The position of the head in space: a kinematic analysis in patients with cervical dystonia treated with botulinum toxin.

Many instruments have been employed in recent years in order to quantify the posture and motion of the head in normal and pathological subjects. Evaluations of this type present many difficulties related to the influence of individual and external factors and to the accuracy of the system used. In patients with cervical dystonia (CD) the only rating scales currently used are semi-quantitative and subjective. More precise information on disease severity and response to the treatment is needed. Posture and motion of the head were evaluated by means of ELITE motion analyser (BTS, Milan, Italy) in 6 patients with the left laterocollis form of CD undergoing treatment with botulinum toxin (BTX). The method emerged as very useful for the quantification of the therapeutic response (which was more marked in motion than in posture). We found an inverse relationship between the degree of motion improvement and the restriction of motion before treatment.