Vestibular Deficits Leading to Disequilibrium and Falls in Ambulatory Amyotrophic Lateral Sclerosis

Abstract Objective To assess vestibular deficits in response to disequilibrium in ambulatory individuals with amyotrophic lateral sclerosis (ambALS). Design All participants completed standard protocols for the Sensory Organization Test (SOT) by computerized dynamic posturography. Setting Multidisciplinary amyotrophic lateral sclerosis clinic at an academic medical center. Participants Study participants (N=34) consisted of ambALS (n=19) and healthy controls (HC) (n=15). Interventions Not applicable. Main Outcome Measures Equilibrium scores (ESs) obtained from averaged sway amplitude in condition 5 (ES5) and condition 6 (ES6) of the SOT. Results In conditions of altered somatosensory information with vision absent or vision sway-referenced, the mean ± SD scores for ambALS (ES5=51.4±22.5; ES6=50.8±22.1) were lower than those for HC (ES5=65.4±11.7, P ≤.03; ES6=58.9±12.5, P >.05). Seven ambALS (37%) experienced a total of 19 falls during the sway-referenced support test conditions. There were no falls in the HC. Conclusions Nearly 37% of ambALS with normal clinical balance testing have decreased ability to use the vestibular input and required increased reliance on visual input for postural orientation to sustain equilibrium. The mechanism of this alteration in sensory preference is not completely clear. Extrapyramidal involvement early in ALS may be indicated.