Research Review By Dr. Michael Haneline©

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Date Posted:

July 2020

Study Title:

Effect of Manual Therapy and Therapeutic Exercise Applied to the Cervical Region on Pain and Pressure Pain Sensitivity in Patients with Temporomandibular Disorders: A Systematic Review and Meta-analysis

Authors:

La Touche R, Garcia SM, Garcia BS, et al.

Author's Affiliations:

Department of Physiotherapy, La Salle Higher Center for University Studies, Autonomous University of Madrid, Madrid, Spain.

Publication Information:

Pain Medicine 2020 (in press); doi: 10.1093/pm/pnaa021

Background Information:

Temporomandibular disorders (TMDs) primarily affect the 20 to 40-year-old age group, show a higher prevalence in females and are the second most common cause of orofacial pain after dental pain. Although not fully understood, the etiology of TMDs is thought to be multifactorial – related to structural, psychological, and functional factors.

Because of the functional, anatomical, and neurophysiological relationship between the temporomandibular joint (TMJ) and the upper cervical spine, TMDs are often associated with other craniocervical conditions, such as neck pain and headache. Also, the facial area and cervical spine have a common innervation that involves afferent neurons of the trigeminocervical complex.

Manual therapy (MT) involving TMJ mobilization and soft tissue techniques to improve function and reduce pain are commonly used in the treatment of TMD. Cervical MT techniques are also commonly added to craniofacial treatments to address the previously mentioned relationships between the craniofacial area and the upper cervical spine.

Cervical spine manipulation or mobilization techniques have been shown to have a positive effect on pain intensity in TMD patients and it is thought that cervical MT could increase the therapeutic effectiveness of MT applied to the TMJ and facial region. Cervical MT could also be used in TMD patients who are not good candidates for MT in the mandibular region.

The effectiveness of cervical spine MT for patients with TMD and the comparison of cervico-craniomandibular MT versus cervical treatment remains unclear. Therefore, the objectives of this study were:
  1. to perform a systematic review and meta-analysis on the effectiveness of cervical MT in patients with TMD; and
  2. to compare the effectiveness of cervico-craniomandibular MT treatment versus cervical treatment in patients with TMD.

Pertinent Results:

Literature Search Results & Study Characteristics:
After duplicates were removed, the literature search produced 53 studies, of which six were included in the review. However, only five of them were eligible for the metanalysis. All of the included studies had a low risk in selection bias, whereas they all had high or unclear risk of performance bias because of the way blinding was carried out.

In four of the studies, all patients had TMD and craniofacial pain, with a total sample size of 163 (mostly female) patients. The other two studies included patients with headache and TMD, with a total sample size of 88 patients (again, mostly females). Cervical and craniomandibular MT techniques were employed in these two studies.

In the studies that compared cervical manual therapy vs. other nonmanual therapy interventions, the MT techniques that were utilized in the cervical treatment groups included cervical mobilizations or high-velocity manipulations along with muscle conditioning.

Meta-analysis of the cervical MT intervention studies demonstrated statistically significant reductions in short-term pain intensity for the cervical manual therapy groups, with large clinical effects in three of the studies (1-3). There were also significant increases in pressure pain threshold (PPT) measures, ranging from 0.98 to 1.5 kg/cm2 for the masseter muscle and 0.8 to 1 kg/cm2 for the temporalis muscle.

In the studies that compared cervical manual therapy vs. cervico-craniomandibular manual therapy interventions, the cervico-craniomandibular MT techniques that were utilized included TMJ mobilizations and neuromuscular and nerve tissue techniques along with coordination exercises for masticatory muscles and therapeutic exercises. The cervical therapies involved MT, which included muscle and nerve tissue techniques and joint mobilizations, together with therapeutic exercises and self-care counseling.

Two of the studies (4, 5) compared standalone cervical MT with combined cervical and craniomandibular MT interventions. One study reported significant reductions in pain intensity at three months follow-up for both interventions, although at six months, only the combined cervical and craniomandibular treatments showed greater improvement than the cervical intervention. The other study reported significant differences between the groups at each follow-up.

The meta-analysis for these studies showed statistically significant differences in the short-term reduction of pain intensity, as well as the short-term reduction of pain-free maximal mouth opening (MMO), both with large clinical effects.

Clinical Application & Conclusions:

The authors concluded that there was moderate-quality evidence regarding the beneficial effects of cervical manual therapy versus non–manual therapy interventions on pain intensity and PPT. The evidence was downgraded because of inconsistencies between the studies.

They also suggested that there was low-quality evidence to support the conclusion that cervico-craniomandibular manual therapy versus cervical manual therapy interventions could provide positive effects regarding pain intensity and pain-free MMO. This evidence was also downgraded because of study quality as well as inconsistencies.

The use of craniomandibular and cervical MT for treating patients with TMD showed a decrease in short-term pain intensity and pain-free maximum mouth opening (MMO), and the authors thought these findings support the application of MT in craniomandibular and cervical regions in patients with TMD. However, the number of included studies was small and of low-quality; accordingly, these results should be interpreted with caution while we await further research in this area.

Editor’s Note: As noted, there is evidence supporting an integrated treatment approach for TMD patients including addressing cervical and TMJ function via manual methods. These interventions are safe and certainly worth a trial of care to see if improvement can be made. Although not included in the scope of this particular review, I always found stress management to be important for TMND patients, particularly those with chronic issues. This can include things like increasing exercise, recommending mindfulness/meditation and even addressing ancillary issues like hydration, nutrition and sleep. TMDs, as with so many other conditions, often require the right combination of therapies for the individual patient sitting in front of you – your challenge as a clinician is to find the right combination!

Study Methods:

This was a systematic review and metanalysis that was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines.

Four biomedical databases were searched using a comprehensive list of search terms. The searches were conducted by two independent reviewers who used the same methodology. They also manually screened the reference sections of the included articles for additional studies. Any differences in search results were resolved by consensus.

The methodological quality of the included studies was assessed by 2 reviewers who worked independently using an assessment tool from the Cochrane Handbook for Systematic Reviews of Interventions. The resulting risk of bias was assessed as being “low risk,” “high risk,” or “unclear risk.” Any disagreements between the reviewers were resolved by consensus.

The overall quality of evidence was evaluated using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) rating system. The evidence was categorized into the following four levels:
  1. High quality: Further research is very unlikely to change our confidence in the estimate of effect.
  2. Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and might change the estimate of effect.
  3. Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.
  4. Very low quality: Any estimate of effect is very uncertain.
A statistical analysis of the included studies’ pooled data was performed to compare the outcomes that were reported in the studies.

Study Strengths / Weaknesses

This was a well-done systematic review and meta-analysis which produced evidence that is useful in clinical practice. The review was conducted according to the PRISMA guidelines and the authors followed the guidelines appropriately.

The authors did acknowledge several study limitations, including:
  • Heterogeneity in the included studies regarding the inclusion and exclusion criteria as well as the types and frequency of MT interventions (ex. manipulation, mobilization, exercise).
  • Relatively low methodological quality of the included studies.
  • An inability to have the study protocol registered.
Accordingly, they suggested that more studies with higher methodological quality and homogenous treatment protocols are needed.

Additional References:

  1. Corum M, Basoglu C, Topaloglu M et al. Spinal high-velocity low-amplitude manipulation with exercise in women with chronic temporomandibular disorders. Man Medizin 2018; 56(3): 230–8.
  2. Calixtre LB, Oliveira AB, de Sena Rosa LR et al. Effectiveness of mobilisation of the upper cervical region and craniocervical flexor training on orofacial pain, mandibular function and headache in women with TMD. A randomised, controlled trial. J Oral Rehabil 2019; 46(2): 109–19.
  3. La Touche R, Paris-Alemany A, Mannheimer JS et al. Does mobilization of the upper cervical spine affect pain sensitivity and autonomic nervous system function in patients with cervicocraniofacial pain? Clin J Pain 2013; 29(3): 205–15.
  4. Garrigos-Pedron M, La Touche R, Navarro-Desentre P et al. Effects of a physical therapy protocol in patients with chronic migraine and temporomandibular disorders: A randomized, single-blinded, clinical trial. J Oral Facial Pain Headache 2018; 32(2): 137–50.
  5. von Piekartz H, Ludtke K. Effect of treatment of temporomandibular disorders (TMD) in patients with cervicogenic headache: A single-blind, randomized controlled study. Cranio 2011; 29: 43–56.