Spontaneous Abnormal Vertical Eye Movements of Coma

Abstract

Spontaneous vertical eye movements in the critical care setting are often a source of confusion and alarm; while their origin remains at least partly theoretical, understanding their classification and associated clinical implications can inform the diagnostic workup and further clinical management. This case describes a patient who demonstrated ocular dipping: slow conjugate downward eye movements with a quick return to primary gaze. Ocular dipping is a rare phenomenon that was initially described in patients with hypoxic brain injury and has since been described in only a handful of cases. Dipping resides in a spectrum of spontaneous vertical eye movements, with ocular bobbing being the first of these described eye movements. Ocular bobbing is characterized by a fast downward movement followed by a slow return to the mid gaze position which is classically associated with pontine injury. Other vertical eye movements that can be seen in patients with a disorder of consciousness include other variations of ocular bobbing and dipping, vertical myoclonus, and small-amplitude mainly vertical movements.