Comparison of the Effects of Vapocoolant Spray and EMLA Cream on Pain During Needle Electromyography

Comparison of the Effects of Vapocoolant Spray and Topical Anesthetic Cream on Pain During Needle Electromyography: a Randomized Controlled Clinical Trial

The purpose of this study is to compare the effects of vapocoolant spray and topical lidocaine 2.5% + prilocaine 2.5% cream (EMLA) on reducing pain during needle electromyography.

The study was conducted on patients with patients that underwent needle EMGs in the lower extremity between July and August 2011 at the university hospital. The patients were divided into a total of three groups by random assignment: a control group that did not receive pretreatment, a group that received ethyl chloride vapocoolant spray and a group that received topical anesthetic cream (EMLA cream®).The patients with spray group, they were sprayed with ethyl chloride vapocoolant spray for 5 seconds from a distance of 30 cm just before the needle EMG, and patients with EMLA cream, they received an application of topical anesthetic cream on the needle electrode insertion site 60 minutes before the needle EMG. The 37-mm monopolar needle electrode was vertically inserted into the medial head of the gastrocnemius muscle in all patients.

To assess the degree of pain for each group, patients were asked to indicate their level of pain on a 100 mm VAS (0, no pain; 100, worst intolerable pain) after the needle EMG in the gastrocnemius muscle.

In both experimental groups, a 5-point Likert scale was used to evaluate patient satisfaction with the pain reduction method used and their willingness to use the same analgesic method in another EMG.

Inclusion Criteria:

• Patients who had a normal schedule of needle EMGs in the lower extremity.

Exclusion Criteria:

1. those who refused to participate in the experiment
2. those who were unable to understand a VAS and Likert scale
3. those with a history of allergic reaction to vapocoolant spray or lidocaine
4. those with a history of cold intolerance (Raynaud's syndrome, etc.)
5. those who took oral pain medications or used topical anesthetics within 24 hours of the experiment
6. those who exhibited abnormal lower extremity sensation during the physical examination or who showed pain on gastrocnemius