Middle Ear Myoclonus: An Overview

Introduction:

Abnormal contractions of the middle ear muscles result in the middle ear myoclonus (MEM). This condition shows tinnitus. Tinnitus appears as a clicking or buzzing sound that can be observed by an outside person as well as the individual himself. MEM is due to the contractions occurring in the tensor tympani and stapedius muscle.

What Is Middle Ear Myoclonus (MEM)?

When muscles get spasm or twitch due to abnormal contractions, especially in the middle ear is known as MEM. This term is used to explain the symptoms of tinnitus. Muscles affected are the tensor tympani and stapedius. These muscles protect from sounds, thereby dampening the sounds which are loud and coming from outside as well as inside of the ear, like own voice, chewing, etc. MEM is also known as MEM tinnitus. This condition can be seen in six out of 10000 people and is very rare.

The tensor tympani muscle is attached to the hammer-like malleus bone. This bone transmits vibrations to the eardrum. When this muscle gets spasms, thumbing or clicking sounds can be heard.

The stapedius muscle gets attached to the stapes bone, and this bone transmits sounds to the cochlea. When this muscle gets spasms, buzzing or crackling sounds may be heard.

What Is the Cause of the Middle Ear Myoclonus?

The definite cause of MEM is not known.

MEM is caused by the following reasons

• Exposure to loud sounds like artillery fire or nearby firecracker explosions.

• Stress has the tendency to increase the discomfort of spasms.

• Spasms of the facial nerve or the palate can also cause MEM.

• Irritability of the trigeminal nerve and facial nerve that control the actions of middle ear muscles may cause MEM.

Other causes for myoclonic movements are segmental myoclonus which is associated with brain stem innervated muscles, brain tumors, vascular deformities, trauma, anxiety, demyelinating disease, and viral infection.

What Are the Signs and Symptoms of the Middle Ear Myoclonus?

Signs and symptoms depend on the muscles of the middle ear affected due to spasms.

Stapedius typically contracts in response to loud sounds, and the tensor tympani's response to loud sounds is unclear.

• Clicking sounds are due to tensor tympani muscle spasms.

• Thumbing sounds are irregular in nature and not in time of heartbeats.

• Crackling sounds are due to spasms of the stapedius muscle.

• Fluttering sounds are generally related to stapedius muscles.

• Itching of the face may be present in some individuals.

• Lack of sleep due to all these sounds.

• Throbbing, tapping, crackling, bubbling, ticking, twitching, and blowing sounds may also be observed.

Repetition, pitch, and intensity of sounds may vary depending on the individual.

Tinnitus may be of two types. They are subjective and objective. Subjective is the one in which sounds are heard by the affected person, and objective is the one which can also be heard by another person as well. Tinnitus means the perception of sound when there is an absence of an external auditory stimulus.

Similar symptoms can be seen among other conditions as well. They are palatal myoclonus, typewriter tinnitus, and eustachian tube disorders. Hence these need to be differentiated during the diagnosis.

What Are the Methods Used to Diagnose the Middle Ear Myoclonus?

MEM is diagnosed mostly by the observation of several sorts of symptoms.

• Medical history is taken.

• A complete clinical examination is done

• Direct visualization of the muscle spasm can be done to arrive at a final diagnosis.

Otoendoscopy: It offers a large field of vision using direct or lateral vision endoscopes which provide an excellent visualization with a reduced surgical approach.

Office-based Transtympanic Endoscopy: It is done through the perforation made by laser-assisted myringotomy (LAM).

Impedance Audiogram: Assessment method for the middle ear. It measures the sum of resistance that a sound wave produces on its way through the middle ear to cochlear receptors.

Acoustic Reflex Decay Test: It is done to diagnose tumor-induced pathologies affecting the auditory nerve.

Objective Tool: Forceful eyelid closure syndrome is associated with a strong movement of the tensor tympani muscle.

Brain MRI: This imaging is used to identify the lesions of the brain.

Tympanometry: It is an impedance bridge that can document rhythmic changes in the eardrum compliance.

Electroencephalography (EEG): It is done to determine the source of noises or myoclonus in the brain in order to rule out other disorders.

Electromyography (EMG): An instrument records the electrical activity from the muscles involved in the action as well as in rest.

Magnetic Resonance Imaging (MRI): In this procedure, magnetic fields and radio waves are used to produce detailed images.

How to Treat Middle Ear Myoclonus?

Treatment of MEM depends on the severity of the condition.

Treatment can be started with noninvasive methods that include counseling, relaxation to relieve stress, hypnosis, and acupuncture.

• Medications: Anticonvulsants, sedatives, muscle relaxants, and benzodiazepines are all helpful.
• Therapies: Botulinum toxin has been used in treating stapedial myoclonus. These are given as injections that block the release of chemical messengers that trigger muscle contractions. Therapy like white band noise masking device was successfully used to treat MEM.
• A noninvasive method called the zygomatic hand pressure technique is used. In this technique, lacing the fingers and applying pressure from the palms on the zygomatic bone is done. A pressure of 2 pounds is applied for 30 seconds or till the clicking sounds stop.
• Surgery: This involves tympanotomy with tensor tympani or stapedius tenotomy. It is found that releasing muscle attachment helps in reducing or eliminating tinnitus. Suctioning of middle ear tendons helped in relieving the symptoms of MEM.

Conclusion:

The ear is an important organ of the body. Slight discomfort in this organ may hamper the quality of an individual. MEM is a serious condition as its signs and symptoms are going affect the quality of life and pose many problems to leading a day-to-day life. Hence it becomes vital to know about the condition, its causes, signs and symptoms, treatment aspects, etc. Knowing about this help in identifying the disease at the earliest. Early diagnosis help in getting effective treatment.