EEG-EMG Zeitschrift fur Elektroenzephalographie, Elektromyographie und verwandte Gebiete最新文献

Specific alterations of EEG tracings with Moyamoya syndrome are only observed in children. They consist in a gradual frequency decrease and amplitude activation after hyperventilation. This is referred to as re-build-up phenomenon. Thus, a tentative diagnosis of Moyamoya syndrome in children may be based on the EEG finding, to be radiologically confirmed by angiography.

Polygraphic sleep recordings were performed in 12 sober alcoholic patients, 8 young normals and 12 healthy elderly subjects. An automatic sleep analysis including two different methods (standard and adaptive) of SWS scoring was used. The standard method is based on amplitude dependent rules according to Rechtschaffen and Kales. The basis for classification of SWS in the adaptive method is the relative increase of the integrated delta-activity during NREM sleep. Whereas in young and elderly normal subjects the method used has no influence on the duration of SWS during the night, the amount of SWS in alcoholic patients is significantly higher when applying the adaptive sleep analysis compared with the results of the standard method. Alcoholics show the lowest level of integrated delta activity during NREM and also the shortest duration of SWS resulting from the standard sleep analysis. On the contrary the relative dynamic of EEG synchronization and the duration of SWS measured by the adaptive sleep analysis are comparable with the values of normal subjects. The general decrease of the delta activity during sleep in sober alcoholics is assumed to be not a reflection of the reduction of SWS.

In standard concentric needle electromyography the typical triphasic potential of a motor unit (MUP) consists of the spike component and the positive initial and terminal parts. Whereas the main spike is generated by a few muscle fibers located close to the tip of an electrode, the initial and terminal parts represent the sum of activities of a large proportion of fibers within the motor unit. The size of the initial and terminal part is assessed by measuring the duration of the MUP. In addition to the duration we calculated the mean absolute voltage outside the spike component: The signal was digitized and several individual MUPs of the same motor unit were averaged. The point of maximal negative rise was identified. Then the mean absolute voltage between -5 ms and +5 ms around this point, excluding the interval from -1 ms to +1 ms, was calculated. This parameter is exactly defined and unambiguous. The biceps brachii muscles of 30 healthy volunteers were examined in order to establish normal values. In 24 patients suffering from various myopathies 18 had significant (p less than 0.01) reduced initial and terminal parts, whereas only 13 patients showed decreased potential duration (according to Buchthal 1957).

Four patients with an absence status induced by drugs, are described. In three patients the use of neuroleptics was the probable cause, in the other indomethacin could be incriminated. As yet an absence status after treatment with these medicaments has not been described. Clinically, the diagnosis was not unequivocal. The EEG gave clear results, rapidly indicating the cause of the patient's clinical condition.

In static magnetic fields as used in MRT-equipment for clinical diagnosis the "spontaneous" EEG is triggered by each heart activity. The registered signal is characterized by an oscillation of potentials in the frequency range of 8 to 10/s, mostly beginning with the higher frequency. These data sampled are dependent of the magnetic flux vector, but not regularly and independent of the point of lead. These results point to a transition from the isotropic distribution of EEG-currents to an anisotropic state by static magnetic fields.

For testing saccadic eye movements three methods are used today: the coil-, the infrared- and the electrode-method. All of these techniques are endowed with advantages and disadvantages. The electrode-method that uses the dipole-character of the eye needs a DC-amplifier with small noise and drift error. The amplifier described here complies with these requirements. It has been used for a long time and disapproves the general opinion that the coil- and the infrared-method are the more expensive but in all cases the better methods.

70 patients with Completed stroke were studied and the findings of routine EEG, EEG mapping and CT were compared. It could be shown, that the EEG mapping revealed significantly more often focal changes corresponding with the clinical signs (83%) than the routine EEG (57%). Hypodense lesions in CT were seen in 54 patients. Identical results of EEG mapping and CT were found in 50 patients, EEG mapping and routine EEG were identical in 46 patients. The EEG mapping provided additional lateralisation in 12 patients with negative CT findings and in 21 patients with negative routine EEG. In patients with hypodense lesions in CT the EEG mapping revealed significantly more often focal changes (85%) than the routine EEG (59)%).

In 68 children without brain-disease, 3 months to 8 years of age, auditory non-target event-related potentials have been elicited. A 500 Hz-tone of 500 ms duration served as frequent stimulus, while a seldom (20%) and irregularly offered 2000 Hz-tone of the same duration produced the event-related potentials. Comparison between the four kinds of successively recorded potentials (100% 500 Hz, 80% 500 Hz with 20% 2000 Hz, and 100% 2000 Hz) led to the identification of potentials reflecting discrimination of the two sounds, since their latencies significantly differed in the event-related potential from the other three kinds of potentials. Latencies of the peaks in the event-related potentials showed evidence of maturation with increasing age. Normal values with 2.5-sigma border of the latencies of the event-related peaks were compiled bringing about the possibility to use the method in the clinical work-up of children with brain diseases.

Event-related potentials were recorded in a sentence reading paradigm. Sentences were either terminated by a semantically and grammatically appropriate word (word from a different grammatical class syntactic error), a semantically inappropriate word (semantic error) or a semantically appropriate word with a wrong case inflection (morphosyntactic error). For all three types of errors the event-related potential was characterized by a negativity in the 250-600 ms range (N400). The possible implications of these findings for models of sentence processing are discussed. It is concluded that the results strongly support interactive models of sentence processing.