Determinants of pain in needle electromyography

Abstract

Objectives: Although previous literature has attempted to characterize patients' pain during electromyography (EMG) based on the size and type of needle used, none have assessed the relationship between the needle insertion technique and pain. Methods: The effects of needle type and needle movement within muscle on the immediate and residual pain during needle EMG were measured in a double-blind study of 48 patients with diverse clinical problems but no sensory loss. Results: The results demonstrate that when using a standard insertion technique characterized by large needle movement, the monopolar needles were less painful than concentric needle electrodes. However, when using small needle movements (1 mm or less), pain associated with concentric needles was significantly reduced with no difference between the needle types. Examiner experience, gender, previous EMG, reported pain tolerance, pain on nerve conduction studies and other factors did not predict the amount of pain. The type of needle and type of needle movement did not effect the sensitivity of identifying abnormalities. Conclusions: These findings would support the hypothesis that although a monopolar needle electrode is less painful when using a standard technique, the needle-handling technique, specifically small needle movements, plays a large role in determining pain when using concentric needle electrodes.