Risk stratification of vertebral artery vulnerability during surgery for XXXX with or without an occipitalized atlas.

@entity1 @entity1317 @entity717 @entity9807 @entity130
CONTEXT: Variability in dimensions and course of vertebral artery (VA) makes it vulnerable to injury during surgery for @entity9807 (AAD) with or without an occipitalized atlas. AIMS: This prospective study attempts to define anatomical variations that render VA at the craniovertebral junction (CVJ) vulnerable to injury during transoral decompression and posterior stabilization procedures; and, to propose a classification that helps in preoperative risk stratification. SETTINGS AND DESIGN: A prospective study. MATERIALS AND METHODS: 104 @entity1 (65 with AAD; 39 controls) underwent a three-dimensional multiplanar computed tomographic angiogram to study anatomical variations in VA size, course, and anomalous medial deviation as well as in the type of axial isthmus and @entity717 /tilt at the CVJ. The VA/foramen transversarium diameter; "stretched loop" sign of VA; and C1-2 facet joint angle were also assessed. STATISTICAL ANALYSIS USED: A medial VA deviation that brought it in close proximity to the trajectory of the surgical approach was evaluated (P  <= 0.05 significant). RESULTS: An increased predisposition to @entity1317 was present in 23 (35.4%) @entity1 (persistent first intersegmental artery [n = 20; 30%]; fenestrated VA [n = 1; 1.53%], and low-lying posterior inferior cerebellar artery [n = 2; 3.0%]) where VA crossed the C1-2 facet joint; 8 (12%) with an anomalous medial deviation; 12 (18%) with a high-riding VA at C2 and a narrow axial isthmus; and 13 (20%) with rotation/tilt at the CVJ. A normal score of 5 was obtained in 21 @entity1 ; and a score of 6-9 (that progressively indicated an increased vulnerability of VA to @entity130 ) in 44 @entity1 . The "AAD with an occipitalized atlas" group was associated with a significant medial deviation of VA (right: P = 0.00 and left: P = 0.001). CONCLUSIONS: A preoperative detailed risk assessment of anatomical variations in the size and course of VA at the CVJ significantly reduces chances of its @entity130 .
