Left embryonic posterior cerebral artery

Embryonic posterior cerebral artery is actually a disease. If you find that you have left embryonic posterior cerebral artery during examination, don't panic. Although patients with left embryonic posterior cerebral artery disease are prone to headaches, high blood pressure and other diseases, left embryonic posterior cerebral artery disease is not incurable. Next, we will introduce to you the basic knowledge of the embryonic posterior cerebral artery.

Fetal posterior cerebral artery

The posterior cerebral artery (fPCA) is a common variation of the circle of Willis. According to its structure, it is divided into two types: complete embryonic posterior cerebral artery and partial embryonic posterior cerebral artery. The complete embryonic posterior cerebral artery refers to the posterior cerebral artery without anterior communicating segment, which is directly derived from the posterior communicating artery; the partial type is mainly supplied by the internal carotid artery. The incidence of unilateral pfPCA was 11%-29%, and the incidence of bilateral pfPCA was 1%-9%. The incidence of unilateral cfPCA is 4%-26%, while the incidence of bilateral cfPCA is only 2%-4%.

Studies have shown that collateral compensation plays an important compensatory role in cerebral ischemic diseases. Congenital absence or maldevelopment of collateral branches will affect the prognosis of the disease. The blood supply of cfPCA comes entirely from the ipsilateral internal carotid artery, and there is no P1 connection between the ipsilateral anterior and posterior circulations. In addition, the blockage of the tentorium cerebelli prevents the anterior and posterior circulations from being anastomosed, and ultimately makes it impossible for the ipsilateral anterior and posterior circulations to form compensation. When the ipsilateral internal carotid artery system or vertebral basilar artery system is ischemic, it may cause more serious ischemic diseases. The blood supply of pfPCA mainly comes from the internal carotid artery, and a small part may come from the posterior circulation. If the diameter of P1 is not much different from that of the ipsilateral PCoA, there may still be some connection. If P1 is poorly developed, its anterior and posterior circulations cannot establish effective collateral compensation.

The presence of embryonic posterior cerebral arteries does not increase the incidence of occipital lobe infarction, but rather reduces it. However, when the posterior cerebral artery on the side of occipital lobe infarction is a complete embryonic posterior cerebral artery, we consider it to be an "anterior circulation infarction". If the occipital lobe has a dual blood supply, lesions in the anterior and posterior circulation may cause it. Embryonic posterior cerebral artery is also associated with posterior communicating artery aneurysm and migraine with aura. Its presence may also prevent white matter degeneration from occurring.

Imaging diagnosis

There are several methods for diagnosing fPCA, including digital subtraction angiography (DSA), CTA, magnetic resonance angiography (MRA), and ultrasound. DSA is an invasive examination that requires pressurized injection of contrast agent in the anterior and posterior circulations. It does not reflect the physiological state of the circle of Willis, but it is still the gold standard for the diagnosis of small blood vessels. CTA diagnosis of embryonic posterior cerebral artery is highly consistent with DSA, but requires intravenous injection of contrast agent. MRA is noninvasive, can distinguish blood vessels of 0.8 mm, and can reflect the clinically significant variations of the Willis circle. Transcranial color Doppler ultrasound (TCCD) can demonstrate the embryonic posterior cerebral artery.