Electromyographic characterisation of abdominal wall trigger points developed after caesarean section and response to local anaesthesia: an observational study

Abstract

Objective: This study examines the electromyography pattern of abdominal trigger points developed after a caesarean section, and the association between clinical response and local anaesthetic injection. Design: Prospective cohort study. Setting: A tertiary university hospital. Population: Twenty-nine women with chronic pelvic pain associated with trigger points after a caesarean section were included in the study. Methods: Participants received needle electromyography before treatment, then underwent a treatment protocol consisting of trigger-point injection of 2 ml of 1% lidocaine. The protocol was repeated once a week for 4 weeks. The clinical responses of the patients were compared 1 week after and 3 months after treatment. The clinical trial is registered with the Brazilian Clinical Trials Registry (REBEC) under RBR-42c6gz (www.ensaiosclinicos.gov.br/rg/RBR-42c6gz/). Main outcome measures: Needle electromyography and algometry results and pain reduction. Results: Fifteen patients had abnormal electromyography findings; 14 had normal findings. The rates of response 1 week and 3 months after treatment within the abnormal electromyography group were 95 and 87%, respectively. In the normal group, the rate was 38% both 1 week after and 3 months after treatment. Conclusions: Trigger points developed after caesarean section, even without clinical symptoms or signs of neuralgia, may originate from neuropathies. Electromyographic abnormalities were associated with pain remission after anaesthesia injection; normal electromyography findings were associated with undiagnosed causes of pain, such as adhesions. Tweetable abstract: Trigger points developed after caesarean section are neuropathies, even in the absence of classical neuralgia.