Quantitative gait analysis in essential tremor reveals impairments that are maintained into advanced age

Background: Essential tremor (ET) patients seem to have impaired gait and balance, yet surprisingly few studies have utilized quantitative analysis to study these impairments. With one exception, these prior studies examined gait on a treadmill, which does not approximate functional environmental conditions (level ground). Moreover, these studies tested middle-aged subjects so it remains unclear whether ET patients maintain a pattern of deficits that is in excess of that seen in controls, even into advanced ages. Methods: 104 ET subjects (86.0±4.6, range=75-97 years) and 40 similarly aged controls (84.1±4.2, range=74-94 years) underwent gait testing using the GAITRite^® mat under standard walk and tandem walk conditions on level ground. Results: In standard walk, ET patients demonstrated deficits related to gait speed (lower velocity and cadence, p= 0.0001), dynamic imbalance (increased double support percent, p= 0.01), and gait asymmetry (increased step time difference, p= 0.003). During tandem walk, ET patients had lower velocity (p= 0.002) and cadence (p= 0.003), and more mis-steps (p< 0.008) compared with controls. For all variables, ET patients performed more poorly than controls even into advanced ages, as demonstrated in linear regression models. Conclusions: ET patients demonstrated decrement in gait speed, dynamic balance and gait symmetry during standard walk and clear balance impairment during tandem walk. This constellation of impairments is consistent with a cerebellar deficit. ET patients maintained this pattern of deficits, in excess of that seen in controls, into advanced age, reinforcing the importance of gait and balance impairment in this disorder.