Biomedical subjects
Publications and source records attributed to E D Louis.
A patient developed focal fibrotic myopathy after many years of intramuscular heroin use. While such changes have been associated with chronic intramuscular injections of pentazocine and meperidine, a similar myopathy resulting from chronic intramuscular heroin has not been convincingly described.
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The tetanus toxin model of epilepsy, involving direct microinjection of toxin into the mammalian brain, has a number of advantages relative to other chronic models. However, chronic seizure foci have been confined primarily to the hippocampus. In the present study, 5 cats received total doses of 7.5-22.5 ng of tetanus toxin applied to the left primary motor cortex through an epidural cannula. After 2-18 days, all 5 cats exhibited similar persistent epileptiform syndromes. Three distinct types of spontaneous seizures were noted: focal motor seizures of variable complexity, focal motor seizures with secondary generalization, and epilepsia partialis continua. All cats required anticonvulsant therapy. Simple focal motor seizures, which predominated, were electrographically characterized by 3-5 Hz spike-sharp wave activity, originating in the left motor cortex, associated with contralateral shoulder and forepaw clonus and jacksonian spread. Electrographic activity quickly spread to ipsilateral neocortical structures, and in longer episodes to the cingulate gyri. Seizure foci were still active as long as 37 days after toxin injection. Light microscopic damage attributable to the toxin was absent. These experiments further generalized the tetanus toxin model and confirmed its advantages.
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UNLABELLED: BACKGROUND/SETTING: It is well recognized that mild tremor is common among older adults, but the prevalence and clinical characteristics of this tremor have not been studied in detail. OBJECTIVES: To examine a cohort of normal older adults to: (1) ascertain the prevalence of mild test-detectible tremor; (2) quantify the severity and functional impact of this tremor, and (3) determine whether age, gender and concomitant illness predict the severity of tremor. PARTICIPANTS: 76 normal older adults >55 years of age (mean age = 73.7 years). DESIGN: Healthy older adults were identified in a community-based case-control study of essential tremor in Washington Heights-Inwood, New York. All subjects underwent a medical interview and a videotaped neurological examination. The examination included six tests: arm extension, pouring water, drinking water, using a spoon, finger-to-nose movements, and drawing spirals with each arm. Two neurologists rated the severity of tremor using a 0 to +3 clinical rating scale and a total tremor score (TTS) was calculated (range = 0-36). Forward stepwise linear regression was used to determine the association between TTS and other variables. RESULTS: Virtually all (75 or 98.7%) showed signs of tremor (TTS > 0.5). The mean TTS = 6.3 (range = 0-14.5), corresponding to a tremor that was either mild or intermittent. Twenty-eight of 76 (36.8%) received tremor ratings of +2 (clearly oscillatory tremor of moderate amplitude and usually present) during at least one of the six tests; a tremor rating of +2 was 2.1 times more likely to occur in the nondominant than in the dominant hand. Those who were aged 57-74 years had a lower mean TTS (5.8) than those aged 75-93 (6.8), but this was not significant. Only 2 patients (2.6%) answered 'yes' to the question 'do you have uncontrollable shaking in your hands?' None was taking medication to treat tremor. Gender, ethnicity, concomitant illness (diabetes, arthritis, heart disease), and medications were not associated with a higher TTS. CONCLUSION: Mild but test-detectible tremor was present in almost all normal older adults, and in one-third this tremor attained a moderate amplitude during at least one activity. Characterization of this tremor would be of value to practitioners who care for older adults.
A number of experimental (i.e., animal) models have been developed to induce chronic focal epilepsy. Three of the most commonly employed are the alumina cream, kainic acid, and the electrical kindling techniques. A fourth approach involving the application of minute quantities of tetanus toxin to discrete brain sites, although relatively under-utilized, may be favorably compared to the aforementioned models.