Tinnitus may be audible in one ear, both ears or in the head, and some people describe it as emanating from outside the head. Most patients report an increased awareness of tinnitus in quiet surroundings. It consists of an intermittent or continuous rushing, ringing, hissing or buzzing noise and it may be low, medium or high-pitched. The location and severity of tinnitus is not predictive of the distress experienced by the patient. Tinnitus is also commonly associated with hyperacusis, which is characterised by a reduced tolerance to sounds at levels which would not cause discomfort in normal individuals.

Tinnitus is frequently associated with hearing loss (Box 7.1) which may be conductive, sensorineural or mixed, but may also occur in individuals with normal or near-normal hearing. Hearing loss resulting from noise exposure and prebyacusis is frequently associated with tinnitus. Tinnitus may also be a feature of specific diseases such as Menière’s disease. Rarely, unilateral tinnitus may be the only symptom of a vestibular schwannoma.

Medical conditions associated with tinnitus include metal (zinc) or vitamin deficiencies, cardiovascular disorders such as a stroke, metabolic disorders such as diabetes, thyroid disease and hyperlipidaemia, and neurological disorders such as multiple sclerosis, head injuries, whiplash injuries or meningitis.

Tinnitus may also occur as a complication of certain ototoxic drugs such as non-steroidal anti-inflammatories (NSAIDs), salicylates, quinine, aminoglycosides, loop diuretics and antineoplastic drugs such as cisplatin. The ototoxic effects of NSAIDs, salicylates and quinine are dose dependent, occur at high doses and are generally reversible. Although the ototoxic effects of aminoglycosides and chemotherapeutic agents such as cisplatin are dose dependent, they can also be ototoxic at therapeutic levels, and cause permanent cochlear damage.

Other medical causes include autoimmune inner ear disease and neoplastic conditions such as a vestibular schwannoma or a meningioma.

There is a high co-morbidity between clinically significant tinnitus and anxiety and depression. Furthermore, subjects with both tinnitus and depression tend to report more severe tinnitus than those without depression.

If the patient complains of pulsatile tinnitus, the clinician should conduct an extensive search for a skull base tumour or a vascular abnormality. There are numerous vascular causes of pulsatile tinnitus (Box 7.2); the most common being arteriovenous malformations (AVM) and fistulas. Carotid abnormalities such as atherosclerosis and aneurysms can also cause pulsatile tinnitus. Additional causes include an aberrant carotid artery, a high-riding jugular bulb and a glomus tumour. A glomus tumour may present as a red hue behind the tympanic membrane which blanches with positive pressure on carrying out pneumatic otoscopy.