Jonathan H. Smith, MD,
Jennifer E. Fugate, DO and
Daniel O. Claassen, MD
From the Department of Neurology, Mayo Clinic & Mayo College of Medicine, Rochester, MN.
Address correspondence and reprint requests to Dr. Daniel O. Claassen, Department of Neurology, University of Virginia, PO Box 800394, Charlottesville, VA 22908
An orbital bruit represents increased blood flow through thecollateralarterial system and intracranial arterial supply.In the correctclinical context, the presence of an orbitalbruit should makethe examiner suspect either a severe stenosisor occlusion ofeither the ipsilateral or the contralateralinternal carotidartery (ICA).
Orbital bruits can represent compensated perfusionto the contralateralhemisphere. This occurs as flow velocityincreases through theipsilateral ICA and through the anteriorcommunicating artery.Thus, blood flow moves from the asymptomaticside to the occludedvascular territory.
When listening foran orbital bruit, auscultate by placing thebell of the stethoscopeover the patient’s closed eye.In an effort to eliminatethe noise of rhythmic eyelid flutter,the patient should thenbe instructed to open both eyes andgaze at a point across theroom. If necessary, the eyelid canbe passively shut using thebell of the stethoscope.
Although not featured on many popularstethoscopes, a deep andnarrow bell (i.e., the Ford-Bowlesstethoscope) is ideal forthe purpose of ocular and arterialauscultation.
Orbital bruits are also found in systemic illness (severe anemia,thyrotoxicosis) and vascular anomaly (carotid-cavernous fistula,arterial vascular malformation).
An 83-year-old right-handed man presented with increasing episodesof right limb shaking over a 9-month period. Each episode lastedseveral minutes and was brought on by both exertion and orthostaticintolerance. Medical history was significant for metabolic syndromecomplicated by coronary artery disease and dialysis-dependentend-stage renal disease. One month prior to presentation, theselimb-shaking episodes increased in frequency and were also notedduring dialysis. Over this same time interval, routine bloodpressure assessment revealed a decrease of 10 to 20 mm Hg insystolic pressure.
At presentation, he was diagnosed with probable limb-shakingtransient ischemic attacks. While his neurologic examinationwas essentially unremarkable, cerebrovascular examination identifieda high-pitched systolic left cervical bruit at the level ofthe carotid bifurcation, and a right orbital bruit. MRI didnot demonstrate any acute or chronic infarcts. Carotid ultrasoundrevealed high-grade left internal carotid artery (ICA) stenosis.Cerebral angiogram demonstrated an estimated 95% focal, short-segmentstenosis with calcifications at the left carotid bifurcation(figure, A). Collateralization to the left anterior and middlecerebral arteries was provided by flow through the anteriorcommunicating artery, in addition to collateral flow from theleft external carotid artery (ECA) (figure 1, B and C). Thelatter results were anticipated on the basis of the cerebrovascularexamination.
Figure Cerebral angiogram findings in a patient with an orbital bruit
Left carotid angiogram (A) reveals high grade, short segment carotid stenosis (white arrow) at the bifurcation. Left carotid angiogram (B) demonstrates retrograde flow across the ophthalmic artery (white arrow) to the supraclinoid internal carotid artery from the left external carotid artery (black arrow). Cerebral angiogram performed from the right carotid artery (C) shows collateral filling of the left anterior and middle cerebral arteries (white arrow).
In 1928, Harvey Cushing referred to cephalic auscultation asa "forgotten practice," commenting that it was "the one thingmost likely to be neglected in a routine neurologic examination."1Utilizing the bell of the stethoscope, proper auscultation ofthe skull involves listening to the orbits, frontal region,temporal region (including the mastoid process), and atlanto-occipitalregion. Generally speaking, bruits are a consequence of increasedblood velocity or turbulence, and result from a spectrum ofboth benign and pathologic conditions. As described by C. MillerFisher2 in 1957, the physical finding of an orbital bruit cansometimes provide evidence for the presence of contralateralinternal carotid occlusion or stenosis. In our patient, thepresence of an orbital bruit provided valuable clinical informationregarding collateralization, carotid occlusion, and a robustanterior cerebral circulation.
Collateralization is an important process in stroke physiology,and can influence both ischemic localization and size of infarct.Regarding collateralization and intracerebral blood flow, primarycollateralization results from an acute vascular occlusion,while secondary collateralization develops over longer periodsof time. In primary collateralization, blood flow redistributionoccurs primarily within the circle of Willis. Secondary collateralizationcan occur via both leptomeningeal collaterals and external carotidarterial flow. Compensatory ECA flow occurs in a retrogrademanner via the ophthalmic artery.
Compensatory increased flow through the nonoccluded carotidmay account for the bruit occurring over the eyeball contralateralto the stenosis.3 However, carotid siphon stenosis ipsilateralto the ocular bruit has also been demonstrated to be a verycommon occurrence.4 With this in mind, the finding of a unilateralcarotid bruit or a lateralizing neurologic deficit can furtheraid in the interpretation of an ocular bruit. Importantly, thesignificance of a carotid bruit can be judged by the findingsof increasing focality and duration, along with a higher pitch.
An additional clinical sign of increased ophthalmic arterialflow is the presence of dilated episcleral arteries, which havebeen reported as a manifestation of secondary collateralizationfrom progressive ICA stenosis.5 Palpation of the branches ofthe facial artery can be useful in assessing a hyperdynamicexternal carotid system ipsilateral to a high-grade ICA lesion.6However, common carotid disease will result in decreased pulsationsipsilateral to the lesion. Several branches may be palpated,including the angular arteries on the sides of the nose, andthe superficial temporal arteries, anterior to the tragus. Retrogradeophthalmic artery flow may be inferred by a loss of the supraorbitalpulsation upon compression of the superficial temporal artery,as ophthalmic arterial flow is dependent on ECA flow throughthe superficial temporal artery.7 Retrograde supraorbital arterialflow may also be demonstrated by ultrasound Doppler, which canbe a useful extension of the bedside examination.
In this patient, the presence of orbital bruits informed theexaminer of both vascular disease and compensatory collateralization.The patient’s severe carotid stenosis manifested clinicallyas limb-shaking transient ischemic attacks.8 The history andneurovascular examination guided the diagnostic evaluation stronglyaway from a pursuit of focal motor seizures and toward a vascularetiology.
If multifocal cranial bruits are identified, the examiner shouldconsider additional diagnoses. For instance, hyperdynamic statessuch as thyrotoxicosis and anemia, in addition to structurallesions, such as an arteriovenous fistula or carotid-cavernoussinus fistula, may also be identified by an ocular bruit. Thisagain emphasizes the importance of a thorough history and physicalexamination.
Wadia NH, Monckton G. Intracranial bruits in health and disease. Brain 1957;80:492–509.[Free Full Text]
Fisher CM. Cranial bruit associated with occlusion of the internal carotid artery. Neurology 1957;7:299–306.[Free Full Text]
Lauritzen M, Alving J, Paulson OB. Orbital bruits and retinal artery pressure in internal carotid artery occlusion. Clin Neurol Neurosurg 1981;83:7–10.[Medline]
Hu HH, Liao KK, Wong WJ, et al. Ocular bruits in ischemic cerebrovascular disease. Stroke 1988;19:1229–1233.[Abstract/Free Full Text]
Countee RW, Gnanadev A, Chavis P. Dilated episcleral arteries: a significant physical finding in assessment of patients with cerebrovascular insufficiency. Stroke 1978;9:42–45.[Abstract/Free Full Text]
Fisher CM. Facial pulses in internal carotid artery occlusion. Neurology 1970;20:476–478.[Free Full Text]
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Ali S, Khan MA, Khealani B. Limb-shaking transient ischemic attacks: case report and review of literature. BMC Neurol 2006;6:5.[Medline]
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