Giant thrombosed aneurysm of the vertebral artery in childhood: an extremely rare case

European Journal of Radiology 28 (1998) 102 – 105

Case report

Giant thrombosed aneurysm of the vertebral artery in childhood: an extremely rare case M. U8 nal Kiris¸og' lu a,*, Engin Uc¸ar a, Arif O8 su¨n a, Metin Manisalı b, U8 mit Acar a, Tansu Mertol a a

Department of Neurosurgery, Dokuz Eylu¨l Uni6ersity, School of Medicine, Inciraltı, 35 340 Izmir, Turkey b Department of Radiology, Dokuz Eylu¨l Uni6ersity, School of Medicine, Inciraltı, 35340 Izmir, Turkey Received 21 April 1997; received in revised form 9 June 1997; accepted 10 June 1997

Abstract In childhood, a significant proportion of giant aneurysms usually occur at the vertebrobasilary system. Nonetheless, giant totally thrombosed aneurysm which only involves the vertebral portion of the vertebrobasilary system is very rare. Up to this time, in childhood, a few giant aneurysm originating from vertebral artery have been reported, and to our knowledge only one case was reported to be totally thrombosed. The enlargement tendency of totally thrombosed aneurysms and management of these cases are still controversial. Thus, diagnosis and follow-up of cases where a radical approach could not be performed require a multi-modality radiologic approach. In this study, we reported a case of angiographically occult giant thrombosed vertebral artery aneurysm, which is extremely rare, and discussed the importance of CT and MRI in evaluation of these patients before surgical treatment. © 1998 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Giant aneurysm; Vertebral artery; Thrombosis; Radiologic imaging; Surgery

1. Introduction

2. Case report

The incidence of aneurysms in childhood ranges between 0.5 and 4.6% [1 – 3]. Including all decades, giant aneurysms constitute approximately 5% of all the aneurysms reported in a large series [4 – 6]. Among these, except a couple of cases, giant aneurysm noted at vertebral artery localization in the pediatric age group, is extremely rare [1,3,6 – 32]. In this study, we present an extremely rare pediatric case with totally thrombosed giant aneurysm in a vertebral artery location.

A 10-year-old boy with an acute onset of pain lasting over 1 month on the left cervical region, was referred to our department following treatment for meningitis. Neurological examination was normal on admission. Computed tomography (CT) showed an extraparenchymal mass, 3× 3 ×4 cm in size, with a well-defined margin in the left lateral medullary cistern location. Following contrast administration despite peripheral enhancement there was no significant density change in the center of the lesion (Fig. 1). Routine T1 (pre-postcontrast) and T2-weighted spin-echo magnetic resonance images (MRI) confirmed the mass in the left lateral medullary cistern location. In both sequences, the center of the lesion was isointense with the brain

* Corresponding author. Tel.: +90 232 2595959, 3305/3300; fax: + 90 232 2787595.

0720-048X/98/$19.00 © 1998 Elsevier Science Ireland Ltd. All rights reserved. PII S0720-048X(97)00083-1

M.U8 . Kiris¸og' lu et al. / European Journal of Radiology 28 (1998) 102–105

and hyperintense peripherally (Fig. 2). On digital subtraction angiography (DSA) examination, the left vertebral artery was originating from the left subclavian artery but the distal portion was not visualized (Fig. 3). Posterior circulation was maintained by the right vertebral artery and there was no aneurysmal contrast filling (Fig. 4). With the suspicion of a giant thrombosed aneurysm and thrombotic involvement of the left vertebral artery, the patient underwent a bilateral suboccipital craniectomy. A giant vertebral artery aneurysm was present in the left paramedullar location. Following the trapping procedure performed with a proximal clip placed a few mm distal to the origin of posterior inferior cerebellar artery (PICA), and a second clip placed distal to the aneurysm, the aneurysm was removed. Except transient IX and X cranial nerve injury, postoperative neurological examination was normal. One year after the surgery, the patient was intact from neurological sight.

3. Discussion Vertebral artery aneurysms are relatively uncommon [7,32]. Up to this time, a few giant vertebral artery aneurysms [2,13,33,34] have been reported in childhood. Among these only one case was totally thrombosed and this case was only evaluated with CT in the preoperative period [13]. Preoperative radiologic examination in these cases is extremely important. Angiography may be non-diagnostic or frequently misleading with respect to the aneurysm size, especially when the aneurysms are partially or totally thrombosed. CT and MR imaging that possess the advantage of multi-planar imaging provide more detailed information regarding the size and content of the aneurysms [9,35,36]. On CT images, due to patent unthrombosed part of the lumen,

Fig. 1. On contrast enhanced axial CT image, aneurysm in left medullar cistern is seen. In the periphery of the lesion there is contrast fixation but the center of the aneurysm do not show significant enhancement.

103

Fig. 2. On T1-weighted (TR/TE: 600/20) contrast enhanced spin-echo MR image totally thrombosed giant aneurysm is seen compressing the medulla oblongata. The center of the lesion is isointense with cerebellar parenchyma. The periphery of the lesion is hyperintense, and there is no edema or heterogeneity in surrounding parenchyma.

partially thrombosed aneurysms frequently show central enhancement known as ‘target sign’ [26]. In contradiction to this, the central portions of completely thrombosed aneurysms often remain hypo- or isodense following contrast administration. Peripheral ring enhancement and mural calcification could be seen, especially in aneurysms that had long-standing thrombosis, and an organizing clot [13,15,35,37]. CT findings, in our case, were compatible with completely thrombosed aneurysms that had no calcification but peripheral ring enhancement. MRI is an excellent imaging modality in evaluating the giant aneurysms. With this technique, various degrees of thrombus formation within the aneurysm can be detected as inhomogeneous regions that are isointense or hypointense relative to the brain on T1 and T2-weighted images. Nonetheless, due to layers of thrombosis at different ages, the thrombotic area may have a laminated appearance. In these cases, a perilu-

Fig. 3. Angiographic examination performed by aortic flash. Due to thrombosis the distal portion of left vertebral artery after its origin from left subclavian artery is not visualized.

104

M.U8 . Kiris¸og' lu et al. / European Journal of Radiology 28 (1998) 102–105

Fig. 4. Subtracted image at the level of posterior fossa. Posterior fossa circulation is maintained by right vertebral artery. There is no aneurysmatic filling.

minal layer of high signal intensity on both sequences due to free methemoglobin, and marked hypointensity within the wall of the aneurysm on T2-weighted images due to hemosiderin-laden macrophages could be seen. When present, perianeurysmal hemorrhages could be seen as regions of hyperintense signal on T1-weighted images and either hypointense or hyperintense signal on T2-weighted images (depending on the age of hemorrhage) [9]. In contrast to totally thrombosed giant aneurysms, partially thrombosed aneurysms, most frequently demonstrate heterogeneous laminated appearance, due to thrombosis in various stages and blood flow. In cases, especially where the aneurysms are not completely filled with cloth, horizontal artifact across the plane of the aneurysm could be seen, indicating patency and intraluminal flow [36]. CT and MR images of these cases may mimic solid masses, and biopsic examination in these circumstances could be catastrophic. Nonetheless, factors like location, contrast enhancement behavior and edema permit differential diagnosis to a certain degree. Absence of edema is helpful in differentiating these aneurysms from neoplastic pathologies like metastasis. Also, the absence of homogeneous contrast enhancement behavior in aneurysms help in differentiating these lesions from pathologies, like neurinoma and meningioma. In our case, on MR images, we did not observe any signal void in the central portion of the aneurysm and there was no horizontal artifact secondary to phase misregistration. The signal changes were compatible with centrally subacute, peripherally more chronic thrombus formation. Nonetheless, the increase in signal intensity of the periphery of the lesion following Gd-DTPA administration in T1-weighted series was also in favor of capsular vascularization. On axial images obtained under the aneurysm, absence of pulsation artifact and hypointensity in the left vertebral

artery location was also suggestive of thrombosis involving the left vertebral artery. The management of intracranial aneurysms vary with regard to the location and size of the aneurysm, age of the patient and coexisting systemic diseases [38]. Especially the complex anatomy of giant aneurysms in vertebral artery location frequently creates an extremely difficult management dilemma; therefore detailed preoperative evaluation is extremely important in these cases [39]. Thus, in aneurysms originating from vertebral artery location, if PICA is proved to be the major supplier to medulla it must remain patent proximal to clip at surgery [31]. However when PICA arises from the aneurysm, it is a problem. In such cases, extra-intracranial by pass or PICA-PICA anastomoses is needed [40]. In these cases, a second enigma is whether aneurysmectomy is an indication. Aneurysmectomy is indicated for those causing neurologic deficits [27]. However, even silent, totally thrombosed aneurysms possess a potential for enlargement. Hecht et al. [15] and Nagahiro et al. [22], reported the enlargement of giant vertebral artery aneurysms either to be due to recurrent hemorrhages into the wall (which could be easily appreciated on MR images) or to transmitted blood pulsation, especially when the parent artery is occluded at surgery. Nonetheless, in our case, the hyperintense signal on periphery of the aneurysm was homogeneous rather than heterogeneous, excluding the possibility of significant recurrent hemorrhagic episodes. In conclusion, giant vertebral artery aneurysms possess a potential of continuous growth, which could be easily appreciated on MR images. Therefore, in these cases we recommend a radical approach, and if radical approach could not be performed a close radiologic follow-up regardless of surgical choice is necessary.

References [1] Ferrante L, Fortuna A, Celli P, Santoro A, Fraioli B. Intracranial arterial aneurysms in early childhood. Surg Neurol 1988;29:39 – 56. [2] Gutierrez FA, Bailes J, McLone DG. Intracranial aneurysm and pseudo-aneurysm occuring during infancy and childhood: diagnosis and surgical result. Concepts Pediatr Neurosurg 1987;7:153 – 68. [3] Lansen TA, Kasoff SS, Arguelles JH. Giant pediatric aneurysm treated with ligation of the middle cerebral artery with the drake tourniquet and extracranial-intracranial bypass. Neurosurgery 1989;25:81 – 5. [4] Sindau M, Keravel Y. Giant intracranial aneurysms, therapeutic approach. Neurochirurgie 1984;32:1 – 114. [5] Sontag VKH. Giant intracranial aneurysms: a review of 13 cases. Surg Neurol 1977;8:81 – 4. [6] Yas¸argil MG. Giant intracranial aneurysms. In: Yas¸argil MG, editor. Microneurosurgery, vol 2. Stuttgart: George Thieme Verlag, 1984:296 – 303.

M.U8 . Kiris¸og' lu et al. / European Journal of Radiology 28 (1998) 102–105 [7] Andoh T, Shirakami S, Nkashima T, Nishimura Y, Sakai N, Yamada H, Ohkuma A, Tanabe Y, Funakoshi T. Clinical analysis of a series of vertebral aneurysm cases. Neurosurgery 1992;31:987 – 93. [8] Artmann H, Vonofakos D, Mu¨ller H, Grau H. Neuroradiologic and neuropathologic findings with growing giant intracranial aneurysm. Surg Neurol 1984;21:391–401. [9] Atlas SW, Grossman RI, Goldbegr HI, Hackney DB, Bilaniuk LT, Zimmerman RA. Partially thrombosed giant intracranial aneurysms: correlation of MR and pathologic findings. Radiology 1987;162:111 – 4. [10] Ausman JI, Diaz FG, Sadasivan B, Gonzeles-Portillo M, Malik GM. Giant intracranial aneurysm surgery: the role of microvascular reconstruction. Surg Neurol 1990;34:8–15. [11] Barth A, Tribolet N de. Growth of small saccular aneurysms to giant aneurysms: presentation of three cases. Surg Neurol 1994;41:277 – 80. [12] Cedzich C, Schramm J, Ro¨ckelein G. Multiple middle cerebral arter aneurysms in an infant: case report. J Neurosurg 1990;72:806 – 9. [13] Dolenc V. A tumor-simulating giant aneurysm of the vertebral artery. Zentralbl Neurochir 1983;44:215–20. [14] Hammon WM, Kempe LG. The posterior fossa approach to aneurysms of the vertebral and basiler arteries. J Neurosurg 1972;37:339 – 47. [15] Hecht ST, Horton JA, Yonas H. Growth of a trombosed giant vertebral artery aneurysm after parent artery occlusion. Am J Neuroradiol 1991;12:449–51. [16] Hosobuchi Y. Direct surgical treatment of giant intracranial aneurysms. J Neurosurg 1979;51:743–56. [17] Hourihan MD, Gates PC, McAllister VL. Subarachnoid hemorrhage in childhood and adolescence. J Neurosurg 1984;60:1163 – 6. [18] Hacker RJ. Intracranial aneurysms of childhood: a statistical analysis of 500 cases from the world literature. 34th Annual Meeting of The Southern Neurosurgical Society, White Sulphur Springs, West Virginia (abstr.). Neurosurgery 1982;10:775. [19] Sarwar M, Batnitzky S, Schecther MM. Tumorous aneurysms. Neuroradiology 1976;12:70–97. [20] Meyer FB, Sundt TM, Fode NC, Morgan MK, Forbes GS, Mellinger JF. Cerebral aneurysms in childhood and adolescence. J Neurosurg 1989;70:420–5. [21] Michael WF. Posterior fossa aneurysms simulating tumours. J Neurol Neurosurg Psychiatry 1974;37:218–23. [22] Nagahiro S, Takada A, Goto S, Kai Y, Ushio Y. Thrombosed growing giant aneurysms of the vertebral artery: growth mechanism and management. J Neurosurg 1995;82:796–801. [23] Ostergaard JR, Voldby B. Intracranial arterial aneurysms in children and adolescents. J Neurosurg 1983;58:832–7. [24] Patel AN, Richardson AE. Ruptured intracranial aneurysms in the first two decades of life: a study of 58 patients. J Neurosurg 1971;35:571 – 6.

. .

105

[25] Polis Z, Brzezinski J, Chodak-Gajewicz M. Giant intracranial aneurysm. J Neurosurg 1973;39:408 – 11. [26] Sorensen P, Lundorf E. Giant aneurysm of the vertebral artery simulating intracranial tumour at the foramen magnum. Neuroradiology 1988;30:359. [27] Sugita K, Kobayashi S, Takemae T, Tanaka Y, Okudera H, Ohsawa M. Giant aneurysms of the vertebral artery. J Neurosurg 1988;68:960 – 6. [28] Sundt TM, Piepgras DG. Surgical approach to giant intracranial aneurysms: operative experience with 80 cases. J Neurosurg 1979;51:731 – 42. [29] Wakui K, Kobayashi S, Takemae T, Kamijoh Y, Nagashima H, Muraoka S. Giant trombosed vertebral artery aneuryms managed with extracranial-intracranial bypass surgery and aneurysmectomy. J Neurosurg 1992;77:624 – 7. [30] Yamada K, Hayakawa T, Ushio Y, Iwata Y, Koshino K, Bitoh S, Takimoto N. Therapeutic occlusion of the vertebral artery for unclippable vertebral aneurysm: relationship between site of occlusion and clinical outcome. Neurosurgery 1984;15:834–8. [31] Yamaura A. Diagosis and treatment of vertebral aneurysms. J Neurosurg 1988;69:345 – 9. [32] Storrs BB, Humphreys RP, Hendrick EB, Hoffman HJ. Intracranial aneurysms in the pediatric age-group. Child’s Brain 1982;9(5):358 – 61. [33] Ganti SR, Steinberger A, McMurtry JG III, Hilal SK. Computed tomographic demonstration of giant aneurysm of the vertebrobasiler system: report of eigt cases. Neurosurgery 1981;9:261 – 7. [34] Khayata MH, Spetzler RF, Mooy JJA, Herman JM, Rekate HL. Combined surgical and endovascular treatment of a giant vertebral artery aneurysm in a child: case report. J Neurosurg 1994;81:304 – 7. [36] Forbes, G. Intracranial aneurysms: diagnostic consideration. RSNA Special course in Neuroradiology 1994:47 – 56. [35] Schubiger P, Valavanis A, Hayek J. Computed tomography in cerebral aneurysms with special emphasis on giant intracranial aneurysms. J Comput Assisted Tomogr 1980;4:24 – 32. [37] Rao KCVG, Lee SH. Cerebrovascular anomalies: In: Strak DD, Bradley WG, editors. Magnetic Resonance Imaging. St Louis: Mosby, 1988:473 – 506. [38] Herman JM, Rekate HL, Spetzler RF. Pediatric intracranial aneurysms: simple and complex cases. Pediatr Neurosurg 1991;17(2):66 – 72. [39] Greene KA, Marciano FF, Hamilton MG, Herman JM, Rekate HL, Spetzler RF. Cardiopulmonary bypass, hypothermic circulation arrest and barbiturate cerebral protection for the treatment of giant vertebrobasilar aneurysms in children. Pediatr Neurosurg 1994;21(2):124– 33. [40] Ausman JI, Diaz FG, Mullan S, Gehring G, Sadasivan B, Dujovni M. Posterior inferior to posterior inferior cerebellar artery anastomosis combined with trapping for vertebral artery aneurysm: case report. J Neurosurg 1990;73:462 – 5.