Ferreira et al. BMC Neurology (2019) 19:257 https://doi.org/10.1186/s12883-019-1492-2 CASE REPORT Open Access Persistent trigeminal artery in a patient with posterior circulation stroke treated with rt-PA: case report Axel Ferreira1* , Paulo S. Coelho1 and Vítor Tedim Cruz1,2 Abstract Background: A persistent trigeminal artery (PTA) is a non-involuted embryonic vessel that connects the cavernous part of the internal carotid artery with the posterior circulation. In the adult it is associated with multiple pathological conditions including trigeminal neuralgia, ophthalmoplegia, hypopituitarism, intracavernous fistula, brain aneurysms and posterior circulation strokes. The latter may occur through steal phenomena or thrombosis in the anterior circulation. PTA associated vertebrobasilar hypoplasia has yet to be associated to TIA like events, however, in the reported case, that seems to be the case with reported vertigo being probably linked to vertebrobasilar insufficiency. Case report: We present a case of an 82-year-old man with sudden onset neurological deficits, including left hemiparesis with crural predominance, vertical nystagmus, right internuclear ophthalmoplegia, dysarthria and dysmetria on the left arm. CT angiography disclosed basilar artery hypoplasia in the proximal two thirds and a persistent trigeminal artery. He was diagnosed with acute ischemic stroke. He was submitted to rt-PA with partial reversion of deficits. Conclusion: The ischemic events related to PTA remain a rare cause of stroke with specific pathophysiological mechanisms and implications. They may occur through steal phenomena or thrombosis in the anterior circulation. Upon literature review, in the described case both mechanisms seem possible, however the transient episodes of vertigo could have been the first sign of vertebrobasilar insufficiency. Keywords: Posterior trigeminal artery, Stroke, Vertebrobasilar insufficiency, Saltzman classification, CT angiography Background The trigeminal arteries have their origin in the embryonic vessels that connect the cavernous portion of the developing internal carotid arteries (ICA) and the paired longitudinal neural arteries that will later form the basilar artery (BA) [1, 2]. While the trigeminal artery usually involutes after the development of the posterior communicating artery (PcoA) there are cases, for reasons still unclear, where it remains persistent [2]. The PTA is the most common persistent embryonic carotid–basilar anastomosis [1]. Prevalence varies from 0.12 to 1% in studies using magnetic resonance angiography imaging or classical angiography * Correspondence: axelferr@gmail.com 1 Neurology Department, Hospital Pedro Hispano, ULS Matosinhos, Porto, Portugal Full list of author information is available at the end of the article [3–8]. In this paper we will briefly explain what is a PTA and to what pathologies it can be associated, we will review the meaning of a PTA in a posterior circulation stroke through a clinical case and we will present a table that summarizes the PTA related strokes reported in literature. The different variations of the PTA can be cataloged using the Saltzman classification (Fig. 1), [1, 9, 10]. In Saltzman type 1, also called fetal PTA, the PTA insertion in the BA is distal to the anterior inferior cerebellar artery (AICA) and proximal to the superior cerebellar artery (SCA) and, in some cases, the BA proximal to the insertion of the PTA may be hypoplastic and the PcoA of the same side may be absent. In the Saltzman type 2 there is usually no hypoplasia of the BA, the PTA inserts proximally to the SCA, supplying them, and the PCAs are predominantly supplied by the PcoA. In the © The Author(s). 2019 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Ferreira et al. BMC Neurology (2019) 19:257 Page 2 of 6 Fig. 1 – Schematic representation of the vertebrobasilar system, a) without PTA, b) with Saltazman type 1 PTA, showing BA hypoplasia proximal to the PTA, c) with Saltazman type 2 PTA, showing the PCAs predominantly supplied by the PcoA. BA – basilar artery, ICA – internal carotid artery, PCA – posterior cerebral artery, PcoA – posterior communicating artery, PTA – persistent trigeminal artery, VA – vertebral artery Saltzman type 3 variant, the PTA inserts directly into one of the cerebellar arteries, without having an anastomosis with the BA. In the case of Slatzman type 3 there are 3 variants: the type 3a variant that terminates in SCA; the type 3b variant, and the the most common one, that terminates into AICA; and type 3c variant that terminates into posterior inferior cerebellar artery (PICA) [1, 2]. In one study of 4.650 patients that underwent brain MRA, the prevalence of each type using the Saltzman classification was as follows: type I, 24%; type II, 16%; type III, 60% [7]. The PTA is linked to several pathologies, including vascular nerve compression syndromes, like trigeminal neuralgia (more prevalent in patients with PTA) [11, 12] or ophthalmoplegia due to oculomotor or abducens palsy [12–14]. It is also linked to hypopituitarism due to compression of the pituitary stalk [14, 15], spontaneous or traumatic intracavernous fistula [16] and brain aneurysms. Although there is no agreement that brain aneurysms are more prevalent in patients with PTA [4, 7, 17], the PTA itself is prone to aneurysms due to its bifurcation [1]. Finally, the PTA is also related to ischemic stroke, although, to our knowledge it has never been linked to TIA by vertebrobasilar insufficiency [18–30]. We present in Table 1 a structured summary of the PTA related stroke cases reported in literature. Case presentation An 82-year-old man, presented to the emergency department, on February 2018, after sudden onset of left hemiparesis and vertigo. Symptoms started during a period of greater physical effort, upon participation in a zumba class. His past medical history included transient episodes of vertigo during exercise in the previous months, an anterior circulation right hemispheric stroke in 2015, that left no sequels, and hypertension controlled with a combination of 10 mg lisinopril and 2.5 mg amlodipine. The neurologic examination revealed mild left hemiparesis with facial involvement and crural predominance, vertical nystagmus, right internuclear ophthalmoplegia, dysarthria and dysmetria on the left arm. The total National Institutes of Health Stroke Scale (NIHSS) score was 6. The plain brain CT scan was normal and a CT angiography showed hypoplasia of both vertebral arteries, the left terminating as the PICA, while the right gave origin to the BA. The BA had a filiform aspect in its proximal two thirds, having a normal caliber in the distal remaining third, after receiving a communicating artery from the cavernous segment of the left internal carotid artery, a PTA (Fig. 2). No abrupt stop of flow was identified. Echocardiogram showed severe dilation of the left auricle, as well as mild dilation of the right auricle and a 35 mm dilation of the proximal portion of the ascending aorta. Electrocardiogram was normal and a 48 h cardiac telemetry monitoring didn’t show any periods of arrhythmia. Lipid profile showed borderline high low density lipoprotein level, at 139 mg/dL. The patient underwent treatment with recombinant tissue plasminogen activator (rt-PA) at two hours of symptom onset, this decision was based on the clinical presentation and in the absence of hemorrhage in the CT scan. Shortly after treatment the NIHSS score was 2, maintaining a slight paresis of the left leg and dysmetria on the left arm. Months later, the patient showed no neurologic sequelae. Discussion and conclusions PTA can be associated with many different vascular events. Patients with PTA and vertebrobasilar hypoplasia have a tendency to have a decreased vascular supply to the posterior fossa [19], this fact renders them susceptible to ischemic events. In this context, in the case of a stenosed carotid artery, a steal phenomenon can occur, and this can lead either to vertebrobasilar insufficiency or hemodynamic brain Symptoms Headaches, visual disturbances, right-sided numbness progressing to dysarthria and right-sided motor deficit with central facial palsy Right hemiparesis and numbness of the left face Aphasia, dysarthria and right hemiparesis Dysarthria and right hemiparesis (grade 4/5) Transient diplopia and right-sided numbness which resolved in 10–15 min, 2 days later horizontal nystagmus and diplopia, right hemisensory loss to light touch and pinprick, tongue deviation to the right, decreased fine motor function in the right hand and slow right finger-to-nose performance Retrograde and anterograde amnesia, superior homonymous quadrantanopias, and could not identify colors Transient ill-defined visual disturbance and a mild right-sided hemiparesis Identification 42yo F (2010) [18] 47yo M (1992) [19] 54yo M (2006) [20] 55yo M (2010) [21] 56yo M (2014) [22] 58yo M (2016) [23] 62yo F (2006) [24] Left mesencephalic Bilateral occipital infarcts involving the parahippocampal and lingual gyri Left ventral pons and left superior cerebellar peduncle Left ventral hemipontine infarction Left middle cerebral artery and posterior cerebral artery territories Ventral pontine lacunar infarct Left anterolateral pontine infarction Territory Confirmed by neuroimaging Right high-grade ICA stenosis (80%) hypoplastic vertebral arteries, right PTA Saltzman type 1 Hypoplastic vertebrobasilar circulation, with a persistent right trigeminal artery supplying the rostral basilar artery Saltzman type 1 Thrombosis of a persistent left trigeminal artery Saltzman type 1 Ipsilateral tortuous primitive trigeminal artery Salytzman type 1 Embolization to the posterior circulation through the PTA Saltzman type 1 Hypoplasia of the VAs and VB Saltzman type 2 Internal carotid artery (ICA) and PTA occlusion Saltzman type 1 Arteries involved and saltzman classification of PTA ICA endarterectomy Unknown None Unknown None Urokinase Heparine Treatment Table 1 Summary description of PTA related stroke episodes found upon literature review, cases are ordered according to patient’s age at symptom onset No deficits Unknown Unknown Unknown No deficits Hemiparetic gate Residual right motor deficit Patient outcome Ferreira et al. BMC Neurology (2019) 19:257 Page 3 of 6 Symptoms 1. Left facial palsy, right hemiparesis and left medial longitudinal fasciculus syndrome. 2. Hemiparesis and hemihypesthesia including pain and touch on the left side. Sudden loss of consciousness and quadriplegia Sudden loss of consciousness and left hemiparesis Dysarthria and right hemiparesis Weakness of the lower extremities, and blindness of the left eye Mild dysmetria and intentional tremor affecting the right arm, tandem gait ataxia, and right-sided hemianopia, preceded several weeks by intermittent vertigo Dysphasia and dysarthria with dizziness and cough Identification 63yo M (1998) [25] 67yo M (2015) [26] 67yo M (2015) [27] 70yo M (2010) [28] 73yo M (2014) [29] 76yo M (2016) [30] 80yo F (2010) [29] Right pontine infarct Border-zone territory between the MCA and the posterior cerebral artery (PCA) Multiple infarcts in the anterior and posterior circulation (cardioembolisms) Left pontine infarction None Right cerebral hemisphere 1. Left basal part of the pons 2. Right basal part of the pons Territory Confirmed by neuroimaging PTA between left vertebral artery and ipsilateral external carotid artery, right vertebral artery hypoplasia Saltzman type 2 Left ICA stenosis (75%) and left PTA, BA hypoplasia below the PTA Saltzman type 1 Persistent primitive trigeminal artery, basilar artery hypoplasia Saltzman type 1 Embolic occlusion of the PTA Saltzman type 1 Right ICA occlusion with PTA, BA, posterior cerebral artery and superior cerebellar artery hypoperfusion Saltzman type 1 Right middle cerebral artery (MCA) and BA occlusion Saltzman type 1 Basilar artery middle portion stenosis (80%) Saltzman type 1 Arteries involved and saltzman classification of PTA Unknown ICA endarterectomy Unknown rt-PA rt-PA and thrombectomy through the ICA and PTA Thrombectomy of the MCA and of the BA through the PTA 1. None 2. Urokinase Treatment Unknown Resolution of the intermittent vertigo Unknown No deficits Mild facial and left hand paresis Lucid and with moderate left hemiparesis 1. Slight left facial palsy and right hemiparesis 2. No new deficits Patient outcome Table 1 Summary description of PTA related stroke episodes found upon literature review, cases are ordered according to patient’s age at symptom onset (Continued) Ferreira et al. BMC Neurology (2019) 19:257 Page 4 of 6 Ferreira et al. BMC Neurology (2019) 19:257 Page 5 of 6 Fig. 2 – Head CT scan showing the PTA, a) volume rendering technique showing PTA anastomosing the left ICA with de the terminal portion of the BA, b) arrow indicating PTA originating from the left ICA, c) arrow showing hypoplastic BA proximal to the anastomosis. IC – internal carotid artery, T – trigeminal artery, B – basilar artery, P – posterior cerebral artery stem infarction [31]. In the case of BA occlusion however, if the occlusion is proximal to the insertion of the PTA, the PTA can have a protective effect in the distal territory [25]. In the case of an anterior circulation thrombus, the PTA can lead to migration of the thrombus to the BA, possibly causing a posterior circulation stroke [20, 24]. Finally, in BA hypoplasia, PTA also opens the possibility for thrombectomy in the posterior circulation [26, 27]. Despite all the variety of ischemic events related with PTA, thrombosis of this vessel remains a rare phenomenon, although there is a case report of PTA thrombosis related with internal carotid dissection [18]. Our patient had a congenital Saltzman type 1 PTA variant and presented with symptoms suggestive of acute brainstem infarction that partially resolved after the administration of rt-PA. The clinical manifestations are compatible with an ischemic lesion of the basis pons, causing an ataxic hemiparesis syndrome, and extending to the tegmental region, affecting the longitudinal medial fasciculus. This suggests that the most affected territory was dependent from the small perforating vessels of the BA. Furthermore, the patient was exposed to extenuating exercise when the symptoms started, this favors the possibility that the event was due to a steal phenomenon, but the fact that the patient had no great artery disease and the fact that the patient improved after rt-PA suggests that the mechanism could also have been thromboembolic. Upon literature review both mechanisms seem possible. We would also like to emphasize that the reported episodes of vertigo probably corresponded to previous transient ischemic attacks (TIA) in the same area, possibly being the first sign of vertebrobasilar insufficiency. To our knowledge this is the first case study to point out the possibility of having several transient episodes (in this case of vertigo) compatible with vertebrobasilar insufficiency as a premonitory sign of PTA related stroke. Abbreviations AICA: Anterior inferior cerebellar artery; BA: Basilar artery; ICA: Internal carotid artery; NIHSS: National Institutes of Health Stroke Scale PcoA - posterior communicating artery; PTA: Persistent trigeminal artery; rt-PA: Recombinant tissue plasminogen activator; SCA: Superior cerebellar artery; TIA: Trasient ischemic attacks; VA: Vertebral artery Acknowledgements Not Applicable. Authors’ contributions AF, MD – main author. PSC, MD – data interpretation and substantively revised the work. VTC, MD PhD - substantively revised the work. All authors have read and approved the manuscript. Funding No funding was obtained for this article. Availability of data and materials Not applicable. Ethics approval and consent to participate Not applicable. Consent for publication The principal author has received the consent form from the patient concerned in the case we report to publish his clinical data, we have the consent form in file in case it is requested by the editor. Competing interests No competing interests to be declared. Author details 1 Neurology Department, Hospital Pedro Hispano, ULS Matosinhos, Porto, Portugal. 2EPIUnit, Institute of Public Health University of Porto, Porto, Portugal. Received: 10 July 2019 Accepted: 9 October 2019 References 1. Meckel S, Spittau B, McAuliffe W. The persistent trigeminal artery: development, imaging anatomy, variants, and associated vascular pathologies. Neuroradiology. 2013;55(1):5–16. 2. Azab W, Delashaw J, Mohammed M. Persistent primitive trigeminal artery: a review. Turk Neurosurg. 2012;22(4):399–406. 3. Uchino A, Kato A, Takase Y, Kudo S. Persistent trigeminal artery variants detected by MR angiography. Eur Radiol. 2000;10(11):1801–4. 4. O'Uchi E, O'Uchi T. 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