Freezing of gait in patients with advanced Parkinson's disease

Background. Freezing of Gait (FOG) is one of the most disturbing and least understood symptom in advanced stage of Parkinson's disease (PD). The contr ibution of the underlying pathological process and the antiparkinsonian tre atment to the development of FOG are controversial. Objective. To study the relationships between clinical features of PD and t herapeutic modalities in patients with advanced PD and FOG. Methods. Consecutive patients with 5 years or more of PD symptoms (n = 172) (99 men) with mean age at symptoms onset of 58.3 +/- 13.2 years and mean s ymptoms duration of 11.8 +/- 5.6 years were studied. Clinical data were col lected during the last office visit through physical examination, detailed history, review of patients' charts, and other documents. A patient was con sidered as "freezer" if he/she reported recent experience that the legs got stuck to the ground while trying to walk. The presence df dyskinesia, earl y morning dystonia or significant postural reflex abnormalities were assess ed through history and neurological examination. Duration of treatment with antiparkinsonian drugs was calculated from history charts. Chi square and t test were used to compare the patients with and without FOG. Logistic reg ression was used for the comparison of association between the presence of FOG (dependent variable) disease duration and disease stage (explanatory va riables) and duration of treatment with anti-parkinsonian drugs. Results. The study population consisted of 45 patients at Hoehn and Yahr (H &Y) stage 2.5 (26%), 104 patients at stage 3 (60.5%), and 23 patients at H& Y stages 4-5 (13.5%). Ninety one patients (53%) reported FOG at the time of the study. Severity of the disease expressed by H&Y stage at "off" was a s ignificant contributing factor for FOG with a significant trend (z = 4.38, p < 0.0001), as was longer duration of levodopa treatment, and confirmed by FOG using the multivariate logistic regression (p = 0.01 and p = 0.004, re spectively). Using a univariate model, longer duration of treatment with do pamine agonists contribute to the appearance of FOG (p = 0.07) while longer duration of amantadine treatment decreased the appearance of FOG (p = 0.09 ). There was a significant association between FOG and the presence of dysk inesia (p < 0.002), early morning foot dystonia (p < 0.003) and significant postural instability (p < 0.0005). Conclusion. FOG is a common symptom in advanced PD. It is mainly related to disease progression and levodopa treatment.