The protective effect of persistent trigeminal artery in patients with ischemic stroke
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Almost all case reports related to persistent trigeminal artery indicated that the existence of persistent trigeminal artery may increase the risk of ischemic stroke. However our case demonstrated that the persistent trigeminal artery may also play a protective role in preventing severe ischemic stroke by functioning as collateral circulation.
We reported a patient with left internal carotid artery occlusion with persistent trigeminal artery manifesting only as a minor acute ischemia stroke exhibiting acute onset of dizziness and difficulty in walking. Brain MRI showed two small areas of restricted diffusion on diffusion-weighted imaging in the left hemisphere. The digital subtraction angiography showed his left middle cerebral artery and bilateral anterior cerebral artery were supplied by the basilar artery via a persistent trigeminal artery. Furthermore, CT perfusion showed no remarkable difference between the two hemispheres.
Persistent trigeminal artery may have a protective role in the setting of an acquired occlusion of homolateral internal carotid artery. Therefore, it is important to fully assess the presence of the persistent trigeminal artery in acute ischemic stroke.
KeywordsPersistent trigeminal artery (PTA) Cerebrovascular disorders Stroke Anastomosis Risk
Digital subtraction angiography
Internal carotid artery
Persistent trigeminal artery
Persistent trigeminal artery (PTA) is one of the most common types of the carotid- vertebrobasilar anastomoses occurred incidentally in adults, with reported incidence of 0.1 to 0.6% of all cerebral angiograms . Due to its anatomical proximity to the trigeminal nerve, there have been some case reports on its association with trigeminal neuralgia. Similarly, there are also some reports on the associations between the PTA with intracranial aneurysms and carvernous sinus fistulas [2, 3]. Moreover it is rarely reported in the setting of acute ischemia stroke, especially with the internal carotid artery (ICA) occlusion. Meanwhile, Almost all of these case reports related to stroke indicated that it may increase the risk of ischemic stroke [4, 5, 6]. However, its protective effect in the setting of ischemic stroke was rarely reported. Herein, we reported a case of left ICA occlusion with PTA manifesting only as a minor acute ischemia stroke. And its role in cerebrovascular disease has also been discussed.
A 64-year-old man with a 13-year history of coronary heart disease and 7-year history of hypertension was admitted to our hospital for acute onset dizziness and unsteady gait for one week. He reported acute onset of dizziness and difficulty in walking, and these symptoms would become worsened when he got up from the bed or sofa. On admission, his blood pressure was 135/85 mmHg and heart rate was 66 beats/min; and neurological examination revealed nystagmus on horizontal gaze. His pupillary reflexes and extraocular movements were intact, no limb weakness and sensory deficits were found; and bilateral finger--to-nose and heel-to-shin tests were normal. Additionally, bilateral Babinski signs were absent. However, Romberg sign was impossible to evaluate as the patient could not be able to cooperate with further examination.
Discussion and conclusions
The role of PTA in ischemic stroke has not been fully understood. The vast majority of case reports on the role of PTA in the setting of ischemic cerebrovascular disease supported the viewpoint that the existence of PTA may increase the risk of ischemic stroke [4, 5, 6]. This mechanism has been well explained by the hypothesis that PTA may play a role as an embolic pathway to the posterior circulation from the ICA . Some other rare instances had also been reported such as PTA thrombosis resulting from the extensive of thrombosis in the occlusive carotid dissection attributed to brainstem infarction . Similarly, the compression of pons from the PTA also could cause brainstem transient ischemia stroke . These two aforementioned cases are also in line with the above viewpoint that, existence of PTA may increase the risk of ischemic stroke.
This case report has some strength. Firstly, our case indicated that the PTA may also play a protective role in preventing severe ischemic stroke by functioning as collateral circulation. This was consistent with the finding that the PTA has a collateral support value in patients who underwent the balloon occlusion test of the ICA . Secondly, to the best of our knowledge, this was the first case in a real patient that demonstrated the protective role of PTA in the setting of acute occlusive cerebrovascular disease by using the combination of the cerebral angiogram and CT perfusion. In most instances, the flow direction of patients with PTA was from the carotid to the basilar artery, which well explained the reason why patient with ICA stenosis and PTA may develop ischemic stroke of the posterior circulation . However, in accordance with the case of Lochner and colleagues , the cerebral angiogram of our case showed that the flow direction of the PTA was from the basilar artery to the ICA territory. Moreover, since there was no remarkable difference between the two hemispheres, the CT perfusion further proved the protective role of PTA. So it can be assumed that the PTA may be crucial to the patients in the presence of ICA occlusion or severe stenosis.
In conclusion, PTA may have a protective role in the setting of an acquired occlusion of homolateral ICA. Therefore, it is important to fully assess the presence of the PTA in acute ischemia stroke.
The authors thank Lvming Zhang for her assistance in the preparation of the images.
YK, YCX and PFW evaluated and managed the patient. YHX and PFW performed the DSA. YCX wrote the manuscript. PFW finalized the manuscript. All authors read and approved the final manuscript.
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The written informed consent has been obtained from the patient for publication this Case Report and any accompanying images.
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
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