Tortuosity of cervical ICA clinical significance

Variations in the course of cervical ICA are reported in the literature as coiling, looping, kinking or tortuousness of the vessel.
The clinical relevance of morphological anomalies of extracranial ICA is a matter of debate because of up to date the natural  history of kinking, coiling and tortuosities of this artery is not well known.
It is well known that the intracranial portions of the ICA are highly tortuous, while its cervical course is almost straight. There are two points of fixation at the cervical portion of the ICA: at the bifurcation of the common carotid artery and at its entry into the temporal bone. If the vessel is longer than the distance between these two points, curvatures and loops develop.
Several authors consider these variations as congenital anomalies of the aortic arch arteries  while others consider it being caused by artheriosclerosis, fibromuscular hyperplasia , degenerative lesions, hypertension or aging .
Tourtuous extracranial ICA needs no treatment as long as the patient does not have a cerebrovascular ischemic sign or a neurological complaint.

Duplication of fetal PCA MRA

3 D TOF Non Contrast MR Angiography of Brain shows:
Non visualisation of left MCA from its origin along with its cortical branches implies to occlusion.
Left PCA has fetal origin - a common anatomical variation but in that it shows Duplication, two fetal PCAs on left side seen arising from ICA - a rare normal anatomical variation.