Bilateral persistent trigeminal artery variants diagnosed by MR angiography

Posterior circulation ischaemic stroke-a review part I: anatomy, aetiology and clinical presentations

Posterior circulation ischaemia is a clinicopathological condition with complex symptomatology associated with an infarction within the vertebrobasilar arterial system. Posterior circulation strokes account for about 20-25% of all ischemic strokes and remain a significant cause of patient disability and mortality. Diagnosis can be challenging because presenting symptoms are often non-focal and because there is a substantial overlap in symptoms and signs of ischaemia in the anterior circulation. Despite better imaging techniques, diagnosis and treatment of life-threatening conditions, such as basilar artery occlusions, are often delayed. Therefore, early detection of symptoms and causes of posterior circulation ischaemia is essential for choosing the most appropriate therapy. In this review, we summarise the anatomy, aetiology, typical presentations and characteristic findings of common strokes resulting from disease in the vertebrobasilar arterial system.

Right persistent trigeminal artery variant (PTAV) and tiny left PTA associated with bilateral ophthalmic arteries arising from the cavernous segments of the internal carotid arteries

Persistent trigeminal artery (PTA) and its variant (PTAV) are the most prevalent types of carotid-vertebrobasilar anastomosis, but bilateral anastomoses are exceedingly rare. We report a case of a right PTAV and tiny left lateral-type PTA from which the cerebellar artery (presumed anterior inferior cerebellar artery) arose. And also, bilateral ophthalmic arteries arose from the cavernous segments of the internal carotid arteries and entered the orbits via the superior orbital fissures. Selective cerebral angiography, especially 3-dimensional angiography, is superior to magnetic resonance (MR) angiography to identify rare variations of the cerebral arteries. Careful observation of MR angiographic source images is important for identifying unique arterial coursing.

A Functional Perspective on the Embryology and Anatomy of the Cerebral Blood Supply

The anatomy of the arterial system supplying blood to the brain can influence the development of arterial disease such as aneurysms, dolichoectasia and atherosclerosis. As the arteries supplying blood to the brain develop during embryogenesis, variation in their anatomy may occur and this variation may influence the development of arterial disease. Angiogenesis, which occurs mainly by sprouting of parent arteries, is the first stage at which variations can occur. At day 24 of embryological life, the internal carotid artery is the first artery to form and it provides all the blood required by the primitive brain. As the occipital region, brain stem and cerebellum enlarge; the internal carotid supply becomes insufficient, triggering the development of the posterior circulation. At this stage, the posterior circulation consists of a primitive mesh of arterial networks that originate from projection of penetrators from the distal carotid artery and more proximally from carotid-vertebrobasilar anastomoses. These anastomoses regress when the basilar artery and the vertebral arteries become independent from the internal carotid artery, but their persistence is not uncommon in adults (e.g., persistent trigeminal artery). Other common remnants of embryological development include fenestration or duplication (most commonly of the basilar artery), hypoplasia (typically of the posterior communicating artery) or agenesis (typically of the anterior communicating artery). Learning more about the hemodynamic consequence that these variants may have on the brain territories they supply may help understand better the underlying physiopathology of cerebral arterial remodeling and stroke in patients with these variants.

Bilateral persistent trigeminal arteries with unilateral trigeminal artery to cavernous sinus fistula. A case report

A 59-year-old man who denied a history of trauma presented with left pulsatile tinnitus and left orbital swelling for six months. Digital subtraction angiography showed a left persistent trigeminal artery (PTA) with a trigeminal artery to cavernous sinus (trigeminal-cavernous sinus) fistula and a right PTA. Transarterial detachable coil embolization of the left trigeminal-cavernous sinus fistula was performed, and the symptoms subsided. There has been no report of bilateral PTAs with a spontaneous fistula connected from one PTA to the ipsilateral cavernous sinus. This paper reports such a rare circumstance.