Hand preference is selectively related to common and internal carotid arterial asymmetry

ABSTRACT

This study documents relationships between handedness and carotid arterial asymmetries. The article is divided into two sections, considering first geometric (n = 195) and then haemodynamic (n = 228) asymmetries. In the geometric study, diameters, lengths, and angles of the common carotid arteries in left and right-handed participants were measured using computed tomography angiography scans. Resistance to blood flow was calculated according to Poiseuille’s formula. In the haemodynamic study, peak systolic and end-diastolic velocity, vessel diameter, and volume flow rate of the common, internal, and external carotid arteries were measured in left and right-handed participants, using Doppler ultrasonography. The findings reveal for the first time that the extracranial arteries supplying the cerebral hemispheres are asymmetrical in a direction that increases blood flow to the hemisphere dominant for handedness. Significant handedness interactions were identified in arterial length, diameter, resistance to blood flow, velocity and flow volume rate (p < .001). Arterial resistance and volume flow rates significantly predicted hand preference and proficiency. Our findings reveal a vascular correlate of handedness, but causality cannot be determined from this study alone. These asymmetries appear to be independent of aortic arch anomalies, suggesting a top-down, possibly demand-driven, pattern of development.

KEYWORDS:

• Handedness
• cerebral lateralization
• common and internal carotid arteries
• arterial asymmetry
• arterial geometry and haemodynamics

Acknowledgements

We are indebted to Morton and Partners Radiologists, Prof Leonie Scholtz from Scholtz and Partners Diagnostic Radiologists, Dr Albert L. Spanengberg and Casper van Vyk from Burger Radiologists, and Kevin Ernstzen from Groote Schuur Hospital for supplying the case material for the geometric analysis. We would also like to thank Nadia Davids for her help in administrating the Doppler ultrasound. The financial assistance of the Harry Crossley Foundation is acknowledged.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Anica Jansen van Vuuren http://orcid.org/0000-0002-6775-4216