Introduction:
Needle electromyography (EMG) is an essential part of electrodiagnosis (EDX) in neuromuscular disorders. As in all invasive procedures there is a risk of bleeding complications, but which is rare according to the current literature. Controlled, prospective studies that include patients under anticoagulation or antiplatelet therapy are lacking and would be difficult to conduct.
Case reports:
We describe two patients with no history of coagulopathy who developed an intramuscular hematoma after needle EMG. They had been under therapeutic anticoagulation but this had been discontinued, and their standard coagulation parameters had returned to normal prior to the EMG. One patient was found to have a rare genetic defect in thromboxane synthesis with associated markedly impaired platelet aggregation, while no obvious cause of the bleeding was found in the second patient. However, it could have been due to an unexpectedly strong anticoagulatory response to the oral anticoagulant apixaban.
Conclusion:
One must be aware of the increased risk of bleeding events in patients with therapeutic anticoagulation. These can occur even when the recommendations regarding discontinuation of anticoagulant drugs for the procedure have been followed. The patient must be actively questioned for ongoing use of NSAIDs, and if pain therapy is required alternatives with no antiplatelet activity should be given. A larger data pool of adverse EMG events would aid in risk assessment and decision making.