Unilateral Aplasia versus Bilateral Aplasia of the Vertebral Artery: A Review of Associated Abnormalities

Table 6

Left VA aplasia versus bilateral VA aplasia.

Number	Parameters			Left VA		Bilateral VA
				46 cases		31 cases
(1)	Incidence			59.74%		40.26%
(2)	Gender
	Female			31.16%		14.28%
	Male			25.97%		24.67%
	Female/male/unknown gender			45.44%/50.64%/3.89%
(3)	Persistence of CVBA
	Unilateral persistence of CVBA			82.60%		59.07%
	Bilateral persistence of CVBA			4.35%		34.48%
	Persistence of two different CVBAs			4.34%		3.22%
	Persistence of determined CVBA
	PPIA			43.47%		54.83%
	PPHA			34.78%		32.25%
	PPTA			13.04%		9.67%
	Unusual arterial anastomoses					6.45%
(4)	Additional vascular variants
		Uni-	Bi-	Uni-	Bi-	Uni-	Bi-
		CCA		3.22%
		ICA		6.52%
		ACA		3.22%
	Associated aplasia of other blood vessels	PCoA	PCoAs	8.69%	8.69%	3.22%	9.67%
		BA				3.22%
		AICA		3.22%
		SA		3.22%
		Some dural sinuses/bilateral; IJV				3.22%
	Hypoplastic right VA			34.78%
	Unusual origin or side branches or termination or hypoplasia of other arteries or additional anastomoses			39.13%		41.93%
(5)	Associated vascular pathology
	Aneurysms of definitive arteries			8.69%		19.35%
	Aneurysms of CVBAs			4.34%		3.22%
	Different cerebral pathology (except that of aneurysms)			41.30%		41.93%
	Noncerebral pathology			4.34%		0

VA, vertebral artery; CVBA, carotid-vertebrobasilar anastomosis; PPIA, persistent primitive proatlantal intersegmental artery (without mark of the type); PPHA, persistent primitive hypoglossal artery; PPTA, persistent primitive trigeminal artery; ECA, external carotid artery; ICA, internal carotid artery; ACA, anterior cerebral artery; PCoA, posterior communicating artery; BA, basilar artery; SA, subclavian artery; IJV, internal jugular vein.