Purpose : Cerebellar disorders usually manifest with balance impairment and ataxia. However, oculomotor abnormalities can result from cerebellar lesions and can sometimes be symptomatic. The purpose of this study is to better define the symptoms and eye movement abnormalities found in patients with cerebellar disorders.
Methods : We performed a retrospective study of patients with cerebellar disorders examined by one of us (FXB) in the Neuro-Ophthalmology Unit of the Jules-Gonin Eye Hospital. We studied the usual demographic data, etiologies of cerebellar disorders, type of oculomotility disturbances, as well as presence or absence of visual symptoms.
Results : We retrieved 169 patients , 82 women and 87 men, median age 46 years (4-86yrs). Etiologies of cerebellar disorders were : vascular (20%), demyelinating disease (17%), tumoral (12%), secondary to neurosurgery/radiotherapy (10,5%), hereditary (10%), post-traumatic (9,5%), toxic (7,5%), degenerative (5%), infectious/inflammatory (4,5%), congenital (2,5%), Arnold-Chiari (1%) and paraneoplastic (0,5%). Oculomotility abnormalities were: saccadic pursuit (83%), decreased vestibulo-ocular suppression (79%), dysmetric saccades (73%), multidirectional nystagmus (55%), downbeat nystagmus (16, 5%), skew deviation/ocular tilt reaction (12%), square waves jerks (10,5%), internuclear ophthalmoplegia (8%) and upbeat nystagmus (6,5%). The visual acuity decreased (>2 lines) during dynamic examination in 58% of patients for distance vision and in 91% of patients for near visual acuity, more so for near than for distance. Sixty-one patients (36%) were visually symptomatic, complaining of either oscillopsia due to nystagmus (42/169) and/or decreased vision during motion secondary to altered VOR suppression (25/169). All patients with skew deviation complained of diplopia versus two-thirds of patients with internuclear ophthalmoplegia.
Conclusions: An oculomotor cerebellar syndrome (a variable combination of saccadic pursuit, dysmetric saccades, nystagmus, and altered suppression of VOR by fixation) is commonly found in patients with cerebellar disorders. However the majority of patients are visually asymptomatic, as only thirty percent will complain of oscillopsia and/or decreased vision during motion, an unusual but important symptom to recognize.