Spontaneous Up-Beat Nystagmus in a Case of Wilson's Disease

A 21-year-old man, who suffered from Wilson's disease and showed spontaneous up-beat nystagmus, was examined using neurological, neurotological and biochemical examinations.The results obtained were as follows:(1) Neurological examination revealed the presence of the Kayser-Fleischer ring, dysarthria, dysphagia and cerebellar ataxia of the upper and lower limbs. CT examination showed moderate cerebral cerebellar atrophy, in addition.(2) Biochemical examination detected decrease in the ceruloplasmin and copper of the blood serum.(3) Neurotological examination revealed abnormalities of the oculomotor system, as indicated by spontaneous up-beat nystagmus, inhibitory response to both horizontal and vertical optokinetic stimulation and saccadic vertical eye movements on eye tracking. Furthermore, the spontaneous nystagmus described above was characterized by the following findings:1) It was intensified in frequency and amplitude when upward gaze was carried out. In contrast, it was lessened when downward gaze was made.2) It was lessened when the test for spontaneous nystagmus was carried out with Frenzel's spectacles.With reference to the previously reported investigations and the above-mentioned results, the following conclusions were drawn:(1) In a certain group of patients with Wilson's disease, the lesion is located not only at the basal ganglia, but also possibly extended to the cerebellum and the brain stem, particularly the midbrain tegmentum.(2) Dysfunction of the oculomotor system relating to vertical eye movements is possibly reinforced by the simultaneous presence of cerebellar dysfunction, which ensues the appearance of spontaneous up-beat nystagmus.