Carotid blood flow in abnormal head posture: a prospective observational study exploring facial asymmetry in strabismus.

PURPOSE: To investigate whether abnormal head posture (AHP) induces changes in common carotid artery blood flow (CCBF), thereby leading to the development of facial asymmetry in the setting of strabismus and ocular torticollis. METHODS: This was a prospective observational study of pediatric subjects in an urban ophthalmology clinic who underwent bilateral carotid artery ultrasound examination with spectral Doppler in an upright, straight-head posture and with a head tilt of 30°-45° to the right and left. The primary outcome was change in carotid flow on the side of the head tilt. The secondary outcome was change in blood flow on the contralateral side of the head tilt. RESULTS: Seventeen subjects were enrolled, and 34 carotid arteries were assessed. There was no significant difference between upright, straight-head position and head tilt in ipsilateral (7.8 ± 1.8 mL/s vs 7.5 ± 2.0 mL/s [P = 0.4312]) or contralateral (7.8 ± 1.8 mL/s vs 8.1 ± 2.4 mL/s [P = 0.3401]) CCBF. CONCLUSIONS: CCBF does not fluctuate with AHP and thus does not appear to be the etiology for facial asymmetry in strabismus.