Muscle Injection in Treating Masseter Myalgia Following TMJ Inflammation Subsided

Objectives: Among orofacial pain patients, masseter myalgia is a common but also a frustrated problem. Many treatments have been proposed to alleviate the symptom, however, no single treatment can yield a constant positive outcome. Patients presenting masseter myalgia might have different underlying patho-physiologies; such mechanism heterogeneity might account for the embarrassment of treatments. It is commonly seen clinically that the local masseter maylagia appeared following initial reduction of TMJ arthralgia after taking NSAIDs. Interestingly hardly further improvement can be seen by taking more NSAIDs; and painful taut bands can be easily revealed within masseter muscle. We hypothesized that such local myalgia might be a consequence of sensitization due to inflammation within or around TMJ. Some patients have received trigger point injection in the masseter muscle and showed very positive responses. The aim of this study was thus to evaluate the effects of muscle injections in treating local masseter myalgia confined to a restricted indication. aterials & Methods: Patients who met the following inclusion criteria were suggested to have muscle injection therapy. The chief complaint of first visit was the pre-auricular pain, which could be provocated either by maximal mouth opening or palpation on TMJ. This pain should respond well with NSAID of anti-rheumatic usage, mostly Votaren 100 mg/day for a week. When further medication won’t result in more pain reduction, and at least in the ipsilateral masseter muscle should present painful taught bands. These patients were then sent to an experienced physician in the clinic of physical therapy for muscle injection. 1% xylocaine without epinephrine was used for muscle injection through standard trigger point injection technique (Hong C-Z, 1994). If patient met the inclusion criteria but didn’t want to accept muscle injection, self-care protocols including relaxation exercises, hot packing, and muscle massage were instructed and served as controls. Pressure-pain threshold (PPT) and visual analog scale (VAS) mouth opening (mmo) were measured at baseline, 1 week, 2 weeks, and 1 month. An additional measurement was done 20 minutes after injection.esults: 25 female patients (mean age 29.45±6.16 years) received muscle injection treatment and 25 female patients (mean age 27.3 ±6.95years) were as controls. Treatment outcomes of muscle injection and self-care program represented by PPT and VAS are shown from Fig. 1 to Fig. 4. After the injection, the severity of local myalgia was worsen initially, but in one month it reduced significantly in comparison with the baseline (Paired t-test, p<0.05 for both PPT and VAS). In the control group, there was no significant difference between PPT measured at baseline and one month (Paired t-test, p>0.05). The VAS scoring was no significant difference between one month follow up and baseline (Paired t-test, p>0.05). All subjects received injection showed increased mmo at one month, however, only 8 controls had mmo increasing at one month.onclusions: uscle injection seems to be effective, at least short-term, in treating local masseter muscle pain after TMJ inflammation has been controlled.