Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved. Natural History and Management of Blunt Traumatic Pseudoaneurysms of the Internal Carotid Artery The Harborview Algorithm Based Off a 10-Year Experience Ryan P. Morton, MD,  Michael R. Levitt, MD,  Samuel Emerson, MD, PhD,  Basavaraj V. Ghodke, MD,  y Danial K. Hallam, MD,  y Laligam N. Sekhar, MD,  Louis J. Kim, MD,  y and Randall M. Chesnut, MD  Objective: To define the natural history of, and treatment strategy for, blunt traumatic internal carotid artery (ICA) pseudoaneurysms. Background: The natural history and management of traumatic ICA pseu- doaneurysms is controversial. Methods: We retrospectively identified all traumatic ICA pseudoaneurysms diagnosed on head/neck computed tomographic angiography at a high- volume trauma center over a 10-year period. Radiographic and clinical data were recorded, and a treatment algorithm was derived. Results: Forty-three pseudoaneurysms were diagnosed in 39 patients. All patients were treated with daily aspirin unless contraindicated, and 82% underwent daily transcranial Doppler ultrasonography with embolic monitor- ing. A rate of 8 or more emboli per hour was predictive of embolic stroke (P ¼ 0.0076). Acute ischemic or embolic stroke was seen in 7 patients (16%) with an overall mortality in this subpopulation of 42% (n ¼ 3). Four patients (9%) underwent acute surgical treatment (parent vessel sacrifice and/or arterial bypass) for ongoing ischemia. Long-term radiographic and clinical follow-up was obtained for 36 surviving patients (mean ¼ 8 months; range: 1 week–5 years), all of whom were maintained on daily aspirin. No delayed ischemic or embolic events were reported. For ICA pseudoaneurysms treated with aspirin and observation alone, 9 (28%) increased in size, 17 (53%) decreased or stabilized, and 6 (19%) resolved. Enlargement of 5 mm or more in maximal diameter underwent delayed endovascular treatment with a 100% obliteration rate and no complications. Conclusions: Traumatic ICA pseudoaneurysms are safely treated with daily aspirin, embolic monitoring, and radiographic surveillance. Acute stroke or hemorrhage, or delayed radiographic progression, are indications for endo- vascular or surgical treatment. Keywords: blunt cerebrovascular injury, carotid cavernous fistula, pseudoaneurysm, stroke, transcranial Doppler ultrasonography (Ann Surg 2016;263:821–826) B lunt traumatic internal carotid artery (ICA) pseudoaneurysms are on the spectrum of blunt cerebrovascular injury (BCVI), classi- fied as Biffl grade III on the most commonly used grading system 1 (Table 1). There is a paucity of literature on the radiographic and clinical natural history of these lesions, with a reported acute stroke rate of 10% to 33% in several small series. 2–4 Although urgent endovascular stenting was initially the favored treatment, 5 that notion has recently been challenged. 2,6 To better characterize these lesions, we report the largest single series of traumatic pseudoaneur- ysms of the ICA and include long-term radiographic and clinical follow-up. We also propose a treatment algorithm based on these outcomes. METHODS This study was approved by the institutional review board. We retrospectively examined all head and neck computed tomographic angiography (CTA) reports from trauma admissions using a keyword computerized search of all reports containing the keywords ‘‘Biffl’’ and/or ‘‘blunt’’ and/or ‘‘traumatic’’ and/or ‘‘pseudoaneurysm’’ between January 2004 and January 2014. These reports were then manually sorted and the imaging reviewed to find all blunt traumatic pseudoaneurysms of the ICA. All diagnoses were performed by board-certified neuroradiologists, and penetrating traumatic injuries were excluded. Radiographic and clinical data were recorded. Clinical outcomes were recorded using the modified Rankin Scale (mRS) (Table 2). Statistical analysis was performed with either the Fisher exact test or the Student t test when appropriate. Our institution’s BCVI screening protocol is adapted from the Denver 1 and Memphis 7 criteria and has been published previously (Table 3). 8 After blunt ICA pseudoaneurysm was diagnosed, all patients underwent serial neurological examination and were treated with daily aspirin (81 mg or 325 mg orally, or 300 mg rectally) initiated within 24 hours of admission unless contraindicated due to intracranial hem- orrhage or severe systemic polytrauma. In patients with such contra- indications, aspirin was started as soon as deemed possible by the neurosurgical and critical care services. Patients in whom stroke was suspected [either from neurological deficit or transcranial Doppler (TCD) results] underwent confirmatory magnetic resonance imaging. In addition, and fairly unique to our institution, any patient with a confirmed BCVI received TCD ultrasonography emboli monitoring of the ipsilateral middle cerebral artery (MCA) within 24hours of admission. A registered vascular technician (RVT) with specialized TCD training places the patient in the supine position with the head slightly elevated and uses a 2 MHz pulsed wave probe on the Philips iu22 ultrasound to identify the ipsilateral MCA. The transducer can then be fixed to the head using a monitoring headband or held manually. The Philips iu22 ultrasound machine has a pre-set high intensity transient signal (HITS) detector, which will automati- cally detect emboli versus artifact. If HITS are to be counted manually, we lower the gain so that the embolic signals can be seen within the spectral display (Fig. 1, arrow). The power level may also be decreased if needed. The time average mean of the maximum spectral outlining envelope should be turned off and the rapid sweep speed should be avoided, as it will compress the waveform. For a From the  Department of Neurosurgery, University of Washington at Harborview Medical Center, Seattle, WA; and yDepartment of Radiology, University of Washington at Harborview Medical Center, Seattle, WA. Disclosures: Dr Sekhar is a stockholder in SpiSurgical and Viket Medical Inc. Dr Kim is a consultant for Aesculap Inc and a stockholder in SpiSurgical. Dr Ghodke is a paid proctor and consultant for ev3/Covidien and a stockholder in Viket medical Inc. However, no financial support was received for this study, and there are no conflicts of interest related to this article. Reprints: Ryan Morton, MD, Department of Neurological Surgery, Box 359766, Harborview Medical Center, 325 9th Ave, Seattle, WA 98104. E-mail: rymorton@uw.edu. Copyright ß 2015 Wolters Kluwer Health, Inc. All rights reserved. ISSN: 0003-4932/14/26105-0821 DOI: 10.1097/SLA.0000000000001158 Annals of Surgery  Volume 263, Number 4, April 2016 www.annalsofsurgery.com | 821 ORIGINAL ARTICLE