The possible involvement of spinal alpha motor neurons, dorsal root ganglia and sensory fibers in human chronic Chagas' disease was previously demonstrated. More recently neuropsychological and sensory evoked potentials studies suggest the existence of central nervous system abnormalities in these patients. We assessed the state of central motor pathways in 46 patients with chronic Chagas' disease and 30 healthy volunteers by means of percutaneous cortical and spinal electrical stimulation. No significative slowness in pyramidal tracts (PT) conduction was found when comparing both groups. Neither any individual patient exhibited abnormally delayed PT conduction values beyond the upper normal limit of the healthy volunteers. These results suggest that, in contrast with other neural systems, the large myelinated PT fibers are usually spared in human chronic Chagas' disease.

Estudios previos han demostrado que la enfermedad de Chagas cronica (ECHC) humana puede comprometer Ias motoneuronas espinales alfa, el ganglio de la raiz dorsal y Ias fibras sensitivas perifericas. Mas recientemente otras investigaciones han senalado que algunos de estos pacientes presentan anomalias en pruebas cognitivas y de potenciales evocados sensoriales, sugiriendo tambien la existencia de compromiso central en esta entidad. En linea con estos ultimos hallazgos hemos estudiado el estado de la conduccion motora central en 46 pacientes con ECHC y en 30 voluntarios sanos. Para ello se emplearon tecnicas de estimulacion electrica cortical transcraneana y espinal percutanea. No se encontro un enlentecimiento significativo en la conduccion piramidal del grupo con ECHC comparado con los voluntarios sanos. Considerados individualmente, en ningun paciente con ECHC la conduccion corticoespinal presento valores que excedieran el limite superior normal del grupo control. Estos resultados sugieren que a diferencia de lo que ocurre con otros sistemas neurales, Ias fibras piramidales mielinizadas de grueso calibre se encuentran usualmente indemnes en pacientes con ECHC.

Between 1974 and 1987 we have examined 50 patients with the diagnosis of myasthenia gravis. Female preponderance (2,5: 1) was found. Also, it was observed that most of the patients were aged between 20 and 49 years. Beside the clinical examination, the following tests were performed: (1) edrofonium test, (2) supramaximal repetitive nerve stimulation, (3) serum acetylcholine antibodies titers and (4) intraperitoneal passive transference of patient's sera to mice and recording of meepp's amplitude in the phrenic-diaphragm preparation in vitro. These four tests gave positive values for myasthenia in 90 to 100% of the cases. Thymus radiological examination was carried out by pneumomediastinography, which proved to correlate with the hsitological picture of the gland, and computed tomography, which disclosed some discrepances with the histology. Treatment was based on anticholinesterase drugs, corticosteroids and thymectomy, being the corticosteroids the most valuable therapeutical tool. Nine patients treated with steroids disclosed transitory worsening of their signs and symptoms at very early stages after onset of corticosteroid therapy, 6 of them had a disfavorable course in their follow-up. This observation seem to have value in the early prognosis of the disease.

Durante la observacion de 50 pacientes con Myasthenia gravis entre los anos 1974 y 1987 se encontro un predominio del sexo femenino en la proporcion de 2,5 a 1 y mayor frecuencia de presentacion en Ias 3ª y 5ª décadas de la vida. Luego de la evaluacion clínica, el diagnóstico fué confirmado mediante: (1) prueba dei edrofonio, (2) estímulo nervioso repetitivo, (3) dosaje de anticuerpos antirreceptor colinérgico y (4) transferencia pasiva del suero al raton con ulterior niedicion de la amplitud de mepp's. La positividad diagnostica vario entre el 90 y el 100%, segun el tipo de prueba empleada. El estúdio radiológico del timo fué hecho con neumomediastinografía. obteniendose excelente correlación con la descripcion histológica de la glândula, y con tomografia computada, que demostro menor eficiência diagnostica. El tratamiento fué implementado en base a anticolinesterásicos, timectomía y corticoterapia inmunosupresora, evidenciandose con esta última mejores resultados. Nueve pacientes desarrollaron peoria transitória del cuadro muscular al iniciarse el tratamiento esteroideo, 6 de ellos exhibieron posteriormente evolucion desfavorable. Esta observacion aparenta tener valor pronóstico en la evolucion de la MG.

Eleven patients with chronic lead intoxication were submitted to somatosensory evoked potential (SEP) studies. All patients demonstrated increased lead blood levels and reduced ALA D activity in red blood cells. Three patients showed delayed spinal arrival (N13 wave), four delayed cortical arrival (N20 wave), and three prolonged central conduction time (time elapsing between N13 and N20 waves) (see table 1). No relationship was found between the abnormal findings and the levels of lead or ALA D. Time of intoxication was not related to the altered electrophysiological features either. The findings reported suggest that, beside the well known peripheral involvement in chronic lead intoxication, some patients may develop central nervous system impairment perhaps related to myelin involvement as suggested by the prolonged SEP central conduction time.

Once pacientes con cifras elevadas de plombemia y disminuidas de delta aminolevulínico dehidrasa (ALA D), fueron estudiados mediante la realización de potenciales evocados somatosensitivos obtenidos por estimulación del nervio mediano, midiendo el ingreso medular, el arribo cortical v el tiempo de conducción central (TCC). Los datos fueron comparados con controles. Se correlacionaron con las deterniinaciones bioquímicas y con el tiempo de exposición al tóxico. Por encima dei limite superior control, se encontro el ingreso medular en tres pacientes, el arribo cortical en cuatro y el TCC en tres. Los valores de N13,N20 y TCC no mostraron correlación con los parâmetros bioquímicos ni con el tiempo de exposición al tóxico. Estos hallazgos sugieren que, si bien la neuropatía periférica condiciona el retraso dei ingreso medular y del arribo cortical, es probable que exista también compromiso de la mielina central en algunos de los pacientes crónicamente expuestos.

Seventy five patients with the diagnosis of chronic Chagas' disease were studied by employing EPs techniques. Two of them had delayed arrival of the signal to the Erb's point and one to the spinal cord when looking at SEPs. TWo patients had increment of the time interval between waves 1st and IIIrd, when studying PEATs. These findings were interpreted as due to peripheral nerve fibers damage, a feature described in previous papers. The, most striking finding was the prolonged time interval between waves N13 and N20 (SEPs) found in two patients and between waves IIIrd and Vth (PEAT) seen in 7 affected subjects. These observations suggested the development of some sort of CNS involvement, perhaps related to myelin damage, in patients who reached the chronic state of the infection.

Setenta y cinco pacientes con el diagnóstico de enfermedad de Chagas crónica fueron estudiados con el empleo de los potenciales evocados cerebrales. Tres de ellos tuvieron retardo del arribo de la senal a) punto de Erb ó al ingreso medular en los potenciales evocados somatosensitivos (PESS). Dos pacientes presentaron incremento del intervalo entre las ondas I y III en los potenciales evocados auditivos de tronco (PEAT). Estos hallazgos fueron interpretados como debidos al dano en la fibra nerviosa periférica, un hecho descripto en trabajos previos. El hallazgo mas sorprendente fue la prolongación del intervalo de tiempo entre las ondas N13-N20 en los PESS, hallandose en dos pacientes y entre las ondas III y V en los PEAT en 7 sujetos. Estas observaciones sugieren de algun modo, el compromiso de sistema nervioso central, quizás relacionado al daño de la mielina, en pacientes en estadio crónico de la infección.

Um grupo de pacientes com paralisia de Bell foi estudado com o objetivo de descobrir a presença de comprometimento nervoso periférico subclínico. 20 pacientes, 8 homens e 12 mulheres com paralisia de Bell recente como única enfermidade, foram examinados. Em todos os casos outras causas de polineuropatia foram excluídas. Os pacientes foram estudados com exames de líquido cefalorraqueano; latência distal nos nervos faciais do lado afetado e do lado sadio e velocidade de condução motora máxima; latência distal dos nervos mediano e peroneiro direitos. O exame de LCR foi normal em tcdos os casos. A latência do nervo facial foi anormal em todos os pacientes no lado afetado e, no lado clinicamente sadio, diferia significativamente do grupo controle. A metade dos pacientes mostrou valores anormais na velocidade motora máxima e/ou na latência distal de ambos os nervos, como sejam: mediano e peroneiro. Esses resultados estão de acordo com publicações anteriores nas quais se afirma que outros nervos craneanos podem estar afetados na paralisia de Bell. Temos encontrado uma elevada frequência de polineuropatia nesta enfermidade. Estes achados nos levam a crer que, em alguns enfermos, a paralisia de Bell é um componente de uma doença mais disseminada afetando outros nervos craneanos e periféricos.

A group of patients with Bell's palsy were studied in order to disclose the presence of subclinical peripheral nerve involvement. 20 patients, 8 male and 12 female, with recent Bell's palsy as their unique disease were examined, in all cases other causes of polyneuropathy were ruled out. Patients were investigated with CSF examination, facial nerve latencies in the affected and in the sound sides, and maximal motor nerve conduction velocities, as well as motor terminal latencies from the right median and peroneal nerves. CSF laboratory examination was normal in all cases. Facial nerve latencies were abnormal in all patients in the affected side, and they differed significantly from those of control group in the clinically sound side. Half of the patients showed abnormal values in the maximal motor nerve conduction velocities and motor terminal latencies of the right median and peroneal nerves. These results agree with previous reports which have pointed out that other cranial nerves may be affected in Bell's palsy. However, we have found a higher frequency of peripheral nerve involvement in this entity. These findings, support the hypothesis that in some patients Bell's palsy is the component of a more widespread disease, affecting other cranial and peripheral nerves.

An electrophysiological study was carried out searching for variations in the innervation of the muscles of the hand. For this purpose a simple and non time-consuming technique was designed for stimulating the ulnar and median nerves at the elbow and wrist. Recordings were performed with surface electrodes at the abductor pollicis brevis, adductor digiti minimi and first dorsal interosseus muscles. Several anomalous innervation patterns of the intrinsic muscles of the hand were found, and the innervation of the first dorsal interosseus by the median nerve was the most frequent.

Para investigar las probables variaciones en la inervación de los músculos intrínsecos de la mano y/o la anastomosis entre los nervios mediano y cubital, se estudiaron 24 manos, estimulando en forma percutánea a dichos nervios, registrándose en abductor polliçis brevis (APB), adductor digiti minimi (ADM) y primer interóseo dorsal (PID). Se halló una frecuente inervación del PID por el mediano. Se describe la técnica utilizada, comentando incidência, importancia y probable comportamiento en distintas patologias de las variaciones halladas.

Muscular fatigue mechanisms were partially analyzed in patients with pyramidal lesions by using a computer device on line with a conventional electromyograph. Both the normal and the affected side were compared with control groups. The recordings were done throughout a ten minutes period and the maximal M wave was also measured at the starting and at the end of the procedure. The findings suggested that central events play a major role in the development of muscular fatigue in spastic muscles due to pyramidal damage.

Para evaluar algunos de los componentes de la fatiga muscular en el daño piramidal, se seleccionó un grupo de 15 pacientes con hemiparesia faciobraquiocrural de severidad variable, los cuales fueron sometidos a un esfuerzo muscular, durante el cual se evaluaron los cambios de la frecuencia y duración de los potenciales positivos y negativos del EMG, asi como los sufridos por la onda M máxima al principio y fin del mismo. El estudio fue realizado en el lado parético, el contralateral y en un grupo control de voluntarios sanos, comparándose los resultados de los 3 grupos. Las curvas de frecuencia y duración del lado parético, el sano y el control mantuvieron las mismas tendencias, así como fue homologable el comportamiento de la onda M máxima en los 3 casos, lo cual indica que en la espasticidad, debido a daño de la vía piramidal, al igual que en la población normal, bajo las presentes condiciones de estudio, es el factor central el condicionante principal en el desarrollo de fatiga muscular.

In a group of patients chronically denervated and other with primary muscle involvement a search was made for mechanisms involved in the muscular fatigue. It was found that there was no major differences between patients chronically denervated and controls, while in those others with primary muscle disorders a loss of functional motor units during effort and a transient impairment of neuromuscular transmission play a role together with the central events normally occuring in fatigue.

Utilizando un método de cuantificación del electromiograma, se investigaron parte de los mecanismos centrales y periféricos responsables de la fatiga muscular en enfermos crónicamente denervados y en pacientes con compromiso muscular primitivo. Se observó en los denervados que los mecanismos de fatiga muscular, no difieren mayormente de los observados en el grupo de sujetos sanos, por el contrario, en los miopáticos a más del componente central, existen otros de orden periférico, tales como la pérdida de unidades motoras funcionantes durante el esfuerzo y el bloqueo temporario de la transmisión neuromuscular, que contribuye al desarrollo de la fatiga.

Muscular fatigue was investigated in 13 healthy people by employing a simple device which comprises a computer on line with a conventional EMG equipment able to automatically measure the frequency and duration of free-run EMG recording. The procedure was carried out in the extensor digitorum brevis muscle by using surface electrodes throughout 10 minutes of voluntary maximal effort. The maximal M wave as well as the muscle response to repetitive nerve maximal stimulation was also explored at the beginning and at the end of the experiment. It was observed a decrease of the potentials frequency discharge and an increase of their duration without major changes in the M wave amplitude neither in the muscle response to the repetitive nerve discharge. The findings pointed out to the central factors as the main responsible for the development of muscular fatigue.

Se estúdio la fatiga muscular en 13 sujetos normales; para ello, fueron sometidos a un esfuerzo sostenido durante 10 minutos previo y posterior, al cual se realizo la medición de la onda M máxima. Durante el esfuerzo y cada 2 minutos, se obtuvieron cuantificaciones de la frecuencia y duración de las ondas positivas y negativas del EMG. Los resultados, mostraron diferencias significativas de estos valores, en función del tiempo de esfuerzo realizado, mientras que las mediciones de la onda M máxima inicial y final, no fueron diferentes, todo lo cual lleva a jerarquizar el factor central como el más importante en el desarrollo de fatiga, bajo nuestras condiciones de estudio, que son además de sencilla aplicación clínica.

An electrophysiological study has been made of the thenar, hypothenar, soleus and extensor digitorum brevis muscles and their inervation in 90 patients with chronic Chagas' disease. Some of them showed a reduced number of functional motor units with increased size of many of the surviving units. No decremental muscle response was found to repetitive nerve stimulation. Motor and sensory conduction velocities as well as motor terminal latencies were on the normal range. These findings suggested that the muscle changes resulted from a primary defect of the alpha spinal motoneurone soma.

90 pacientes afectados por enfermedad de Chagas crónica fueron estudiados electrofisiológicamente procediéndose a cuantificar Ias unidades motoras actuantes en los músculos de la eminencia tenar, eminencia hipotenar, soleo y extensor corto de los dedos. Se halló que muchos de ellos poseían un número reducido de unidades, en tanto que buena parte de las sobrevivientes mostraban su tamaño aumentado. No se encontró alteración en los valores de velocidad. de conducción nerviosa motora o sensitiva ni tampouco en las cifras de latencia residual motora. La respuesta muscular al estímulo repetitivo del nervio fué igualmente normal. Los hallazgos hechos sugirieron que las alteraciones musculares halladas en estos pacientes pueden, obedecer a la existencia de un defecto primario en el soma de la motoneurona alfa medular.

Gastrocnemius muscle biopsies were performed in 7 subjects with chronic Chagas' disease. On clinical and laboratory grounds the selected patients were judged to be healthy, being the only abnormality found the presence of positive serum tests for Chagas' disease. Fibre type grouping of either type I or type II was observed in 5 of the 7 patients. Furthermore, in 2 of the 5 patients showing muscle fibre groupings, angular fibres reacting with NADH and non-specific sterase were also found. These observations strongly suggest denervation associated with reinervation. This picture often can be observed in the skeletal muscle of patients with well compensated denervatory conditions who do not show clinical evidences of denervation.

En 7 pacientes afectados por enfermedad de Chagas crónica se procedió al estúdio biópsico del músculo gastrocnemio. Los pacientes seleccionados mostraran como única anormalidad la presencia de tests positivos en suero para la enfermedad de Chagas. Agrupamiento de fibras musculares de tipo I y II fué observado en 5 de aquellos; en 2 de estos últimos 5 se encontro, además, fibras anguladas que se teñian intensamente con NADH y esterase no especifica. Las observaciones hechas sugirieron la presencia de denervaçión seguida por reinervación, cuadro que puede ser observado con asiduidad en el músculo esquelético de pacientes con afecciones denervatorias bien compensadas y en los que no existen evidencias clinicas de ese compromiso.

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.

A detailed electrophysiological study has been made of the extensor digitorum brevis, thenar, hypothenar and soleus muscles in one patient with myotubular or centronuclear myopathy. The main finding was a noticeable reduction in the population of active motor units in all the investigated muscles. The remainer units showed normal sizes. The experimental observations have been interpreted in terms of a neuropathic process.

Un estudio electrofisiológico detallado fué hecho en los músculos extensor corto de los dedos, de la eminencia tenar, de la eminencia hipotenar y soleo en un paciente con el diagnóstico de miopatía miotubular o centronuclear. El hallazgo principal fué una notoria reducción en el número de unidades motoras activas en todos los músculos investigados, en tanto que las unidades remanentes mostraron tamaño conservado. Las observaciones hechas se han interpretado como favoreciéndo la génesis neurógena en el desarrollo de este proceso.