Epub: Finke et al. Dynamics of saccade parameters in multiple sclerosis patients with fatigue. J Neurol. 2012 Jun.
Background: Fatigue is one of the most frequent and disabling symptoms in MS. The mechanisms underlying fatigue remain poorly understood and objective measures to quantify fatigue are unavailable to date.
Objective: To investigate whether analysis of ocular motor movements can provide diagnostic information in MSers with fatigue, 37 MSers (21 female, age 44 ± 9 years) and 20 age- and gender-matched healthy controls were prospectively recruited. Fatigue was assessed with the fatigue severity scale (FSS). 25 MSers were fatigued (defined as FSS ≥4) and 12 MSers were not. Subjects performed a saccadic fatigue task that required execution of uniform saccades over a period of 10 min.
"Saccadic eye movements are rapid movements from side-to-side or up-and-down; the type of movements that are used to watch tennis. In contrast pursuit movements are slow eye movements to track an object. The following video demonstrates how we measure saccadic eye movements."
Saccadic amplitude (size), latency (time from stimulus) and peak velocities (speed) during the task were analysed and selected parameters analysed.
Results: Fatigued MSers showed a significantly larger decrease of saccadic peak velocity and amplitude when compared to MSers without fatigue and healthy controls. Furthermore, fatigued MSers showed significantly longer latencies compared to non-fatigued MSers and healthy controls. Peak velocity change over time and latencies correlated with FSS scores. The best parameter to discriminate between fatigued and non-fatigued patients was peak velocity change over time.
Conclusions: Assessment of peak velocity, amplitude and latency in a saccade fatigue task is a promising approach for quantifying fatigue in MSers.
"This study is important as it may allow us to use eye movements to test drugs that target fatigue. I wonder what fampridine will do to eye movements. Below are two YouTube videos on the affect of fampridine on walking speed; imagine these videos being replaced by eye movement ones. Exciting? I think so!"
Fampridine responder 1
Fampridine responder 2