Neuroradiology

Neuroradiology 17, 227-229 (1979)

© by Springer-Verlag 1979

Ruptured Aneurysm of an Azygos Anterior Cerebral Artery A. Kondo, T. Koyama, J. Ishikawa, K. Iwaki and T. Yamasaki Department of Neurosurgery, Fukui Red Cross Hospital, Fukui, Japan

Summary. A ruptured saccular aneurysm of the azygos pericallosal artery was found and clipped successfully in a woman of 47 years. Aneurysm of an azygos pericallosal artery is extremely rare.

cerebral artery was slightly larger than the left (Figs. 1 and 2). Bilateral proximal anterior cerebral arteries united to form a large single trunk to the

Key words: Saccular aneurysm -- Azygos pericallosal artery

Introduction The anterior cerebral arteries may unite to form a common single trunk which is called the azygos or unpaired anterior cerebral artery. Aneurysms of the unpaired anterior cerebral artery are extremely rare; only nine cases have been reported in the literature. Recently we found and operated on a ruptured aneurysm of the azygos pericallosal artery.

Case History A woman, aged 47, suddenly developed severe headache, mainly frontal, associated with nausea. A lumbar puncture at another hospital revealed bloody CSF. A right carotid arteriogram disclosed a saccular aneurysm of the pericallosal artery. When she entered our hospital, she had no neurological deficit.

Angiography Transfemoral selective left internal carotid and vertebral arteriograms were performed. No vascular anomalies were found in the vertebrobasilar system. On AP and oblique views of the left internal carotid arteriogram a horizontal portion of the right anterior

Fig. 1. AP projection of left internal carotid arteriogram without contralateral carotid compression. A single trunk of anterior c e r e bral artery (lower arrows) divides into two branches where sacculax aneurysm (upper arrow) originates. Proximal portion of middle internal frontal artery is not clearly visualized in this film

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Fig. 2. Oblique view of left internal carotid arteriogram with contralateral carotid compression. Horizontal portion of fight anterior cerebral artery is slightly larger than left. An azygos artery first gives off frontopolar artery (lower arrow) then middle internal frontal artery (upper arrows), and divides into two branches

Fig. 3. Lateral projection of left internal carotid arteriograrn shows single pericallosal artery with middle internal frontal artery (left long arrow) at genu of corpus callosum and then divides into two branches: posterior internal frontal artery (right long arrows) and distal portion of pericallosal artery (short

arrows) genu of the corpus callosum (lateral projection) and in the distal portion of this azygos artery, a pea-sized saccular aneurysm was noticed at the point where this unpaired artery divided into two branches just after giving off a middle internal frontal artery directly from the pericallosal artery (Fig. 3). Postoperative right internal carotid arteriogram with contralateral carotid compression also showed the same anomalous vasculature.

Discussion

The anatomical variants of unpaired anterior cerebral arteries are found more frequently in fetuses or in infants than in adults [4, 8]. According to Baptista's review of the literatures, 23 of 2153 adult brains (1.0%) had unpaired anterior cerebral arteries [2]. And only one case was found among 381 brains in his own series. Alpers et al. [1] found a single vessel in

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six of 350 selected brains. Baptista [2] described three types of anomalies occurring in the distal anterior cerebral artery: (a) a true azygos artery from which all major branches are given off to both hemispheres; (b) a bihemispheric anterior cerebral artery where both right and left anterior cerebral arteries are present, but one is rudimentary and most of the major branches to both hemispheres arise from the other anterior cerebral artery; (c) a triple anterior cerebral artery with the accessory anterior cerebral artery arising from the anterior communicating artery. Our case was judged to belong to type (a) from the angiographic and operative findings. Aneurysms of the pericallosal arteries are not common. These aneurysms constitute 2.5-9.8% of all intracranial arterial aneurysm,; [3, 6, 9, 11, 13, 14, 15]. In the authors' clinic, five cases of pericallosal artery aneurysms were found which constituted 4.0% of all intracranial aneurysms. Aneurysms of the unpaired anterior cerebral artery', either ruptured or unruptured, are extremely rare and only nine cases are found in the literature: three of 22 distal anterior cerebral aneurysms by Pool et al. [12], three of 17 by Laitinen et al. [6], one of 126 by Baptista et al. [2], one of LeMay et al. [7] and one of Katz et al. [5]. The proximal portion of the pericallosal artery was found at operation to be a true single trunk. This single artery gave off a middle internal frontal artery at the dorsal and posterior part of the genu of the corpus callosum and then bifurcated where the saccular aneurysm originated. This aneurysm was clipped successfully without causing any neurological deficit.

2. Baptista, A.G.: Studies on the arteries of the brain. II. The anterior cerebral artery: some anatomic features and their clinical implications. Neurology 13, 825-835 (1963) 3. Crawford, T.: Some observations on the pathogenesis and natural history of intracranial aneurysms. J. Neurol. Neurosurg. Psychiatry 22, 259-266 (1959) 4. De Vriese, B.: Sur la signification morphologique des artrres crrrbrales. Arch. Biol. 21, 357-457 (1905) 5. Katz, R. S., Horoupian, D. S., Zingesser, L.: Aneurysm of azygous anterior cerebral artery. Case report. J. Neurosurg. 48, 804-808 (1978) 6. Laitinen, L., Snellman, A.: Aneurysms of the pericallosal artery: A study of 14 cases verified angiographically and treated mainly by direct surgical attack. J. Neurosurg. 17, 447-458 (1960) 7. LeMay, M., Gooding, C.A.: The clinical significance of the azygos anterior cerebral artery (ACA). Am. J. Roentgenol. Radium Ther. Nucl. Med. 98, 602-610 (1966) 8. Lesem, W.W.: Comparative anatomy of anterior cerebral artery. Postgrad. Med. 20, 455-465 (1905) 9. Locksley, H. B.: Report on the cooperative study of intracranial aneurysms and subarachnoid hemorrhage, Section V, part 1. J. Neurosurg. 25, 219-239 (1966) 10. Marino, R. Jr.: I. Anatomo-radiological study of its cortical territories. Surg. Neurol. 5, 81-87 (1976) 11. McKissock, W., Paine, K., Walsh, L.: Further observations on subarachnoid haemorrhage. J. Neurol. Neurosurg. Psychiatry 21, 239-248 (1958) 12. Pool, J.L., Potts, D.G.: Aneurysms and arteriovenous anomalies of the brain. Diagnosis and treatment, p. 139. New York: Harper and Row 1965 13. Suzuki, J., Yoshimoto, T., Uchida, K.: Surgical treatment of distal anterior cerebral artery aneurysms. Neurol. Surg. (Tokyo). 5, 29-33 (1977) 14. Wilson, G., Riggs, H. E., Rupp, C.: The pathologic anatomy of ruptured cerebral aneurysms. J. Neurosurg. 11, 128-134 (1954) 15. Yasargil, M. G., Carter, L. P.: Saccular aneurysms of the distal anterior cerebral artery. J. Neurosurg. 40, 218-223 (1974) Received: 11 September 1978

References 1. Alpers, B.J., Berry, R.G., Paddison, R.M.: Anatomical studies of the circle of Willis in nonnal brain. Arch. Neurol. Psychiatry 81, 409-418 (1959)

Dr. A. Kondo Department of Neurosurgery Fukui Red Cross Hospital 2-4-1 Tsukimi Fukui 910, Japan

Ruptured aneurysm of an azygos anterior cerebral artery.

Neuroradiology Neuroradiology 17, 227-229 (1979) © by Springer-Verlag 1979 Ruptured Aneurysm of an Azygos Anterior Cerebral Artery A. Kondo, T. Koy...
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