Static and dynamic balance function in spasmodic torticollis

The consequences of abnormal head posture on static and dynamic balance ski ll were studied in a group of 10 patients with idiopathic spasmodic tortico llis (ST). In static conditions, body sway was assessed using a conventiona l force platform with eyes open and with eyes closed. Standardized dynamic balance conditions were produced using a rocking platform; lateral and ante roposterior dynamic balance skills were assessed by measuring linear displa cement both of the body base and of the head. Dynamic tests were repeated 6 weeks after botulinum toxin treatment in all patients. Patients' results w ere compared with those obtained from 10 control subjects. In static condit ions, ST patients did not differ from control subjects, but in dynamic cond itions, balance parameters were greater in the patient group than in the co ntrol group. This was true for the lateral direction and for dynamic balanc e parameters recorded both before and after botulinum toxin treatment. Eye closure significantly increased dynamic balance parameters in both groups. However, the effect of eye closure was greater in the patient group than th e control group, especially for lateral sway, suggesting that patients used vision to compensate for the dynamic balance disturbance induced by the sp asmodic torticollis. Despite a significant improvement of head posture in a ll patients after botulinum toxin treatment, no significant changes in dyna mic balance parameters were observed between the first and second test. The possible origins of the dynamic balance disturbance observed in ST patient s are discussed.