Using an unbiased stereological technique, the total numbers of pigmented and non-pigmented neurons were estimated in the substantia nigra of seven patients with Parkinson's disease and seven control patients. Compared with the controls, in which the average total number of pigmented neurons was 550 000, the number of neurons was reduced by 66% in the patients. The average total number of non-pigmented neurons was 260 000 in controls and reduced by 24% in the patients. A significant correlation (r = 0-81) existed between the total numbers of pigmented and non-pigmented neurons in the controls, whereas a similar correlation (r = 0 72) in the patients fell just short of statistical significance. The Exclusion criteria common to the two groups were primary and secondary tumours, infection of the CNS, or a history of alcohol or drug abuse. Also excluded were brains from patients who had been comatose for more than 24 hours before death and those not removed within 72 hours of death. All brains were analysed blindly by one investigator.

Quantitation of hippocampal neurons was performed in 20 patients with generalized epilepsy. Twelve suffered from partial seizures. The neuronal numbers were compared with the control series of patients without epilepsy. It was established that there were fewer neurons in the hippocampi from patients with epilepsy than from those of controls. The neuron loss was particularly marked in the endfolium (field H3), the granule cells (fascia dentata), and particularly in the caudal (anterior) part of the structure. Frequent, generalized epileptic seizures and long duration of the epileptic disorder influenced the neuron loss. In some parts of the pyramidal band (field H1), the neuron loss appeared at a younger age, which leads one to suspect its particular involvement in the seizure mechanism. The neuron loss was not related to the different types of seizures investigated. The results support the hypothesis of neuron loss as an ongoing process in patients with epilepsy, whatever the type of epilepsy, when tonic-clonic seizures, as is very common, are present.

Despite the small number of cases in the study these data indicate that treatment with LTG during pregnancy might be relatively safe. Larger prospective studies are needed to obtain adequate power for statistical analysis.

Approximately 25% of patients with epilepsy will have their first seizure after the age of 25 years. These individuals will need special attention with regard to etiology. Brain tumor is one of several causes that may be suspected. The present study of 221 patients with late-onset epilepsy from the University Clinic of Neurology, Hvidovre Hospital, Copenhagen, Denmark, was undertaken to look for means to select those cases in which computerized tomography (CT) scan should be performed. Brain tumor was the cause in 16% and cerebrovascular infarctions in 14%. The major etiological group was the one in which no cause could be detected (38%). Alcohol abuse as the etiology--defined as cases with a history of long-standing alcohol overuse, concomitant signs of alcohol intoxication, and spontaneous recurrent epileptic seizures--made up a group of one-fourth of all the patients with late-onset epilepsy. Comparison of the history, clinical symptoms and signs, EEG abnormalities, and CT scan speaks in favor of some consideration being given to the first three parameters before the CT scan is performed.

The aim of this study was to determine the density and pattern of distribution of the neurons in the human hippocampus, and twenty-nine brains of healthy individuals were examined. The cells counted in each unit area were the pyramidal cells in the H-fields and the granule cells. Difference in density was found between all H-fields. The neuronal density was highest in the H2-fields. The density decreased through the transitional area H1-2 and H1, with the lowest density in H3. The neuronal density increased in all H-fields in the antero-posterior direction, while the granule cells decreased in density. In the individual brain there was a positive correlation found respectively between high and low cell density in the different H-fields. The pyramidal cell density decreased in persons more than 68 years old. No difference was found between neruonal cell density in the two sides of the brain. Sex did not influence the neuronal cell density.