It is generally considered that oculomotor system is spared in ALS and that oculomotor abnormalities  were alarming for the physician who is considering this diagnosis. However, gaze-palsy, nystagmus and abnormal ocular saccades have been reported within ALS patients, especially with long survival.

To describe Saccadic Eye Movements (SEM) abnormalities in patients with Amyotrophic Lateral Sclerosis (ALS) and to discuss the value of studying  oculomotor function in the management and understanding of the disease.

A prospective study was conducted in Neurology Department in Razi Hospital (November 2017-September 2018), including patients with ALS. Epidemiological and clinical findings were analyzed.  All patients underwent a recording of SEM. Pursuit, prosaccade and antisaccade  tasks were performed.

Fifty patients were included (mean age: 61 ± 10.9 years; Sex ratio: 1.7; mean age of disease onset: 58.2 ± 11.1 years). Disease duration was 3.3 ±0.9 years. Inaugural symptoms were spinal in 84% and bulbar in 16%. Non motor symptoms were identified in 25 patients (50%): dysautonomic dysfuction (28%),sensory disturbances (24%), cognitive impairment (4%), and clinical oculomotor dysfunction (4%). SEM tasks were normal in 12 patients (24%). Ocular horizontal pursuit was impaired in 21 patients (42%). Saccades latencies were prolonged in 13 patients (26%). Anti-saccades errors were found in 12 patients (24%). Hypometric saccades and Square-wave jerks were identified respectively in 2 patients (4%).

Our study confirmed high prevalence of Saccadic Eye Movements abnormalities in ALS, indicating widespread impairment of motor and extramotor areas of the brain. The study of oculomotor dysfunction holds significant promise an additional tool to evaluate ALS neuropathological process spreading  and to understand pathophysiology of the disease.