Eye Movement Disorders in Movement Disorders

Abstract

Oculomotor assessment is an essential element of the neurological clinical examination and is particularly important when evaluating patients with movements disorders. Most of the brain is involved in oculomotor control, and thus many neurological conditions present with oculomotor abnormalities. Each of the different classes of eye movements and their features can provide important information that can facilitate differential diagnosis. This educational review presents a clinical approach to eye movement abnormalities that are commonly seen in parkinsonism, ataxia, dystonia, myoclonus, tremor, and chorea. In parkinsonism, subtle signs such as prominent square wave jerks, impaired vertical optokinetic nystagmus, and/or the “round the houses” sign suggest early progressive supranuclear gaze palsy before vertical gaze is restricted. In ataxia, nystagmus is common, but other findings such as oculomotor apraxia, supranuclear gaze palsy, impaired fixation, or saccadic pursuit can contribute to diagnoses such as ataxia with oculomotor apraxia, Niemann‐Pick type C, or ataxia telangiectasia. Opsoclonus myoclonus and oculopalatal myoclonus present with characteristic phenomenology and are usually easy to identify. The oculomotor exam is usually unremarkable in isolated dystonia, but oculogyric crisis is a medical emergency and should be recognized and treated in a timely manner. Gaze impersistence in a patient with chorea suggests Huntington's disease, but in a patient with dystonia or tremor, Wilson's disease is more likely. Finally, functional eye movements can reinforce the clinical impression of a functional movement disorder.

Ocular Biomarkers for Alzheimer Disease Dementia

“…The retina is part of the central nervous system with direct connection with different brain areas; it has even been suggested that axons of the optic nerve facilitate the transport into the brain of amyloid precursor protein created in retinal ganglion cells . Many brain areas are involved in oculomotor control and neurodegenerative diseases present with oculomotor and saccadic abnormalities . Patients with AD and other neurodegenerative diseases may report decreased vision, visual field changes, visual hallucinations, and other visual symptoms .…”

“…4 Many brain areas are involved in oculomotor control and neurodegenerative diseases present with oculomotor and saccadic abnormalities. 7 Patients with AD and other neurodegenerative diseases may report decreased vision, visual field changes, visual hallucinations, and other visual symptoms. 8 The ocular changes that occur in AD include abnormal pupillary reaction, decreased contrast sensitivity, loss of retinal ganglion cells and retinal nerve fiber layer (RNFL), peripapillary atrophy, and retinal thinning, tortuosity of blood vessels, and deposition of β-amyloid in the retina.…”

Oculomotor Apraxia as an Early Presenting Sign of Juvenile‐Onset Huntington's Disease

“…Gaze fixation is also affected due to an inability to inhibit saccades towards a stimulus. [5][6][7] In our case, oculomotor apraxia was a striking feature seen early in the disease course of Juvenile HD compared to the motor manifestations which were subtle and later progressed. Earlier onset of eye abnormalities can be seen in those with a higher CAG repeat 7 yet this would generally occur later in the disease course following onset of motor signs.…”

“…Markham and Knox first described “oculomotor apraxia” in patients with HD in 1965 4 . The earliest eye movement abnormalities are difficulty initiating voluntary saccades and slow saccadic velocity 5–7 . To initiate eye movements patients will blink or head thrust and were thus felt to have an “oculomotor apraxia.” Smooth pursuit is initially preserved 6,7 .…”

Vertical Supranuclear Gaze Palsy in Primary Familial Brain Calcification Associated with a Novel SLC20A2 Mutation

“…5 While the recent MDSGene Review did not describe VSGP as a manifestation of clinically affected PFBC cases, 3 the increasing number of reported individuals with PSP-like features with or without other motor or cognitive symptoms or midbrain calcification raises the possibility of this syndrome being a clinical phenotype of PFBC. Given this, we suggest that PFBC should be a diagnostic consideration for individuals presenting with a PSP-like syndrome, along with other conditions outlined in a recent review by Kassavetis et al 6 The finding of VSGP in patients harboring distinct genetic changes in SLC20A2 and MYORG argues against a specific genotype-phenotype correlation and suggests that this feature may arise from inherent PFBC pathophysiological mechanisms irrespective of the causative gene. The variable involvement of the midbrain in such cases supports the earlier hypothesis whereby alterations in pathways in or projecting to the midbrain are thought to underlie gaze impairments in PFBC.…”