How do you diagnose middle ear myoclonus?

Diagnosing Middle Ear Myoclonus

The diagnosis of middle ear myoclonus is primarily based on history, clinical examination, and long-time-based tympanometry, with special attention to the presence of rhythmic tympanic membrane movements that correspond to the patient's tinnitus. 1

Clinical Presentation

• Patients typically present with rhythmic, clicking or buzzing tinnitus that is often unilateral 2
• The sound characteristics are diverse, including "stepping on snow" sounds, rhythmic drumming, or white noise 3
• Tinnitus may be induced by specific triggers such as external sounds, body position changes, touching the skin around the face and ears, speaking, chewing, or blinking 3
• The tinnitus is often objective (can be heard by the examiner) and corresponds to visible tympanic membrane movements 4

Diagnostic Approach

Physical Examination

• Perform microscopic examination of the ears to detect rapid rhythmic movements of the tympanic membrane that coincide with the patient's tinnitus 4
• Look specifically for tympanic membrane flutter with the same frequency as the reported tinnitus 3
• Pneumatic otoscopy can help assess tympanic membrane mobility, which remains normal in middle ear myoclonus (unlike in otitis media with effusion) 5
• Otomicroscopy provides a magnified binocular view with good depth perception when there is uncertainty about normal structures 5

Audiological Testing

• Long-time-based tympanometry is crucial for diagnosis, showing waveforms with the same frequency as the patient's tinnitus 1, 3
• Even in cases where tympanic membrane activity is not visible by otoscopy, long-time tympanogram examination may still detect waveforms with the same frequency as the tinnitus 3
• Standard audiometric testing typically shows normal hearing in patients with middle ear myoclonus 3

Additional Testing

• Rule out palatal myoclonus, which is the primary differential diagnosis 2
• Consider facial electromyography to evaluate for associated facial nerve involvement 3
• Imaging studies may be performed to rule out other pathologies, but are not specifically diagnostic for middle ear myoclonus 3

Diagnostic Challenges

• Some patients may show no visible tympanic membrane activity on otoscopy despite having middle ear myoclonus, making long-time tympanometry essential 3
• The condition must be differentiated from other causes of objective tinnitus, including vascular abnormalities and palatal myoclonus 6
• When standard diagnostic methods are inconclusive, exploratory tympanotomy may serve as both a diagnostic and therapeutic procedure 4
• In rare cases, a novel diagnostic approach involves trans-canal microscopic middle ear exploration with injection of botulinum toxin into the stapedius and tensor tympani muscles to confirm the diagnosis 7

Diagnostic Algorithm

1. Obtain detailed history of tinnitus characteristics (rhythmic, clicking, buzzing) and potential triggers 3
2. Perform microscopic examination of the tympanic membrane looking for synchronous movements with the tinnitus 4
3. Conduct long-time-based tympanometry to detect waveforms matching the tinnitus frequency 1, 3
4. Rule out other causes of objective tinnitus through appropriate testing 2
5. If diagnosis remains uncertain, consider exploratory tympanotomy or botulinum toxin injection as both diagnostic and therapeutic options 7, 4

Common Pitfalls

• Failing to distinguish middle ear myoclonus from other causes of objective tinnitus such as vascular abnormalities 6
• Relying solely on visible tympanic membrane movements, as some cases may only be detected through long-time tympanometry 3
• Missing associated conditions that may trigger or exacerbate middle ear myoclonus, such as blepharospasm or facial nerve disorders 2
• Overlooking the possibility of bilateral involvement, as approximately 16% of cases may affect both ears 3