Electromyogr Clin Neurophysiol. 2002 Jul-Aug; 42(5): 307-11.

The muscle twitch in myofascial pain relief: effects of acupuncture and other needling methods.

Chu J, Schwartz I.

Department of Rehabilitation Medicine, Ground Floor, White Building, Hospital of the University of PA, 3400 Spruce Street, Philadelphia, PA 19104, USA. jechu@mail.med.upenn.edu

Proposed is that needling methods such as acupuncture, primarily effect pain relief in myofascial pain through a local mechanism, elicitation of muscle twitches. Occasionally, diagnostic needling procedures such as electromyography (EMG) can relieve such pain through insertional intramuscular movements of the needle electrode. This results in stimulation of the motor end-plate zones (MEPZs), eliciting muscle twitches. As needle elicitation of muscle twitches is a common diagnostic technique to identify myofascial trigger points (MTrPs), muscle twitches elicited at such points may be therapeutic, not just diagnostic. Occasionally evoked small local muscle twitches are observed in pain relieving methods using needle penetration or manipulation, such as classical or electrical acupuncture and intramuscular stimulation (IMS). Twitch elicitation has been observed to be essential to obtain myofascial pain relief associated with the needling methods of automated and electrical twitch-obtaining intramuscular stimulation (ATOIMS and ETOIMS). These two methods facilitate the elicitation of larger force twitches by mechanical or electrical stimulation respectively at motor end-plate zones.