Clinical<FONT FACE=Symbol>¾</FONT>neurological and electroneuromyographic evaluation of the indeterminate chronic form of Chagas disease

Avaliação clínico-neurológica e eletroneuromiográfica da forma indeterminada da doença de Chagas

THESES

CLINICAL¾NEUROLOGICAL AND ELECTRONEUROMYOGRAPHIC EVALUATION OF THE INDETERMINATE CHRONIC FORM OF CHAGAS DISEASE (ABSTRACT)^*. THESIS. BELO HORIZONTE, 2001.

EUSTÁQUIO CLARET DOS SANTOS^**

OBJECTIVE - To evaluate if alterations exist in patients with the indeterminate chronic form of Chagas disease, through a clinical ¾ neurological and electroneuromyographic study.

METHOD - From March 1996 to April 1999, 49 patients with the indeterminate chronic form of Chagas disease sent to me by the "Chagas Disease Out-Patient Reference Centre" of the Clinical Hospital of the Federal University of Minas Gerais (UFMG) were submitted to the clinical-neurological and electroneuromyographic study. Seventy-six healthy volunteers, who had no Chagas disease, were examined and some of the reference values for the electroneuromyographic study were thus obtained. The electroneuromyographic study consisted of sensory and motor conduction of nerves of superior and inferior members; late response study ("F" wave and "H" reflex) of tibial posterior nerve; electromyography strictly defined; and computed motor unit counting.

RESULTS - Considering the anthropometric characteristics of the two groups (sex, color, age and height) no differences were found that could influence the results.

The exam of muscular force and sensibility (superficial and deep) of the Chagas disease patients was normal. There were reflex alterations in significant number in Chagas disease patients (83.7% for the radial; 81/6% for the triceps; 72.4% for the biceps; 49% for the ankle; 38.8% for the patellar). The electroneuromyographic study including the motor unit counting was normal in 13 of the 49 Chagas disease patients (26/5%). The great majority of the Chagas disease patients presented a normal study result of sensitive and motor conduction (71.4%). The carpal tunnel syndrome was observed in nine patients with the indeterminate chronic form (18.4%). In everybody there was a decrease of the speed of sensitive conduction of the median nerve. An increase of distal motor latency was present in five patients (10.2%). Other conduction alterations found were: a decrease of the speed of sensitive conduction of the ulnar nerve in one case (2.0%); decrease of the speed of motor conduction of the fibular nerve in one case (2.0%); reduction of the width of the potential motor of the right ulnar nerve in one case (2.0%); and reduction of the width of the potential motor of the posterior tibial nerve bilaterally, in one case (2.0%). The study of the sural nerve was normal in both groups (Chagas disease patients and controls). The motor unit counting for the biceps muscle was normal in all the Chagas disease patients. Reduction of the motor unit counting was observed in the abductor pollicis brevis muscle in 15 patients (30.6%) and in the extensor digitorum brevis muscle in ten patients (10.2%). Still with relationship to the motor unit counting there was a correlation between its decrease and clinical complaints in six patients (40%); alteration of the clinical-neurological exam in two patients (13.3%); and, with the electroneuromyography, in four patients (26.7%). The "H" reflex study showed an absence of this response in Chagas disease patients (42.9%) and the control group (9.2%), frequently quite elevated in the first group. The latencies of the "F" waves were normal in all the Chagas disease patients indicating normal function of the proximal segment of the posterior tibial nerves.

CONCLUSIONS - Paresthesia in hands, associated to Tinel's sign and/or pain in the Phalen's maneuver characterized carpal tunnel syndrome clinically and was confirmed by sensory and motor conduction studies. This find observed in the Chagas disease patients can be interpreted as a susceptibility of the nerve to the compression, associated to some other factor, and not necessarily to the disease. A hypoactive tendon reflex and the absence of the "H" reflex implicates subclinic neuropathy. Decreased motor unit counting in distal muscles of inferior and superior members was observed in 10% to 30% of cases. Biceps motor unit counting was normal in all patients. We do not have sufficient elements to attribute such finds to Chagas disease and these alterations could stem from traumatic processes. The above findings could be related to a frustrated or subclinic disturbance, or even to minimal sequels of a previous process, which happened in the acute phase, without more evident clinical repercussions. At no time could a specific, irrefutable and unequivocal involvement of the peripheral nervous system be defined in the indeterminate form of Chagas disease, as established in literature for the autonomous nervous system.

KEY WORDS: Chagas disease, electromyography, nervous conduction, peripheral nervous system, neuromuscular disorders.

**Address: Rua Domingos Vieira, 273 / 907, 30150 240 Belo Horizonte MG, Brasil. E-mail: [e-mail].b

*

Avaliação clínico-neurológica e eletroneuromiográfica da forma indeterminada da doença de Chagas (Resumo). Tese de Doutorado, Faculdade de Medicina da Universidade Federal de Minas Gerais (Área: Medicina Tropical). Orientador: Manoel Otávio da Costa Rocha.

Publication Dates

• Publication in this collection
  19 July 2002
• Date of issue
  June 2002