Review Article

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

Table 8

Single left VA aplasia versus right VA aplasia.

NumberParametersLeft VA aplasiaRight VA aplasia
46 cases31 cases

(1)Incidence59.74%40.26%

(2)Gender
 Female31.16%18.18%
 Male25.97%18.18%
 Female/male/unknown gender49.34%/44.15%/6.49%

(3)Persistence of CVBA
 Unilateral persistence of CVBA82.60%80.64%
 Bilateral persistence of CVBA4.34%0
 Persistence of two different CVBA4.34%0
 Persistence of determined CVBA
  PPIA43.47%16.13%
  PPHA34.78%51.61%
  PPTA13.04%6.45%
  Unusual arterial anastomoses06.45%

(4)Additional vascular variants
 Associated aplasia of other blood vesselsUni-Bi-Uni-Bi-Uni-Bi-
CCA3.22%3.22%
ECA3.22%
ICA6.45%6.45%
ACA3.22%3.22%
PCoAPCoAs8.69%12.90%6.45%
BA3.22%
AICA3.22%
SA trunk3.22%
SA branches3.22%
 Hypoplastic (opposite) VA34.78%41.93%
 Unusual origin or side branches or termination or additional anastomoses39.13%32.25%

(5)Associated vascular pathology
 Aneurysms of definitive arteries8.69%25.80%
 Aneurysms of CVBAs4.34%3.22%
 Other cerebral pathology41.30%35.48%
 Noncerebral pathology4.34%9.67%

VA, vertebral artery; CVBA, carotid-vertebrobasilar anastomosis; PPIA, persistent primitive proatlantal intersegmental artery; PPHA, persistent primitive hypoglossal artery; PPTA, persistent primitive trigeminal artery; CCA, common carotid artery; ECA, external carotid artery; ICA, internal carotid artery; ACA, anterior cerebral artery; PCoA, posterior communicating artery; BA, basilar artery; SA, subclavian artery.