Tinnitus: Causes, Symptoms, Diagnosis and Treatment

Tinnitus is a common yet frequently unsettling experience in which a person hears sounds no one else can perceive. Those affected often report a steady ringing, low buzzing, high-pitched hissing, or even a pulsing whistle that may come from one ear, the other, or both at the same time. Though in many cases it poses no immediate health threat, persistent or intense tinnitus can shape daily life, disturb sleep, and handcuff concentration.

This condition is not a disease in itself but a symptom that may arise from a variety of underlying causes, most of which are associated with the auditory system. In some cases, tinnitus may also be influenced by psychological or systemic factors.

Common Causes of Tinnitus

Tinnitus can result from a wide range of pathological and non-pathological conditions. Some of the more commonly recognized causes include:

1. Acoustic Trauma

Prolonged or sudden exposure to loud sounds, such as gunfire, heavy machinery, or amplified music, can result in acoustic trauma. This condition damages the delicate hair cells within the cochlea, causing inner ear injury that often leads to sensorineural hearing loss and tinnitus. Because these hair cells cannot regenerate once destroyed, the damage is usually permanent.

2. Barotrauma

Barotrauma is a condition in which atmospheric pressure changes suddenly. Individuals may experience this rapid pressure change during air travel or diving which can injure the tympanic membrane (eardrum). In severe cases, this may result in perforation, causing both hearing loss and tinnitus.

3. Obstruction of the External Auditory Canal

Earwax (cerumen), foreign objects, or infections such as otitis externa can cause blockage of the ear canal and may disrupt sound transmission, which can lead to tinnitus. Removal of the obstruction usually alleviates the symptom.

4. Otosclerosis

Otosclerosis is a hereditary disorder in which abnormal growth of bone occurs in the middle ear, particularly around the stapes bone. It causes progressive conductive hearing loss and is frequently associated with tinnitus.

5. Ménière’s Disease

It is a disorder of the inner ear in which episodes of vertigo, fluctuating hearing loss, sensation of fullness in the ear, and tinnitus occurs. The cause is believed to be related to an abnormal volume or composition of endolymphatic fluid.

6. Drug-Induced Ototoxicity

Certain medications are known to be ototoxic, meaning they can harm the auditory nerve or inner ear structures, leading to tinnitus and hearing loss. The mechanisms vary depending on the drug.

1. Gentamicin: It is an aminoglycoside antibiotic commonly used in the form of ear drops to treat ear infections. However, it can accumulate in the inner ear fluids and damage the sensory hair cells of the cochlea and vestibular system. This ototoxic effect (damage to the inner ear) may cause permanent tinnitus and hearing loss due to irreversible hair cell destruction.
2. Salicylates (e.g., aspirin): High doses of salicylates can alter cochlear blood flow and affect the function of outer hair cells. This disruption in auditory processing often results in temporary tinnitus, which typically resolves once the medication is discontinued.
3. Quinine: Quinine was commonly used in the past to treat malaria caused by Plasmodium falciparum, particularly in cases resistant to chloroquine. It is also effective against other Plasmodium species, including P. vivax and P. malariae. However, as a side effect, this drug can interfere with cochlear blood circulation and disrupt hair cell function. This may lead to tinnitus, which is usually reversible after stopping the medication.
4. Alcohol: Excessive or acute alcohol consumption can affect the fluid balance and neurotransmitter activity in the inner ear. These changes may temporarily alter auditory nerve function, causing tinnitus that generally subsides as alcohol levels decrease.

7. Systemic Conditions

There are several systemic medical disorders that can cause tinnitus or worsen tinnitus by affecting the blood flow, nerve function, or metabolic activity within the auditory system. These include:

1. Hypothyroidism: Low thyroid hormone, especially low levels of thyroxine (T4), can slow overall metabolic processes, including those in the auditory pathways. This reduced metabolic activity may impair cochlear function, increasing susceptibility to tinnitus. Proper thyroid hormone replacement therapy often alleviates the symptom.
2. Hypertension: Although uncommon, persistently high blood pressure can increase vascular pressure around the inner ear. This may contribute to pulsatile tinnitus, a type of tinnitus where the perceived sound is rhythmic and often synchronized with the heartbeat. Controlling blood pressure through medication and lifestyle changes can sometimes improve the symptoms.
3. Aneurysms: An aneurysm is an abnormal bulging or ballooning of a blood vessel wall caused by weakness in the vessel structure. Intracranial or extracranial aneurysms, particularly those involving the carotid artery or vertebral circulation, can create turbulent blood flow. This turbulence produces rhythmic “whooshing” sounds characteristic of pulsatile tinnitus. In severe cases, early diagnosis is essential to prevent life-threatening complications.
4. Glomus Jugulare Tumors: These are very rare, highly vascular tumors that arise near the base of the skull and are closely associated with pulsatile tinnitus. The abnormal blood flow within the tumor creates turbulence, producing a distinct rhythmic noise. Surgical removal or radiation therapy is often required to manage both the tumor and its associated tinnitus.

Symptoms of Tinnitus

There are several types of tinnitus and its severity varies significantly among affected individuals. The symptom is generally categorized as:

1. Subjective Tinnitus

This is the most common type of tinnitus, in which only the affected person can hear the perceived sound. It may present as ringing, buzzing, hissing, or roaring and is typically related to auditory system disorders.

2. Objective Tinnitus

This is a very rare type of tinnitus and sometimes be heard by an examiner using a stethoscope placed near the ear. It is usually caused by vascular or muscular abnormalities in and around the ear.

3. Pulsatile Tinnitus

This type is characterized by rhythmic “whooshing” or pulsating sounds that are often synchronized with the heartbeat. It is commonly associated with vascular disorders such as hypertension, aneurysms, or glomus jugulare tumors.

Diagnosis

A thorough clinical assessment is essential to determine the underlying cause of tinnitus and to guide proper treatment. This includes:

1. Laboratory Investigations

1. Complete Blood Count (CBC): A CBC test can be useful in identifying systemic conditions that may contribute to tinnitus. An increased white blood cell count may indicate infection or inflammation, while low hemoglobin levels may suggest anemia, which can reduce oxygen delivery to the auditory system and exacerbate tinnitus.
2. Serum Drug Levels: Monitoring the serum concentrations of known ototoxic medications, such as gentamicin and salicylates, is essential during systemic therapy. Elevated levels increase the risk of cochlear or vestibular toxicity, which may lead to tinnitus or hearing loss. Dose adjustment or discontinuation may be required if toxicity is suspected.
3. Thyroid Function Tests (TFTs): A thyroid profile or thyroid function test is useful for evaluating hypothyroidism. If the level of thyroxine (T4) is low and TSH (Thyroid Stimulating Hormone) is high, it indicates primary hypothyroidism, as the pituitary gland increases TSH production to stimulate the underactive thyroid. In secondary hypothyroidism, T4 levels are low and TSH levels are normal or low because the pituitary does not produce enough TSH despite low T4. Both primary and secondary types of hypothyroidism can slow auditory pathway function and increase susceptibility to tinnitus. Proper treatment of hypothyroidism can improve symptoms in affected patients.

2. Audiological and Specialist Assessments

When a routine exam shows unusual results or a patient has red-flag symptoms, they should be referred to an audiologist or otolaryngologist for more detailed testing. Standard tests performed at this stage include:

1. Pure Tone Audiometry

Pure tone audiometry is a standard diagnostic procedure used to determine hearing thresholds for both air conduction (via headphones) and bone conduction (via a bone vibrator). It helps the doctor characterize not only the degree of hearing loss (mild, moderate, severe, or profound) but also its type, which may be conductive, sensorineural, or mixed. The test is essential for tinnitus assessment because sensorineural hearing loss, often caused by cochlear hair cell damage, is one of the most common underlying factors in tinnitus.

2. Tympanometry

Tympanometry evaluates the mechanical function of the middle ear by applying varying air pressures in the ear canal while measuring eardrum mobility. This provides an objective assessment of middle ear status. The test can detect middle ear effusion, eardrum perforations, or ossicular chain abnormalities, which may contribute to conductive hearing loss and tinnitus. Tympanometric findings are usually represented graphically (tympanograms), allowing clinicians to quickly identify abnormal middle ear pressure or stiffness.

3. Acoustic Reflex Testing

Acoustic reflex testing measures the involuntary contraction of the stapedius and tensor tympani muscles in response to loud sounds. The presence, absence, or abnormal pattern of this reflex provides valuable information about the integrity of the auditory pathway, including the cochlea, auditory nerve, and brainstem connections. Absent or elevated acoustic reflex thresholds can indicate cochlear lesions, retrocochlear pathology (e.g., vestibular schwannoma), or middle ear dysfunction, which are sometimes associated with tinnitus.

4. Speech Perception Thresholds

This test assesses the lowest intensity level at which a patient can correctly recognize and repeat familiar speech material, typically measured in decibels (dB). It provides a functional measure of hearing ability, translating pure-tone audiometric results into real-world communication performance. Difficulty in understanding soft or conversational speech often correlates with tinnitus severity, as patients with hearing loss may experience increased auditory strain and stronger perception of tinnitus.

3. Imaging and Advanced Diagnostics

CT scans and MRI play an important role in identifying structural or retrocochlear causes of tinnitus, but their use should be judicious and guided by clinical findings. While these imaging modalities are invaluable for detecting serious conditions such as vestibular schwannomas, vascular malformations, or cochlear anomalies, routine imaging for all tinnitus patients is not recommended.

Because CT scans and MRI are expensive, time-consuming, and may expose patients to unnecessary risks. These risks include radiation exposure from CT scans and incidental findings on MRI that can lead to anxiety and further unnecessary testing. Therefore, imaging should be reserved for cases with red-flag symptoms only.

When clinical suspicion points to a structural lesion, such as an acoustic neuroma, vascular malformation, or cochlear anomaly, appropriate imaging studies are essential to confirm the diagnosis and guide treatment planning.

1. CT Scan of the Temporal Bone

CT scan of the temporal bone is useful for evaluating bony structures of the ear. It provides detailed visualization of the petrous ridge, middle ear cavity, and cochlea. This imaging modality is highly effective in detecting otosclerosis, ossicular chain abnormalities, superior semicircular canal dehiscence, or other bony irregularities. Additionally, it may incidentally reveal space-occupying lesions or congenital malformations that could contribute to tinnitus or hearing loss.

2. Cranial MRI

A contrast-enhanced MRI (using agents such as gadobutrol) remains the gold standard for assessing soft tissue structures. It is valuable for detecting vestibular schwannomas (acoustic neuromas), meningiomas, or other retrocochlear pathologies that may present with tinnitus and asymmetric hearing loss. MRI can also evaluate vascular malformations, inflammatory changes, or cochlear nerve anomalies that might not be visible on CT scan. Whenever possible, timely referral for MRI should be considered when red-flag symptoms are present, such as unilateral tinnitus, progressive asymmetric hearing loss, or neurological deficits.

Treatment and Management of Tinnitus

There is no universal cure for tinnitus; however, several management strategies can help reduce its intensity and improve the patient’s quality of life.

1. Sound Therapy

1. White Noise Generators: These are devices that produce a constant, neutral sound (similar to static from a radio or the hum of a fan). The steady background noise helps to blend with or cover the ringing, buzzing, or hissing of tinnitus, making it less noticeable.
2. Hearing Aids with Masking Features: For people with both tinnitus and hearing loss, modern hearing aids not only amplify external sounds but also have built-in sound generators that play soft masking noises (white noise, ocean waves, or gentle tones) and reduces the brain’s focus on internal tinnitus noises.
3. Environmental Sound Enrichment: This involves using natural or ambient sounds, such as soft music, rainfall, ocean waves, or even a fan running in the background, to create a sound-rich environment. This background sound partially “drowns out” tinnitus and makes it less intrusive, especially in quiet places where tinnitus tends to be more noticeable.

2. Cognitive Behavioral Therapy (CBT)

CBT does not eliminate tinnitus but helps patients cope with its psychological effects, such as anxiety and insomnia, by changing their response to the sound.

3. Tinnitus Retraining Therapy (TRT)

This method combines low-level sound therapy with directive counseling to promote habituation. Over time, the brain learns to classify tinnitus as an unimportant sound, reducing its perceived severity.

4. Medication

There is no specific drug approved for tinnitus. However, in selected cases, medications such as anxiolytics or antidepressants may be prescribed to manage associated anxiety, depression, or sleep disturbances.

5. Lifestyle Modifications

Stress management, regular exercise, and reduction of stimulants such as caffeine, nicotine, and alcohol can help minimize tinnitus perception.

Takeaways

1. Tinnitus is a symptom, not a disease, and may arise from auditory, systemic, or psychological causes.
2. Common causes include acoustic trauma, ear infections, Ménière’s disease, otosclerosis, ototoxic drugs, and systemic conditions such as hypothyroidism and hypertension.
3. Symptoms vary depending on the type of tinnitus.
4. Diagnosis requires a systematic approach, beginning with clinical evaluation, laboratory tests, audiological assessments, and, in selected cases, advanced imaging (CT scan or MRI).
5. Management focuses on symptom relief, as no universal cure exists. Effective approaches include sound therapy, CBT, tinnitus retraining therapy, and lifestyle modifications.
6. Early identification and treatment of underlying causes can prevent progression.
7. Psychological support plays an important role, as stress and anxiety often worsen tinnitus perception.