Introduction:
Myoclonus means a spasmodic jerky contraction of the muscle. Stapedial myoclonus is a condition that occurs in the middle ear. In this condition, there is a continuous or intermittent sound heard in the ear. These sounds can be heard by the outside person who is standing near the ear.
What Is Stapedial Myoclonus?
The ear is made up of the outer, middle, and inner ear. The middle ear transmits sound vibrations to the inner ear from the outer ear. The middle ear consists of three bones- malleus, incus, and stapes. Stapedius and tensor tympani are the two muscles present in the middle ear. These muscles contract to control the vibrations in the ear caused by sounds.
In stapedial myoclonus, continuous or intermittent sounds are heard by an individual as well as by an outside person from the ear. There will not be any movement of the eardrum in the case of the stapedial myoclonus as it is attached to the stapes and not inserted into the eardrum.
The stapedius muscle is very sensitive to sound than the tensor tympani. This muscle has a protective reflex. Its function is to reduce the sound through modulation of the middle ear impedance and prevents background sound. It may contract internal vocalization to reduce self-stimulation. This muscle is supplied by the facial nerve and has a high oxidative capacity.
What Are the Symptoms of Stapedial Myoclonus?
The stapedius muscle, when it gets spasms, creates vibrations and sounds. Symptoms are
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Buzzing, clicking, and crackling sounds are heard in the ear.
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The sounds become loud when outside noise is present and become softer in a quiet environment. These sounds may be described as bubbling, thumping, whooshing, gushing, ticking, throbbing, fluttering, or tapping.
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These sounds are caused due to noise, stress, and facial nerve spasm.
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These sounds are uncontrollable, and they stop for a short burst of time and start again.
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Another person can hear these sounds when that person stands near the ear of an affected person.
What Are the Causes of Stapedial Myoclonus?
Tinnitus means the perception of sound when there is an absence of an external auditory stimulus. Characteristics of tinnitus, like quality, pitch, location, and variability, may tell about the cause of the condition.
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 caused by stapedial myoclonus is rare. In this condition, daily activities like eating, talking, and walking are affected. The definitive cause for stapedial myoclonus is not known. Some of them include loud sounds like firecracker explosions, stress, facial nerve spasm, or palate spasm. Other causes like brain tumors, vascular deformities, trauma, anxiety, demyelinating disease, and viral infection.
How to Diagnose Stapedial Myoclonus?
There is a scarcity of diagnostic methods to diagnose stapedial myoclonus. Hence most of them are treated without any definitive diagnosis.
In this condition, sounds can be heard from outside. The following methods are used.
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Tympanometer: It is an impedance bridge that can document rhythmic changes in the eardrum compliance.
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Otoendoscopy: It offers a large field of vision using direct or lateral vision endoscopes which provide an excellent visualization with a reduced surgical approach.
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Office-based transtympanic endoscopy is done through the perforation made by laser-assisted myringotomy ( LAM).
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Exploratory Tympanostomy: It is a surgical approach to the middle ear and its structure for diagnosis.
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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.
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Electroencephalography (EEG): It is done to know the origin of sounds arising or myoclonus in the brain to rule out other conditions.
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Electromyography (EMG): An instrument records the electrical activity from the muscles involved in the action as well as in rest.
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Magnetic Resonance Imaging (MRI): In this procedure, magnetic fields and radio waves are used to produce detailed images.
What Are the Treatments for Stapedial Myoclonus?
Treatment options for stapedial myoclonus vary from mild to severe. Treatment can be started with noninvasive methods that include counseling, relaxation to relieve stress, hypnosis, and acupuncture.
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Medications: These include anticonvulsants, sedatives, muscle relaxants, and benzodiazepines.
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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.
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Surgery: This involves tympanotomy with tensor tympani or stapedius tenotomy. It is found that releasing muscle attachment helps in reducing or eliminating tinnitus.
A study showed that for three months, the individual should be treated with medical and supportive therapy to relieve the symptoms of tinnitus, and after that decision to be made for sectioning of the muscles-tensor tympany or stapedius muscle.
Transection of the stapedial tendon helps in relieving the symptoms.
What Is the Differential Diagnosis for Stapedial Myoclonus?
Medical history and physical evaluation help in finding the differential diagnosis. Stapedial myoclonus and palatal myoclonus is very high with tensor tympany syndrome, as all three present similarly. Other conditions which present similarly are patulous eustachian tube, arteriovenous fistula or malformations, carotid artery stenosis, and atherosclerotic diseases.
What Is the Prognosis of Stapedial Myoclonus?
Sounds produced in stapedial myoclonus are not harmful but may be life-threatening. Tinnitus may cause stress in the individual. Hence exact cause should be found and treated accordingly.
If an otolaryngologist is not sure of the diagnosis, a neuro otolaryngologist must be consulted.
Conclusion:
Stapedial myoclonus is a condition in which the sounds can be heard from the ear which may be continuous or intermittent. Symptoms may affect the quality of life of an individual. Hence knowing in detail about the condition helps one to take action to resolve the problem. Early diagnosis helps one to achieve an effective treatment. This, in turn, helps in improving the quality of life.
