Abnormalities of smooth pursuit in Parkinson's disease: A systematic review. (2021)

• Record Type: Journal Article
• Authors: Frei, Karen
• Is Part Of: Clinical parkinsonism & related disorders. Volume 4(2021)
• Publication Date: 2021
• Subjects: Oculomotor abnormalities -- Smooth pursuit eye movements -- Saccadic pursuit -- Parkinson's disease; Parkinson's disease -- Periodicals; Movement disorders -- Periodicals; 616.833005
• DOI: 10.1016/j.prdoa.2020.100085
• Languages: English
• ISSNs: 2590-1125

Abstract

Highlights: Abnormalities of saccades, vergence and smooth pursuit have been found in PD. SPEM abnormalities in PD consist of reduced gain and saccadic pursuit. PD patients have normal SPEM interspersed with catch up and anticipatory saccades. SP may reflect an inability to inhibit extraneous saccades or be a sign of executive dysfunction. Degeneration of SNr in PD may be reason behind SPEM abnormalities in PD. Abstract: Smooth pursuit eye movement (SPEM) abnormalities are commonly seen in Parkinson's disease (PD). Both reduced speed and saccades seen during SPEM, also known as saccadic pursuit (SP), have been studied in PD. A comprehensive literature review analyzed 26 studies of SPEM and PD. It appears that a greater proportion of PD patients have SPEM abnormalities consisting of reduced SPEM gain and/or SP compared to the normal population. It is not clear whether SPEM abnormalities are present early in the disease or begin sometime during disease progression. SPEM abnormalities may be correlated with disease severity but do not fluctuate or respond to dopaminergic medication in the same manner as other motor symptoms in PD. SPEM in PD is composed of normal SPEM interspersed with SP composed of both catch up and anticipatory saccades. This differs from other neurodegenerative disorders and may be related to an inability to inhibit extraneous saccades or to increased distraction reflecting executive dysfunction. Because the basal ganglia are involved in SPEM physiology, degeneration of the SNr neurons in PD may explain abnormal SPEM in this disorder. Since dementia, aging and medication effects influence SPEM, they should be controlled for in future studies of SPEM in PD. SP is easily detected on clinical exam and may be a biomarker for the disease or for disease progression. Oculomotor testing can be an important part of the Parkinson's exam.