Two categories based on whether observer can hear the tinnitus (objective) or not (subjective).
Objective—much less common than subjective
Vascular—typically corresponds to pulse (aka, pulse synchronous tinnitus); may be venous, arterial, or combination (arteriovenous) source or secondary to high-output cardiac state, tumors, other; (pulse synchronous tinnitus may be subjective also)
Pathogenesis:
– Venous sources
Jugular bulb: high riding and large, turbulent flow, dehiscent jugular plate at level of middle ear
Sigmoid sinus: diverticulum, turbulent flow, dehiscent sigmoid plate
Other venous structures: aberrant condylar vein, superior petrosal sinus, inferior petrosal sinus; aberrant vein contacting labyrinthine structures
– Arterial sources
Carotid artery: cervical carotid dissection, aneurysm, or stenosis; aberrant carotid artery; carotid body tumor; dehiscent carotid plate within the middle ear
Persistent stapedial artery: derived from internal carotid artery, passes through obturator foramen of stapes superstructure
– Arteriovenous (AV) malformations and dural AV fistulas
May be associated with venous drainage leading to enlarged cortical veins (high rate of bleeding)
Often associated with sigmoid/transverse sinus and prior craniotomy
– Tumors
Paraganglioma, middle ear adenoma, choristoma, facial nerve neuroma, hemangioma
Any tumor (or encephalocele) contacting the ossicular chain or TM may lead to pulse synchronous tinnitus (subjective or objective)
– High cardiac output states: anemia, thyrotoxicosis, pregnancy, beriberi, etc.
Diagnosis: Auscultation with stethoscope, Toynbee tube, palpation of peri-auricular tissue
– CT angiography
– Magnetic resonance angiography (MRA)/magnetic resonance venography (MRV)
– Formal cerebral angiography (small risk of stroke)
Treatment: based on etiology and severity of symptoms
– Selective embolization, surgical resection/clipping, and radiosurgery are options for dural AV fistulas and malformations.
– Surgical excision or combination of surgery and radiosurgery may be used for tumors.
– High output states should be medically corrected.
– Anatomic vascular abnormalities may or may not be amenable to intervention.
Nonvascular—typically presents as clicking sensation
Palatal myoclonus—rapid (50-200 beats/min) irregular clicking caused by eustachian tube opening and closing from palatal musculature contraction.
– Symptoms often worse during times of stress
– Diagnosed by prolonged tympanogram showing movement with palatal contraction; may visualize palate with nasopharyngoscope as well; Toynbee tube may be used to auscultate rhythmic sound
– Treated with muscle relaxants or botox in refractory cases
– Often associated with central nervous system disease; MRI of posterior fossa should be performed to assess
Stapedial or tensor tympani muscle spasm
– Can be heard as clicking or crackling noise
– Diagnosis similar to above, but without observed palatal muscle contractions
– Treated with muscle relaxants or sectioning of tendons if refractory
Patulous eustachian tube—symptoms worsen with respiration and are often described as roaring sensation; autophony
– Can be diagnosed by TM movement with respiration, but not always visualized. Prolonged tympanometry may also be helpful
– Placement of head in dependent position for relief of symptoms
May be associated with temporomandibular joint disorders, normal swallowing that leads to TM movement (latter may be heard as single click with Toynbee tube)
Subjective
Incidence: 10% of population
Can arise due to numerous conditions, many of which are poorly understood
Most commonly occurs secondary to hearing loss
Presbycusis, noise-induced hearing loss, acoustic neuroma, and Meniere disease are common associated problems
Most pharmacologic agents that induce tinnitus are reversible
Partial list includes aspirin, aminoglycosides, loop diuretics, caffeine, and alcohol
Characteristics:
Buzzing, clicking, humming, chirping or hissing type sounds are commonly described.
Roaring quality may be associated with Meniere disease.
Pulsatile or pulse-synchronous sounds may be described, despite not being audible to observer.
– Encephalocele against ossicles may cause pulsatile tinnitus
– Idiopathic intracranial hypertension
Common in obese, middle-aged females
Associated visual disturbances and headache
Sounds may be intermittent or continuous
– SBUTT: Sudden, brief, unilateral, tapering tinnitus; common in normal individuals
Pathogenesis
Most likely occurs due to functional abnormalities of the auditory portion of the central nervous system (CNS)
Neural plasticity may cause reorganization in the auditory nuclei in response to a more peripheral event. This may then induce a hyperactive state causing tinnitus. Possible peripheral events include
– Decreased or abnormal peripheral input (hair cell loss, etc.).
– A pathological insult may lead to decreased or abnormal spontaneous time pattern firing of auditory nerve fiber
This may be the cause in cases of nerve compression in acoustic neuromas and vascular loops
Other CNS centers likely play a role in the perception of tinnitus
– Cranial nerve centers (trigeminal) influence the auditory system.
– Amygdala, the limbic system, and other centers dealing with emotion may play a role as well.
– May explain why some individuals with normal audiograms may develop tinnitus.
Diagnosis
Complete history to evaluate for potential sources of trauma, ototoxicity, noise exposure, etc.
Otomicroscopy to evaluate the ear canal, tympanic membrane, and middle ear space
– Debris, wax, hair, foreign body, other materials may cause tinnitus.
Standard audiometric testing should be done to evaluate hearing thresholds and word recognition scores.
Otoacoustic emission testing may be performed to document outer hair cell function.
Tinnitus matching may be performed in contralateral ear to characterize frequency and volume of tinnitus.
– No correlation between tinnitus characteristics and patient aggravation level.
– Approximately 50% of patients studied have tinnitus amplitude of 5 dB.
If vascular etiology is considered, work up as above.
Treatment
Avoidance of noise/medication/other source of potential injury.
Counseling patients plays a major role in tinnitus treatment.
– Patients should be screened for anxiety and depression as these often exacerbate tinnitus symptoms.
– All medications should be reviewed.
– Dietary triggers such as high-salt diet, alcohol intake, and caffeine should be discussed.
Over time, approximately 25% of patients have near symptom resolution, 50% report significant improvement, and 25% remain stable.
Bedside masking (whether actual masking device versus fan or radio between stations) should be used in those bothered by bedtime symptoms.
Hearing aid—first line of treatment in patients with associated hearing loss.
– Return of previously lost sounds may mask tinnitus.
– If tinnitus refractory, can use masking device (or tinnitus instrument) in hearing aids.
Creates sound stimulus in hopes of masking tinnitus
Can also be used independent of hearing aids
– Use of masking device in hearing aid increases likelihood of tinnitus control from 25% to 55%.
Tinnitus retraining therapy—combination of counseling and broadband sound exposure habituate patient to tinnitus.
– Patients are exposed to 16 hours of broad-band noise per day.
– Noise is initially presented low but slowly increased to a level where the tinnitus is just still audible to the patient.
– Ideally over a year a patient will either no longer hear tinnitus or be undisturbed by it.
Biofeedback therapy—requires patient cooperation in undergoing therapy with psychologist
– Uses various triggers such as increased temperature or pulse for patient to recognize increased focus on tinnitus. Using these triggers patients can learn to focus attention away from tinnitus.
– Significant overlap with stress reduction.
Neuromodulators—special auditory devices that deliver a combination of tones, music, and other sounds, based on a patient’s unique tinnitus characteristics, in an effort to effect change in auditory neural pathways
Transcranial magnetic stimulation—repetitive treatments, designed to alter perception of tinnitus; still investigational with little supportive data in terms of efficacy
Cochlear implant placement—unilateral placement is being offered in some centers for disabling tinnitus; in conjunction with single-sided deafness, may represent emerging treatment option; still investigational with limited data
Medication
– Treatment of underlying anxiety and depression can help patients contend with tinnitus
– Various supplements, such as melatonin, lipoflavinoids, niacin, among others, have been suggested for tinnitus treatment
– Psychotropic medications, including low-dose anti-depressants, antianxiety medications, selective serotonin reuptake inhibitors (SSRIs), and benzodiazepines, have also been used for tinnitus treatment
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