Abstract
Chronic myofascial pain (CMP) of the masticatory muscles is a common chronic pain disorder in the orofacial region. CMP is characterized by a trigger point (TP) on a myofascial taut band, the palpation of which induces reproducible pain. Trigger point injection (TPI) and fascia hydrorelease (FHR), in which local anesthetics are injected into a trigger point and adhesions of fascia, are often performed for CMP because of the high therapeutic effect on pain relief. CMP is caused by abnormal sympathetic nerve excitement that leads to a vicious cycle of reflexes by vasoconstriction of the arterioles in muscles. Therefore, an agent with vasoconstrictive action has not been previously used for TPI and FHR. We report two cases in which TPI and FHR was performed using local anesthetics with vasoconstrictive actions, providing successful pain relief. TPI and FHR were performed using NeoVitacain® injection (dibucaine hydrochloride, sodium salicylate, calcium bromide) as a general procedure in our department. Both patients complained of an unsatisfactory effect on pain relief, and the duration was not long enough. Consequently, the agents were switched from NeoVitacain® to lidocaine with adrenaline and ropivacaine, respectively. As a result, sufficient pain relief was obtained in both cases. Adrenaline, a vasoconstrictor, was added to the local anesthetic to prolong the anesthetic effect. Ropivacaine has a long anesthetic effect because of its strong protein binding and unique vasoconstrictive action at concentrations used clinically. The pain relief obtained in the present two cases of CMP might have arisen from the vasoconstrictive actions of these two agents.
