Neuro-radiology Neuroradiology (1992) 34:283-286 9 Springer-Verlag 1992 Bilateral persistent trigeminal arteries presenting with brain-stem infarction Y. Okada, T. Shima, M. Nishida, T. Yamada, K. Yamane, S. Okita, and R. Kagawa Department of Neurosurgery, Chugoku Rousai Hospital, Kure, Japan Received: 23 August 1991 Summary. A 43-year-old male with a left hemiparesis due to brain-stem infarction associated with bilateral persistent trigeminal arteries is reported. T h e clinicopathological and radiographic significance of persistent carotid-basilar arterial a n a s t o m o s e s in vertebrobasilar territory ischaemic attacks is also discussed. Key words: Brain-stem infarction - Persistent trigeminal artery - M a g n e t i c r e s o n a n c e imaging - Cerebral angiogr a p h y - Vertebral artery occlusion A l t h o u g h the primitive trigeminal artery (PTA) is the m o s t c o m m o n type of persistent carotid-basilar arterial anastomosis, and is estimated to be present in 0.1-0.6 % of individuals in large angiographic series [1-5], bilateral P T A s are extremely rare. We could find only two cases of angiographically d e m o n s t r a t e d bilateral P T A s [6, 7]. T h e clinicopathological significance of persistent carotid-basilar arterial a n a s t o m o s e s has n o t b e e n clarified, because most cases have b e e n shown incidentally by angiographic exploration of s u b a r a c h n o i d h a e m o r r h a g e [3, 8-11], cranial nerve p r o b l e m s [12], brain t u m o u r s [1, 13], h e a d injury [14] or cerebral ischaemia [15-22]. In these cases, brain-stem circulation w o u l d be principally via a persistent carotid-basilar anastomosis. Therefore, the clinicopathological and radiographic features of these cases should be investigated to clarify the pathogenesis of v e r t e b r o b a silar insufficiency. We describe a case of brain-stem infarction in a patient with bilateral P T A s and discuss the clinicopathological features in brain-stem ischaemia with carotid-basilar arterial anastomoses. Case report A 43-year-old right-handed man complained of left-sided weakness and impaired sensation involving the face. He was alert but hypertensive (170/86 mmHg) on admission. Positive findings on neuro- logical examination were left hemiparesis and nmnbness. Routine laboratory examination revealed normal haemoglobin, haematocrit, red blood cells, platelet count and blood sugar. An electrocardiogram did not reveal arrhythmia or atrial fibrillation. Although CI" on admission showed no evident lesion, 4 days later a small low-density area could be seen on the right side of the pons. Cerebral blood flow was investigated by the xenon 133 inhalation method using single photon emission computed tomography, which did not demonstrate an evident low-perfusion area. Cerebral angiography was performed via the femoral route. Bilateral common carotid artery injections revealed mild stenosis (20-30%) of both carotid bifurcations. A selective right internal carotid angiogram demonstrated a PTA, through which the contrast medium flowed into the basilar artery, giving excellent visualization of the contralateral posterior cerebral (PCA) and both superior cerebellar arteries (SCA) (Fig.la, b). The vertebrobasilar arterial system proximal to the PTA was poorly seen. The ipsilateral PCA was visualized via a well-developed posterior communicating artery. A left internal carotid angiogram revealed another PTA, through which only the ipsilateral SCA was filled (Fig. 1 c, d). The vertebral arteries were investigated by intra-arterial digital subtraction angiography. There was no visualization of either vertebral artery origin from the subclavian arteries. The left vertebral V2-V4 segments filled via collaterals, along with the thyrocervical and occipital arteries (Fig.2). Magnetic resonance imaging (MRI) at 1.5 T demonstrated brainstem infarction, seen on T2-weighted images as a heterogenous highintensity area on the right side of the upper part of the pons (Fig. 3). As neither occlusive atherosclerotic lesions nor sources of emboli could be definitely identified, the patient was treated conservatively. During 3 months of rehabilitation his motor function recovered gradually, enabling him to walk without support. Discussion T h e P T A arises where the internal carotid artery leaves the carotid canal and enters the cavernous sinus. T h e first angiographic description of this vessel was by Sutton [23], and it has subsequently b e e n f o u n d not to be rare. To our knowledge, however, bilateral P T A s are extremely rare: even w h e n o t h e r types of persistent carotid-basilar anastomoses are included, only six cases (including ours) are to be f o u n d in the English literature [6, 7, 24, 25]; their clinicopathological features are summarized in Table 1. 284 Fig.1. Cerebral angiograms demonstratebilateral primitive trigeminal arteries (arrows) Fig.2. Intra-arterial digital subtraction arch aortogram does not define the origin of either vertebral artery from the subclavian artery. In the upper cervical region, the left vertebral artery can be seen filling through anastomoses (arrow) Fig.3. MRI demonstrates heterogeneous high-intensity in the right side of the upper pons (arrow) Saltzman [26] classified PTAs as follows: type I, the PTA supplies the entire vertebrobasilar arterial system distal to the anastomosis with poor filling of the posterior communicating artery; type II, the PTA mainly fills the SCA on both sides, while the P C A receives its blood through the posterior communicating artery; type III combines the two. Other rare types have been reported, such as those directly filling the ipsilateral SCA [27], anterior [28] or posterior inferior cerebellar arteries [29]. In our case, the right PTA supplies the craniad basilar artery, contralateral PCA and both SCAs, and the left PTA fills only the ipsilateral SCA. With the advent of angiography persistent carotid-basilar anatomoses have been discovered as coincidental an- giographic findings in patients with head trauma, tumours, subarachnoid haemorrhage and vertebrobasilar ischaemic attacks. Various researchers have attempted to correlate these persistent embryological arteries with other intracranial lesions. Eadie et al. [2] pointed out that the only significant association is between an isolated oculomotor palsy and a persistent trigeminal artery. However, there have been several reports of patients with a carotidbasilar anastomosis presenting with vertebrobasilar territory ischaemia. In general, brain-stem ischaemia has been ascribed to vertebrobasilar arterial occlusion due to atherosclerotic lesions [30, 31], embolism [20-22, 32] and external compression [33]. The circulation in the vertebrobasilar arterial system is known to be very complicated in 285 Table 1. Clinical and angiographic features of bilateral persistent carotid-basilar arterial anastomoses Authors (year) Karasawa et al. (1976) Age Sex (years) 28 F Symptoms Anastomoses Vertebral arteries Diagnosis Headache (SAH) L POA R PTA L occluded R occluded Angiomatous malformation 39 M Unconscious, headache, vertigo (SAH) Bil. PHA L absent R thin SAH Binet and Young (1977) 60 F Gait disturbance, headache Bil. PTA L small R absent Cerebellar tumour Taguchi et al. (1978) 45 F Double vision, exophthalmos Bil. PTA L hypoplastic R normal Hyperthyroidism Tanaka et al. (1983) Present case 69 F Hemiparesis, dysphasia 43 M Hemiparesis R PTA L hyp0plastic L proatlantal artery R not defined Bil. FTA Both absent from origin Middle cerebral artery occlusion Brain-stem infarct F, Female; M, male; SAH, Subarachnoid haemorrhage; L, left; R, right; Bil., bilateral; PTA, primitive trigeminal artery; POA, primitive otic artery; PHA, primitive hypoglossal artery occlusive diseases because of well-developed collateral channels. For example, even with bilateral vertebral artery occlusion, the clinical features and outcome are very variable [30, 31]. Caplan [30], reviewing 31 bilateral vertebral artery occlusions, suggested that the pathogenesis of vertebrobasilar ischaemic attacks in this condition was due principally to chronically reduced vertebrobasilar perfusion pressure and that extracranial-intracranial bypass would be effective in some cases. The vertebral arteries tend to be hypoplastic or underdeveloped when the posterior circulation is mainly supplied via persistent carotid-basilar arterial anastomosis. In our case, neither V1 segment could be observed by arch aortography; only the left V 2 - V 4 segments were seen, filling via collateral vessels in the neck. The ischaemic lesion was situated in the upper part of the pons, supplied by the basilar artery through the right PTA-basilar artery system. Accordingly, in patients with a persistent carotid-basilar arterial anastomosis three might be two possible mechanisms of brain-stem ischaemia: low-perfusion pressure in the vertebrobasilar system and embolization from the stenotic carotid lesions and/or the heart. Five cases of embolic stroke with a carotid-basilar anastomosis have been reported [20-22]. Angiographically, they showed causative stenoses of the cervical internal carotid artery and were successfully treated by carotid endarterectomy. The results of operation indicated the pathogenesis in these cases would be microembolism originating from the cervical internal carotid artery, through a persistent carotid-basilar anastomosis. In their review of the literature, Stern et al. [21] suggested that there might be a higher incidence of posterior fossa ischaemic attacks associated with persistent carotid-basilar anastomoses than previously thought. As Naritomi et al. [34] suggested, haemodynamic factors and dysautoregulation could also play a part in the pathogenesis of vertebrobasilar territory ischaemic attacks. Thus, the circulatory effects of a persistent carotid-basilar anastomosis should be investigated in detail to assess its clinicopathotogical significance in vertebrobasilar insufficiency. References 1. Breutman ME, Fields WS (1963) Persistent hypoglossal artery. Arch Neurol 8:369-372 2. Eadie MJ, Jamieson KG, Lennon EA (1964) Persistent carotidbasilar anastomosis. J Neurol Sci 1:501-511 3. George AE, Lin JR Morantz RA (1971) Intracranial aneurysm on a persistent trigeminal artery. Case report. J Neurosurg 35: 601-604 4. Krayenbuhl HA, Yasargil MG (1982) Cerebral arteries. In Huber P (ed) Cerebral angiography,Thieme, Stuttgart, pp 57-61 5. Wollschlaeger G, Wollschlaeger PB (1974) The circle of Willis. In: Newton TH, Potts GD (eds) Radiology of the skull and brain angiography. Mosby,St Louis, pp 1195-1196 6. Binet EE Young RF (1977) Bilateral persistent trigeminal arteries. Case report. J Neurosurg 47:619-622 7. Taguchi Y, Irikura T, Suzuki T, Nakamura N (1978) Unusual primitive trigeminal artery. Report of two cases. No to Shinkei (Tokyo) 30:1209-1214 8. Huber P, Rivoir R (1974) Aneurysm on a persistent left hypoglossal artery. Case report. Neuroradiology 6:277-278 9. Yamanaka C, Uozumi T, Okada Y, Iguchi T (1987) Cerebral aneurysm associated with persistent trigeminal artery and occlusion of subclavian artery. Neurol Med Chir (Tokyo) 27:132-138 10. Kodama N, Ohara H, Suzuki J (1976) Persistent hypoglossal artery associated with aneurysms. Report of two cases. J Neurosurg 45:449451 11. Wolpert SM (1966) The trigeminal artery and associated aneurysm. Neurology 16:610-614 12. Kempe LG, Smith DR (1969) Trigeminal neuralgia, facial spasm, intermedius and glossopharyngeal neuralgia with persistent carotid basilar anastomosis. J Neurosurg 31:445-451 13. Begg AC (1961) Radiographic demonstration of the "hypoglossal artery". A rare type of persistent anomalous carotid-basilar anastomosis. Clin Radio112:187-189 14. Carbomin C, Benedetti A, Cerri D, et al (1976) A case of persistent hypoglossal artery. Neurochirurgia 19:231-236 15. Harrison CR, Luttrell C (1953) Persistent carotid-basilar anastomosis. Three arteriographically demonstrated cases with one anatomical specimen. J Neurosurg 10:205-215 16. Wise BL, Palubinskas AJ (1964) Persistent trigeminal artery (carotid-basilar anastomosis). J Neurosurg 21:199-206 17. Jackson FE (1964) Case report and technical note. Syncope associated with persistent hypoglossal artery. J Neurosurg 21:139-141 18. Nakayama T, Fukumura A, Matsukada Y, Ozaki H (1970) Carotid-basilar anastomosis: primitive hypoglossal artery. Kumamoto Med J 23: 14-20, 1970 286 19. Debaene A, Farnarier R Dufour M, Legr6 J (1972) Hypoglossal artery, a rare abnormal carotid-basilar anastomosis. Neuroradiology 4:233-238 20. Waller FT, Simons RL, Kerber C, et al (1977) Trigeminal artery and miroemboli to the brain stem. Report of two cases. J Neurosurg 46:104-106 21. Stern J, Correll JW, Bryan JN (1978) Persistent hypoglossal artery and persistent trigeminal artery presenting with posterior fossa transient ischemic attacks. Report of two cases. J Neurosurg 49:614-619 22. Quencer RM, Simon J (1979) Transient bilateral occipital lobe ischemia: microembolization through a trigeminal artery. Neuroradiology 18:273-275 23. Sutton D (1950) Anomalous carotid-basilar anastomosis. Br J Radio123:617~519 24. Karasawa J, Kikuchi H, Furuse S, et al (1976) Bilateral persistent carotid-basilar anastomoses. AJR 127:1053-1056 25. Tanaka Y, Hara H, Momonse G, et al (1983) Proatlantal artery and trigeminal artery associated with an aneurysm. Case report. J Neurosurg 59:520-523 26. Saltzman GF (1959) Patent primitive trigeminal artery studied by cerebral angiography. Acta Radio151:329-336 27. Teal JS, Rumbaugh CL, Bergeron RT, et al (1972) Persistent carotid-superior cerebellar artery anastomosis: a variant of persistent trigeminal artery. Radiology 103:335-341 28. Ito J, Takeda N, Suzuki Y, et al (1980) Anomalous origin of the anterior inferior cerebellar arteries from the internal carotid artery. Neuroradiology 19:105-109 29. Chambers AA, Lukin R (1975) Trigeminal artery connection to the posterior inferior cerebellar arteries. Neuroradiology 9: 121123 30. Caplan LR (1983) Bilateral distal vertebral artery occlusion. Neurology 33:552-558 31. Bogousslavsky J, Gates PC, Fox AJ, Barnett HJM (1986) Bilateral occlusion of vertebral artery: clinical patterns and long-term prognosis. Neurology 36:130%1315 32. Pessin MS, Daneault N, Kwan ES, et al (1988) Local embolism from vertebral artery occlusion. Stroke 19:112-115 33. Toole JE Tucker SH (1960) Influence of head position upon cerebral circulation. Studies on blood flow in cadaver. Arch Neurol 2: 616~523 34. Naritomi H, Sakai F, Meyer IS (1979) Pathogenesis of transient ischemic attacks within the vertebrobasilar arterial system. Arch Neuro136:121-128 Dr. Y. Okada Department of Neurosurgery Chugoku Rousai Hospital 1-5-1 Hirotagaya Kure 737-01 Japan