Approach
A complete history and physical exam should be directed at determining the underlying cause of tinnitus.[14] Auscultation of the periauricular area and of the neck should be performed to assess for bruit or venous hum in patients with pulsatile or a humming-like tinnitus. All patients should undergo an audiogram with pure-tone threshold, speech discrimination, and tympanometry.
Prompt audiologic exam is recommended in patients with tinnitus that is unilateral, persistent (≥6 months), or associated with hearing difficulties.[14] Imaging is not recommended in patients with nonpulsatile bilateral tinnitus, symmetric hearing loss, and an otherwise normal history and physical exam.[1][34][35]
History
A history eliciting information about the quality, duration, frequency, and symptoms associated with the tinnitus should be delineated. Associated features such as hearing loss, vertigo, ear infections, trauma, noise exposure, and other antecedent events may provide clues to possible underlying causes.
A history of cerebrovascular accident or transient ischemic attack increases suspicion for carotid disease.
A history of episodic roaring tinnitus, aural fullness, fluctuating low frequency hearing loss, and episodic vertigo is suggestive of Meniere disease.
Pulsatile sounds may be noted in arteriovenous malformation (AVM), severe anemia, thyrotoxicosis, middle ear inflammation, glomus tumor, dehiscence of jugular bulb or carotid artery, benign intracranial hypertension, partial stenosis of a carotid artery, or a persistent stapedial artery.[6]
Clicking sounds may be indicative of repetitive contraction of tensor veli palatini, tensor tympani, and temporomandibular joint syndrome. Palatal myoclonus can be a consideration.[11] Additionally, hairs near the tympanic membrane can create similar sounds.
History of visual changes, especially when these are accompanied by headaches, can lead to a diagnosis of arteriovenous fistula (AVF). Visual changes are present in 25% of patients with AVF.[10]
Progressive hearing loss with tinnitus and advancing age suggests presbycusis.
Noise-induced hearing loss and presbycusis may produce high-pitched tinnitus.[3]
Venous hum, Meniere disease, or cerumen impaction may produce low-pitched tinnitus.
Unilateral tinnitus may be noted with vestibular schwannoma, unilateral cerumen impaction, otitis media, and otitis externa. Unilateral, constant tinnitus may be associated with a cerebellopontine angle tumor or a glomus tumor.
Bilateral tinnitus may be noted in patients with bilateral hearing loss.
Palatal myoclonus is a type of objective tinnitus that occurs with repetitive rapid contraction of soft palate muscles. The patient notices the noise while chewing and swallowing.
History of polyuria/polydipsia demonstrates possible presence of diabetes mellitus as a cause of tinnitus.[10] Diarrhea and palpitations may be present in thyrotoxicosis and occasionally in a secreting glomus tumor.[10]
A detailed medication history should be taken, as many drugs, such as aspirin, aminoglycosides, certain narcotics, furosemide, ethacrynic acid, and cisplatin, are associated with tinnitus.[12]
Physical exam
A complete head and neck exam should be performed, which includes tuning-fork tests and a cranial nerve exam.
Auscultation over the neck, mastoid, and ear canal may reveal a carotid bruit, venous hum, AVMs, and myoclonic clicks.
Cerumen must be removed from the external auditory canal for a thorough exam of the canal and tympanic membrane. Erythema of the canal, an obstructing mass, cholesteatoma, erythema of the tympanic membrane, perforation, or effusion may be seen.
A glomus tumor presents as a red mass behind an intact tympanic membrane that blanches with positive pressure (Brown sign). A red hue that overlies the promontory and does not blanch by pneumotoscopic pressure is characteristic of the active phase of otosclerosis (Schwartze sign).[10]
The Weber and Rinne tuning-fork tests aid in the classification of sensorineural or conductive hearing loss.
A cranial nerve exam (cranial nerve V, VIII, IX, X, or XI) may elicit asymmetries in the presence of vestibular schwannoma.
Investigations
All patients should undergo audiometry with pure-tone threshold, word recognition scores, and tympanometry.
How to perform an examination of the ear.
Pure-tone testing tests the peripheral part of the auditory system. Tinnitus is rarely caused by anything serious, and is commonly associated with a high-tone hearing loss (regardless of its cause). Typically, only basic investigations are required. However, poor performance on word recognition tests may indicate a central nervous system abnormality. Asymmetric sensorineural hearing loss warrants further imaging with magnetic resonance imaging (MRI) to rule out a retrocochlear etiology: namely, vestibular schwannoma. Computed tomography (CT) scan of the temporal bones may be ordered in all patients with conductive hearing loss.[10]
Laboratory evaluation to determine suspected underlying etiologies could be considered. These tests include complete blood count, lipid panel, thyroid tests, glucose, and fluorescent treponemal antibody absorption assay.[10]
Patients should be referred to an otolaryngologist or neurotologist for these investigations if they fall into any of the following groups:
Patients with tinnitus who also have an asymmetric audiogram differing by ≥10 dB across 2 separate frequencies
Patients with tinnitus associated with sudden sensorineural hearing loss or vertigo
Patients with pulsatile tinnitus
Patients with unilateral tinnitus
Patients whose tinnitus does not improve with cessation of medications that may have caused the tinnitus (e.g., aspirin) or with the control of an underlying condition (e.g., hyper- or hypothyroidism).
MR angiography (MRA) and CT angiography (CTA) aid in the diagnosis of vascular abnormalities such as AVMs, aneurysms, and stenotic carotid arteries in patients with pulsatile tinnitus.[35] Carotid angiography may be required if CTA and MRA fail to diagnose a vascular lesion and pathology is highly suspected. Imaging also demonstrates glomus tumors and other middle ear masses.
Auditory brainstem response (ABR) should be considered for patients with asymmetric otologic symptoms (unilateral tinnitus or hearing loss) to rule out a tumor, multiple sclerosis, or other neural causes. Limitations of the ABR include significantly reduced reliability of the test in patients who have >60 dB of hearing loss at 2000 hz. Additionally, there is a 22% false negative rate for vestibular schwannomas that are smaller than 2 cm. Thus the best test to rule out a tumor of the internal auditory canal and cerebellar pontine angle is an MRI with gadolinium.
Further tests to define and monitor tinnitus
Minimal masking level (MML) determines the minimum level of external tone that makes the tinnitus tone inaudible. It should be performed in patients with bothersome tinnitus.[36]
Residual inhibition is done immediately after MML and determines the amount of noise that is able to suppress tinnitus.
Loudness-discomfort-level testing is performed in patients who have reduced loudness tolerance.[36] About 30% to 45% of patients with tinnitus have loudness intolerance.[2] Loudness and pitch-matching is occasionally done to provide reassurance for the patient that the sounds he or she experiences are real.[10]
Some experts recommend additional tests such as otoacoustic emissions, functional MRI, positron emission tomography scan, or magnetoencephalographic studies; while these are interesting from an experimental standpoint they are in their infancy in their ability to target specific therapy.[37] Repetitive transcranial magnetic stimulation and direct electrical stimulation of the brain are being considered and have had varying results.[9][30][38]
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