EMLA partially relieves the pain of EMG needling
Tóm tắt
The aim of this study was to evaluate the efficacy of the topical analgesic cream EMLA in alleviating the pains caused by needling in electromyography (EMG). During the course of regular neurophysiology clinics, 34 Caucasian patients of both sexes, aged 21 to 69 yr (mean 38.5 ± 11.4 SD), scheduled for electromyography, were studied. The EMLA was spread thickly on two EMG sites on each arm: E site, on the lateral dorsal aspect of the forearm and A site, on the thenar eminence. Randomization was pre-established. Whenever EMLA was applied blindly on one of the sites of the arm, the placebo was applied on the homologous site of the other arm. After at least 45 min of application (range 45–145 min, mean = 72.3 ± 22.2), the needle was inserted into the skin and into the muscle. Then the electromyographist asked the patient to score his degree of pain on a visual analogue scale (VAS 1–10 cm) for each level of insertion. The results showed that on the skin of E site, the pain was less after EMLA than placebo (VAS = 0.75 ± 1.36 vs 3.10 ± 1.75, P = 0.0001). The untreated E site (placebo) was less sensitive than the untreated A site (VAS = 3.10 ± 1.75 vs 6.09 ± 1.96, P = 0.0001). Muscle insertion on E site was less painful on the EMLA sites than placebo (VAS = 2.83 ± 2.45 vs 5.73 ± 2.30, P = 0.0001). The VAS scores for skin and muscle insertion on A site were identical whether EMLA or placebo had been applied. We did not find any correlation between duration of application and VAS scores. We conclude that EMLA application is effective in easing the pain of EMG needling in the skin and extensor digitorum muscle at the forearm but is ineffective when applied for the time allotted in the present study to the skin of the palmar surface of the hand or over the muscle abductor brevis pollicis.
Tài liệu tham khảo
Evers H, Von Darnel O, Juhlin L, Ohlsén L, Vinnars E. Dermal effects of compositions based on the eutectic mixture of lignocaine and prilocaine (EMLA). Br J of Anaesth 1985; 57: 997–1005.
Ehrenström-Reiz S, Reiz S, Stockman O. Topical anaesthesia with EMLA, a new lidocaine-prilocaine cream and the cusum technique for detection of minimal application time. Acta Anaesthesiol Scand 1983; 27: 510–2.
Smith M, Gray BM, Ingram S, Jewkes DA. Double-blind comparison of topical lignocaine-prilocaine cream (EMLA) and lignocaine infiltration for arterial cannulation in adults. Br J Anaesth 65: 240–3.
Raja NR, Meyer AM, Campbell JN. Peripheral mechanisms of somatic pain. Anesthesiology 1988; 68: 571–90.
Winlelmann RK. Cutaneous Sensory Nerves.In: Seminars in Dermatology. 1988; 7: 236–68. Philadelphia: W.B. Saunders Company.
Lynn B. Cutaneous Sensation.In: Lowell A Goldsmith (Ed.). Physiology, Chemistry and Molecular Biochemistry of the Skin. 2nd ed., London: Oxford University Press, 1991; 779–815.
The Skin and its Appendages (The Integument).In: Text-book of Histology. Leeson CR, Leeson TS, Paparo AA. 5th Ed., Philadelphia: WB Saunders Company, 1985; 291–309.
Bjerring, Arendt-Nielsen L. Depth and duration of skin analgesia to needle insertion after topical application of EMLA cream. Br J of Anaesth 1990; 64: 173–7.
Nott MR. Relief of injection pain in adults EMLA cream for 5 minutes before venepuncture. Anaesthesia 1990; 45: 772–4.