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Gate Theory: How Vibration Can Trick Your Brain Into Not Feeling Pain!

Dermatologists perform procedures every day that require the use of lidocaine for numbing effect. Unfortunately, although the lidocaine is very effective for numbing to make the procedure comfortable, the lidocaine injection itself can sting and produce pain.

Techniques that we employ at MassDerm include buffering the lidocaine to make it less acidic (less sting), injecting room temperature lidocaine rather than chilled (refrigerated) whenever possible, and using a slow, gentle injection into the less sensitive layers of the skin.

In some cases, when patients report discomfort despite use of these methods, we employ a vibrating kinetic anesthesia device (VKAD or “anodyne”).  Some preliminary studies have indicated that VKADs help reduce the pain of procedures and it is thought that the mechanism relates to the Gate Theory of Pain.  According to the “Gate Theory,” sensory neurons carrying pain sensation from your skin and sensory neurons carrying vibratory sensation from your skin both transmit signals to the same afferent neurons which in turn sends information to your brain. The neurons activated by vibratory sensation inhibit the afferent pain nerves, thereby blocking or inhibiting the message sent by the neurons that sensed pain. Therefore, by producing a strong vibratory sensation, we can “trick” the body into not feeling the pain sensation as strongly.

A new article in the Journal of the American Academy of Dermatology (JAAD) provides strong data supporting the effectiveness of VKADs in the realm of dermatology for use with lidocaine injections in the setting of skin biopsies and excisions of the skin.  These findings are consistent with our own observations with patients at MassDerm, and we are very pleased to see reliable data in support of this practice which we will continue to use for appropriate patients in our clinic.

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