Differentials
Meniere's disease
SIGNS / SYMPTOMS
Presents with a quadrad of symptoms: tinnitus, episodic vertigo lasting 15 minutes to 24 hours, unilateral aural fullness, and hearing loss.
In most cases only one ear is involved, but the condition is bilateral in 10% to 30% of cases.[40]
INVESTIGATIONS
Clinical diagnosis.
Audiometry usually reveals unilateral sensorineural hearing loss.
Acoustic neuroma (schwannoma)
SIGNS / SYMPTOMS
Benign tumour that commonly arises from the vestibular nerve.
As the tumour grows it compresses the cochlear and vestibular nerves, usually causing unilateral hearing loss, tinnitus, and dizziness. Can also interfere with the trigeminal nerve, causing facial numbness.
If the tumour becomes large, it will eventually compress the fourth ventricle and cause hydrocephalus and life-threatening brainstem compression.
INVESTIGATIONS
MRI is necessary to rule out acoustic neuroma in patients with subjective unilateral tinnitus, asymmetrical audiogram, and normal ear examination.
Glomus tumour
SIGNS / SYMPTOMS
Glomus tympanicum tumours arise from the cochlear promontory and are usually visible otoscopically as a red, pulsatile mass behind an intact tympanic membrane.
Glomus jugulare tumours arise from paraganglia in the adventitia of the jugular bulb. When a glomus jugulare tumour is confined to the jugular fossa, otoscopic examination is normal.
Both types of glomus tumour can cause pulsatile tinnitus in 60% of patients.[7]
INVESTIGATIONS
Small glomus tympanicum tumours are best seen on high-resolution computer tomography (HRCT) scans.
The earliest abnormality detectable on cross-sectional images of a glomus jugulare tumour is erosion of the lateral and anterior walls of the osseous jugular fossa on HRCT scan.
Dehiscent jugular bulb
SIGNS / SYMPTOMS
Most common cause of diagnosable pulsatile tinnitus.[7]
Jugular bulb is the dilation of the upper jugular vein between the sigmoid sinus and the jugular vein at the junction. A high-riding jugular bulb is above the level of the floor of the external auditory canal or tympanic annulus.
A dehiscent high jugular bulb is visible at otoscopy as a smooth, bluish mass.[41]
INVESTIGATIONS
Visible on MR angiography.
Thin-section bone algorithm CT scans demonstrate the anatomy of temporal bone better and help in the diagnosis.[41]
Otosclerosis
SIGNS / SYMPTOMS
The hard, mineralised bones of the inner ear turn into a more vascular and immature bone, resulting in excessive bone growth and fixation of the stapes at the oval window.
Eventually leads to conductive hearing loss.
Approximately 90% of people with otosclerosis are unaware of their hearing loss and do not seek treatment when the loss is mild. Tinnitus is present in 75% of patients with otosclerosis and is characterised by a broad-band hissing sound, humming sound, or discrete tones.
INVESTIGATIONS
Conductive hearing loss on audiometry.
Otitis media
SIGNS / SYMPTOMS
Associated with fever, earache, nausea, vomiting, or tinnitus.
Diagnosed by otoscopy and visualisation of red, bulging tympanic membrane. Decreased movement of tympanic membrane is the main diagnostic factor of otitis media.
INVESTIGATIONS
Clinical diagnosis.
Myoclonus
SIGNS / SYMPTOMS
Tensor and levator veli palatini, salpingopharyngeus, and superior constrictor muscle myoclonus are all causes of objective tinnitus.
Myoclonus of these muscles leads to rhythmic involuntary jerking movements of soft palate and causes tinnitus that has a clicking nature.[7][13]
INVESTIGATIONS
Clinical diagnosis.
Multiple sclerosis
SIGNS / SYMPTOMS
Demyelinating disease of the central nervous system. Tinnitus, with or without hearing loss, has been reported during exacerbation of the disease by a minority of patients.
INVESTIGATIONS
MRI of the brain with gadolinium confirms white matter lesions.
Patulous eustachian tube
SIGNS / SYMPTOMS
Usually occurs after adenoidectomy or weight loss.
Causes clicking sounds with swallowing, aural fullness, autophony.
Head-hanging relieves the symptoms due to dilation of veins.[7]
INVESTIGATIONS
Diagnosed by otomicroscopy that shows movement of tympanic membrane with respiration.
Cerebrovascular disease
SIGNS / SYMPTOMS
Tinnitus occurs if there is turbulence of the blood flow in a narrow or abnormal artery.
Aneurysms, atherosclerosis, and aberrance of the carotid artery can result in pulsatile, objective tinnitus.
Atherosclerosis of the carotid artery can be suspected in patients with risk factors such as hyperlipidaemia, hypertension, diabetes mellitus, and smoking.
Audible carotid bruit on physical examination.
Aberrant carotid artery may be visualised in the mesotympanum as a red or white mass that does not blanch with pneumo-otoscopy.
INVESTIGATIONS
Diagnosed on duplex ultrasonography.
CT scan can also show the aberrant carotid artery.
Arteriovenous malformation (AVM)
SIGNS / SYMPTOMS
Dural AVMs occasionally present with pulsatile tinnitus.
Audible bruits can be heard by auscultation of the retroauricular region.
INVESTIGATIONS
Diagnosed on MRI and MR angiography (MRA).
Carotid angiography should be considered if no disease was found on MRA and clinical suspicion is high.[7]
Dural arteriovenous fistula
Salicylate overdose
SIGNS / SYMPTOMS
Ingestion of about 150 mg/kg of salicylate produces mild toxicity, and >500 mg/kg of this drug is lethal.
Presents with acute onset of tachypnoea, tachycardia, hypotension, seizure, encephalopathy that may progress to coma.
Auditory symptoms of tinnitus and deafness.
Tinnitus occurs when serum salicylate concentration exceeds 30 mg/dL.
INVESTIGATIONS
Elevated serum levels of salicylate.
Benign intracranial hypertension
SIGNS / SYMPTOMS
May present with headaches, visual disturbances, aural fullness, and tinnitus.
Most commonly seen in white women aged between 20 and 50 years with a BMI above the healthy range.[43][44][45][46]
INVESTIGATIONS
Increase in intracranial pressure.
May see papilloedema and increased opening pressure on lumbar punctures.
Persistent stapedial artery
SIGNS / SYMPTOMS
Aberrant artery that arises from the obturator foramen and travels adjacent to the oval window/stapes. May cause conductive hearing loss often mistaken for otosclerosis. Most commonly unilateral pulsatile tinnitus.[6]
INVESTIGATIONS
CT will often show an absent or underdeveloped foramen spinosum and soft tissue mass along the oval window.
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