Freezing of gait: Risk factors and clinical characteristics

Abstract

Freezing of gait (FOG) is a common, unique, and remarkably disabling episodic symptom in parkinsonism, affecting over 60% of patients with Parkinson's disease (PD) and is more common in patients with progressive supra-nuclear palsy (PSP) and vascular parkinsonism. In the early stages of PD, FOG is short lasting, resulting in mild disability, however, as the disease progresses it becomes a major cause of falls and loss of independence. The development of FOG in a patient with PD has recently been associated with several clinical risk factors and specific locomotion gait disturbances: (1) as PD progresses the possibility of developing FOG is increased; (2) gait and postural disturbances as initial motor symptoms increase the risk for FOG, while tremor as the initial or predominant motor symptom decreases the risk for development of FOG; (3) the presence of depression in the early or late stages of PD increases the risk for development of FOG; (4) long term treatment with dopamine agonists (excluding levodopa) was associated with a higher frequency of FOG at the early stages of PD; and (5) mental loading or dual tasking while walking increases the risk of FOG. While walking regularly (at the inter-freezing state of locomotion) PD patients who are prone to freeze, experience increased stride-to-stride variability in time and asymmetry in swing time between the left and right legs, which, in general, is not correlated with normal asymmetry in PD motor symptoms. FOG in PD is a symptom, which in most instances, improves with levodopa treatment and results in an episode which is shorter in time and which is more dynamic. MAO-B inhibition (selegiline and rasagiline) has been shown to decrease FOG severity in the early and late stages of PD. In summary, FOG is an episode, which can occur in a sub-group of PD patients who experience specific dys-rhythmicity in stepping and bi-hemispheric coordination. Furthermore, mental, as well as motor states, can increase the risk of development of FOG. Therefore, we conclude that improved treatment of the risk factors will decrease FOG frequency and severity.