Myofacial Pain and TMJ

The Use of Electromyographic Biofeedback
for the Treatment of Facial Pain

Leonard G. Hudzinski, Ph.D.
Director, Biofeedback Services, Department of Psychiatry,
Ochsner Clinic and Alton Ochsner Medical Foundation
New Orleans, Lousiana

P.J. Walters, DDS
Chairman, Department of Maxillofacial Surgery,
Ochsner Clinic, New Orleans, Louisiana

Introduction

It is estimated that approximately 70 to 90% of patients with facial pain have either a primary or secondary muscle disorder and that pain in these patients can be alleviated with biofeedback(1). Facial pain usually results from acute overstretching of muscles, whiplash, muscle fatigue, oral surgery or immobilization of muscle or as a consequence of a muscle-bracing oral habit, such as clenching and/or grinding and malocclusion.

The pain experienced most often is described as a dull deep ache that is usually constant and active for months, sometimes for years. The pain is usually more intense on awakening, and is frequently unilateral or one-sided. Often, clicking or popping sounds originating from the temporomandibular joint (TMJ) area are reported. Mandibular movements are limited because patients have difficulty opening their mouth. The jaw often deviates to the affected and painful side of the face. The pain may radiate into the temple muscles and down into the sternocleidomastoid muscle and splenius capitis muscles as well as to the zygomatic process.

Biofeedback of the TMJ muscles has proven to be most effective in patients for whom arthritis and other non-muscle-related etiology have been ruled out. Biofeedback is important in the treatment of TMJ dysfunction because it alerts patients to excessive and inappropriate muscle activity, and teaches proper TMJ functioning by helping patients to develop muscle relaxation skills. Reducing muscle tightness and contraction generally reduces or eliminates the pain. Cram and Steger(2), Schneider and Wilson(3), and Hudzinski and Lawrence(4,5) have contributed to advances in myofacial pain monitoring and therapy with conventional electromyographic (EMG) equipment. The following procedures are designed to help monitor muscle contraction dysfunction, to establish or confirm its diagnosis, and thereby to direct the clinician to a treatment strategy.

EMG Biofeedback and Treatment

Begin treatment with a basic explanation of the relationships between muscle contraction, stress and perceived facial pain. In brief, stress may cause muscles to contract, and prolonged or frequent contraction of muscles causes and may sustain facial pain. The explanation is critical to treatment and can be especially helpful in the patient's management of stress. Explaining how the process and instrumentation of biofeedback can reduce heightened muscle activity provides the patient with an understanding of pain and an improved sense of control, which in turn helps to relieve stress, anxiety and depression.


Active EMG Scanning

Until recently, the process of muscle scanning has been open to significant measurement artifact. The MyoTrac(TM) EMG unit eliminates many measurement shortcomings through the use of MyoScan(TM), a miniature scanning sensor so advanced that generally no skin preparation is required, allowing a sight to be scanned or monitored in seconds. MyoScan(TM) is designed to be used even in electrically noisy areas where other EMG's typically fail, and offers a choice of wide or narrow bandwidth monitoring.

Using the MyoTrac(TM) EMG System

Place the MyoScan(TM) sensor over the masseter muscle site (Figure 1) using a disposable triode electrode. Ask the patient to relax the facial muscles, keeping the lips closed (the teeth need not touch) and record the average EMG activity levels for approximately 3 to 5 minutes. Document the average EMG on the left side or the right side or preferably both, using a second MyoTrac(TM) or one of Thought Technology's dual-channel EMG's, such as the MyoTrac2(TM), MyoDac2(TM), ProComp(TM), or FlexComp/DSP(TM). Once scanning of the masseter muscle is complete, the MyoTrac(TM) biofeedback monitor helps the patient train the masseter and related muscles by reinforcing the appropriate relaxation activity and monitoring the contraction. To accelerate the rate of learning, the scale reading and threshold settings are reset to raise the level of difficulty. The LED bargraph's visual feedback, or varying proportional sound, rewards the patient for consistency and quality of effort.

Technique for Masseter Training

In the first treatment session, acquaint the patient with the EMG equipment, review the myofacial data, and explain the treatment goals of relaxing the facial muscles that move the TMJ. Train the patient in muscle awareness and biofeedback while instructing him/her to decrease muscle tightness or tension or both. Review the material in Tables 1 and 2 on helpful hints and habits for facial pain patients.

Figure 2. Table 1

Figure 3. Table 2

Settings on the new MyoTracTM:

Set gain switch to x10 Set threshold setting to 5uV Set on/cont/thr switch to threshold Set internal switches to off/off/abv/wide

If the red lights are on when the masseter and its related muscles are relaxed, the threshold dial is turned counterclockwise toward the higher numbers until the green lights come on. Similarly, the absence (disappearance) of the audio feedback signal can be provided as reinforcement to the patient in relaxation training. When the patient has relaxed to the pre-selected level determined by the threshold selector, the audio feedback will turn off. In this case, the patient attempts to keep the audio feedback signal off for as long a time as possible. When the trainee is successful in keeping the feedback signal off for at least 80% of the time, the threshold selector is turned down a small amount, establishing a lower muscle tension level as the criterion for audio feedback disappearance (if the signal is less than 10 uV, change the gain switch to x1). The patient then trains for the disappearance of the audio feedback signal at the new threshold setting. Through daily use of feedback, the patient learns to identify contraction in the masseter muscles and will be increasingly able to relax those muscles as needed.

One particularly effective treatment approach a clinician can use across each session involves shaping muscle awareness and relaxation. After applying the electrode over the masseter muscle, allow the patient a 30-second rest period or artifact elimination period in which swallowing, change of position, etc. are encouraged. Ten trials of controlling contraction in the myofacial muscles are given during each session (Table 3). Give verbal reinforcement only when the patient lowers muscle potential. If EMG activity is significantly lowered, reinforce the behavior correspondingly. If EMG activity is only slightly decreased, reward the patient comparably with mild verbal reinforcement and shaping techniques. (Shaping is the gradual development of a correct response by means of small initial attempts, the first tentative steps taken in the right direction toward a particular goal). By using the EMG threshold setting and reinforcement, a particular behavior may be shaped to a desired microvolt level.

It may be useful to demonstrate to the patient the initial asymmetry between the left and right masseter. The MyoTrac2TM is a self-contained dual-channel EMG monitoring system similar to the MyoTrac(TM) but with memorization of EMG and computer interfacing capabilities. These devices provide a clearer graphical visualization of the effects of training, and can record session to session progress. As well as the MyoTrac2(TM), the MyoDac2(TM), ProComp(TM) and FlexComp/DSP(TM) instruments can interface with IBM compatible computers.

Figure 4. Table 3

A particularly effective monitoring procedure involves comparing non-stress to stress-related stimuli. While the patient is seated, assess facial muscle activity during and immediately after a discussion about a non-emotional issue, such as activities that can be used to promote relaxation. Compare the non-stress data to muscle activity measured after a 3-5 minute discussion of an emotional issue, such as the patient's facial pain and its impact on daily functioning. Note the differences between the emotional and non-emotional material as reflected in the microvolt levels related to the EMG monitoring.

Devote a portion of each treatment session to correcting the patient's dysponetic myofacial patterns as documented through the myofacial evaluation. Behaviors that evolve into inappropriate muscle-bracing are often referred to as being dysponetic.

Dysponetic myofacial patterns can include clenching, grinding, gritting, gnashing, and clicking of teeth. They may also include the contact of teeth during chewing of cheeks or lips, pencils, pipes, or even gum. Dysponetic patterns might also include less obvious activity, such as imbalanced breathing or posture, contraction of muscles in the neck, shoulder or thorax - all of which are diagnosable and treatable through EMG scanning methods or multi-measurement procedures.

Examples of dysponetic patterns may be helpful. Many patients with TMJ dysfunction experience gradual and increasing muscle asymmetries that result in pain. In an attempt to maintain a pain-free state or to reduce pain, the patient may alter the position of the mandible very slightly. Although this positioning may relieve pain initially, it often leads to soreness in other muscles of the face and jaw because of the strain and pulling of muscle, particularly on the opposite side of the face. Muscles not only become sore because they are contracted but also because they are shortened. These muscle imbalances are frequently responsible for soft tissue pain wherever muscle strain is experienced, in areas of the neck, head, back, and even the chest.

Home Training with MyoTracTM

To enhance treatment effects, EMG monitoring in the patient's workplace and home is very useful. MyoTrac(TM) and MyoTrac2(TM) feature a delayed alarm feature which allows muscle activity to exceed the threshold limit for 4 seconds before an audible alert is heard. The patient can carry out normal talking, yawning and other movements, and only be warned by a continuous tone when muscle activity has been above threshold for greater than 4 seconds.

To set the new MyoTracTM in this mode:

  1. Set off/cont/thr switch to threshold
  2. Set internal switches to off/alarm/above/wide
  3. Instruct the patient to place a "triode" electrode over the masseter area, relax the jaw and set the bargraph display to be 2 or 3 green LEDs to the left of the yellow LED, and then to go about daily activity. This process will provide continual feedback and training in a real-life environment.

There is also some evidence that nocturnal monitoring and a threshold triggered alarm may alleviate or diminish nocturnal bruxism. To set MyoTrac(TM) for nocturnal use, follow the previous procedure, however set the "lock" switch in the battery compartment to ON. This will lock the tone, waking the patient when TMJ activity exceeds threshold for more than 4 seconds. The patient is obliged to turn the unit OFF and then ON again. If privacy is desirable, the earphone can be used.

Conclusion

Facial muscle activity may be shaped to a desired microvolt level by using EMG biofeedback with threshold functions and reinforcement. Clinical evidence documents that the masseter muscles can be trained to release and relax.6 Ongoing and regular training will produce long-term beneficial effects, allowing the patient to remain pain-free, even under conditions that arouse tension. Using the MyoTrac(TM) EMG to monitor and evaluate patient progress is basic to a patient's achieving the goal of treatment success.

REFERENCES

  1. Dohrman RS, Laskin DM: An evaluation of electromyographic biofeedback in the treatment of myofacial pain-dysfunction syndrome. J Am Dent Assoc, 96:656-662, 1978.
  2. Cram JR, Steger JC: EMG scanning in the diagnosis of chronic pain. Biofeedback and Self-Regulation, 8:229-242, 1983.
  3. Schneider CJ, Wilson ES: Special Consideration for EMG Biofeedback Training. Wheat Ridge, CO: Foundation of Biofeedback Practice, Biofeedback Society of America, 1985.
  4. Hudzinski LG, Lawrence GS: Significance of EMG surface electrode placement models and headache findings. Headache, 28:30-35, 1988.
  5. Hudzinski LG, Lawrence GS: Myofacial Pain and the Temporomandibular Joint. In Cram JR (ed): Clinical EMG for Surface Recordings, 2nd ed. Nevada City, CA Clinical Resources, pp 329-351, 1990.
  6. Budzinski TH, Stoyva S: An electromyographic feedback technique for teaching voluntary relaxation of masseter muscle. J Dent Res, 52:116, 1973.
  7. Chaco J: Electromyograph of the masseter muscles in Costen's syndrome. J of Oral Med. 28: 45-46, 1973.
  8. Clark GT, Beemsterboer PL, Rugh JD: Nocturnal masseter muscle activity and symptoms of masticatory dysfunction. J. of Rehab., 8: 279-285, 1981.
  9. Gessel AH: Electromyographic biofeedback and tricyclic antidepressants in myofacial pain dysfunction syndrome: psychological predictors of outcome. J Amer. Dental Assoc., 91: 1048-1057, 1975.
  10. Glass AG, Rao SM: Bruxism: a critical review. Psych. Bulletin, 84: 767-781, 1977.
  11. Malamed BG, Mealiea WL, Jr.: Behavioral intervention in pain related problems in dentistry. The Comprehensive Handbook of Behavioral Medicine, Vol 2 (pp. 241-259). Culver City, CA, Spectrum Int., Inc, 1981.
  12. Scott DS, Lundeen TF: Myofacial pain involving the masticatory muscles: an experimental model. Pain 8: 207-241, 1980.

 

Copyright, 1997 The Biofeedback Foundation of Europe