Carpal tunnel syndrome: long-term nerve conduction studies in 261 hands

Abstract

Objective: To compare a long-term carpal tunnel syndrome (CTS) on nerve conduction studies (NCS) in hands treated non-surgically. Method: We retrospectively selected 261 symptomatic CTS hands (166 patients), all of them confirmed by NCS. In all cases, at least 2 NCS were performed in an interval greater than 12 months. Cases with associated polyneuropathy were excluded. NCS parameters for CTS electrodiagnosis included a sensory conduction velocity (SCV) ≤46.6 m/s (wrist to index finger, 14 cm) and distal motor latency (DML) ≥4.25 ms (wrist to APB, 8 cm). Results: 92.8% were women; mean age was 49 years (20-76); the mean interval between NCS was 47 months (12-150). In the first exam, the median sensory nerve action potential (SNAP) and the compound action muscular potential were absent in 9.8% and 1.9%, respectively. In the second/ last exam, SCV worsened in 54.2%, remained unchanged in 11.6% and improved in 34.2%. SNAP amplitude worsened in 57.7%, remained unchanged in 13.1% and improved in 29.2%. DML worsened in 52.9%, remained unchanged in 7.6% and improved in 39.5%. Overall, NCS parameters worsened in 54.9%, improved in 34.3% and remained unchanged in 10.8%. Conclusion: Long-term changing in NCS of CTS hands apparently were not related to clinical symptomatology and could lead to some difficulty in clinical correlation and prognosis. Aging, male gender and absent SNAP were more related to NCS worsening, regardless the mean interval time between the NCS. Key WOrDS: carpal tunnel syndrome, median nerve, nerve conduction studies, compressive neuropathy, long-term electrophysiological evaluation. síndrome do tunel do carpo: estudo evolutivo de parâmetros de condução nervoso em 261 mãos Resumo-Objetivo: Comparar evolutivamente parâmetros de condução nervosa (CN) na síndrome do túnel do carpo (STC) em mãos não submetidas à cirurgia. Método: Foram selecionadas retrospectivamente 261 mãos (166 pacientes) com STC sintomática confirmadas por CN e que posteriormente realizaram exame controle com intervalo ≥12 meses; foram excluídos casos com polineuropatia. Os parâmetros eletrodiagnósticos anormais foram: velocidade de condução sensitiva (VCS) ≤46,6 m/s, segmento pulso-II dedo, e latência distal motora (LDM) ≥4,25 ms, segmento pulso-APB (8 cm). Resultados: 92,8% eram mulheres; a média de idade foi 49 anos (20-76); o tempo médio entre os exames foi 47 meses (12-150); 9,8% e 1,9% não apresentaram potenciais de ação do nervo sensitivo (PANS) e potenciais de ação muscular compostos, no primeiro exame. No segundo exame a VCS piorou em 54,2%, ficou igual em 11,6% e melhorou em 34,2%; a amplitude do PANS piorou em 57,7%, ficou igual em 13,1% e melhorou em 29,2%; a LDM piorou em 52,9%, ficou igual em 7,6% e melhorou em 39,5%. Incluindo todos os parâmetros eletrofisiológicos, houve piora em 54,9%, melhora em 34,3% e permaneceram sem alterações 10,8%. Conclusão: As anormalidades da CN na STC podem oscilar ao longo do tempo e aparentemente independem da sintomatologia clínica, dificultando a correlação e prognóstico; idade mais av...

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