Muscle spasm pain involves the interface of the neuromuscular junction. It is here where nerves synapse with muscle tissue. Neuromuscular stimulation causes muscles to contract in a complicated process involving calcium channels and calcium ion exchange, shortening of muscle spindles and complex coordination between extensor and flexor muscle groups.

Damage to nerves that contribute to the neuromuscular junction can cause acute and chronic spasm. Additionally only pieces of the muscle may be affected, causing myofascial trigger points to form. Muscle spasm of any type can be very painful and can easily break through even strong opioid medication. Additionally, muscle spasm can cause referred pain to other muscle groups, especially from myofascial trigger points. Inflammation of fascia covering the muscles can cause acute and chronic inflammation.

Treatment can include rest, ice, heat, message, muscle relaxers, anti-inflammatories, trigger point injections, and Lidoderm patches. Lidoderm can be quite effective due to sodium channel blockade at the nerve muscle interface. This can be a very helpful adjunct to trigger point injections, resulting in increased periods of relief. There is also some evidence that Lidocaine has local anti-inflammatory effects. Trigger point injections should be done with 1% or 2% Lidocaine, without celestone or other steroidal adjunctives. Lidocaine is used to allow multiple penetration of the myofascial trigger point with a 25 to 27 gauge needle, to help the muscle spasm release. This should be followed by a muscle stretch exercise.