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

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.