Assessment of Postural Orientation and Equilibrium In Early Amyotrophic Lateral Sclerosis (ALS)

ALS is a progressive neurodegenerative disorder involving primarily upper and lower motor neurons. The progressive loss in motor neurons leads to weakness, fatigue, spasticity, and loss of balance. Falls are reported in 30-35% of ALS patients prior to enrolment to ALS clinic. This early loss of balance may not be detected by the classical neurological exam, or the standard clinical balance scales. Understanding the impairments in the balance control system which leads to fall during the course of ALS is a prerequisite for the clinical decision-making process in order to develop a proper balance rehabilitation program and fall prevention strategies for these patients.

Patients and control subjects will undergo balance system evaluation consisting of the following testing:

1. Sensory Organization Test Protocol

Standardized EquiTest assessment protocol:

Sensory Organization Test (SOT) - will be used to measure change how well participants maintain balance under progressively more difficult test conditions, which either disrupt or remove visual and proprioceptive feedback. Visual and proprioceptive environments will be altered systematically for fixed support and sway-referenced support and surround conditions, and under normal (eyes open), absent (eyes closed), and sway-referenced vision (eyes sway-referenced). Under sway-referenced conditions, the platform on which the subject stands and/or the visual surround also move proportionally to their AP sway. During SRC the floor and visual surround are controlled by a servomechanism (Gain=1.0) to follow movements of the subjects' center of gravity. Sway-referencing eliminates accurate somatosensory and/or visual information used to orient the body. Performance under sway-referenced visual conditions shows the participant's ability to suppress conflicting visual inputs and to rely on alternative systems for maintaining equilibrium (table 1).