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Aberrant ectatic internal carotid artery in the middle ear.


We report the case of a 34-year-old man with pulsatile tinnitus and a reddish mass in the anteroinferior quadrant of the middle ear. Physical examination and imaging were unable to establish a diagnosis, so an exploratory tympanotomy was performed. Exploration revealed the presence of an ectatic aberrant internal carotid artery in the middle ear. Aberrations of the internal carotid artery in the middle ear are rare. Even so, our case is unusual in that all initial investigations had failed to establish the diagnosis. This case highlights the limitations of modern imaging techniques in certain situations.


The presence of a vascular mass in the middle ear can pose considerable diagnostic problems for the otologist. Most patients so affected present with variable symptoms of pulsatile tinnitus, hearing loss, and aural fullness. Recent advances in medical imaging allow for an accurate diagnosis of most vascular anomalies that affect the temporal bones. However, imaging modalities have their limitations, so a cautious approach is necessary when dealing with a vascular pathology in the middle ear. In this article, we report a case that illustrated some of these limitations.

Case report

A 34-year-old man presented with a history of right-sided pulsatile tinnitus of 4 months' duration. He had no other otologic symptoms. Examination detected a reddish mass in the anteroinferior quadrant of the middle ear that did not appear to be pulsatile. Findings on audiometry and tympanometry were normal.

High-resolution computed tomography (CT) of the temporal bones in both the axial and coronal planes with 2-mm cuts was performed. The scans revealed that the carotid canal on the affected side was slightly smaller than the canal on the opposite side; CT also suggested some dehiscence of the right carotid canal in the anteroinferior quadrant of the middle ear (figure 1). Because the diagnosis was still unclear, magnetic resonance imaging (MRI) was performed, but it showed that the size and position of the carotid vessels on both sides were normal (figure 2). Next, magnetic resonance angiography (MRA) was requested, and it showed that the internal carotid artery (ICA) on the affected side was significantly smaller than the ICA on the left; MRA also revealed that an area of the right ICA had almost no blood flowing through it (figure 3). Also, there did appear to be prominent collateral circulation on the right.

Because we were still unable to find an explanation for the apparent middle ear mass, we performed an exploratory tympanotomy. We located the red tissue mass in the anteroinferior quadrant of the middle ear and found that it was attached to the promontory. The mass was soft and compressible, and there was little pulsation. Gentle dissection around the mass revealed the presence of a defect in the adjacent promontory, which we identified as the carotid canal. Based on these intraoperative findings, we made a diagnosis of an aberrant ectatic ICA. No further intervention was required, and the patient experienced no postoperative sequelae.




Aberrations of the ICA are rare, and only a handful of cases have been reported in the English-language literature. (1) Numerous causes have been proposed to explain the etiology of these aberrations; among them are the absence of a carotid canal (2) and the persistence of embryonic vasculature that may pull the ICA into the tympanic cavity. (3)

A theory proposed by Bold et al seems to be the most consistent with the facts of our case. (4) Bold et al hypothesized that the formation of an aberrant ICA requires (1) a dehiscence of the horizontal intrapetrous portion of the ICA, which is seen in 1% of the population, (5) (2) the absence of the vertical segment of the ICA secondary to regression or a lack of development, and (3) the presence of an alternate vascular route to the horizontal portion of the ICA. The ICA normally develops from the third branchial arch. In the event that the vertical segment of the ICA regresses or does not develop, a communication persists between it and the external carotid artery, which is derived from the second branchial arch. We should note that in our case, the vessel did not appear to be lateral to the vestibular line of Lapayowker, which is a vertical line that extends from the lateral border of the vestibule and defines the presence of an aberrant ICA. (6) We assume that this was why a diagnosis could not be reached prior to the exploratory tympanotomy.


The current gold standard for the assessment of any suspected vascular anomaly of the middle ear is high-resolution contrast-enhanced CT in both the axial and coronal planes. Yet even this may fail to differentiate between a highly vascularized glomus tumor and another vascular anomaly. (7) If such is the case, MRI and MRA are indicated. Conventional angiography is superior to MRA, which is limited by its flow-related characteristics. (8) However, since conventional angiography is an invasive procedure with an inherent risk, it should be performed only when the diagnosis is unclear or if treatment is planned. (9)

The management of an aberrant ICA in the middle ear is not controversial. In fact, in most cases, no treatment is required. (10) This is fortunate because manipulation of an aberrant artery might cause a stroke. (3,11,12) Indications for intervention include intractable symptoms (e.g., troublesome tinnitus) and aneurysmal dilation of the aberrant vessel. Some authors have suggested the use of fascia, bone graft, and Silastic sheeting to separate the aberrant vessel from the middle ear; results have been variable. (13,14) In our patient, exploration was carried out to confirm the diagnosis of an aberrant ICA, and the procedure was abandoned as soon as confirmation was achieved.


(1.) Anand VK, Casano PJ, Flaiz RA. Diagnosis and treatment of the carotid artery in the middle ear. Otolaryngol Head Neck Surg 1991; 105(5):743-7.

(2.) Pirodda A, Sorrenti G, Marliani AF, Cappello I. Arterial anomalies of the middle ear associated with stapes ankylosis. J Laryngol Otol 1994;108(3):237-9.

(3.) Sinnreich AI, Parisier SC, Cohen NL, Berreby M. Arterial malformations of the middle ear. Otolaryngol Head Neck Surg 1984; 92(2):194-206.

(4.) Bold EL, Wanamaker HH, Hughes GB, et at. Magnetic resonance angiography of vascular anomalies of the middle ear. Laryngoscope 1994; 104( 11 Pt 1 ): 1404-11.

(5.) Myerson M, Rubin H, Gilbert J. Anatomic studies of the temporal bone. Arch Otolaryngol 1934;20:195-210.

(6.) Lapayowker MS, Liebman EP, Ronis ML, Safer JN. Presentation of the internal carotid artery as a tumor of the middle ear. Radiology 1971;98(2):293-7.

(7.) Remley KB, Coit WE, Harnsberger HR, et al. Pulsatile tinnitus and the vascular tympanic membrane: CT, MR, and angiographic findings. Radiology 1990;174(2):383-9.

(8.) Makow LS. Magnetic resonance imaging: A brief review of image contrast. Radiol Clin North Am 1989;27(2): 195-218.

(9.) Miller S, Weill A, Maillard JC, et al. Aberrant internal carotid artery presenting in the midline retropharyngeal space: Case report. Can Assoc Radiol J 1997;48(1):33-7.

(10.) McElveen JT Jr., Lo WW, el Gabri TH, Nigri P. Aberrant internal carotid artery: Classic findings on computed tomography. Otolaryngol Head Neck Surg 1986;94(5):616-21.

(11.) Steffen TN. Vascular anomalies of the middle ear. Laryngoscope 1968;78(2):171-97.

(12.) Hunt JT, Andrews TM. Management of aberrant internal carotid artery injuries in children. Am J Otolaryngol 2000;21(1):50-4.

(13.) Ruggles RL, Reed RC. Treatment of aberrant carotid arteries in the middle ear: A report of two cases. Laryngoscope 1972;82(7): 1199-1205.

(14.) Glasscock ME III, Dickins JR, Jackson CG, Wiet RJ. Vascular anomalies of the middle ear. Laryngoscope 1980;90(1):77-88.

Adnan Safdar, FRCS; Joseph P. Hughes, FRCS; Rory McConn Walsh, FRCS

From the Department of Otolaryngology-Head and Neck Surgery, Beaumont Hospital, Dublin, Ireland.

Corresponding author: Adnan Safdar, FRCS, 4 Sir Kenneth Luke Blvd., Mulgrave, VIC 3170, Australia. Phone: 61-4-0783-8033; fax: 61-3-9928-8517; e-mail:
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Article Details
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Author:Safdar, Adnan; Hughes, Joseph P.; Walsh, Rory McConn
Publication:Ear, Nose and Throat Journal
Article Type:Case study
Geographic Code:8AUST
Date:Apr 1, 2008
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