An electromyographical investigation of 80 patients with chronic Chagas' disease was made. It was found that 79% of the studied patients had EMG manifestations of old and chronic denervation of the upper and lower limbs without clinical features of nervous system involvement.

Fueron estudiados 80 pacientes portadores de la forma crónica de la enfermedad de Chagas mediante el empleo de técnicas convencionales de electromiografia de detección. Los hallazgos evidenciaron en el 79% de los pacientes signos de denervación antigua tanto en miembros superiores como inferiores, aúnque con predominio en estos últimos. En ningún caso hubo manifestacionrs clínicas concomitantes.

Foi feito estudo eletromiográfico do curto extensor dos dedos e dos músculos tenares e hipotenares em 25 pacientes com polimíosite crônica e aguda. Foi encontrada diminuição no número de unidades motoras funcionantes em alguns pacientes com polimíosite crônica e somente em um caso de polimíosite aguda. Os tamanhos das unidades restantes sugerem que os resultados podem ser explicados em termos de um envolvimento primário dos músculos especialmente na polimiosite aguda, ao passo que na polimiosite crônica ocorre uma combinação de acometimento primário e neurogênico.

An electrophysiological study has been made of the extensor digitorum brevis, thenar and hypothenar muscles in 25 patients with chronic and acute polymyositis. It was found a reduction of the number of functioning motor units in some patients with chronic polymyositis and only in one of those affected by acute polymyositis. The sizes of the surviving units suggested that the results could be explained in terms of a primary muscle involvement mainly in acute polymyositis, while in chronic polymyositis a combination of primary and neurogenic involvement of muscle fibers might take place.

Ten patients treated with vincristine were submitted for electrophysiological examination. It was investigated the number of motor units within the thenar muscle following a technique described previously (Sica et al. — 1974); motor and sensitive conduction velocities as well as motor distal latencies in the median nerve were studied following conventional techniques. The behaviour of the evoked muscle potential with repetitive supramaximal stimulation over the median nerve was also investigated. The findings were compared with control groups. The estimated number of motor units was disminished in eight of ten patients and the average number was significantly different from the control group (control 318 ± 71 UM; patients 174 ± 84 UM; P < 0.001). The potential amplitudes in most of the surviving units were reduced, others remaining within the normal range. This makes apparent that the peripherical nervous system fails to compensate adequatly and, furthermore, a loss of individual muscle fibres occurs within some individual units. The conduction velocities of the fastest conducting motor nerve fibres were reduced and motor distal latencies prolongued (Table 1). Maximal impulse conduction velocities were measured in sensory fibres. In 5 of 7 subjets investigated the values laied just beyond the lower limit of the normal range. The amplitude of the sensory orthodromic evoked potential in the median nerve at the wrist was disminished almost in the whole group. The decremental muscle response to repetitive nerve stimulation, can be interpreted as the result of the damage at the neural apparatus at the motor end plate; it was observed in 57% of the patients. In summary, evidences have been registered showing that the nervous supply to the muscle is affected in patients treated with vincristine; the motor unit behaviour under this conditions is discussed.

Diez pacientes afectados por diversas patologías que requerían tratamiento crónico con Vincristina, fueron sometidos a estudios electrofisiológicos en los que se valoró: el número de unidades motoras (UM) funcionantes en los músculos de la eminencia tenar, los valores de los incrementos medios de UM, velocidad de conducción motora y su latencia residual en el nervio mediano, la velocidad de conducción sensitiva del mismo nervio y el estado de la transmisión neuromuscular. Los valores obtenidos fueron comparados con grupos controles. Los resultados mostraron disminución del número de UM; las UM remanentes presentaron amplitud reducida junto a otras cuyo tamaño no superaba el del grupo control, hecho que sugiere la incapacidad de lograr una reinervación adecuada. Las velocidades de conducción motora y sensitiva mostraron valores diminuídos, con mayor compromiso en los segmentos distales. Junto a estos datos se halló respuesta miasteniforme al estímulo repetitivo. Todos estos resultados permiten postular la existencia de un compromiso de la unidad motora, abarcando todos sus segmentos, en pacientes intoxicados con Vincristina.