Persistent hypoglossal artery: Diagnostic

Transcription

1 Persistent hypoglossal artery: Diagnostic therapeutic considerations concerning carotid thromboendarterectomy and Gary A. Fantini, MD, Linda M. Reilly, MD, and Ronald J. Stoney, MD, New York, N.Y., and San Francisco, Calif. Fetal anastomotic connections between the developing internal carotid and basilar arterial systems are via the three presegmental arteries: the otic artery, the hypoglossal artery, and the trigeminal artery. After formation of the posterior communicating artery from the caudal branch of the internal carotid artery, the presegmental arteries are generally obliterated. Rarely, however, these primitive carotid-basilar anastomoses will persist into adult life, and may be detected as incidental findings at the time of cerebral angiography during evaluation of the patient with suspected cerebrovascular disease. In addition, persistence of such anastomoses may result in the coexistence of anterior and posterior circulation symptoms, precipitating diagnostic confusion. Two patients with symptoms and persistent hypoglossal artery undergoing carotid thromboendarterectomy are discussed, with emphasis on clinical presentation, diagnostic criteria and intraoperative management. (J VAse StJRa 1994;20:995-9.) Anastomotic connections between the developing internal carotid and basilar arterial systems exist in early fetal life, at a time when embryonic length is 4 to 5 mm) These vessels are named after the cranial nerves with which they course, and include the trigeminal artery, otic artery, and hypoglossal artery. These primitive vessels are present for less than i week; their involution coincides with development of the posterior communicating artery. Rarely, these primitive carotid-basilar anastomoses will persist into adult life and may be detected as incidental findings at the time of cerebral angiography in the evaluation of the patient with suspected cerebrovascular disease. The presence of this vascular anomaly may create diagnostic confusion during evaluation of suspected cerebrovascular symptoms, and specific questions of technique may arise during the performance of carotid thromboendarterectomy. This report de- From the Department of Surgery and Division of Vascular Surgery (Dr. Fantini), The New York Hospital and Cornell University Medical College, New York, and Department of Surgery and Division of Vascular Surgery (Drs. Reilly and Stoney), Moffitt- Long Hospitals, University of California, San Francisco. Supported in part by the Pacific Vascular Research Foundation, San Francisco. Reprint requests: Gary A. Fantini, MD, The New York Hospital- Cornell Medical Center, Suite F-1920, 525 East 68th St., New York, NY 1002I. Copyright I994 by The Society for Vascular Surgery and International Society for Cardiovascular Surgery, North American Chapter /94/$ /4/59573 scribes two patients with symptoms with persistent hypoglossal artery who underwent carotid thromboendarterectomy, with emphasis on clinical presentation, diagnostic criteria, and intraoperative management. CASE REPORTS Case 1. A 67-year-old white man experienced a single episode of dizziness with vertigo, diplopia, and right-sided weakness, which resolved spontaneously over a 2 hour period. His medical history was remarkable for hypercholesterolemia, tobacco use, hypertension, and myocardial infarction. There was no history of stroke. Physical examination revealed normal carotid pulsations, without bruit. There was no neurologic deficit. Noninvasive evaluation by B-mode ultrasonography revealed irregular lesions at the origin of both internal carotid arteries (ICA), producing moderate stenosis. Computed tomography of the head was normal. Cerebral angiography revealed a persistent hypoglossal artery on the left. There was a moderate stenosis of the left ICA approximately 3 cm above the carotid bifurcation and extending to and involving the origin of the hypoglossal artery (Fig. 1). The left vertebral artery was not visualized. The right carotid bifurcation was normal. At operation with the patient under general anesthesia, the stump pressure, measured in the distal common carotid artery after clamping the proximal common carotid and external carotid arteries, was 65 mm Hg. Carotid thromboendarterectomy was performed without a shunt. The plaque involved the ICA at the origin of the hypoglossal artery. Distal endpoints were satisfactory in both of these arteries. The arteriotomy was closed primar- 995

2 996 Fantini, Reilly, and Stoney JOURNALOF VASCULARSURGERY December 1994 Fig. 2. Arch aortogram demonstrates absence of left vertebral artery and hypoplasia of right vertebral artery (case 2). Fig. 1. Selective injection of left common carotid artery reveals persistent hypoglossal artery. There is moderate stenosis of left ICA approximately 3 cm above carotid bifurcation, extending to and involving origin ofhypoglossal artery (case 1). ily. Ischemia time was 30 minutes. The patient awoke from anesthesia without neurologic deficit. The postoperative course was normal from a neurologic standpoint, however, hypertension precipitated a neck hematoma that required evacuation and drainage several hours after operation. The remainder of the postoperative course was uneventful, and the patient was discharged on the fifth postoperative day. He has had no further cerebrovascular symptoms during 61/2years of follow-up. Duplex scanning reveals continuing patency of the ICA, without evidence of recurrent stenosis, although an image of the high origin of the hypoglossal artery has not been obtained. Case 2. A 62-year-old white woman complained of intermittent diplopia of 3 months duration. Nine months before, the patient had a left hemispheric stroke manifested by dysarthria and right arm paresis, which completely resolved. A second left hemispheric stroke occurred 4 months ago, resulting in mild residual right upper extremity paresthesias and lack of fine motor coordination in the hand. The patient's medical history was remarkable for non-insulin-dependent diabetes and tobacco use. Neuroophthalmologic evaluation revealed intermittent diplopia most exaggerated on tight gaze, with right superior quadrantic homonymous visual field defect. Duplex scanning of the carotid arteries revealed an irregular lesion of the left carotid bifurcation, producing a moderate stenosis of the proximal ICA. Computed tomography scanning of the head confirmed the previous left cerebral infarction.

3 Volume 20, Number 6 Fantini, Reilly, and Stoney 997 Fig. 3. Selective injection of left common carotid artery reveals persistent hypoglossal artery and absence of posterior communicating artery. There is high-grade stenosis at origin of left internal carotid artery, with ulceration (case 2). Arch aortography revealed a common origin of the left common carotid artery and the innominate artery. There was moderate stenosis of the proximal left subclavian artery. The left vertebral artery was absent, and the right vertebral artery was hypoplastic (Fig. 2). A persistent left hypoglossal artery arose from the ICA approximately 4 cm above the carotid bifurcation, and the posterior communicating artery was absent (Fig. 3). A high-grade stenosis at the origin of the left ICA had ulceration. No significant stenosis of the right carotid bifurcation was present. At operation with the patient under general anesthesia, the stump pressure, again measured in the distal common carotid artery after clamping the proximal common carotid and external carotid arteries, was 67 mm Hg. Carotid thromboendarterectomy was performed, achieving an excellent feathered endpoint in the ICA approximately 1 cm proximal to the takeoffof the hypoglossal artery. The long arteriotomy was closed primarily. Ischemic time was 51 minutes. Intraoperative duplex scanning revealed a patent reconstruction, including the origin of the hypoglossal artery. The postoperative course was uneventful, and the patient was discharged on the third postoperative day. The patient has remained symptom free for 6 months. The origin of the hypoglossal artery has not been identified during routine postoperative surveillance with the duplex scarlner. DISCUSSION Anterior and posterior circulation symptoms may coexist in the presence of persistent carotid-basilar communication. Therefore, although carofid-basilar anastomoses rarely persist into adulthood, the dual presence of anterior and posterior circulation symptoms should not prevent the clinician from obtaining an arteriogram. Noninvasive evaluation by duplex scanning was unable to detect this anomalous artery in either of the presently reported cases, and identification of a persistent carotid-basilar anastomosis by noninvasive means has not been reported. The persistent hypoglossal artery usually originates from the ICA above the area where images normally are obtained by B-mode ultrasonography. Widmann and Sumpio 2 have recently reported a patient with evidence of severe ICA stenosis by duplex scanning, in whom arteriography revealed a persistent hypoglossal artery without evidence of ICA or hypoglossal artery stenosis. Therefore it appears that a persistent hypoglossal artery may produce increased flow velocities in the ICA, simulating ICA stenosis. The presence of a persistent carotid-basilar communication and the suspicion that a greater than usual proportion of hemispheric perfusion is being supplied by the ipsilateral ICA has led more than one author to recommend the routine use of a temporary indwelling shunt during performance of carotid thromboendarterectomy 2-4 and routine electroencephalographic monitoring. 2 Another author has reported the simultaneous use of two Javid shunts

4 998 Fantini, Reilly, and Stoney December 1994 otic artery/i posterior communicating artery ~ r t e r y hypoglossal arteq pro-atlantal intersegmental artery y anastomosis between vertebral and occipital artery i cervical intersegmental artery Fig. 4. Carotid-basilar and carotid-vertebral anastomoses, which may persist into adult life. (Bard, Inc., Billerica, Mass.) to perfuse both the ICA and the hypoglossal artery, s We have continued to use a temporary indwelling shunt on a selective basis during routine carotid thromboendarterectomy in the absence of a persistent carotid-basilar communication. A shunt is placed if any of the following conditions are present: (1) ICA stump pressure less than 50 mm Hg; (2) contralateral ICA occlusion; (3) ipsilateral stroke within the past 3 months. We applied these same criteria in the management of the presently reported cases involving persistent carotidbasilar communication; therefore the use of a temporary indwelling shunt was deemed unnecessary because collateral flow was adequate. Electroencephalographic monitoring is not routinely used. Because accurate placement of the distal end of the shunt may be difficult because of the takeoff of the hypoglossal artery, its routine use is probably unnecessary and may be ill-advised. In the event that an indwelling shunt is indicated, care must be exercised during placement to avoid trauma to the ICA, while ensuring adequate perfusion of both the ICA and the hypoglossal artery. 6 Early in embryonic development, critical anastomoses between the carotid and basilar circulation are provided by the three presegmental arteries: the otic artery, the hypoglossal artery, and the trigeminal artery. The proatlantal intersegmental artery courses suboccipitally to form an anastomosis between the carotid and vertebral artery and therefore is not considered a true carotid-basilar communication. After formation of the posterior communicating artery from the caudal branch of the ICA, the presegmental arteries are normally obliterated, starting with the otic artery, followed in turn by the hypoglossal and trigeminal arteries. 7 Rarely, these primitive carotid-basilar anastomoses will fail to obliterate and persist into adult life (Fig. 4). The

5 Volume 20, Number 6 Fantini, Reilly, and Stoney 999 trigeminal artery is the most common of these primitive communications to persist into adulthood, with an estimated incidence of 0.1% to 0.2%. 7 The hypoglossal artery is the second most commonly encountered primitive artery to persist, and the otic artery is the least common persistent carotid-basilar anastomosis. Persistence of the proatlantal intersegmental artery is rare, with only several angiographically documented cases reported. 8 Differentiating angiographic features of the proatlantal intersegmental artery have been described by Anderson and Sondheimer 9 and include a suboccipital, horizontal course nearly identical to that of the vertebral artery, except that it does not pass through the foramen transversarium of any vertebral body before entering the skull through the foramen magnum. In contrast, Lie 7 proposed that the following four criteria be fulfilled for diagnosis of primitive hypoglossal artery in 1968: (1) the artery arises in the cervical region at the level of C1 to C3 as a robust branch from the ICA; (2) after a somewhat tortuous course the artery proceeds through the anterior condyloid foramen (the hypoglossal canal) to the posterior fossa; it does not traverse the foramen magnum; (3) the basilar artery is filled only beyond the point of junction with the anastomosis; (4) the posterior communicating arteries are absent (i.e., are not visible on the arteriogram). In addition, Lie 7 noted that the vertebral artery is either aplastic on the ipsilateral side and hypoplastic on the contralateral side, or hypoplastic on both sides. These criteria were subsequently revised by Brismar ~ on the basis of the case report of a persistent hypoglossal artery in which a welldeveloped posterior communicating artery was present, to include only the following two criteria: (1) a persistent primitive hypoglossal artery should leave the ICA as an extracranial branch; (2) it should pass through the anterior condyloid foramen before joining the caudal part of the basilar artery. Finally, it is important to recall that the posterior cerebral artery may arise from the ICA as an anatomic variant, thus the initial presentation of carotid bifurcation atheroma may be symptoms referable to the posterior circulation. ~ REFERENCES 1. Padget DH. The development of the cranial arteries in the human embryo. Contr Embryol Carneg Inst 1948;32: Widmann MD, Sumpio BE. Persistent hypoglossal artery: an anomaly leading to false-positive carotid duplex sonography. Ann Vasc Surg 1992;6: Ouriel K, Green RM, DeWeese JA. Anomalous carotidbasilar anastomoses in cerebrovascular surgery. J VASC SURG 1988;7: McCarmey SF, Ricci MA, Labreque P, Symes ]F. Persistent hypoglossal artery encountered during carotid endarterectomy. Ann Vasc Surg 1989;3: Brown L, Partridge H, Eckstein MR. Bifurcation of the cervical internal carotid artery. Arch Surg 1986;121: Pinkerton JA Jr, Davidson KC, Hibbard BZ. Primitive hypoglossal artery and carotid endarterectomy. Stroke 1980; 11: Lie TA. Persistent carotid-basilar and carotid-vertebral anastomoses. In: Lie TA, ed. Congenital anomalies of the carotid arteries. Amsterdam, The Netherlands: Excerpta Medica Foundation Offices, 1968: Tsukamoto S, Hori Y, Utsumi S, Tanigake T, Horiike N, Otani R. Proatlantal intersegmental artery with absence of bilateral vertebral arteries. I Neurosurg 1981;54: Anderson RA, Sondheimer FK. Rare carotid-vertebral anastomoses with notes on the differentiation between proaflantal and hypoglossal arteries. Neuroradiology 1976; 11: i0. Brismar J. Persistent hypoglossal artery, diagnostic criteria. Acta Radiologica Diagnosis 1976;17: Pessin MS, Kwan ES, Scott RM, Hedges TR III. Occipital infarction with hemianopsia from carotid occlusive disease. Stroke 1989;20: Submitted March 13, 1994; accepted Aug. 1, 1994.