Incidence of Horizontal Canal Benign Paroxysmal Positional Vertigo as a Function of the Duration of Symptoms:

Objectives: The incidence of horizontal canal involvement in benign paroxysmal positional vertigo (HC-BPPV) varies between reports. One of the reasons for these differences is that the duration of symptoms was not considered. Because of the high spontaneous resolution rate in HC-BPPV and the medical referral system, the frequency of HC-BPPV might change according to the duration of symptoms. We evaluated the frequency of involved canals in BPPV according to the duration of symptoms. Study Design: A retrospective review. Methods: A retrospective review was conducted involving 589 patients diagnosed with BPPV from January 2001 to December 2006. The patients were divided into 3 groups according to the duration of symptoms: Group A included patients who sought evaluation in the clinics within 24 hours from the onset of symptoms (n = 328); Group B was composed of patients who experienced symptoms from 24 hours to 7 days (n = 87) before evaluation; and Group C patients had symptoms for more than 7 days (n = 174) before evaluation. The frequencies of involved canals were assessed and compared between the groups. The correlation between the frequency of involved canals and symptom duration was also analyzed. Results: The posterior, horizontal, and anterior canals were involved in 61.8, 35.3, and 2.9% of the patients, respectively. However, the frequency of HC-BPPV was 40.5% in Group A, 33.3% in Group B, and 26.4% in Group C (p < 0.01). There was a significant negative correlation between the frequency of HC-BPPV and the duration of symptoms (r = -0.670; p < 0.01). Conclusion: The incidence of HC-BPPV was higher than reported; however, it significantly decreased according to the duration of symptoms.