AbstractBackgroundIn recent years, a variety of clinical types of amyotrophic lateral sclerosis have come to be recognized. As some patients present with oculomotor abnormalities both clinically and pathologically, the progressive supranuclear palsy variant of amyotrophic lateral sclerosis has been proposed.AimTo describe atypical cases of motor neuron disease with abnormal extraocular movements mimicking progressive supranuclear palsy.MethodsWe present three motor neuron disease patients with slow saccades, who were aged 57, 63 and 62 years. Neurological examinations found vertical gaze palsy in two patients. The two patients who presented extrapyramidal signs were regarded as motor neuron disease with parkinsonism, whereas the other was diagnosed with amyotrophic lateral sclerosis. Their saccades were investigated by visually‐guided saccade and memory‐guided saccade tasks, and were compared with those of 14 age‐matched normal participants (60.3 ± 1.9 years).ResultsIn all these patients, the visually‐guided saccade latencies were significantly prolonged compared with normal participants, whereas the memory‐guided saccade latencies were not. The velocity and amplitude of saccades of the patients were significantly reduced in visually‐guided saccade and memory‐guided saccade in comparison with normal participants.ConclusionThe patterns of saccadic abnormalities in the patients were similar to those of progressive supranuclear palsy patients, suggesting that some patients with motor neuron disease show saccade abnormalities similar to those of progressive supranuclear palsy patients from the clinical and physiological perspective. Motor neuron disease with slow saccades and parkinsonism, as reported here, suggest the existence of progressive supranuclear palsy‐variant amyotrophic lateral sclerosis.