[Single fibre electromyography in 18 patients with amyotrophic lateral sclerosis]. / Electromiograma de fibra única en 18 pacientes con esclerosis lateral amiotrófica.

INTRODUCTION: Single fibre electromyography (SFEMG) is a method that complements conventional electromyography and studies the activity of individual muscle fibres and of the neuromuscular junction. AIMS. We attempt to demonstrate the presence of reinnervation disorders by studying Jitter, fibre density (FD) and the presence of neurogenic blocks in patients with amyotrophic lateral sclerosis (ALS). PATIENTS AND METHODS: SFEMG was carried out on 18 patients diagnosed with ALS. All the patients were submitted to a voluntary SFEMG in the extensor digitorum communis muscle of the fingers on the most affected side. RESULTS: The SFEMG in the extensor digitorum communis muscle of the fingers showed alterations in 13 out of the 18 patients studied (72%). FD was the most reliable parameter for translation of the motor neuron instability and increased in all cases. This was followed by the mean and the maximum individual (62%) Jitter and, lastly, the percentage of blocks (38%). CONCLUSIONS: In ALS, the parameters studied with SFEMG were modified in 72% of the cases studied. There is an overall correlation between the length of time the patient has had the disease and the modifications in the SFEMG (21.5 versus 13.7 months). The degree of clinical involvement is higher (6.5/13) in those who present an altered SFEMG compared to those who present a normal SFEMG (5.3/13).

Electromiograma de fibra única en 18 pacientes con esclerosis lateral amiotrófica / Single fibre electromyography in 18 patients with amyotrophic lateral sclerosis

Introducción. La electromiografía de fibra única (SFEMG) es un método complementario a la electromiografía convencional y estudia la actividad de las fibras musculares individuales y de las placas motoras. Objetivo. Intentamos evidenciar la presencia de alteraciones de reinervación estudiando el jitter, la densidad de fibras (DF) y la presencia de bloqueos neurogénicos en pacientes afectados de esclerosis lateral amiotrófica (ELA). Pacientes y métodos. Practicamos una SFEMG a 18 pacientes diagnosticados de ELA. A todos se les practicó una SFEMG voluntaria en el músculo extensor común de los dedos del lado más afectado. Resultados. La SFEMG en el músculo extensor común de los dedos, está alterada en 13 de los 18 pacientes estudiados (72%). La DF ha sido el parámetro más fiable para traducir la inestabilidad de la motoneurona, y aumentó en todos los casos. Le siguió el jitter medio y el máximo individual (62%), y, por último, el porcentaje de bloqueos (38%). Conclusiones. En la ELA los parámetros estudiados con la SFEMG se alteran en el 72% de los casos estudiados. Existe una correlación global entre el tiempo de evolución de la enfermedad y la alteración de la SFEMG (21,5 frente a 13,7 meses). El grado de afectación clínica resulta mayor (6,5/13) en los que presentan una SFEMG alterada que en los que la presentan normal (5,3/13)

Introduction. Single fibre electromyography (SFEMG) is a method that complements conventional electromyography and studies the activity of individual muscle fibres and of the neuromuscular junction. Aims. We attempt to demonstrate the presence of reinnervation disorders by studying Jitter, fibre density (FD) and the presence of neurogenic blocks in patients with amyotrophic lateral sclerosis (ALS). Patients and methods. SFEMG was carried out on 18 patients diagnosed with ALS. All the patients were submitted to a voluntary SFEMG in the extensor digitorum communis muscle of the fingers on the most affected side. Results. The SFEMG in the extensor digitorum communis muscle of the fingers showed alterations in 13 out of the 18 patients studied (72%). FD was the most reliable parameter for translation of the motor neuron instability and increased in all cases. This was followed by the mean and the maximum individual (62%) Jitter and, lastly, the percentage of blocks (38%). Conclusions. In ALS, the parameters studied with SFEMG were modified in 72% of the cases studied. There is an overall correlation between the length of time the patient has had the disease and the modifications in the SFEMG (21.5 versus 13.7 months). The degree of clinical involvement is higher (6.5/13) in those who present an altered SFEMG compared to those who present a normal SFEMG (5.3/13)