Nystagmus – What's new?

Abstract

Nystagmus is defined as to-and-fro oscillations of the eyes initiated by a slow drift of the eyes away from desired position and followed by either quick phases (jerk nystagmus) or slow drifts in the opposite direction (pendular nystagmus). There are a multitude of nystagmus types, etiologies, and mechanisms – each with different clinical implications and pharmacological treatments; thus, proper pattern identification of nystagmus is critical to accurate neurological diagnosis and effective therapeutic intervention. The most common acquired nystagmus types seen clinically that occur in central gaze and thereby may cause disabling oscillopsia (i.e., a subjective sense of visual motion) are acquired pendular nystagmus (APN) and pure vertical jerk nystagmus (upbeat = UBN, downbeat = DBN). The two most common forms of APN are horizontal/elliptical APN in multiple sclerosis and vertical/torsional APN with simultaneous spontaneous palatal movements in oculopalatal tremor. Oculopalatal tremor typically begins weeks to months after a brainstem stroke and is associated with hypertrophic degeneration of the inferior olive. UBN is most common with medullary lesions from multiple sclerosis or in the setting of Wernicke encephalopathy. DBN occurs with many pathologies affecting the cerebellum, especially the cerebellar flocculus/paraflocculus or nodulus/uvula. Recent updates to be highlighted include a slowly progressive form of oculopalatal tremor called progressive ataxia and palatal tremor (PAPT) and diagnostic insights to be gained from careful examination of the behavior of UBN and DBN in different gaze positions and following provocative maneuvers (e.g., head shaking, supine position).