Tinnitus.

Tinnitus is the perception of sound without a corresponding external sound source. This condition affects approximately 14% of adults, with approximately 2% experiencing severe symptoms. Underlying mechanisms of tinnitus suggest involvement of both peripheral and central processes, in which cochlear injury and deafferentation may trigger maladaptive plasticity, increased central gain, and thalamocortical dysrhythmia, modulated by limbic and salience networks. Neuroinflammation, somatosensory-auditory coupling and other factors, such as stress, may contribute to chronicity. Clinical expression is heterogeneous. Tinnitus is often comorbid with hearing loss, hyperacusis, migraine, anxiety, depression, mild cognitive impairment, insomnia and temporomandibular disorders, influencing assessment and care. Diagnosis comprises distinguishing objective (including pulsatile) from subjective tinnitus, recognizing red flags (for example, pulse-synchronous tinnitus requiring vascular imaging), quantifying hearing with audiometry and screening for modulating somatic factors. Multimodal management can reduce the effect of tinnitus: tinnitus-focused counselling and cognitive behavioural therapy are first-line treatments, and hearing rehabilitation and targeted treatment of somatosensory contributors are valuable adjuncts. Moreover, emerging neuromodulation, including bimodal stimulation, benefits selected subgroups. New areas of research include biomarkers, deciphering tinnitus genetic architecture, inner ear regeneration, closed-loop neuromodulation and digital therapeutics.