ABSTRACT
Background
Hemi masticatory spasm (HMS) is a rare movement disorder affecting muscles of mastication attributed to dysfunction of motor branch of trigeminal nerve and is characterized by painful spasm of masticatory muscles. Microvascular compression leading to focal demyelination of motor branch of trigeminal nerve is the most speculated on mechanism of HMS. Treatment options range from medical to surgical approaches, but botulinm toxin (BTX) has now become the preferred treatment.
Cases
We report a retrospective review of 7 cases of HMS, supported by electrophysiological and clinical findings. All the cases had excellent response to BTX therapy.
Discussion and Conclusion
In this article, we highlight the delay in diagnosis of HMS attributed to rarity, long course of illness, association with hemiatrophy, “Lichen Sclerosus et Atrophicus,” and scleroderma/morphea. Considering the favorable outcome to BTXs, surgical treatment can be avoided or delayed in majority except secondary cases.
Keywords: hemi masticatory spasm (HMS), hemiatrophy, “Lichen Sclerosus et Atrophicus” (LSA) localized scleroderma, botulinum toxin, masseter inhibitory reflex, segmental morphea
Hemi masticatory spasm (HMS) is a rare movement disorder of unknown origin attributed to dysfunction of the motor branch of the trigeminal nerve, characterized by spasm of the masticatory muscles.1, 2 Spasms occur many times a day and are precipitated by chewing, speaking, eating, and voluntary closure of jaw.1, 2 HMS is more common in women in their third to fourth decade, and there is a frequent association with facial hemiatrophy (FHA), localized scleroderma, or morphea.2, 3 Brief spasms are usually painless, but prolonged spasms are painful. Violent and severe spasms may lead to tongue bite, dislocation of the jaw, or broken teeth. Along with medical and surgical management, recently botulinum toxin (BTX) has been demonstrated to be a successful treatment.1, 2, 3, 4, 5, 6, 7, 8, 9
We report a retrospective review of 7 cases of HMS supported by electrophysiological and clinical findings. All our patients responded well to BTX treatment.
Cases
Demographic Characteristics
We enrolled a total of 7 patients with HMS (4 males and 3 females) over a period of 4 years (2013–2017) from our institute, a tertiary care referral center in the northern part of India. Four of these cases involved the right side, and 3 involved the left side (Table 1). Mean age of these patients was 34 ± 7.79 years (range, 23–45), with a duration of masticatory spasms for 2 to 9 years.
Table 1.
Clinical profile of 8 HMS patients
| No | Age/Sex | Side, | Duration (Years) | Involved Muscles | Additional Features |
|---|---|---|---|---|---|
| Case 1 | 25/M | Left | 4 | Ms and Tm | LSA, Segmental morphea, (L) FHA |
| Case 2 | 34/M | Left | 5 | Ms and Tm | Localized scleroderma, (L) FHA |
| Case 3 | 23/M | Left | 2 | Ms | (L) FHA |
| Case 4 | 39/M | Right | 6 | Ms and Tm | Hypertrophy of (R) Mm |
| Case 5 | 45/F | Right | 9 | Ms | Hypertrophy of (R) Mm, localized scleroderma |
| Case 6 | 38/F | Right | 8 | Ms and Tm | (R) FHA |
| Case 7 | 34 F | Right | 5 | Ms | Hypertrophy of (R) Mm |
Ms, masseter; Tm, temporalis.
Clinical Details
All patients presented with unilateral spasms involving either the masseter or temporalis muscles or both, without any apparent cause. Patients presented with brief or progressively prolonged spasms of single or multiple masticatory muscles of one side, and each episode lasted from a few seconds to several minutes. In all patients, spasms were painful and triggered by activities like chewing, talking, clenching of teeth, or voluntary tapping of the involved muscles. All patients reported increasing severity and frequency of spasms over time and continuous rippling movements of the jaw during each episode. For 3 patients (cases 1, 5, and 6), spasms would occur spontaneously up to seven to eight times per day, and each episode ranged from 3 to 5 minutes. Other patients reported brief spasms occurring three to four times per day, with a duration of a few seconds to 1 to 2 minutes (Video S1). One patient (case 5) complained of cluttering of teeth during these episodes. Two patients (cases 2 and 7) reported worsening of symptoms during winter seasons. None of the patients reported any lateral deviation or dislocation of the jaw or use of tricks to suppress these movements. There was associated Lichen Sclerosus et Atrophicus (LSA) with segmental morphea (involving left side of the face and neck, back of trunk, and left upper and lower limb) in 1 patient (case 1; Fig. 1A) and localized scleroderma of the face in 2 patients (cases 2 and 5). Associated muscle hypertrophy (masseter) was observed in 3 cases (cases 4, 5, and 7), and FHA was observed in other cases (cases 1–3 and 6; see Fig. 1B–G).
Figure 1.
(A) Case 1: examination showing presence of indurated, hyperpigmented plaques with overlying epidermal atrophy with paucity of skin appendages distributed in a segmental pattern on face and neck (left side) suggestive of LSA and segmental morphea. (B) Case 2, with left facial hemi atrophy. (C) Case 3, with left facial hemi atrophy. (D) Case 4, with right masseter hypertrophy. (E) Case 5, with localized scleroderma and masseter hypertrophy. (F) Case 6, with right facial hemi atrophy. (G) Case 7, with right masseter hypertrophy.
There was no sensory deficit or any other movement disorder in these patients. Routine hematological and biochemical tests were normal in all patients, and rheumatoid factor, antinucleotide antibodies, p‐ANCA and c‐ANCA, and antibodies to double‐stranded DNA were found to be negative. Noncontrast CT was done to exclude intracranial pathology in all patients.
Blink reflex was normal in all patients, and surface electromyography showed spontaneous irregular bursts of high‐frequency motor unit potentials (Supporting Information Fig. S1) arising from involved muscles during spasm and disappearance of discharges at rest, ruling out possible functional etiology. Masseter inhibitory reflex (done in 2 patients: cases 1 and 6) showed loss of inhibition in the form of an absent silent period during spasms.
All 7 patients initially received phenytoin (dose, 250–300 mg/day) without any sustainable effect. However, both pain and spasms showed excellent response to local onabotulinumtoxin‐A injection in all patients. Details of BTX therapy in these patients are given in Table 2. All patients reported at least 70% to 80% improvement of pain and spasms (global subjective assessment) at last follow up. There was no reduction in size of hypertrophic muscles in cases 4, 5, and 7. None of the patients developed side effects to BTX injection.
Table 2.
Details of onabotulinum toxin type A (BTX) treatment given to 7 cases of HMS
| Case No. | Muscle Injected | Duration of BTX Treatment (Months) | Duration of BTX Effect After Each Injection (Months) | Mean Latency to Benefit (Days) | Mean Dose of BTX (IU) | Total No. of BTX Injection | Whether Beneficial effect on Pain and Spasm Remaining at Last Follow‐up |
|---|---|---|---|---|---|---|---|
| 1 | Mm and Tm | 36 | 3 to 4 | 5 to 7 | 30 Ms 15 Tm |
11 | Yes |
| 2 | Mm and Tm | 18 | 4 to 6 | 7 to 10 | 20 Ms 20 Tm |
3 | Yes |
| 3 | Mm | 12 | 3 to 4 | 5 to 7 | 20 Ms | 3 | Yes |
| 4 | Mm and Tm | 40 | 4 to 5 | 5 to 7 | 40 Ms 20 Tm |
9 | Yes |
| 5 | Mm | 30 | 3 to 4 | 5 to 7 | 30 Ms | 8 | Yes |
| 6 | Mm and Tm | 30 | 3 to 4 | 5 to 7 | 30 Ms 20 Tm |
8 | Yes |
| 7 | Mm | 28 | 3 to 4 | 5 to 7 | 30 Ms | 7 | Yes |
IU, international unit; Ms, masseter; Tm, temporalis.
Discussion
HMS is a rare movement disorder affecting muscles of mastication, and, to our knowledge, only 55 cases have been reported in literature between 1980 and 2017 (Supporting Information Table S1). A review of these cases showed female predominance (69.1%), with a mean age of 40.71 ± 12.37 years (range, 12–63) and an association with FHA (25.45%), scleroderma/morphea (20%), and hypertrophic muscles (29.1%). However, in our cohort with HMS, we noticed a male predominance and a more frequent association of FHA (57.14% each). Scleroderma/morphea and hypertrophic muscles were observed in 42.86% cases each. The association of LSA (proven by skin biopsy) with HMS has not been reported in literature previously.
The mechanism of HMS is still unclear; however, microvascular compression leading to focal demyelination of the motor branch of the trigeminal nerve is the most speculated one.1, 2, 4 Cruccu et al. observed delayed conduction velocity in the motor branch of the trigeminal nerves at the infra temporal fossa, in the confined space between the lateral pterygoid and skull surface.2 This may justify the focal demyelination and FHA observed in a majority of these cases. Because of the anatomical relationships, nerves to the masseter and temporalis masseter are more predisposed to stretching, angulation, compression, and focal demyelination.1, 2 There are only 4 cases of HMS with involvement of the pterygoid muscles reported in literature so far (Supporting Information Table S1).
Vascular compression near the brainstem is also suggested as the possible etiology.2 Sometimes central causes, like pontine nucleus infarction,5 biopercular syndrome,6 cerebello pontine angle hematoma,10 etc., can be found.
In patients with localized scleroderma and FHA, focal demyelination of peripheral branches of the mandibular nerve secondary to compression and stretching attributed to deep tissue changes is the possible mechanism.3, 4 The pathogenesis of FHA associated with HMS is not clear, and some researchers believe that muscle spasms may be prodromic to the development of superficial atrophy.11 The other proposed mechanisms for FHA include trigeminal neurovasculitis secondary to cell‐mediated immunity, central sympathetic dysregulation, endocrine disturbances, or associated autoimmune pathology.12
HMS is observed in association with connective tissue disease in some patients. However, trigeminal neuropathy attributed to connective tissue disease is an unlikely cause, given that electrophysiological studies show demyelination rather than axonal loss. Also, trigeminal neuropathy associated with connective tissue diseases is usually sensory neuropathy.
Electrophysiology studies in HMS are characterized by rapid irregular bursts of motor unit potential correlating with involuntary muscle spasms.1, 2 There is an absent or reduced masseter silent period and an impaired inhibition of masseter reflex, which is probably attributed to ectopic excitation secondary to focal demyelination.1, 2
Treatment available for HMS includes oral drugs, BTX, and surgery. Oral drugs, such as carbamazepine, phenytoin, and clonazepam, may be useful. BTX has become the preferred treatment because of excellent outcomes.1, 2, 3, 4, 5, 6, 8, 9, 10 On reviewing literature, we could find 18 cases of HMS with excellent response to BTX. All our patients reported great improvement in pain and spasm with BTX. The exact role of microvascular decompression (MVD) of the trigeminal nerve root in patients with HMS is unclear. A few of the reported studies showed favorable outcome, but are of small sample size and with limited follow‐up.13, 14
In this article, we want to highlight the rarity of the condition, male preponderance, long course of illness, association with FHA, scleroderma/morphea/LSA, and excellent response to BTX. Distribution of HMS remained the same for many years, during which time frequency and intensity of the spasms continued to increase. Favorable outcome with BTX indicates that surgery may be delayed or avoided in the majority, except the secondary cases.
Author Roles
(1) Research Project: A. Conception, B. Organization, C. Execution; (2) Statistical Analysis: A. Design, B. Execution, C. Review and Critique; (3) Manuscript Preparation: A. Writing of the First Draft, B. Review and Critique.
D.M.R.: 1B, 1C, 3A
V.G.: 1A, 1B, 1C, 3B
G.S.: 1A, 3B
M.B.S.: 1C, 3B
M.R.: 1B, 3B
Disclosures
Ethical Compliance Statement: Authors confirm that they have read the Journal's position on issues involved in ethical publication and affirm that this work is consistent with those guidelines. Institute review board approval was not needed for this study. Authors have taken informed consents from all patients.
Funding Sources and Conflicts of Interest: The authors report no sources of funding and no conflicts of interest.
Financial Disclosures for previous 12 months: The authors declare that there are no disclosures to report.
Supporting information
Figure S1. Case 1: surface EMG of left masseter showing irregular bursts of motor unit potential occurring at random intervals.
Video S1. Case 7 (34/F), showing intermittent painful spam of right masseter precipitated by speaking and touching over the muscle. Patient has right masseter hypertrophy.
Table S1. Hemi masticatory spasm review of literature.
Acknowledgments
We acknowledge our heartfelt gratitude to all patients and staff at electro physiology lab and botulinum toxin injection clinic.
Relevant disclosures and conflicts of interest are listed at the end of this article.
References
- 1. Auger RG, Litchy WJ, Cascino TL, Ahlskog JE. Hemi masticatory spasm: clinical and electro physiologic observations. Neurology 1992;42:2263–2266. [DOI] [PubMed] [Google Scholar]
- 2. Cruccu G, Inghilleri M, Berardelli A, et al. Pathophysiology of hemi masticatory spasm. J Neurol Neurosurg Psychiatry 1994;57:43–50. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3. Kim HJ, Jeon BS, Lee KW. Hemi masticatory spasm associated with localized scleroderma and facial hemi atrophy. Arch Neurol 2000;57:576–580. [DOI] [PubMed] [Google Scholar]
- 4. Ebersbach G, Kabus C, Schelosky L, Terstegge L, Poewe W. Hemi masticatory spasm in hemi facial atrophy: diagnostic and therapeutic aspects in two patients. Mov Disord 1995;10:504–507. [DOI] [PubMed] [Google Scholar]
- 5. Gunduz A, Karaali‐Savrun F, Uluduz D. Hemi masticatory spasm following pontine infarction. Mov Disord 2007;22:1674–1675. [DOI] [PubMed] [Google Scholar]
- 6. Jimenez‐Jimenez FJ, Puertas I, Alonso‐Navarro H. Hemimasticatory spasm secondary to biopercular syndrome. Eur Neurol 2008;59:276–279. [DOI] [PubMed] [Google Scholar]
- 7. Christie C, Rodriguez‐Quiroga SA, Arakaki T, Rey RD, Garretto NS. Hemi masticatory spasm: report of a case and review of the literature. Tremor Other Hyper kinet Mov (N Y) 2014;4:210. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 8. Kim JH, Han SW, Kim YJ, et al. A case of painful hemimasticatory spasm with masseter muscle hypertrophy responsive to botulinum toxin. J Mov Disord 2009;2:95–97. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 9. Esteban A, Traba A, Prieto J, Grandas F. Long term follow up of a hemi masticatory spasm. Acta Neurol Scand 2002;105:67–72. [DOI] [PubMed] [Google Scholar]
- 10. Gopalakrishnan CV, Dhakoji A, Nair S. Hemimasticatory spasm following surgery for vestibular schwannoma. Mov Disord 2011;26:2481–2482. [DOI] [PubMed] [Google Scholar]
- 11. Delaire J, Lumineau JP, Mercier J, Plenier V. [Romberg's syndrome. Progressive facial hemiatrophy]. [Article in French]. Rev Stomatol Chir Maxilofac 1983;84:313–321. [PubMed] [Google Scholar]
- 12. Pensler JM, Murphy GF, Mulliken JB. Clinical and ultrastructural studies of Romberg's hemifacial atrophy. Plast Reconstr Surg 1990;85:669–674. [PubMed] [Google Scholar]
- 13. Wang YN, Dou NN, Zhou QM, et al. Treatment of hemi masticatory spasm with micro vascular decompression. J Craniofac Surg 2013;24:1753–1755. [DOI] [PubMed] [Google Scholar]
- 14. Wu G, Ouyang J, Zhang Z, Liu R. Observation of effects of different surgical treatments on unilateral masticatory muscle spasm. World Neurosurg 2018;110:e560–e566. [DOI] [PubMed] [Google Scholar]
Associated Data
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Supplementary Materials
Figure S1. Case 1: surface EMG of left masseter showing irregular bursts of motor unit potential occurring at random intervals.
Video S1. Case 7 (34/F), showing intermittent painful spam of right masseter precipitated by speaking and touching over the muscle. Patient has right masseter hypertrophy.
Table S1. Hemi masticatory spasm review of literature.