Use of preoperative functional neuroimaging to predict language deficits from epilepsy surgery.

BACKGROUND: Left anterior temporal lobectomy (L-ATL) may be complicated by confrontation naming deficits. OBJECTIVE: To determine whether preoperative fMRI predicts such deficits in patients with epilepsy undergoing L-ATL. METHODS: Twenty-four patients with L-ATL underwent preoperative language mapping with fMRI, preoperative intracarotid amobarbital (Wada) testing for language dominance, and pre- and postoperative neuropsychological testing. fMRI laterality indexes (LIs), reflecting the interhemispheric difference between activated volumes in left and right homologous regions of interest, were calculated for each patient. Relationships between the fMRI LI, Wada language dominance, and naming outcome were examined. RESULTS: Both the fMRI LI (p < 0.001) and the Wada test (p < 0.05) were predictive of naming outcome. fMRI showed 100% sensitivity and 73% specificity in predicting significant naming decline. Both fMRI and the Wada test were more predictive than age at seizure onset or preoperative naming performance. CONCLUSIONS: Preoperative fMRI predicted naming decline in patients undergoing left anterior temporal lobectomy surgery.

Postoperative changes in cerebral metabolism in temporal lobe epilepsy.

BACKGROUND: Fludeoxyglucose F 18 positron emission tomography ((18)F-FDG-PET) can detect focal metabolic abnormalities ipsilateral to the seizure focus in 80% of patients with temporal lobe epilepsy (TLE). Regions outside the epileptogenic zone can also be affected. We hypothesized that these remote regions might show altered metabolism, tending to return toward normal values, after surgery. DESIGN: Interictal preoperative and postoperative (18)F-FDG-PET metabolism were compared in patients with refractory TLE. Based on pathological findings, disease was classified in the following 3 groups: mesial temporal sclerosis, mass lesions, and no pathological diagnosis. Quantitative PET data analysis was performed using the region-of-interest template previously described. Global normalization was used to adjust for the effect of antiepileptic medication changes. Data were analyzed by Wilcoxon signed rank test and analysis of variance. SETTING: The Clinical Epilepsy Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health. PATIENTS: Twenty-two patients with refractory TLE. RESULTS: Preoperatively, in all groups, cerebral metabolic rate for glucose was decreased ipsilateral to the resection site in inferior lateral temporal, inferior mesial temporal, and inferior frontal areas and thalamus. Postoperatively, in all groups, cerebral metabolic rate for glucose increased in ipsilateral inferior frontal area and thalamus. In the mesial temporal sclerosis group, we found a statistically significant increase in the contralateral thalamus. CONCLUSION: Temporal lobe epilepsy is associated with extensive preoperative decreased metabolism in inferior lateral temporal, inferior mesial temporal, and inferior frontal areas and thalamus. Postoperatively, we found increased IF and thalamic metabolism. Seizures may have a reversible effect on brain areas connected with, but remote from, the epileptogenic cortex. Arch Neurol. 2000;57:1447-1452

Cortical atrophy detected by computed tomography in gasoline station attendants.

BACKGROUND: To evaluate the contribution of leaded gasoline in the presence of abnormal calcifications or cortical atrophy seen in computed tomographies (CT) of the head of occupationally exposed professionals working in the centre of Athens. METHODS: One hundred and twenty-two head CTs from gas station employees and traffic-exposed professionals (taxi and bus drivers) were analyzed for evidence of cortical atrophy or abnormal calcifications. Blood lead level (BLL) of these lead occupationally exposed groups was compared with 37 non-exposed subjects. RESULTS: All three occupationally exposed-to-lead groups had similar blood lead levels compared to the non-exposed group and within the currently accepted norms for lead. No abnormal calcifications were found. Cortical atrophy was more frequently seen in the gas station employees group using univariate and multivariate analysis. In the logistic regression model gas station employment had a stronger impact in developing cortical atrophy [odds ratio of 6.43 (1.46-28.3, 95% CI)] than BLL [odds ratio of 1.4 (1.01-2.05, 95% CI)]. CONCLUSIONS: These results show that employment in gasoline stations may be associated with detectable cortical atrophy in imaging studies and suggest the contribution of a leaded gasoline to its development.

Influence of technetium-99m-hexamethylpropylene amine oxime injection time on single-photon emission tomography perfusion changes in epilepsy.

By digitally computing perfusion changes from ictal or postictal (peri-ictal) injections referenced to those acquired interictally, an enhanced method for localizing the epileptogenic area is reported. Computer-based image processing methods for quantifying regional percent change in the brain are applied to a group of 19 epilepsy patients after the injection of technetium-99m hexamethylpropylene amine oxime (HMPAO) and after acquiring single-photon emission tomography (SPET) data. Each patient's region of epileptogenesis was independently localized through pathology and/or successful surgery. The positive and negative quantitative perfusion changes were plotted as a function of the time of the 99mTc-HMPAO ictal injection. This time scale was normalized relative to the seizure duration and is referenced to the time of seizure termination. Eight patients, injected ictally, demonstrated perfusion increases of 25%-100% in the area of known epileptogenesis. Five patients, injected immediately after seizure cessation, demonstrated excessive perfusion decreases of 30%-92% associated with the region of seizure onset. Six patients, injected well after seizure termination, demonstrated hypoperfusion changes less than 30% at the epileptogenic area. Observations on perfusion changes calculated from 99mTc-HMPAO SPET scans, as a function of normalized time, support a progression from ictal hyper- to excessive hypo-, then finally to persistent interictal hypoperfusion. By applying this perfusion pattern model and by noting the time of injection for peri-ictal images, an improved method for localizing the epileptogenic area is demonstrated.

Blood lead levels of traffic- and gasoline-exposed professionals in the city of Athens.

During the past 10 y, blood lead levels in the population of Athens, Greece, have decreased steadily. This decrease has paralleled the reduction of tetraethyl lead in gasoline and the introduction of unleaded fuel. Blood lead levels and other parameters were studied in 42 gas-station employees, 47 taxi drivers, 47 bus drivers, and 36 controls, all of whom worked in Athens. The blood lead levels did not differ significantly among the four groups (5.64+/-1.7 microg/dl, 5.96+/-1.7 microg/dl, 5.88+/-1.3 microg/dl, and 5.76+/-1.7 microg/dl, respectively). Glutamic-oxaloacetic transaminase (i.e., aspartate aminotransferase) and glutamic-pyruvic transaminase (i.e., alanine aminotransferase) were elevated in gas-station employees, and the former was elevated in taxi drivers. Gas-station employees who smoked had higher blood lead levels than their nonsmoking counterparts. The absence of any difference in the blood lead levels of individuals for whom physical examinations were either normal or abnormal suggests that either lead was not the cause of increased blood lead levels or that its contribution may have been important in the past.