TMJ Arthroscopy with and without Onabotulinumtoxin A in Patients with Arthrogenous and Myogenous Pain

Purpose:

There is no standard of care for the treatment of refractory myofascial pain in patients with concomitant TMJ arthralgia. This comparative study was conducted to determine the effectiveness of botulinum toxin A, as an adjunct to TMJ arthroscopy, for the management of refractory myofascial pain in patients with TMJ dysfunction.

Patients and Methods:

We performed a retrospective review of all patients who presented to the University of Michigan for the treatment of concomitant TMJ arthralgia and myofascial pain between September 2011 and December 2014. We included patients who underwent TMJ arthroscopy with (Btx group) or without (control group) intra-muscular botulinum toxin A injections to sites of tenderness within the masseter and temporalis muscles, for the treatment of TMJ arthritis and refractory myofascial pain. All patients had initial non-surgical therapy that did not resolve their myofascial pain. Patients were stratified into the two groups based on insurance coverage for botulinum toxin A injection. Data collected included demographic, clinical and operative variables. The primary outcome variable was pain score on VAS (0-10). The secondary outcome variables included maximal interincisal opening (MIO), total score for sites of tenderness, total number of tender sites, and diet.

Statistical Analysis:

Outcome scores were analyzed using means and standard deviations and compared between the Btx and control groups using student t-tests.  Pain and maximal interincisal opening were also compared between the Btx and control groups taking into account age, gender and follow-up using regression analysis. All statistical analysis were done in R. 

Results:

We included fifty-two patients (n=30 Btx group; n=22 control group) with a mean age of 42.7 years. Our patient sample included 48 females (92.3%) with a mean follow up of 5.56±1.41 months. Reported duration of symptoms varied widely with an average of 80.26±106.12 months.  Eighteen patients had bilateral (n=12 in Btx group) and 34 had unilateral procedures. The overall pain score on VAS decreased significantly from 6.10±0.71 to 3.65±3.54. MIO increased from 34.85±7.56 to 39.88±6.99 and diet consistency improved from 2.52±0.81 to 1.86±0.85. The mean pain score decreased by 3.24 (6.36±2.00 to 3.12±2.59) in the Btx group and 1.13 in the control group (5.67±1.95 to 4.53±3.09). This was statistically significant (p<0.04). MIO increased from 35.92±7.98 mm to 42.00±5.66 mm in the Btx group, and from 33.42±6.91 mm to 37.06±7.73 mm in the control group. The change in MIO was not significantly different between the two groups (p=0.23). Total score for sites of tenderness decreased by 3.11 in the Btx group and 1.94 in the control group (p=0.33). The extent of pain reduction was dependent on the preoperative pain score recorded (p=0.0427).  There was no difference in terms of the number of complications or procedures performed postoperatively.

Conclusions:

In this pilot study, patients with myogenous and arthrogenous pain underwent TMJ arthroscopy with or without adjunctive botulinum toxin A injection. Improvements in pain score, MIO, and diet scores were observed in both groups. The use of botulinum toxin A lead to a significantly greater improvements in pain score compared to the control group. The use of Botulinum toxin A may be a useful adjunct in the management of refractory myofascial pain. Additional prospective randomized controlled trials are needed to determine its effectiveness.

References:

Von Lindern JJ, Niederhagen B, BergŽ S, et al: Type A botulinum toxin in the treatment of chronic facial pain associated with masticatory hyperactivity. J Oral Maxillofac Surg 61:774, 2003

Kurtoglu C, Gur OH, Kurkcu M, et al: Effect of botulinum toxin-A in myofascial pain patients with or without functional disc displacement. J Oral Maxillofac Surg 66:1644, 2008