Vestibular findings in patients with persistent geotropic positional nystagmus: the 'light cupula' phenomenon

Conclusions: Persistent geotropic nystagmus indicates a condition of a light cupula, which is accompanied by vestibular disability and a high incidence of pathological findings in the vestibular tests. The prevalence of migraine is high. Objectives: To examine subjective symptoms and characteristics of nystagmus in patients with persistent geotropic nystagmus using vestibular tests, as well as possible correlations to migraine in this group. Methods: We enrolled 20 patients with a mean age of 53 years. The slow phase velocity (SPV) of the geotropic nystagmus and the nystagmus with the patient's head in the supine (S) and prone (P) positions was recorded. All patients completed caloric tests, subjective visual horizontal (SVH), and vestibular evoked myogenic potential (VEMP). All tests were repeated at follow-up (FU). Results: SPV of the geotropic nystagmus directed to the left was 5.5 degrees/s and that to the right was 3.5 degrees/s. In 72% of patients, nystagmus in the P position was opposite to that in the S position. The vestibular tests were pathologic in about 60% of patients. At FU geotropic nystagmus was found in 40% of patients, but was significantly less intense. The vestibular test results remained at the same level at FU. Recurrent vertigo was reported in 78% of the patients. In all, 40% of the patients suffered from migraine.