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An intra-articular corticosteroid injection into the temporomandibular joint (TMJ) provides pain relief for some patients with juvenile idiopathic arthritis (JIA) whose orofacial symptoms haven't responded to other pain management strategies, a small pilot study found.

However, the study identified considerable variation in terms of response to the treatment, with few subjects experiencing a total resolution of orofacial pain.

The research team, led by , of the orthodontics section at Aarhus University, in Denmark, concluded that intra-articular steroid injections are a palliative, but not curative, approach to treating refractory TMJ arthritis-related orofacial symptoms.

The prospective, observational study, published in , included 13 patients with JIA, all female, whose median age was 17.2 years. All had a long-standing history of refractory TMJ arthritis-related symptoms with insufficient response to previous pain management treatments.

All participants received cone-beam computerized tomography before the injections, plus three separate clinical examinations -- prior to the treatment, 34 days post-treatment (short-term follow-up) and a mean of 333 days post-treatment (long-term follow-up). The examinations included a pain questionnaire completed by the patients, and a clinical examination completed by the treating orthodontist.

The patients reported the frequency of their orofacial symptoms on a 5-point Likert scale (higher numbers indicate more frequent) and their pain intensity on a visual analogue scale (VAS), with 100 mm being the worst possible pain. Using aspects of orofacial pain frequency and intensity, researchers developed a pain index to calculate the relative change in pain over time. Pretreatment, the mean pain intensity was 62.7 on the VAS scale and the average pain frequency was "several times a day."

The imaging study found radiological signs of osseous TMJ degeneration in all injected joints.

At the short-term follow up, all pain outcome variables were significantly reduced, but at the long term follow-up, only the pain frequency remained significantly reduced compared to pretreatment levels. Pain intensity and the pain index significantly worsened between the short- and long-term follow-ups, which was especially true for patients with high pretreatment pain levels.

Only three patients experienced pain cessation at the short-term follow-up and one patient at the long-term follow-up. At the short-term follow-up, 11 patients had a relative reduction in pain compared to pre-treatment levels, and nine (69%) had a reduction of more than 50%.

Between the two follow-ups, seven patients experienced an aggravation of the reported pain-index levels, suggesting a loss of effect of the steroid injection for some patients. Aggravation of pain was most pronounced in patients with high pretreatment pain levels.

This finding differs from previous studies that reported a better response. The difference, according to the authors, may be due to the inclusion of older patients who had a longer duration of TMJ arthritis.

Six patients in the current study did report a relative pain index reduction at the long-term follow-up of more than 50% compared to the pretreatment levels. "This is a positive findings related to this group of patients with persistent and long-term pain issues failing other pain treatment strategies," wrote the authors.

Since the study had no control group, the design didn't allow them to assess whether this reduction was due to fluctuation of orofacial symptoms or to the real effect of the treatment.

There were no adverse reactions directly related to the procedure.

When assessing maximal unassisted incisal opening capacity and lateral and forward movement of the lower jaw, the researchers found no significant intra-group changes. Despite this, there was inter-patient variation in the functional changes after the treatment, and at the short-term follow-up, there were clinically relevant improvements in some patients.

"From a clinical point of view, our findings support the present clinical indications for the use of intra-articular corticoisteroid injections against TMJ arthritis," wrote the authors. "However, caution should be applied before the use ... in younger patients since concerns about the impact of intra-articular corticosteroid injections on mandibular growth remain an unanswered and relevant consideration."

The findings contribute "new knowledge" since they illustrate that achieving acceptable treatment results in this group of patients "is indeed a very challenging task," according to the authors.

Prospective long-term follow-up studies are now being planned, they noted.

In addition to having no control group, the study had a number of other limitations, including the small number of subjects and lack of pretreatment MRI.

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