Tinnitus

Tinnitus is the perception of sound without an external source. Most tinnitus is subjective, heard only by the patient, and follows altered activity in the auditory system. Objective tinnitus can be heard by the examiner and has a vascular, muscular or eustachian tube source.

Epidemiology. Roughly one in ten adults has chronic tinnitus. A small minority is severely disabled by it. Most patients with chronic tinnitus have some hearing loss, sometimes hidden on routine audiometry.

Classification.

• Subjective versus objective.
• Pulsatile (synchronous with the pulse) versus nonpulsatile.
• Unilateral versus bilateral.
• With or without hearing loss.
• Duration: acute within 3 months, chronic when it persists beyond 3 to 6 months.

Mechanisms.

• Loss of cochlear input raises central gain and causes maladaptive plasticity in the brainstem and auditory cortex.
• Somatosensory input from the jaw and neck can modulate the sound.
• Limbic and attention networks set the level of distress.
• Pulsatile tinnitus arises from turbulent flow, altered pressure transmission or a vascular lesion near the ear.
• Objective clicking arises from muscle spasm, for example palatal or stapedial myoclonus.

History.

• Side, character (hiss, ring, roar, click, thump), continuous or intermittent, synchrony with pulse or breathing.
• Onset: sudden, after noise exposure, head injury or barotrauma, after starting a drug.
• Hearing loss, aural fullness, vertigo (Meniere triad), otalgia, otorrhoea, facial weakness.
• Headache with visual obscurations and obesity (idiopathic intracranial hypertension), neurological symptoms.
• Jaw and neck pain, bruxism.
• Noise exposure (work, firearms, music).
• Ototoxic drugs: aminoglycosides, loop diuretics, cisplatin, salicylates, NSAIDs, quinine and chloroquine, macrolides, vancomycin.
• Anaemia, thyroid disease, hypertension, pregnancy, previous ear disease or surgery.
• Mood, sleep, anxiety, suicidal thoughts, effect on concentration and work.

Examination.

• Otoscopy: wax, perforation, effusion, retrotympanic red mass (glomus tympanicum), cholesteatoma.
• Tuning forks: the Weber test lateralises to the better ear in sensorineural loss.
• Auscultate the neck, periauricular area and orbits for bruits. Check carotid pulses, blood pressure and thyroid.
• Palate movement for myoclonus. Temporomandibular joint, neck trigger points.
• Cranial nerves V, VII and VIII. Fundoscopy for papilloedema. Pallor.

Red flags.

• Unilateral or asymmetric tinnitus, especially with asymmetric hearing loss.
• Sudden hearing loss (within 72 hours).
• Pulsatile tinnitus, particularly unilateral or with papilloedema or a bruit.
• Retrotympanic mass.
• Focal neurological signs, facial weakness, progressive vertigo.
• Head injury. Ototoxic exposure.
• Suicidal thoughts.

Nonpulsatile.

• Cochlear: sensorineural hearing loss (presbycusis, noise induced), Meniere disease, sudden sensorineural hearing loss, ototoxicity, autoimmune inner ear disease, labyrinthitis, perilymph fistula and barotrauma, superior canal dehiscence.
• Retrocochlear: vestibular schwannoma and other cerebellopontine angle tumours (meningioma).
• Middle and outer ear: cerumen impaction, otitis media with effusion, acute and chronic otitis media, otosclerosis, eustachian tube dysfunction, cholesteatoma.
• Infective: syphilis, HIV, mumps, measles, meningitis sequelae.
• Somatosensory: temporomandibular disorders, cervical spine disease, bruxism.
• Neurological: multiple sclerosis, migraine, Chiari malformation, head injury.
• Systemic and drug related: hypertension, diabetes, thyroid disease, vitamin B12 deficiency, renal failure.
• Psychological: anxiety and depression amplify and sustain tinnitus.

Pulsatile.

• Arterial: carotid atherosclerosis or stenosis, carotid dissection, fibromuscular dysplasia, aberrant internal carotid artery, persistent stapedial artery, aneurysm, dural arteriovenous fistula, arteriovenous malformation.
• Venous: idiopathic intracranial hypertension, sigmoid sinus diverticulum or dehiscence, high jugular bulb, venous sinus stenosis.
• Tumour: glomus tympanicum and jugulare paraganglioma, meningioma.
• Hyperdynamic or other: anaemia, thyrotoxicosis, pregnancy, fever, Paget disease, hypertension, aortic valve disease.

Objective nonpulsatile. Palatal myoclonus, stapedius or tensor tympani myoclonus, patulous eustachian tube (breathing synchronous, autophony, eased by lying down), temporomandibular joint clicking.

1. Otoscopy and tuning fork tests for everyone. Check blood pressure.
2. Pure tone audiometry and tympanometry for every patient with persistent tinnitus.
3. MRI of the internal auditory meati and cerebellopontine angle (gadolinium or high resolution T2 sequences) for unilateral or asymmetric tinnitus with asymmetric hearing loss (an interaural difference of 15 dB or more at two or more frequencies), focal neurological signs or sudden unilateral loss.
4. Pulsatile tinnitus: examine and check for papilloedema and bruits first. A retrotympanic mass needs high resolution CT of the temporal bone and MRI or MR angiography. A normal ear needs CT or MR angiography and venography of the head and neck. Catheter angiography is for suspected dural arteriovenous fistula. Lumbar puncture after imaging when idiopathic intracranial hypertension is suspected (opening pressure over 25 cm of cerebrospinal fluid in adults). Carotid duplex ultrasound for suspected carotid disease.
5. Blood tests are not routine for bilateral chronic tinnitus with normal examination. Request full blood count, thyroid function, glucose and lipids when a systemic cause is suspected, and syphilis serology for sudden or fluctuating sensorineural loss.
6. Distress: the Tinnitus Handicap Inventory (0 to 16 slight, 18 to 36 mild, 38 to 56 moderate, 58 to 76 severe, 78 to 100 catastrophic). Screen for depression, anxiety and insomnia.

Limits. Audiometry misses hidden hearing loss. Imaging is of low yield in symmetric bilateral tinnitus. Objective tinnitus needs careful auscultation because investigations can be normal.

Sudden sensorineural hearing loss with tinnitus. Start prednisolone 1 mg/kg orally once daily (maximum 60 mg) for 7 to 14 days as early as possible, ideally within 72 hours, with an urgent audiogram and ENT review. Check glucose; use caution with peptic ulcer or psychosis. Intratympanic dexamethasone is an alternative or salvage option.

Treat the cause.

• Remove wax by irrigation (not with a perforation) or microsuction. Treat otitis media.
• Stop or substitute ototoxic drugs where possible. Salicylate tinnitus is dose related and reversible.
• Control hypertension, anaemia and thyroid disease.
• Meniere disease: low salt diet and betahistine 16 mg orally three times daily (maximum 48 mg daily; evidence is limited).
• Idiopathic intracranial hypertension: weight loss and acetazolamide 250 mg orally twice daily, titrated as tolerated (usual 500 mg to 1 g twice daily, maximum 4 g daily) with specialist direction; avoid in sulphonamide allergy and in early pregnancy; monitor potassium and bicarbonate.
• Vascular and tumour causes: embolisation, stenting or surgery directed by neurosurgery, vascular surgery and ENT.
• Patulous eustachian tube, myoclonus: specialist options including botulinum toxin.

Chronic tinnitus without a treatable cause.

• Explain the benign course and that habituation is usual.
• Hearing aids when hearing loss is present (best supported intervention).
• Cognitive behavioural therapy (best evidence for reducing distress), sound enrichment, tinnitus retraining counselling, sleep measures.
• Treat comorbid depression, anxiety and insomnia on their own merits.
• No drug has proven benefit for tinnitus itself. Benzodiazepines, antidepressants and anticonvulsants are not advised as tinnitus treatment. Ginkgo, zinc and melatonin are not advised.

Monitoring. Repeat audiometry for stable asymmetric findings, MRI surveillance of small schwannomas at 6 to 12 months, and repeat the Tinnitus Handicap Inventory at 3 months.

Referral and escalation. Urgent ENT or audiology for unilateral, asymmetric, pulsatile or sudden tinnitus. Neurology or neurosurgery for cerebellopontine angle lesions or vascular causes. Same day mental health assessment for suicidal thoughts. Psychology for disabling tinnitus.

Admission. Rarely needed: sudden loss needing monitored care, severe vertigo with vomiting, suicidal risk, acute neurological deficit.

Special groups. Children: always test hearing and ask about congenital cytomegalovirus and ototoxic exposure. Pregnancy: pulsatile tinnitus follows the hyperdynamic circulation and may resolve postpartum; avoid acetazolamide in the first trimester. Older adults: review polypharmacy, fit hearing aids early.