Tinnitus: Causes, Symptoms, and Treatment Options - Otolaryngology

Dr. Ye Dawei reply Otolaryngology

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Subject: Q: Is there a way to treat tinnitus? A: Not necessarily treatable.

● Classification of Tinnitus
The phrases "tinnitus is the gradual onset of deafness" and "if tinnitus persists, it will lead to deafness" highlight the potential severity of tinnitus.
The English term for tinnitus comes from the Latin word meaning "ringing." Scholars commonly classify tinnitus based on its underlying causes as follows:
○ Cochlear Tinnitus
Cochlear tinnitus, as the name suggests, is caused by lesions in the inner ear.
The most notable conditions include Meniere's disease and the increasingly common sudden sensorineural hearing loss.
I have previously discussed this in "A Talk on Dizziness," and I will reiterate it here.
1.
Meniere's Disease
When the general public thinks of dizziness, they often think of "Meniere's," and even general practitioners may diagnose it as such.
However, there are not as many cases of Meniere's disease as one might think; many patients complaining of dizziness are often overdiagnosed by physicians.
If the number of Meniere's cases is disproportionately high among patients in a neurotology clinic, the physician's competency in managing dizziness may be questioned.
In simple terms, if a patient presents with dizziness, tinnitus, and hearing loss, the physician will consider this condition.
The renowned Japanese physician Ichiro Chiba even described it as "7 points disease" due to the following characteristics:
1) Severe dizziness: It feels as if the world is spinning and can last for several hours, with the first episode being the most intense.
2) Spontaneous dizziness: It occurs without any apparent trigger and can strike suddenly.
3) Recurrent dizziness: Patients with Meniere's disease often experience repeated episodes, rarely having just one.
4) Reversible dizziness: There are periods of complete normalcy between episodes, and dizziness does not last for several days.
5) Dizziness accompanied by cochlear nerve symptoms: Patients often experience fluctuating hearing loss during acute episodes, with severe tinnitus and sometimes perceive sounds at different frequencies.
6) Hearing loss typically manifests at low frequencies.
7) There may be a "reverberation phenomenon," where patients complain of discomfort in noisy environments like markets or train stations.
Currently, no laboratory tests can definitively diagnose Meniere's disease, making a detailed medical history and basic physical examination crucial.
Patients often experience unforgettable episodes of vertigo accompanied by tinnitus, a sensation of ear fullness, and hearing loss.
These episodes do not occur daily and last longer than the brief episodes seen in benign paroxysmal positional vertigo, nor do they last as long as vestibular neuritis.
Most patients experience dizziness for about 3 to 4 hours before gradually improving, only to have another episode weeks later.
Many elderly patients report having recurrent dizziness since their youth, with gradually worsening hearing and persistent tinnitus.
This condition typically occurs between the ages of 20 and 40 and has a maternal inheritance pattern.
The cause is believed to be endolymphatic hydrops in the inner ear, leading to a sensation of ear fullness.
Treatment primarily involves medical management, including neurotrophic agents, vasodilators, and mild sedatives.
If episodes occur monthly, treatment should last at least four months; if they occur every two months, treatment should last at least five months, which is the interval between episodes plus three months.
If medication is ineffective or the patient cannot tolerate long-term medication, endolymphatic sac decompression surgery may be considered.
2.
Sudden Sensorineural Hearing Loss
"Sudden" implies that the patient can clearly identify a specific day or even moment when they suddenly lost hearing or experienced significant tinnitus.
This is considered an ENT emergency, and patients are generally advised to seek immediate hospitalization.
Some patients may also experience dizziness and vomiting, necessitating differentiation from Meniere's disease.
Typically, it only causes dizziness once, lasting for a day or several days, after which it does not recur, but hearing loss and tinnitus persist.
In contrast, Meniere's disease involves recurrent dizziness, but hearing often recovers more quickly after episodes.
A small number of acoustic neuroma cases may also present with sudden hearing loss, requiring a CT scan for differential diagnosis.
Commonly accepted causes include inner ear circulatory disturbances, viral infections, and autoimmune diseases.
Treatment has shifted from a "shotgun" approach to targeting the specific underlying cause for each case.
1) Inner ear circulatory disturbance: This occurs due to obstruction or spasm of the blood vessels supplying the inner ear, leading to hypoxia and hearing impairment.
It is more common in patients with systemic vascular diseases such as diabetes, hypertension, or hyperlipidemia.
Treatment primarily involves plasma expanders (e.g., Dextran), a glucose polymer with a molecular weight of 40,000 that reduces blood viscosity and prevents thrombosis.
2) Viral infections: Various viruses can infect the inner ear, such as the rubella virus and cytomegalovirus, which can cause congenital deafness; mumps virus, measles virus, herpes zoster virus, and recently prevalent influenza viruses can lead to acquired deafness.
Treatment typically involves corticosteroids, starting with 60 mg daily for six days, then tapering over a total of two weeks.
3) Autoimmune diseases: Patients often have systemic autoimmune conditions such as lupus or rheumatoid arthritis, frequently presenting with bilateral hearing loss.
Diagnosis involves medical history, physical examination, and electronystagmography (ENG) to differentiate between central and peripheral causes.
Hospitalization for at least one week is generally recommended; if hearing does not improve, the patient is discharged; if there is improvement, they may stay for another week.
During hospitalization, daily hearing assessments and monitoring of eye movement changes are conducted, with follow-up every two weeks after discharge for three months.
Prognostic indicators include: 1) earlier treatment correlates with better outcomes; 2) high-frequency hearing loss is associated with poorer prognosis; 3) patients with dizziness have a worse prognosis, while those with tinnitus still have cochlear nerve function, indicating a better prognosis; 4) older age correlates with worse outcomes.
○ Noise-Induced Tinnitus
Generally, noise-induced tinnitus can be divided into chronic noise exposure and acute trauma-induced tinnitus.
The former results from long-term exposure to noisy environments, while the latter can occur from events such as explosions, gunfire, fireworks, or even popular rock concerts among today's youth.
1.
Chronic Noise-Induced Hearing Loss
Modern industrial society has brought prosperity but also created a noisy environment.
Many workplaces can lead to occupational injuries, such as those in railroads, factories, airports, auto repair shops, DJs, arcade workers, and stockbrokers.
Noise levels below 80 decibels are less likely to cause hearing damage, but exposure to noise exceeding 100 decibels for more than eight hours can lead to temporary threshold shifts.
If one avoids noisy environments promptly, hearing can recover.
However, permanent threshold shifts can occur, resulting in irreversible damage to the outer hair cells in the inner ear, leading to fusion or loss of stereocilia.
Labor safety regulations have established permissible noise exposure limits to protect workers' hearing, which can serve as a reference for daily life and work.
In principle, the maximum allowable industrial noise level is 90 decibels, and exposure should not exceed eight hours per day.
2.
Acute Traumatic Hearing Loss
Acute traumatic hearing loss refers to inner ear damage caused by intense external sound stimuli over a short period.
This is a direct physical injury from mechanical waves.
Young people often frequent rock concerts, karaoke, and pubs, experiencing tinnitus, hearing loss, and ear fullness the next day, which can be termed "disco deafness," "karaoke deafness," or "iPod deafness." Following the presidential election, several patients presented with ear fullness, ear pain, and tinnitus after exposure to loudspeakers at campaign headquarters, which could be termed "election deafness." Additionally, the high-pressure shockwaves from events like the Wall Street explosion typically last more than 1.5 milliseconds, while gunfire shockwaves last less than 1.5 milliseconds.
Unlike irreversible hearing loss from long-term noise exposure, these acute incidents can be effectively treated with medication, and prompt treatment is strongly recommended to restore hearing.
However, exposure to noise levels exceeding 130 decibels for extended periods (such as continuous firecrackers at weddings or funerals) can lead to decreased auditory tolerance, similar to the irreversible damage caused by chronic noise exposure.
○ Metabolic Tinnitus
The most common cause of metabolic tinnitus among the population is hyperlipidemia.
Due to the economic prosperity of modern society, there is a widespread phenomenon of nutritional excess, leading to a significant increase in hyperlipidemia cases.
In neurotology clinics, up to 10% of patients may have this condition.
These patients often complain of persistent "dizziness, brain fog, and tinnitus," expressing a general sense of discomfort.
The mechanisms leading to tinnitus include: 1) The blood vessels in the inner ear are very delicate and lack collateral circulation, making it easy for lipids to deposit in the cochlea.
2) Increased blood viscosity can lead to poor circulation and embolism in the inner ear.
Patients with hyperlipidemia seen in internal medicine often have other conditions such as hypertension, diabetes, atherosclerosis, or heart disease, requiring several months of medication before improvement is observed.
In contrast, patients with hyperlipidemia seen in neurotology often present with tinnitus and dizziness as their initial symptoms, without accompanying systemic diseases, and typically feel significantly better after just one week of medication.
Among all symptoms, dizziness responds best to treatment, followed by tinnitus, while hearing loss shows no improvement.
If patients normalize their lipid levels and stop medication without dietary control, recurrence is common; however, once they resume medication, they quickly feel relief.
Blood tests can show lipid levels returning to normal, supporting this observation.
○ Vascular Tinnitus
The vertebral arteries supply blood to the brain and inner ear, merging with the basilar artery and branching into the anterior inferior cerebellar artery, posterior inferior cerebellar artery, and superior cerebellar artery.
If the arteries supplying the inner ear become obstructed or spasmodic, it can easily lead to ischemia, causing abnormal discharges in the auditory nerve, clinically presenting as tinnitus.
Patients often experience dizziness, nausea, vomiting, and hearing loss, along with systemic symptoms such as occipital headaches, neck and shoulder pain, and numbness in the limbs.
This condition is more common in older adults, who often have comorbidities such as hypertension, diabetes, heart disease, and hyperlipidemia.
For vascular tinnitus, which arises from poor blood circulation, traditional treatment often involves vasodilators to achieve therapeutic effects.
However, in cases of atherosclerosis leading to vascular narrowing, vasodilators cause systemic dilation and do not selectively expand the inner ear vessels.
It is now widely accepted that improving hemodynamics, increasing the deformability of red blood cells, and reducing blood viscosity are essential for ensuring the inner ear receives adequate oxygen and nutrients.
"Vasoactive agents," which target this concept, can be derived from natural ginkgo biloba or synthesized.
Red blood cells are approximately 7 micrometers in diameter, while the true diameter of capillaries is only 3 to 4 micrometers.
These medications can enhance the deformability of red blood cells, allowing them to pass more easily through narrowed vessels; they can also act on blood vessels to reduce spasms and prevent platelet aggregation, promoting smoother blood flow.
○ Tumor-Related Tinnitus
In otolaryngology, unilateral tinnitus raises suspicion for two types of tumors: nasopharyngeal carcinoma and acoustic neuroma.
I have previously mentioned these conditions in "A Talk on Dizziness," and I will post about them again.
◎ Acoustic Neuroma
Acoustic neuromas arise along the auditory nerve pathway from the inner ear to the brainstem, most commonly at the cerebellopontine angle (CPA).
Initially, patients may experience gradual unilateral hearing loss or tinnitus.
This tumor grows very slowly, so although it may compress the vestibular nerve, central compensation prevents dizziness.
As the tumor enlarges and compresses blood vessels, it can lead to sudden hearing loss or dizziness.
Over time, symptoms can become quite varied.
If an acoustic neuroma is confined to the internal auditory canal and is less than 1 cm, it may be difficult to detect on a CT scan.
Some have attempted lumbar puncture to introduce air into the ventricles, allowing the patient to lie on their side to see if air fills the internal auditory canal; if an acoustic neuroma is present, air will not fill the canal, known as "air CT." However, this method can cause persistent headaches for about a week due to air in the cranial cavity.
With the advent of MRI, even tumors smaller than 1 cm can be easily diagnosed.
If the tumor grows larger and extends toward the cerebellum or brainstem, it can become life-threatening.
Clinically, patients may present with normal hearing but no response on auditory brainstem responses, necessitating consideration of this condition.
● Prevention is Better than Treatment
From the classifications of tinnitus discussed above, we learn that many causes of tinnitus can be prevented.
Patients with Meniere's disease should pay attention to their diet and avoid excessive salt intake.
The increase in cases of sudden sensorineural hearing loss may be related to modern civilization and lifestyle stress.
Occupational noise exposure often cannot be treated, so controlling noise levels in the workplace is crucial.
Early treatment of acute traumatic hearing loss is very effective, and it is essential to avoid potentially harmful environments.
For metabolic tinnitus, in addition to managing underlying medical conditions, appropriate exercise and avoiding fatty foods can help maintain normal cholesterol levels.
● Self-Assessment for Tinnitus
Through some carefully designed questions, we can often identify the potential causes of a patient's tinnitus.
Here are some simple questions:
1.
Is the tinnitus accompanied by dizziness? Does it get louder during dizziness? Tinnitus associated with dizziness suggests the possibility of "cochlear tinnitus." Meniere's disease, sudden sensorineural hearing loss, and anterior inferior cerebellar artery disturbances are often unilateral; vertebrobasilar insufficiency tends to be bilateral.
In Meniere's disease, tinnitus may become louder during dizziness.
2.
Is the work environment noisy? Have you worked in a high-noise environment for an extended period? Have you been exposed to gunfire or fireworks? As mentioned earlier, human tolerance to noise is 90 decibels, and exposure should not exceed eight hours daily.
If tinnitus occurs, it is essential to leave the noisy environment to prevent irreversible damage to the cochlear hair cells.
Standard ear protection only attenuates noise by 30 to 40 decibels and is ineffective against high-decibel noise from sources like airplane engines, trains, or lathes.
3.
Have you had blood tests for cholesterol levels? Do you have anemia, hypertension, thyroid disease, diabetes, or atherosclerosis? Tinnitus caused by systemic vascular diseases is often bilateral, so it is crucial to rule out these conditions in tinnitus patients.
4.
Are you taking any long-term medications? Have you received antibiotic injections? Some medications, such as aspirin, quinine, contraceptives, antihypertensives, and antipsychotics, can sometimes cause bilateral tinnitus, which resolves upon discontinuation.
Older physicians sometimes administered streptomycin or kanamycin, which could also lead to tinnitus over time.
Therefore, if tinnitus occurs after an injection, it is advisable to stop the injection to prevent irreversible damage.
5.
Is the tinnitus high-pitched or low-pitched? Is it unilateral or bilateral? Auditory nerve lesions typically present with high-pitched tinnitus, while Meniere's disease or middle ear disorders often present with low-pitched tinnitus.
Cochlear tinnitus is usually unilateral, while central vascular tinnitus is often bilateral.
6.
Is the tinnitus synchronized with your heartbeat? Tinnitus that coincides with the heartbeat may indicate a vascular malformation or venous anomaly.
If turning the neck toward the affected side alleviates the tinnitus, it may suggest excessive pulsation in the neck vessels.
7.
Is the tinnitus related to breathing? Common respiratory infections or Eustachian tube obstruction from flying can cause tinnitus, while excessive Eustachian tube opening may also lead to tinnitus, often accompanied by a sensation of ear vibration during breathing.
Bending down to tie shoes can temporarily relieve symptoms due to increased blood flow to the brain.
Dr.
Da-Wei Yeh, Head of the ENT Department, Hsinchu Hospital

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Reply Date: 2009/10/22