Tinnitus

Tinnitus (from Latin tinnīre, meaning to ring) is the perception of sound (ringing, buzzing, humming, hissing, or whistling) in the ears or head in the absence of an external acoustic stimulus. Tinnitus is not a disease in itself, but rather a symptom that can accompany a wide range of pathological conditions.

It is an extremely common phenomenon that can be either temporary or permanent. Depending on whether the sound can be heard by someone other than the patient, tinnitus is classified as subjective or objective.

Aetiology and Pathophysiology

Tinnitus arises from different underlying mechanisms, which determine its type.

Main types of tinnitus are:

• Subjective tinnitus:
  • Description: Accounts for the vast of majority (>99%) of cases. The sound is heard only by the patient.
  • Pathophysiology: The leading contemporary theory describes subjective tinnitus as a “phantom sound” phenomenon. Damage to inner ear sensory receptors (hair cells) reduces auditory input to the brain. In response to this “sensory deprivation,” central auditory pathways in the brainstem and auditory cortex become hyperactive and generate spontaneous neural activity, which is perceived as sound.
• Objective tinnitus:
  • Description: Very rare. The sound represents a true physical phenomenon and, in some cases, may also be heard by the doctor during physical examination (e.g., with a stethoscope).
  • Causes: Typically associated with vascular or muscular abnormalities. Pulsatile tinnitus may result from turbulent blood flow in the vessels adjacent to the ear (e.g., arteriovenous malformations, glomus tumor). Clicking sounds may be caused by contractions (myoclonus) of the middle ear muscles.

Conditions associated with subjective tinnitus:

• Sensorineural hearing loss: This is the most common cause. Ringing in the ears accompanies both age-related hearing loss (presbycusis) and acoustic trauma.
• Ménière’s disease.
• Ototoxic medications.
• Vestibular schwannoma (acoustic neuroma).
• External and middle ear disorders (e.g., otosclerosis, cerumen impaction).
• Head and neck trauma.

Clinical significance

Although tinnitus itself is not life-threatening, chronic intrusive noise can significantly impair quality of life, leading to insomnia, anxiety, depression, and impaired concentration.

Diagnosis is aimed at identifying potentially treatable causes and assessing the impact of tinnitus on the patient. The patient work-up should include the following:

• Medical history: Characterization of the noise (pulsatile, constant), whether it is unilateral or bilateral, and the presence of accompanying symptoms (hearing loss, dizziness).
• ENT examination.
• Comprehensive hearing evaluation: Pure-tone threshold audiometry is mandatory for all patients with tinnitus to detect hidden hearing loss.

At present, there is no universal pharmacologic treatment that can completely eliminate subjective tinnitus. The treatment is comprehensive and focuses on reducing symptom perception and discomfort. Key treatment approaches include sound therapy (e.g., use of white noise, hearing aids), cognitive behavioral therapy (changing negative reactions to noise), and Tinnitus Retraining Therapy (TRT).

Differential Diagnosis

The primary goal is to distinguish common subjective tinnitus from the rare but potentially dangerous objective tinnitus. Pulsatile noise synchronized with the heartbeat is a “red flag” that warrants in-depth examination (CT or MR angiography) to rule out vascular pathology. Unilateral tinnitus, especially when accompanied by asymmetric hearing loss, is an absolute indication for brain MRI to rule out vestibular schwannoma. In the absence of these warning signs, diagnostic efforts focus on identifying associated hearing loss and developing an individualized strategy to help the patient adapt to the symptom.