Objective and self-perceived lower limb weakness in Parkinson’s disease

BACKGROUND: Lower limb weakness is a long-recognized symptom in patients with Parkinson’s disease (PD), described by James Parkinson in his seminal report on ‘paralysis agitans’. However, little is known on the frequency, clinical correlations, and association with objective decrease in muscle strength in such patients. OBJECTIVE: The objective of this study was to assess the frequency of objective and perceived lower limb weakness in patients with PD. METHODS: We studied 90 consecutive patients with PD and 52 age-matched controls. We recorded clinical and demographic variables, as well as perceived weakness and allied abnormal lower limb sensations, including ‘heavy legs’, ‘fatigued legs’, and ‘pain’. Symptoms consistent with restless legs syndrome were not considered. Lower limb strength was determined in both legs by means of the Medical Research Council scale, dynamometric (leg flexion) and weighting machine (leg pressure) measures. RESULTS: Weakness and allied abnormal lower limb sensations were reported in 69% of patients with PD and 21% of healthy controls. Patients with PD had decreased leg pressure compared with healthy controls (p = 0.002). Among patients with PD, an association between perceived leg weakness (and allied sensations) and gait freezing (p = 0.001) was observed in the multivariate regression analysis; however, these variables only explained 30.4% of the variance. Moreover, PD patients with and without abnormal lower limb sensations had similar muscle strength by objective measurements. CONCLUSION: Perceived lower limb weakness and allied abnormal sensations are common in patients with PD. However, there is a dissociation between perceived weakness and objective muscle strength in the lower limbs. These abnormal sensations were mostly related to gait freezing but a causal association is questionable.