Pulsatile tinnitus is a specific type of tinnitus and refers to the perception of rhythmic noise, usually in time with the patient's heartbeat, in the absence of an external source, which is most commonly, but not exclusively, due to underlying vascular pathology.
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Clinical presentation
Patients describe a pulsing noise that sounds like rushing, flowing, or humming. Some recognize synchronization with their pulse and an increase in the sensation with physical activity or in a recumbent position 10.
Tinnitus, including pulsatile tinnitus, is subcategorized as subjective or objective 10:
subjective tinnitus: heard only by the patient
objective tinnitus: heard by the clinician on auscultation (neck or mastoid region)
Non-pulsatile tinnitus is almost always subjective, but some cases of pulsatile tinnitus are objective 11.
Additional findings on the clinical history and physical examination can narrow the differential diagnosis 11:
autophony (hearing one's voice loudly in the affected ear) on top of pulsatile tinnitus suggests either patulous Eustachian tube dysfunction or dehiscent semicircular canal syndrome 11
a low-pitched hum on auscultation and suppression of symptoms with manual pressure on the ipsilateral internal jugular vein suggests a venous etiology
obesity and papilledema on fundoscopy raise the suspicion for idiopathic intracranial hypertension
a retrotympanic vascular mass on otoscopy suggests a neoplasm or vascular anomalies protruding into the middle ear cavity
Pathology
Numerous causes of pulsatile tinnitus are recognized 4,7-11:
Vascular
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venous
idiopathic intracranial hypertension (most common in this category) with or without transverse sinus stenosis
transverse sinus stenosis without idiopathic intracranial hypertension
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variant/anomalous vessel within the temporal bone
sigmoid sinus diverticulum or laterally placed sigmoid sinus 2, with or without sigmoid plate dehiscence (most common in this category)
jugular bulb diverticulum or high riding jugular bulb, with or without jugular plate dehiscence
abnormal mastoid emissary veins
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arterial
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arterial stenosis (usually involving internal carotid artery)
atherosclerosis (most common in this category, especially in the elderly)
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variant/anomalous vessel within the temporal bone
aberrant internal carotid artery (most common in this category)
aneurysm of the internal carotid artery, less commonly vertebral or anterior inferior cerebellar artery
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arteriovenous transition
dural arteriovenous fistula (most common in this category), including caroticocavernous fistula
Hypervascular tumors
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paraganglioma (most common in this category)
intralabyrinthine schwannoma (tinnitus is common, only a minority have pulsatile tinnitus) 15
Non-vascular
temporal bone pathology: e.g. superior semicircular canal dehiscence syndrome, otosclerosis, Paget disease 4,12
palatal myoclonus involving the tensor veli palatini, levator veli palatini, salpingopharyngeus, and/or superior pharyngeal constrictor muscles (most common in this category)
middle ear myoclonus involving the stapedius or tensor tympani muscles
Radiographic features
CT, MRI, ultrasound, and digital subtraction angiography (DSA) provide complementary information in the evaluation of pulsatile tinnitus given the diversity of causes. In patients with pulsatile tinnitus without myoclonus or Eustachian tube dysfunction, the American College of Radiology in 2017 rated the following imaging exams as "usually appropriate" 14:
CTA of the head with contrast
CTA of the head and neck with contrast
CT venography of the head with contrast
CT of the temporal bone without contrast
MRI of the head and internal auditory canal without and with contrast
MRA of the head without and with contrast
The following imaging exams were rated as "may be appropriate" 14:
MRI of the head and internal auditory canal without contrast
MRA of the head without contrast
MR venography of the head without and with contrast
MR venography of the head without contrast
arteriography of the cervicocerebral vessels
ultrasound duplex Doppler of the carotid arteries
Given the wide range of entities that may present with pulsatile tinnitus, it is beyond the scope of this article to discuss each in turn. Rather, please refer to the articles for the specific entities above for individual imaging findings.