3.303 Posturographic correlates of postural instability in patients with idiopathic Parkinson's disease on and off medication

Abstract

Background: Researches characterizing postural instability in idiopathic Parkinson's disease (IPD) provides insights into the possibly disturbed mechanisms for postural control. There is however paucity of researches that are interested in providing multisystem evaluation for detection of possible contribution of different systems to balance disturbance in IPD patients. Objective: To study posturographic correlates of postural instability in IPD and on antiparkinsonian medication to determine the exact pathophysiologic mechanisms underlying their balance problems. Methods: Fifteen IPD patients (on and state) were compared to ten healthy control subjects. Patients underwent clinical examination including Unified Parkinson Disease Rating Scale (UPDRS) and Hoehn Yahr Scale together with posturographic evaluation including sensory organization test, motor control test, and neurotesting (akinesia test, retropulsion test, and bradykinesia test). The posturographic parameters were compared to those of control group. Results: Compared to controls, IPD patients off state had significantly low composite equilibrium score and significantly low visual ratio and visual preference ratio of the sensory organization test. Elevated automatic postural thresholds were detected only to medium sized forward translation during motor control test. Significantly prolonged reaction and movement times together with defective pacing characterized patients’ movement during neurotesting. Partial improvement was found in all clinical subscales and in some of posturographic parameters in response to antiparkinsonian medication. Conclusion: Both sensory and motor components of balance are important contributors to postural instability in IPD. Visual dysfunction dominated sensory abnormality. Motor abnormalities contributing to postural disturbance may be the result of increased rigidity, defective timing components of balance, and defective force generation. (Egypt J Neurol Psychiat Neurosurg. 2010; 47(1): 185-196)