Seasonal distribution and demographical characteristics of carpal tunnel syndrome in 1039 patients

OBJECTIVE: To describe the demographic characteristics of gender, age, and presence of repetitive movements, intake of alcohol and non-steroid anti-inflammatories (NSAI), medical specialties that referred patients to nerve conduction studies and electromyography (NCS-EMG), school attainment, and seasonal distribution in patients with a neurophysiological diagnosis of carpal tunnel syndrome (CTS) in the State of Rio Grande do Sul, Brazil. METHOD: A series of 1039 patients (1549 hands) with neurophysiologically defined CTS was studied. Patients were referred for NCS-EMG in 3 universities and 2 private services, from August 2001 to January 2003. All patients completed a questionnaire containing demographic information. The diagnosis of CTS was established following a pre-established protocol, with defined diagnostic criteria. RESULTS: Around one fourth of patients had already performed NCS-EMG; the greatest frequency of CTS was observed in women (5.6:1) and in patients above the age of 40. Most patients reported performing repetitive movements in their daily routine (69.7%); 12.9% reported use of NSAI and 14.9% regular intake of alcoholic beverages. A greater frequency of CTS was observed in the months of July and August, when compared to the other months of the year. Around 2/3 of the study population had completed at least secondary school. Most requests of nerve conduction studies did not provide a diagnostic hypothesis (59.9%) and neurophysiologic studies were requested mostly by traumatology/orthopedics (71.1%). CONCLUSION: We have concluded that, in our environment, CTS shows some demographical characteristics that are similar to what the literature describes. Also, we have found that most of our sample concluded at least secondary school, and was referred to neurophysiologic studies by orthopedists. To be pointed out is the seasonal distribution of CTS, which demonstrates a significant association with winter months.