Benign paroxysmal positional vertigo (BPPV) is the most common cause of vertigo and is found in 17–42% of patients with vertigo (1). BPPV is caused by dislodged otoconia that enter the semicircular canals (1–3). When there is a change in the static position of the head with respect to gravity, the otolithic debris moves to a new dependent position within the semicircular canals, leading to a false sense of rotation (1). Canalith repositioning procedures (CRPs) can effectively treat BPPV (4–7). CRP results in immediate resolution of BPPV in about 80% of patients after single application, and the success rate increase up to 92% with repetition of the procedure (8). Since CRP differs according to the involved canal, accurate identification of the affected canal is essential for applying an appropriate CRP to each patient with BPPV. By virtue of its relative easiness, CRP may be attempted by the patients. Indeed, addition of self-applied CRP at home was more effective than the CRP alone performed by the clinician (9–11). Since BPPV recurs frequently with an annual recurrence rate of 15–18% (12, 13), self-administration of CRP may be attempted when BPPV recurs if each patient has a predilection for a specific canal, and the affected canal can be predicted based on the involved canal and type of BPPV during the previous event. Until now, few studies have explored the patterns of canal involvement during recurrences of BPPV (12, 14). In this study, we analyzed the involved canal and type of BPPV during the consecutive pairs of attacks in patients with recurrent BPPV. The purpose of this study is to determine whether the patients with BPPV have a tendency to develop the same type of BPPV on the same side during recurrences of BPPV, which would aid in guiding the patients to treat recurred BPPV for themselves by adopting self-administration of an appropriate CRP.

The interval from the initial event to the recurrence ranged from 7 to 3,229 days (median = 192 days). Overall, 50% of the recurrences occurred within 6.4 months from the initial attacks.

In this study, only 24% of patients with idiopathic BPPV show the same type of BPPV on the same side during consecutive pairs of BPPV attacks. This finding is consistent with the results of a previous study that found recurrences of posterior canal BPPV in the same canal only in 33% of patients with unilateral idiopathic posterior canal BPPV (20). All these findings indicate a random chance of the subtypes of BPPV when recurs irrespective of the types of BPPV during the previous attack. We may expect involvement of the same canal in recurred BPPV when the interval is short. However, our data showed no difference in the interval between the concordant and discordant groups and no difference in the patterns of recurrences in the pairs with an interval of ≤30 days and those with an interval of more than 30 days.

Since its first introduction for posterior canal BPPV (4, 21), CRPs became available for each type of BPPV and results in successful treatments in 80–90% of patients when applied appropriately (8, 22, 23). Thus, the prerequisite for successful treatments is an accurate identification of the involved canal and type in BPPV. BPPV is a highly recurrent disorder with a 15% recurrence rate per year and a 50% of recurrences within 40 months (12). Since many video clips have been developed and became available on the video-sharing web sites² for easy application of CRPs for each type of BPPV, self-administration of CRP has become feasible in treating recurred BPPV if the patients have the information on the type of BPPV they are suffering from. However, the video clips of CRP placed on the web sites have an accuracy of 64% (24). Thus, the instruction by experts would be more effective for accurate selection and application of CRP for each type of BPPV, and self-administration would be especially effective in patients with recurred BPPV when they have prior instruction on the application of appropriate CRP for the BPPV recurred. Indeed, a previous study demonstrated that patients can treat BPPV by themselves especially when in-person instructions on CRP were provided by an expert (9, 11).

Patients with BPPV bear an average medical expense of US$2,684.74 per individual in the United States (25) and 364 euros in Spain (26). Even in South Korea where the medical expenses are relatively low, individual patient with BPPV spend about US$180 on average for each attack of BPPV. If the type of recurred BPPV can be predicted, self-administration of CRP would be effective in treating BPPV and would greatly reduce the medical costs and social burden related to this highly prevalent vestibular disorder.

The posterior canal has been known to be involved mostly in BPPV (27, 28), and the right ear is more commonly involved than the left one (27, 29). The frequent involvement of right posterior canal has been explained by the right recumbent position preferred by the people during sleep and dependent location of the posterior canal while lying down (30, 31). Thus, patients may attempt the CRPs designed for the right posterior canal BPPV first and then for the left posterior canal BPPV if the first trial fails. However, recent studies have demonstrated that BPPVs involving the canals other than the posterior one are more prevalent than believed previously (32). The proportion of each type of BPPV depends on the interval from the symptom onset to evaluation, and the higher proportion of posterior canal BPPV has been reported in referral-based dizziness clinics that usually deal with the intractable cases (32). Thus, the real prevalence of posterior canal BPPV may be lower than believed, especially during the acute phase. Indeed, right posterior canal was involved in only 37.5% of our patients with BPPV. Thus, we became interested in whether each patient with BPPV has a predilection for a specific type of BPPV and we can predict the type of BPPV when it recurs based on that observed during the previous event.

In this study, the pattern of recurrences was usually discordant in our patients with idiopathic BPPV. Since we could not predict the type of recurred BPPV based on the type observed during the previous attack, education for self-administration of a specific CRP for recurred BPPV may have a limitation in treating this frequently recurrent disorder. For successful self-treatment of recurred BPPV, other ways to predict the types of BPPV should be developed.

All experiments followed the tenets of the Declaration of Helsinki, and this study was approved by Institutional Review Board of Seoul National University Bundang Hospital (IRB No. B-1707/409-103).

H-JK acquired and analyzed the data and drafted the manuscript. J-SK conducted the design and conceptualization of the study, interpretation of the data, and revision of the manuscript.

J-SK serves as an associate editor of Frontiers in Neuro-otology and on the editorial boards of the Journal of Clinical Neurology, Frontiers in Neuro-ophthalmology, Journal of Neuro-ophthalmology, Journal of Vestibular Research, Journal of Neurology, and Medicine. The other author has nothing to disclose.