Abnormal head posture a new paradigm

Purpose. To determine the most common ocular causes and types of anomalous head position and give details of their functional features. Material and methods. The research included 105 patients with an anomalous head position. Depending on the oculomotor pathology, patients were divided into 6 groups. 1st group – 10 patients with Brown syndrome, 2nd group – 20 patients with Duane syndrome of types 1 and 2, 3rd group – 30 patients with nystagmus, 4th group – 30 patients with n. abducensparalysis, 5th group – 15 patients with n. trochlearisparalysis, and control 6th group – 20 patients with one of the above pathology, but without anomalous head posture (AHP). Results. Out of 105 patients with AHP, 83.8% had both fusion and stereopsis. There was no statistical difference in the rate of fusion or stereopsis among the different AHP types (p=0.580). The control group showed accurately low scores of stereopsis and fusion loss (5.3%) (p=0.001). The overall incidence of amblyopia in all groups of patients with AHP (with Brown, Duyane syndrome, with nystagmus by 3.7 times, with paralysis and paresis of n. abducensand n. trochlearis) is statistically significantly lower (p<0.001) than in the control group. Conclusion. The most common ocular causes of anomalous head position are nystagmus and paralysis of the abducens nerve, as well as Duane syndrome and paralysis of the trochlear nerve. Head rotation is most commonly associated with congenital nystagmus, Duane syndrome, and n. abducens paralysis and paresis. Head tilt or various combinations of head tilt with a raised chin is most characteristic of n. trochlearis paralysis and paresis and Brown syndrome. AHP formation is a «protective» mechanism in terms of developing amblyopia and loss of binocular single vision. Key words: abnormal head position, binocular vision, stereopsis, amblyopia.