Medicine:Middle ear myoclonus

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Short description: Spasms of the middle ear muscles
Middle ear myoclonus
Middle ear structures
SpecialtyOtolaryngology, neurotology
SymptomsObjective tinnitus
TypesStapedial myoclonus, tensor tympani myoclonus
MedicationCarbamazepine, baclofen, clonazepam

Middle ear myoclonus (MEM) is a rare disorder involving involuntary muscle contractions of the middle ear muscles, specifically the tensor tympani and stapedius. The symptoms are characterized by objective tinnitus and a subjective sensation of middle ear muscle contractions. The etiology of MEM is often idiopathic and diagnosis is challenging. Management options can range from conservative pharmacotherapy to surgical intervention.[1]

Signs and symptoms

The most prominent symptom of middle ear myoclonus is objective tinnitus. This tinnitus comes in various forms depending on the involved muscles. Patients typically describe the perceived noises as fluttering, thumping, crackling, clicking, buzzing, or similar sounds. A sensation of muscle contractions may also be present. The myoclonus can be triggered spontaneously or in response to sound stimuli.[1][2][3]

Diagnosis

Diagnosing MEM is challenging and relies heavily on clinical patient history and symptoms. Diagnosis may be supported by observation of to-and-fro eardrum movement during muscle contractions using endoscopic or otoscopic examination.[4] The muscle contractions may also be observed with tympanometry or acoustic reflex decay testing. Hypertrophy of the muscles may be detectable when analyzed with temporal bone CT scans.[1][5]

Differential diagnosis

The differential diagnosis for MEM includes palatal myoclonus, pulsatile tinnitus, and subjective tinnitus. Palatal myoclonus is a condition which includes similar symptoms of objective clicking noises. It involves a different set of muscles within the soft palate. Pulsatile tinnitus produces a rhythmic whooshing or thumping sound that matches the heartbeat. It is typically vascular in nature and unrelated to MEM.[1][4]

Causes

Middle ear myoclonus is a rare disease with unknown etiology. Symptoms originate from involuntary spasms of the tensor tympani and stapedius muscles, causing movement of the ossicles and eardrum.[1]

Management

Medication

Anticonvulsants such as carbamazepine have been reported to reduce or resolve the symptoms of middle ear myoclonus. Other medications tested for treatment are muscle relaxants such as baclofen or benzodiazepines such as clonazepam.[2][6]

Botulinum toxin

Intratympanic botulinum toxin injections into the middle ear cavity have been reported as an effective treatment option for middle ear myoclonus. Approximately 40% of patients have been reported to experience complete resolution and 51% partial resolution, with improvements lasting up to six months. The safety profile of the procedure has not been established.[7]

Injecting botulinum toxin directly into the middle ear muscles is an alternative option for treating MEM. This involves a transcanal surgical approach, which may require general anesthesia. This method is more invasive but allows the toxin to be directly injected into the muscles.[8]

Surgery

In refractory cases of middle ear myoclonus, a surgical tenotomy may be considered. This involves sectioning the tensor tympani and stapedius tendons. The procedure is effective, with approximately 85% of patients experiencing full resolution of symptoms.[6] However, incomplete sectioning or misdiagnosis of the condition can result in failure. There have been reports of the tendons reattaching through scar tissue after the operation, requiring a revision of the procedure.[4] This may be avoided by resecting a portion of the tendons rather than simply sectioning them. Both tendons are often sectioned, as it is difficult to determine the offending muscle. The procedure can be completed using a minimally invasive transcanal approach.[6][9]

Risks of the procedure include those common to middle ear surgery. A unique side effect of the surgery is loudness hyperacusis, which sometimes develops as a result of sectioning the stapedius tendon due to its involvement in the acoustic reflex. This side effect rarely affects quality of life severely, but in cases where it does, the tendons may be artificially reattached with a separate operation.[10]

Epidemiology

The prevalence of middle ear myoclonus is unknown due to its rarity and frequent misdiagnosis. Some clinical research suggests MEM may account for 1.5% of people who experience objective tinnitus. There are no significant differences among men and women in the incidence of MEM. MEM may be most common in individuals aged 20-29.[1]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Grycner, Kamila; Tretiakow, Dmitry; Skorek, Andrzej (2025). "Middle ear myoclonus syndrome – a literature review". Polish Otorhinolaryngology Review 14: 32–36. doi:10.5604/01.3001.0054.9606. PMID 8509697. https://otorhinolaryngologypl.com/article/549606/en. 
  2. ↑ 2.0 2.1 Park, Shi-Nae (2013). "Clinical Characteristics and Therapeutic Response of Objective Tinnitus Due to Middle Ear Myoclonus: A Large Case Series". The Laryngoscope 123 (10): 2516-2520. doi:10.1002/lary.23854. PMID 23918695. https://pubmed.ncbi.nlm.nih.gov/23918695/. 
  3. ↑ Bhimrao, Sanjiv Kumar; Masterson, Liam; Baguley, David (2012). "Systematic Review of Management Strategies for Middle Ear Myoclonus". Otolaryngology–Head and Neck Surgery 146 (5): 698-706. doi:10.1177/0194599811434504. PMID 22261497. https://pubmed.ncbi.nlm.nih.gov/22261497/. 
  4. ↑ 4.0 4.1 4.2 Kim, Dong-Kee; Park, Jung Mee; Han, Jung Ju; Chung, Yun Min; Kim, Jung Min; Park, So Young; Park, Shi Nae (2017). "Long-Term Effects of Middle Ear Tendon Resection on Middle Ear Myoclonic Tinnitus, Hearing, and Hyperacusis". Audiology & Neuro-Otology 22 (6): 343–349. doi:10.1159/000487260. ISSN 1421-9700. PMID 29649793. https://pubmed.ncbi.nlm.nih.gov/29649793. 
  5. ↑ Velasco, Gianfranco; Cho, Hyun Jae; Seo, Young Jun; Lim, Ji Hyung; Han, Jae Sang; Seo, Jae Hyun; Park, Shi Nae (2024). "Computed tomography Scan Size Analysis of stapedius and tensor tympani muscles in middle ear myoclonic tinnitus". Laryngoscope Investigative Otolaryngology 9 (3). doi:10.1002/lio2.1243. ISSN 2378-8038. PMID 38736944. PMC 11081415. https://pmc.ncbi.nlm.nih.gov/articles/PMC11081415/. 
  6. ↑ 6.0 6.1 6.2 Wong, Wai Keat; Lee, Michael Fook-Ho (2022-01-01). "Middle ear myoclonus: Systematic review of results and complications for various treatment approaches". American Journal of Otolaryngology 43 (1). doi:10.1016/j.amjoto.2021.103228. ISSN 0196-0709. https://www.sciencedirect.com/science/article/pii/S019607092100329X. 
  7. ↑ Lim, Ji Hyung; Han, Dowoon; Velasco, Gianfranco C.; Seo, Young Jun; Han, Jae Sang; Park, Jung Mee; Seo, Jae Hyun; Park, So Young et al. (2026). "Efficacy and Safety of Intratympanic Botulinum Toxin Injection on Middle Ear Myoclonic Tinnitus". The Laryngoscope 136 (1): 403–410. doi:10.1002/lary.32447. ISSN 1531-4995. PMID 40709609. PMC 12770869. https://pmc.ncbi.nlm.nih.gov/articles/PMC12770869/. 
  8. ↑ Hutz, Michael J.; Aasen, Margaret H.; Kircher, Matthew (2021). "A Novel Technique for the Diagnosis and Management of Middle Ear Myoclonus". The Laryngoscope 131 (1): E248–E249. doi:10.1002/lary.28579. ISSN 1531-4995. PMID 32057112. https://pubmed.ncbi.nlm.nih.gov/32057112. 
  9. ↑ Moon, Seoungjun; Yeon, Eun-Kyeong; Son, Hyo One; Choi, Jin Woong (2023-06-01). "Transcanal Endoscopic Stapedial and Tensor Tympani Tenotomy for Middle Ear Myoclonus: A Retrospective Case Series of Surgical Outcomes". Otology & Neurotology: Official Publication of the American Otological Society, American Neurotology Society [and] European Academy of Otology and Neurotology 44 (5): 478–482. doi:10.1097/MAO.0000000000003863. ISSN 1537-4505. PMID 37026830. https://pubmed.ncbi.nlm.nih.gov/37026830. 
  10. ↑ Khandalavala, Karl R.; Dornhoffer, James R.; Poling, Gayla L.; Driscoll, Colin L. (2024-06-01). "Tensor Tympani and Stapedial Tendon Reconstruction for Postoperative Hyperacusis after Tendon Lysis for Middle Ear Myoclonus". Otology & Neurotology: Official Publication of the American Otological Society, American Neurotology Society [and] European Academy of Otology and Neurotology 45 (5): 549–551. doi:10.1097/MAO.0000000000004175. ISSN 1537-4505. PMID 38530353. https://pubmed.ncbi.nlm.nih.gov/38530353. 
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