Evaluation of techniques for the study of electromyographic signals.

The objective of this work was the study and the development of techniques for acquiring and processing electromyographic signals that can be used for analysis of the behavior of electromyographic variables during fatiguing dynamic activities. Two of the techniques were the RMS value and the MPF, which are commonly used for the analysis of electromyographic signals measured during isometric contractions. A new technique, called MAEC, was proposed, based on the domain of the Wavelet transform. The results showed that the combination of the three techniques together with the protocol for recording electromyographic signals lead to a useful characterization of the behavior of electromygraphic variables.

Cerebellar hemorrhage after supratentorial surgery for treatment of epilepsy: report of three cases.

OBJECTIVE AND IMPORTANCE: We report three cases of cerebellar hemorrhage complicating supratentorial craniotomies for the treatment of epilepsy. In a literature review, we identified only four similar cases of cerebellar hemorrhage after temporal lobectomy for the treatment of epilepsy. CLINICAL PRESENTATION AND RESULTS: Three young and otherwise healthy patients underwent frontal, occipital, and temporal resections for the treatment of refractory epilepsy. The hemorrhage manifested as peduncular tremor, ataxia, and decerebrate posturing presenting early in the postoperative period. The diagnosis was established by computed tomography and/or magnetic resonance imaging. Benign outcomes were observed for all patients. CONCLUSION: Based on the available data, it is our opinion that brain dislocation resulting from excessive intraoperative cerebrospinal fluid drainage is a possible mechanism for this rare complication of supratentorial craniotomy. The overdrainage seems to be less hazardous when the procedure is performed for the removal of space-occupying mass lesions. In contrast, the resection of nonexpanding tissues, such as in lobectomies for the treatment of epilepsy, may be an additional risk factor, because the incidence of this complication seems to be higher in these situations.

Ultradian components of the sleep-wake cycle in babies.

Behavioral states may be analyzed as expressions of underlying cyclic activity involving several physiological systems. The human sleep-wake cycle in the first year of life shows, in addition to the establishment of circadian rhythmicity around the second month, the dynamics of its ultradian components, as can be seen in the more or less gradual decline of the polyphasic pattern. To detect these changes, we have analyzed the sleep-wake cycle of five babies of different ages (3, 4, 9, 11, and 13 months) observed for 5 consecutive days (Monday through Friday), 10 h (08:00-18:00 h) per day at a kindergarten by the first author, and during the night (18:00-08:00 h) by the parents. Behavioral observations were designed for minimizing interference with the babies' habits. Sleep/wake data were arranged in 60-min intervals, and the relative amount of time spent asleep per interval constituted the time series submitted for statistical analysis. The five resulting time series were submitted to spectral analysis for detecting the composition of frequencies contributing to the observed sleep/wake cycle. Several frequencies were thus obtained for each baby in the ultradian and circadian domain, ranging from one cycle in 2.0 h to one cycle in 24 h. The circadian component was the strongest rhythmic influence for all individuals except for the youngest (3-month-old) baby, who showed a semicircadian component as the main frequency in the power spectrum. Three individuals showed ultradian frequencies in the domain of 3-4 h. Differences in the spectra derive from three possible, and probably not exclusive, causes: 1) ontogenetic changes, 2) different masking effects, and 3) individual differences.