Relationship between freezing of gait (FOG) and other features of Parkinson's: FOG is not correlated with bradykinesia

Background: The pathophysiology of freezing of gait (FOG) is unclear. Objective: To assess the relationships between FOG and other parkinsonian features in Parkinson's disease (PD), focusing on levodopa effects. Methods: Nineteen PD patients with significant FOG in "off" were assessed while "off" and "on". Three observers independently viewed videotapes of a 130-m walk and scored FOG frequency. The Unified Parkinson's disease Rating Scale was used to evaluate clinical state. Results: FOG frequency was not correlated with other parkinsonian features in "off" and only with speech and writing in "on". Levodopa significantly decreased FOG frequency (p < 0.001). This reduction was strongly correlated with improvement of tremor (R = 0.80, p < 0.01) and speech (R = 0.62, p < 0.05), but not with improvement in rigidity, bradykinesia, or balance. Conclusion: Levodopa decreases FOG in PD. FOG is apparently an independent motor symptom, caused by a paroxysmal pathology that is different from that responsible for bradykinesia, rigidity or postural instability. (C) 2003 Elsevier Science Ltd. All rights reserved.