Apogeotropic variant of lateral semicircular canal benign paroxysmal positional vertigo: is there a correlation between clinical findings, underlying pathophysiologic mechanisms and the effectiveness of repositioning maneuvers?

OBJECTIVE: The apogeotropic variant of horizontal semicircular canal (h-SCC) benign paroxysmal positional vertigo (BPPV) is attributed to canalithiasis of the anterior arm or cupulolithiasis. This study is an attempt to distinguish the most effective maneuvers for each case, by investigating any correlation, between the clinical findings or the treatment options and the possible location of the displaced debris. DATA SOURCES: A review of the literature (1990-2012) was conducted via the PubMed database with the search terms "apogeotropic nystagmus and benign paroxysmal positional vertigo." STUDY SELECTION: Articles on central nervous system lesions were excluded. DATA EXTRACTION: The studies included in the analysis provided detailed diagnostic and therapeutic protocols, supported by the resolution of the signs and symptoms through repositioning maneuvers. DATA SYNTHESIS: Descriptive statistics were used to summarize the findings. Intergroup and intragroup comparisons were performed through Pearson's χ or Fischer's exact test.
CONCLUSION: Protocols vary considerably among studies. Nystagmus from seated to supine position is the best studied secondary clinical sign and possibly a clinical indication of cupulolithiasis. In patients with symmetrical responses in the head yaw test, no significant differences can be detected in the occurrence of secondary signs of lateralization compared to patients with asymmetrical responses. The Gufoni maneuver seems to be effective in all pathophysiologic types of apogeotropic h-SCC BPPV. The Barbeque and Vannucchi-Asprella maneuvers mainly target at lithiasis of the anterior ampullary arm. The results of this analysis may imply that different clinical subgroups of h-SCC BPPV may regard to different pathophysiologic and therapeutical mechanisms.