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Eye movements are fundamental diagnostic and progression markers of various neurological diseases, including those affecting the cerebellum. Despite the high prevalence of abnormal eye movements in patients with cerebellar disorders, the traditional rating scales do not focus on abnormal eye movements. We formed a consortium of neurologists focusing on cerebellar disorders. The consortium aimed to design and validate a novel Scale for Ocular motor Disorders in Ataxia (SODA). The primary purpose of the scale is to determine the extent of ocular motor deficits due to various phenomenologies. A higher score on the scale would suggest a broader range of eye movement deficits. The scale was designed such that it is easy to implement by non-specialized neurological care providers. The scale was not designed to measure each ocular motor dysfunction's severity objectively. Our validation studies revealed that the scale reliably measured the extent of saccade abnormalities and nystagmus. We found a lack of correlation between the total SODA score and the total International Cooperative Ataxia Rating Scale (ICARS), Scale for Assessment and Rating of Ataxia (SARA), or Brief Ataxia Rating Scale (BARS). One explanation is that conventionally reported scales are not dedicated to eye movement disorders; and when present, the measure of ocular motor function is only one subsection of the ataxia rating scales. It is also possible that the severity of ataxias does not correlate with eye movement abnormalities. Nevertheless, the SODA met the consortium's primary goal: to prepare a simple outcome measure that can identify ocular motor dysfunction in patients with cerebellar ataxia. • Scale for Ocular Motor Disorders in Ataxia is presented. • The scale is an objective measure of eye movement burden in ataxia. • It is operator friendly and is validated with video oculography. [ABSTRACT FROM AUTHOR]

The clinical features of a lesion confined to the superior cerebellar peduncle (SCP) have not been defined well in human. A 92-year-old woman suddenly developed mild dysarthria and severe imbalance from an isolated unilateral SCP infarction, and examination showed ipsiversive ocular torsion, severe ipsilesional limb ataxia, and truncal ipsipulsion. These findings are well consistent with those observed in monkeys when the SCP was severed. In addition to the dentate-rubro-thalamic projections, the SCP appears to contain the fibers involved in the control of eye motion in the roll plane. [ABSTRACT FROM AUTHOR]

Hereditary spastic paraplegia (HSP) is characterized by progressive spasticity and weakness of the lower extremities. Additional findings include ataxia, extrapyramidal signs, and dementia. Pendular nystagmus (PN) has been reported in some subtypes of HSP caused by PLP1 (SPG2) or paraplegin (SPG7) mutation. To describe the patterns and modulation of PN in HSP, we performed eye movement recording using video-oculography in a Korean family with HSP and PN. The PN was convergent-divergent in the oblique plane with a frequency of 6 to 7 Hz and maximum amplitude at about 1.5°. The nystagmus diminished briefly after blinks and horizontal saccades, and decreased during eccentric gaze and convergence. Horizontal saccades shifted the phase of the oscillations. During lateral gazes, the PN increased in the abducting eye, but decreased in the adducting eye. Vibratory stimuli decreased the nystagmus mostly in the left but not in the right eye. No pathogenic mutation was found in the genetic loci known for causing spastic paraplegia by whole-exome sequencing. The unusual features and modulation of PN in our patients with HSP emphasize the role of disconjugate and disjunctive capabilities of the brain in ocular motor control, and exemplify what can go wrong. [ABSTRACT FROM AUTHOR]