoperfusion, multifocal and bilateral hypoperfusion, or focal hyperperfusion. A focal lesion seen on SPECT has been found in children with tonic-clonic seizures suggesting secondarily generalised seizures. Moreover the pattern seen on SPECT seemed to be related to the clinical status. An extensive impairment found on SPECT was associated with a poor evolution in terms of intellectual performance and seizure frequency. Conversely all children with a normal result on SPECT had less than two seizures per year and normal neurological and intellectual development.