Painful unilateral temporalis muscle enlargement: reactive masticatory muscle hypertrophy

Isolated unilateral temporalis muscle hypertrophy of unknown etiology: a case report and literature review

The initial instance of isolated unilateral temporalis muscle hypertrophy (IUTMH) was reported in 1990. Since then, only few cases have been documented. The cause of this condition remains ambiguous; however, it is presumed to be linked to compensatory and stress-induced hypertrophy. We introduce a rare case of the diagnosis and treatment of IUTMH. A 39-year-old woman presented with a steadily enlarging pain-free swelling on the left side of her face, first noticed a month ago. Apart from a hyperthyroidism medication regimen her medical history was unremarkable. She had no history of temporomandibular joint disease, bruxism, surgery, or trauma. However, she complained of having been under substantial stress lately. Contrast-enhanced magnetic resonance imaging revealed asymmetric temporalis muscle hypertrophy. The treatment plan consisted of administering type A botulinum toxin injections into left temporalis muscle, supplemented by lifestyle changes and relaxation techniques. At a follow-up visit 9 months after the injections, the muscle contour was normalized both in physical and in radiologic examinations. While further supportive evidence is needed, it can be anticipated that cosmetic treatment with botulinum toxin, rather than surgical interventions, will become the standard treatment of IUTMH.

Assessing thickness and stiffness of superficial/deep masticatory muscles in orofacial pain: an ultrasound and shear wave elastography study

INTRODUCTION

Sonoelastography has been increasingly used for non-invasive evaluation of the mechanical features of human tissues. The interplay between orofacial pain and regional muscle activity appears clinically paramount, although only few imaging studies have investigated this association. Using shear wave sonoelastography (SWS), this study ascertained whether orofacial pain induced alterations in the stiffness of superficial and deep masticatory muscles.

METHODS

All participants were systematically evaluated for oral/facial-related conditions, including the area and intensity of pain. SWS was applied to measure the stiffness of the bilateral masseter, temporalis, and lateral pterygoid muscles. The association between orofacial pain and muscle stiffness/thickness was investigated using a generalized estimating equation for adjusting the influence of age, sex, laterality, and body mass index on muscle thickness/stiffness.

RESULTS

A total of 98 participants were included in the present study: 48 asymptomatic controls, 13 patients with unilateral pain, and 37 patients with bilateral orofacial pain. The reliability, quantified by the intraclass correlation coefficient for muscle stiffness measurement, ranged from 0.745 to 0.893. Orofacial pain at the individual muscle level was significantly associated with masseter muscle stiffness. A trend of increased stiffness (p = 0.06) was also observed in relation to the painful side of the temporalis muscle. No significant correlation was identified between the numeric rating scales for pain and stiffness measurements.

CONCLUSIONS

SWS provides reliable stiffness measurements for the superficial and deep masticatory muscles. The ipsilateral masseter and temporalis muscles might be stiffer than those on the side without orofacial pain. Future studies using the present sonoelasotography protocol can be designed to investigate the stiffness changes in the target muscles after interventions.

Unusual Case of Masseter Muscle Hypertrophy in Adolescence—Case Report and Literature Overview

Unilateral hypertrophy of the masseter muscle is a very rare pathological entity in children. Its etiology is uncertain and it requires a high degree of suspicion, as it must be differentiated from other conditions of the masseter area. As there are few pathological studies to elucidate this condition, we report a rare case of unilateral masseter muscle hypertrophy in a 16-year-old female patient with gradual onset of a painless swelling in the posterior left cheek which caused facial asymmetry with repercussions on the patient’s self-image. The diagnosis of unilateral masseter muscle hypertrophy was suggested by clinical examination, ultrasound scanning, and nuclear magnetic resonance, and was confirmed by histologic examination two years later when the patient returned for the surgical correction. The pathological findings report showed fragments of skeletal muscle with hypertrophic fibers associated with normal-sized muscle fibers in both longitudinal and transverse sections. The postoperative evaluation was favorable as both the adolescent and her family were satisfied with her look on the 14th day, 1st year, and 3rd year follow-ups. In conclusion, unilateral masseter muscle hypertrophy in adolescence is a sensitive problem due to the psychological implications of facial appearance. Definite diagnosis and treatment of the hypertrophied muscle is the ideal solution.

Effects of ultrasound-assisted botulinum neurotoxin-A injection in patients with bruxism and masseter hypertrophy

Objectives

This study aims to explore effects of ultrasound-assisted injection of the botulinum neurotoxin-A (BoNT-A) on muscle thickness (MT) in patients with masseter hypertrophy.

Patients and methods

Between December 2018 and December 2019, a total of 20 patients (3 males, 17 females; mean age: 28±6.9 years; range, 18 to 42 years) with bruxism who underwent BoNT-A injections were reviewed retrospectively. The patients were treated using individualized injection dosages and sites. Assessment methods included length between the tragus and the angle of the mouth, maximal bite force, and MT of the masseter muscle. Follow-up data were collected from the hospital electronic database.

Results

There were 26 masseter muscles with masseter hypertrophy in 20 patients. There was a significant difference in ultrasonographic measurements of the relaxed and contracted masseter muscles between the baseline and two weeks, one month and three months after the treatment (p<0.05). In the ultrasonographic measurement of the relaxed masseter muscle, post-treatment third month values significantly differed from the second week values. The differences in the measurement of the line between the tragus and the angle of the mouth between the baseline and two weeks, one month and three months after the treatment were statistically significant (p<0.05). In the maximal bite force measurements, no significant difference was observed between the baseline and post-intervention measurements (p>0.05).

Conclusion

The MT decreases after a single dose of BoNT-A injection in patients with masseter muscle hypertrophy and ultrasonography is a convenient imaging modality for BoNT-A injection to the masseter.

Isolated unilateral temporalis muscle hypertrophy in a child: a case report with literature review

BACKGROUND

Temporalis muscle hypertrophy is a rare entity of masticatory muscle hypertrophy. All types of masticatory muscle hypertrophies have been documented of which temporalis muscle hypertrophy is one. Temporalis muscle hypertrophy is most commonly bilateral and usually associated with other types of masticatory muscles hypertrophy such as masseter or pterygoid hypertrophy. However, isolated unilateral temporalis muscle hypertrophy is extremely rare and only 9 cases have been reported to date in English literature since 1990 with only two patients less than 18 years. There is no exact etiology identified and the diagnosis is made by muscle biopsy combined with imaging study to exclude other possibilities. Age at presentation is ranges from 15 to 65 years with involvement of both sexes. We report the youngest child who is a seven year old girl with right side isolated unilateral temporalis muscle hypertrophy.

CASE PRESENTATION

In this patient, we discuss the youngest child with isolated unilateral temporalis muscle hypertrophy and literature review to date. The patient is a seven year old female presenting with painless swelling of the right temporalis muscle. There had no features of inflammation, trauma, neoplasm or history of parafunctions such as bruxism. The child was not complaining significantly headache or visual disturbances as well. She had undergone radiological assessment with ultrasound scan and contrast MRI. The diagnosis was confirmed by muscle biopsy which shows normal muscle architecture. She was managed conservatively with regular follow up.

CONCLUSION

Isolated unilateral temporalis muscle hypertrophy is extremely rare in children. However this case raises the importance of considering alternative diagnoses despite the condition being rare in the pediatric population.

Isolated unilateral temporalis muscle hypertrophy: First case in an 8-year-old boy and review

INTRODUCTION

Isolated unilateral temporalis muscle hypertrophy (IUTMH) was first described in 1990 and few cases have been published since then. This disease occurs mainly in adults. There is no clear etiology of IUTMH, but bruxism is one of the risk factors. Only two cases have been described before the age of 20 years. To our knowledge, no cases have been described in persons younger than 15 years old. We report the first case of IUTMH in an 8-year-old and review the literature.

MATERIAL AND METHODS

This section is separated into 3 parts: (1) search for and description of clinical cases of IUTMH in our department; (2) literature search to find similar cases; (3) data analysis of all cases found.

RESULTS

Ten patients, including our case, were found over a period of 23 years: five females and five males with a mean age of 32.8 years. One patient was 15 years old. Time between onset and diagnosis was 16.7 months. Half of the patients reported pain and three had experienced bruxism. Most of the patients had non-surgical treatment. One patient evolved favorably with no treatment. One recurrence occurred 10 years later.

DISCUSSION

IUTMH can occur in childhood in a high-stress environment. Diagnosis is based on the history and clinical and imaging findings. Biopsy helps to confirm the diagnosis, but electromyograms and neurological tests contribute little. Bruxism should be taken into account. The treatment with the least inconvenience must be given.