Abstract

Objectives
Patients, who showed persistent geotropic-direction changing positional nystagmus(p-DCPN) tend to have different clinical manifestations from those who showed transient persistent geotropic DCPN(t-DCPN). We investigated the clinical characteristics between p-DCPN and t-DCPN patients, and its recovery rate after canalith repositioning procedure(CRP).
Methods
Based on the duration of nystagmus, 117 geotropic DCPN patients were classified to two groups, p-DCPN and t-DCPN. Barbeque maneuver had been introduced towards the direction of null plane for the p-DCPN patients, and to the direction of stronger nystagmus for the t-DCPN patients.
Results
74 patients showed t-DCPN with latency and 43 patients were classified to the p-DCPN cases. The t-DCPN cases showed more dominant female proportion than those of the p-DCPN cases. No p-DCPN patient showed prompt improvement after the 1st canalolith reposition therapy. Among the t-DCPN patients, 18 canal switch cases were found, but, there was no canal switch cases found among the p-DCPN patients. The CRP has showed less effective for the p-DCPN patients and no canal switch patients found in the t-DCPN patients. Null plane direction among p-DCPN patients, didn’t always match the direction of stronger nystagmus during the supine head roll test.
Conclusions
Due to its distinguishing clinical manifestation, p-DCPN may have different pathogenesis and clinical mechanisms from t-DCPN. And the CRP is not an adequate treatment for the p-DCPN patients. Further study with larger number of enrolled subjects is necessary.

• Keywords: Benign paroxysmal positional vertigo; Horizontal canal; Direction-changing nystagmus