Causes of tinnitus
I met another soldier (a high school friend, SEAL) who experiences tinnitus. The other guys at the table were surprised that he had never mentioned it before…I thought I might post briefly on some basics, just in case you want to send this explanation to your friends/family.
Tinnitus is a perception of feeling an annoying sound in the ears or the head. The term tinnitus is derived from tinnire, a Latin word which means to ring. Typically, a person falsely perceives a sound when there is no actual sound in the external environment i.e. the perception of sound is irrelevant to any external stimuli.
More than 10% of the entire population suffer from tinnitus at a point or another during their lives. On the other hand, approximately 85% of individuals suffering from chronic ear problems complain of tinnitus. The problem can affect children as well as adults; however, the incidence of tinnitus rises with age.
Occasionally, tinnitus is experienced after exposure to a loud noise as a gunshot or amplified sounds as in a music concert. Although this form of tinnitus is somehow annoying, it usually lasts only for a few hours.
What are the causes of tinnitus?
It is worth emphasizing that tinnitus is a mere symptom not a clinical disorder; hence, searching for an underlying cause is mandatory, especially when it has been present for a long period. This is of pivotal importance because tinnitus is sometimes accompanied by sensorineural hearing loss. Special forms of tinnitus such as fluctuating tinnitus, tinnitus with vertigo, pulsatile tinnitus or unilateral tinnitus must be thoroughly investigated.
Tinnitus is categorized into 2 groups:
- Objective tinnitus: is audible to everyone including the complaining individual.
- Subjective tinnitus: is only audible to the affected individual.
Objective tinnitus is rather uncommon. The sound originates in the ear, head or neck because of a vascular or a muscular cause. Muscular tinnitus associates multiple degenerative disorders of the head and neck such as amyotrophic lateral sclerosis which is a neuromuscular disorder that occasionally affects the muscles of the ear leading to myoclonus or a form of repetitive flutter of the tensor tympani and/or stapedius muscles. This leads to an audible and observable flutter originating from the ear.
Palatal myoclonus is another uncommon cause of muscular induced tinnitus. It is the result of rhythmic discharge originating in the inferior olivary nucleus in patients suffering from brainstem lesions. The disorder is usually secondary to trauma, stroke, multiple sclerosis or encephalitis.
Carotid artery aberrances are relatively common causes of objective tinnitus. Furthermore, senile ectatic changes of the carotid artery can lead to tortousity of the blood routes through the neck and ear yielding turbulent flow that can be auscultated.
The jugular vein and jugular bulb can yield a form of tinnitus that is associated with a venous hum. It is often described as a low pitch sound or vibration rather than a ringing sound.
Clinically speaking, subjective tinnitus is sound perception which is unrelated to auditory stimuli. Subjective tinnitus is the result of the brain’s response to deprivation of sensory input from the auditory effector organs. Therefore, subjective tinnitus can be associated with any form of conductive or sensorineural hearing loss. These include chronic ottitis media, otosclerosis, congenital sensorineural hearing loss…etc.