Tinnitus is defined as a sound perceived more than five minutes at a time in the absence of any external acoustic or electrical stimulus to the ear and not occurring immediately after exposure to loud noise, phantom auditory perception, or head noise.

Types

There are two types of tinnitus:

  • Subjective tinnitus: Here tinnitus audible only to the patient. May be due to sensorineural hearing loss due to any cause.
  • Objective tinnitus: Here tinnitus audible not only to patient, but also to the examiner. It usually caused by arteriovenous malformations, glomus tumors, palatal or tympanic myoclonus.

Pathophysiology of Tinnitus

The auditory system consists of two pathways:

  1. Afferent pathway: This provides input to the proximal structure of auditory system. This is predominantly excitatory.
  2. Efferent pathway: This modulates acoustic information. It is predominantly inhibitory. Any pathological alteration at any one level may have functional consequence at the other levels of the auditory system. 

Tinnitus is the consequence of the aberrant spontaneous neuronal activity within the auditory system. It can be due to lesion or dysfunction at the level of cochlea to the uppermost level of the auditory system. Tinnitus related neuronal activity triggers feedback mechanism in order to balance between excitation and inhibition and preserve the homeostasis.

Tinnitus is characterized by process of habituation, so in most cases the tinnitus gradually attenuates. However, some fail to adopt to habituation leading to persistent tinnitus.

Aetiology

  1. Vascular somatosounds- Vascular lesions, either arterial or venous, can produce turbulent blood flow, leading to pulsatile somatosounds.
  2. Myogenic somatosounds: The most common forms are palatal and less common middle ear muscles, tensor tympani and stapedial myoclonus.
  3. Patulous eustachian tube: It leads to to-and-fro movements of the tympanic membrane, synchronous with nasal respiration which can be perceived as ‘blowing’ sound or their own voice reverberation.
  4. Temporomandibular joint abnormality- It causes audible vibratory sound arising from jaw clenching.
  5. Spontaneous otoacoustic emissions can be the reason of tinnitus.

Treatment

  1. Treatment of underlying disorders: In the majority of cases of pulsatile tinnitus underlying pathology can be identified thus allowing a direct treatment of the underlying cause.
  2. Surgical treatment of tinnitus: Auditory nerve section, or cochlear destruction, have provided little evidence of effectiveness and may even make tinnitus worse.
  3. Tinnitus retraining therapy: The TRT implements a habituation-based protocol which includes sound therapy and cognitive-behavioral techniques (CBT).
  4. Instrumentations: Hearing aids are the first line in management for patients with tinnitus and hearing loss. Hearing aids may reduce awareness of tinnitus by amplification of external sounds. Cochlear implants in patients with profound hearing loss have been found useful in abolishing/reducing tinnitus in a significant number of cases.
  5. Noise generators: Sound therapy is currently an essential part of treatment of tinnitus. Tinnitus maskers are wearable behind-the ear or in the-ear devices, used for presentation of sounds in a controlled manner in order to reduce or eliminate the perception of tinnitus.
  6. Pharmacological treatments: pharmacological treatment has a limited contribution to the treatment of tinnitus.
  7. Supplementary treatments include electrical or magnetic stimulation, Ginkgo biloba, Vitamin B12, acupuncture or zinc.