[Video] - Locked-in syndrome patients can't move their eyes side to side, but can move their eyes up and down

[UltimaOnline]

The locked-in syndrome is caused by an insult to the ventral pons, most commonly an infarct, haemorrhage, or trauma. The characteristics of the syndrome are quadriplegia and anarthria with preservation of consciousness. Patients retain vertical eye movement, facilitating non-verbal communication.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC549115/