Case history and examination
The patient is a 53-year-old woman who‘s symptoms had lasted for over 30
years and the pain was troublesome 1-3 times per month. She sought
treatment for facial pain and headache and self-reported bruxism.
The patient had no systemic
diseases, no medication and did not smoke. She had self indentified that
symptoms correlatated often with stress episodes. The patient was
treated with many different TMD treatment modalities such as splint
therapy, non-steroidal anti-inflammatory drugs medication and soft food
diet, but with poor success.
The clinical examination revealed a maximum mandibular opening of 50 mm
and a normal range of eccentric movements. No joint pain or sound was
noted. There was a stable occlusal condition in a musculoskeletal stable
position. According to the pain drawing, the pain that the patient
experienced during the last six months was intraorally and in the areas
of the head, neck, face, and shoulders throughout. Palpation of the
muscles of mastication revealed muscle tenderness in the areas of the
masseter and temporalis with no referred pain. Palpation-induced pain
was familiar to the patient. The diagnosis was local myalgia and
headache attributed to TMD secondary to parafunctional activity and
stress-related muscle co-contraction. Since the symptoms were lasting
for years and the conservative treatments of muscle pain were
ineffective, activity within central nervous system (CNS) could be
involved in the pain input. The diagnosis of centrally mediated myalgia
could not be excluded. In this investigation we decided to try botulinum
toxin injections as a treatment option and combined with comprehensive
assessments of the treatment responses.
The Characteristic Pain Intensity (CPI) score was calculated from the
0-10 ratings of current, worst, and average pain intensity during the
past six months. Before the treatment the score was 7.3. The chronic
pain grade (CPG, baseline to six months, grades 0-IV) was II,
corresponding to ‘High intensity pain, without disability’. Jaw
functional limitations were observed in the following activities:
chewing tough food, smiling, yawning, and tooth brushing. The degree of
pain-related worry was 7 (0-10 scale). Based on the Symptoms
Checklist-90 Revised (SCL-90R) questionnaire, the patient had only mild
symptoms of depression, with an average score of 0.5 (0-4 scale). The
same questionnaire revealed severe sleep disorder, with an average score
of 3.0 (0-4 scale). The average score of non-specific physical symptoms
with pain items was 0.6 and non-specific physical symptoms without pain
items 0.4 (0-4 scale). The initial average electromyography (AEMG) value
of the masseter muscle during clenching with maximum force was 241 mV
and at rest 45 mV, and the average maximum bite force was 580 N (Figure
1).
Clinical diagnosis was based on the standardized clinical examination
protocol and Axis I decision tree of the Diagnostic Criteria for
Temporomandibular Disorders (DC/TMD) [6]. Axis II biopsychosocial
assessment instruments of the Research Diagnostic Criteria for
Temporomandibular Disorders (RDC/TMD) were used to evaluate the effect
of treatment on disability and psychological status [7]. The
following questionnaires were used before the treatment and at each
follow-up visit:
Axis I (Physical findings)
Demographics
Clinical examination form (DC/TMD)
Axis II (Disability & Psychological Status)
- Pain Drawing
- None: number of body areas
with pain = 0
- Mild: number of body areas with pain = 1
- Moderate: number of body areas with pain = 2
- Severe: number of body areas with pain being over 3
- Graded Chronic Pain Scale (GCPS) 1.0
- 0: no TMD pain in the preceding six months
- I: low disability, low pain intensity
- II: low disability, high pain intensity
- III: high disability, moderately limiting
- IV: high disability, severely limiting
GCPS 1.0 grades are derived from seven questions measuring
- Characteristic pain intensity (CPI) (current, worst, average) (range
0-10; 0 = no pain, 10 = worst pain)
- Disability days
- Pain-related interference with daily, social, and work-related
activities
- Questionnaire for measuring jaw functional limitation (11 items withyes or no option: chewing, drinking, exercising, eating
hard foods, eating soft foods, smiling/laughing, sexual activity,
cleaning teeth or face, yawning, talking, having your usual facial
appearance)
- Pain-related worry (range 0-10; 0 = not at all worried, 10 = extremely
worried)
- Ability to control pain (range 0-6) or the ability to decrease pain
(range 0-6)
- RDC/TMD_FIN Depression and Somatization Scores Based on the Symptom
Checklist 90, Revised (SCL-90R) (5-point Likert scale: 0 = not at all,
4 = very much) including the following assessments:
- Symptoms of depression (20 questions)
- Sleep dysfunction (3 questions)
- Non-specific physical symptoms (including pain items) (12 questions)
- Non-specific physical symptoms (without pain items) (7 questions)
EMG of masseter muscle and bite forces were assessed before the
treatment and after the botulinum toxin injections at each follow-up
visit. A series of recordings consisted of an exercise lasting 60
seconds so that every 10th second the patient was asked to bite hard for
5 seconds followed by a 5-second relaxation. The values of AEMG were
selected from the middle of each 5-second relaxation and clench periods.
Maximum bite force was selected from each clench period. Six values of
AEMG and bite force were selected at each patient’s visit, and the
average values were calculated.
The patient received a one-time treatment of 50 units of BoNT-A
(Xeomin®, supplied by Merz Pharmaceuticals GmbH, Germany); 2/3 of the
dose was injected into the bilateral masseter muscles (16.7 units each
masseter) and 1/3 into the bilateral temporalis (8.3 units each
temporalis). Three injections were applied along the inferior border of
the masseter and two injections along the anterior part of the
temporalis. Follow-ups were performed at 2, 11, 16, and 22 weeks after
the botulinum toxin injections.
At two weeks after the injections, there were no significant changes in
pain location, pain intensity, or degree of disability, with chronic
pain grade remaining at II and CPI 6.7. However, functional limitations
were no longer observed. The score for pain-related worry level was 6
(range 0-10). The following scores were obtained from the Axis II
biobehavioural questionnaire (range 0-4): symptoms of depression 0.45,
sleep dysfunction 1.7, and non-specific physical symptoms with and
without pain items 0.3. The AEMG value during clenching with maximum
force dropped to 55 mV and the average maximum bite force to 305N
(Figure 1). No changes occurred to AEMG rest (45 mV).
At 11 weeks after the injections, only the parietal region remained as a
pain area. The chronic pain grade was 0, meaning that TMD pain and its
related disability were no longer present. No functional limitations
were observed. Pain-related worry level was 1 (range 0-10). The
following scores were obtained from the Axis II biobehavioural
questionnaire (range 0-4): symptoms of depression 0.35, sleep
dysfunction 1.0, and non-specific physical symptoms with pain items 0.2
and without pain items 0. The AEMG value during clenching with maximum
force was 74 mV, and the average maximum bite force was 326 N (Figure
1).
At 16 weeks after the injections, the pain distribution level was
moderate with two areas affected: the temporalis and the right side of
the neck. The severity of chronic pain was graded as II and CPI was 6.0.
Nonetheless, no functional limitations were observed. Pain-related worry
level was 5 (range 0-10). The following scores were obtained from the
Axis II biobehavioural questionnaire (range 0-4): symptoms of depression
0.3, sleep dysfunction 1.7, and non-specific physical symptoms with pain
items 0.3 and without pain items 0.1. The AEMG value during clenching
with maximum force was 98 mV, and the average maximum bite force was 488
N (Figure 1).
At 22 weeks after the injections, the pain distribution level was still
moderate, affecting the parietal and temporal regions. CPI score was 0,
with no functional limitations. Pain-related worry level was 5 (range
0-10). The following scores were obtained from the Axis II
biobehavioural questionnaire (range 0-4): symptoms of depression 0.25,
sleep dysfunction 1.0, and non-specific physical symptoms with pain
items 0.2 and without pain items 0. The AEMG value during clenching with
maximum force was 133 mV, and the average maximum bite force was 452 N,
indicating that the physiological effect of BoNT-A was still present
(Figure 1).