Vertebral arteries and cervical rotation: modeling and magnetic resonance angiography studies.
OBJECTIVE
To determine whether lumen narrowing in vertebral arteries during atlanto-axial rotation is due to stretch or localized compression.


METHODS
Experiments with models were made in a private chiropractic clinic, whereas studies of cadaveric specimens were performed in an anatomy laboratory. Doppler ultrasound and magnetic resonance angiography (MRA) studies were carried out in the radiology department of a public hospital.


METHODS
Eight patients had their vertebral arteries examined by use of a Doppler velocimeter and MRA.


METHODS
Stenosis of the vertebral arteries caused by stretch, localized compression, or kinking.


RESULTS
All 16 vertebral arteries from the 8 patients displayed no changes in their lumen dimensions with full cervical rotation, although curves in each of the arteries did change. The model and cadaveric vertebral arteries demonstrated localized compression or kinking of the vessel wall with atlanto-axial rotation contralaterally but revealed no evidence of major contribution of stretching to stenosis.


CONCLUSIONS
The lumen of vertebral arteries is usually unaffected by atlanto-axial rotation. In cases where there is stenosis, this is mainly due to localized compression or kinking. These findings are relevant to premanipulative screening of vertebral arteries with Doppler ultrasound scanning.
Haynes
Michael J
MJ
The Department of Anatomy and Human Biology, The University of Western Australia, Australia.
Cala
Lesley A
LA
Melsom
Alison
A
Mastaglia
Frank L
FL
Milne
Nicholas
N
McGeachie
John K
JK
D000328:Adult; D001268:Atlanto-Axial Joint / Q000098:blood supply; D002102:Cadaver; D002574:Cervical Vertebrae; D003251:Constriction, Pathologic; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D018810:Magnetic Resonance Angiography / Q000379:methods; D008297:Male; D026882:Manipulation, Chiropractic / Q000592:standards*; D008875:Middle Aged; D008954:Models, Biological; D011859:Radiography; D012399:Rotation; D013314:Stress, Mechanical; D018608:Ultrasonography, Doppler; D014711:Vertebral Artery / Q000000981:diagnostic imaging* / Q000473:pathology