Visual-Motion Suppression in Congenital Pendular Nystagmus

Patients with a congenital pendular nystagmus are known not to experience oscillopsia in a normal visual environment. The data of a 31‐year‐old female patient suffering from a congenital pendular nystagmus are presented. The aim of the fluorodeoxyglucose positron emission tomography (FDG‐PET) experiment was to analyze the regional cerebral glucose metabolism (rCGM) during minimal as well as maximal nystagmus. Video‐oculography showed a maximum in frequency of the horizontal pendular nystagmus during gaze to the left, whereas the zone of minimal nystagmus was 10° to the right. Two sessions with an 18F‐fluorodeoxyglucose tracer were performed to analyze cerebral blood‐glucose utilization when fixating an object in the areas of maximal and of minimal nystagmus. A structural MRI in a clinicial 1.5‐T scanner was acquired to superimpose the PET results onto the unique anatomy of the patient. By statistical analysis a significant increase in the rCGM in the cerebellar nodulus and a relative decrease in the area of MT/V5 bilaterally during maximal nystagmus were found. When the patient was looking in her null zone, rCGM was increased in V1 and MT/V5 bilaterally. To the best of the authors’ knowledge, this is the first proof by means of functional imaging of a suppression of oscillopsia in higher‐order visual cortex areas in a patient with a congenital nystagmus.