An electrophysiological investigation of skeletal muscle in human chronic Chagas' disease

Abstract

In a preliminary investigation carried out on patients with chronic Chagas' disease, Pagano et aí. 7 demonstrated that some skeletal muscle denervation occurs in this condition; however they were unable to individualize the site of lesion within the motor unit (m.u.). The present investigation has been design to explore further the denervation which can be found in these patients and an attempt has been made to localize the site of the m.u. where the original lesion occurs.A partial account of this work has been given elsewhere 8 MATERIAL AND METHODS90 patients aged between 7 and 58 years, with chronic Chagas' disease, were studied. All them were judged to be healthy on clinical examination and the diagnosis* was based on the positiveness of, at least, two out of three specific serum tests for Chagas' disease.Coincidental causes of denervation were eliminated by excluding patients over the age of 6012 and any who had had toxic or metabolic disorders known to be associated "with neuropathy.A total of 270 healthy subjects served as controls for one or more electrophysio logical test.The following investigations were carried out: 1) measurements of maximal nerve motor and sensory conduction velocities as well as motor terminal latencies were made in the manner described in previous papers 11; 2) responses of the thenar muscles to repetitive stimulation of the median nerve (one second trams of supramaximal stimuli were given at frequencies of 3, 10 and 30 Hz on the median nerve at the wrist, while the muscle evoked responses were recorded at the thenar muscles with surface electrodes); 3) in a few patients (8 subjects) quantification of the end-plate noise was carried out by employing a tungsten electrode inserted within the extensor digitorum brevis (edb) muscle end-plate area in the manner described by O'Neill and Sicaft; 4) estimations of the numbers and sizes of operative m.u. were performed within the thenar, hypothenar, soleus and edb muscles following the techniques decribed previously 2,0,12; 5) the amount of excitability coming down from the supraspinal structures which is imposed onto the spinal alpha motoneurones was tested in all the patients by applying the excitability coefficient (ec)io. This investigation was carried out in the thenar muscles inervated by the median nerve.Section of Clinical Electroneurophysiology, Hospital Ramos Mejia, Buenos Aires. Argentina.

Histological and histochemical changes of the skeletal muscle in human chronic Chagas' disease

“…However, the electrophysiological evidences presented by Sanz et al 5 hint that the motoneurone soma may be the site of…”

Electromyographycal findings in human chronic Chaga's disease

“…This first approach, although limited to the EMG manifestations, was clear enough to justify a deeper investigation in these patients by employing other techniques with the purpose of obtaining more information about the involvement of the motor unit in this pathological condition (see Sanz et al 7 and Taratuto et al 10 ). SUMMARY An electromyographical investigation of 80 patients with chronic Chagas' disease was made.…”