Congruous Torsional Down Beating Nystagmus in the Third Position of the Semont's Maneuver in Patients Treated for Canalithiasis of Posterior Semicircular Canal Benign Paroxysmal Positional Vertigo: Its Significance and Prognostic Value.

Beatrice Giannoni,Rudi Pecci,Vincenzo Marcelli,Curzio Checcucci,Ilaria Verdolin,Federica Pollastri

doi:10.3389/fneur.2020.00949

Abstract

Due to its mechanical pathogenesis, benign paroxysmal positional vertigo treatment is mainly physical: when posterior semicircular canal is involved, Semont's maneuver is reported as one of the most effective liberating procedures. In the case of a canalolithiasis, the efficacy of the maneuver is corroborated by the appearance of some nystagmus findings during its performance. Liberating nystagmus, that can occur in the second position of Semont's maneuver and whose direction is congruous with the excitation of the affected posterior semicircular canal has proven to be a favorable prognostic sign. On the other hand, in clinical experience, we've frequently verified the appearance of another nystagmus during the execution of the maneuver: upon reaching the third position, when replacing the patient seated, a torsional down beating nystagmus, with the torsional component “congruous” with the stimulation of the vertical semicircular canals of the affected side, can often be appreciated. Such a sign can occur with or without having had the previous liberating nystagmus in the second position and is almost always associated with an intense vertigo and/or body pulsion. In this study, we describe the incidence and characteristics of the congruous torsional down beating nystagmus that can arise by assuming the third position of Semont's maneuver in a cohort of patients treated for posterior semicircular canal benign paroxysmal positional vertigo due to canalolithiasis. In the best of our knowledge, such a sign has never been described and explained before. On the basis of the pathophysiology and of the possible canal receptors stimulation during the different phases of Semont's maneuver, we formulated different hypothesis on how such a nystagmus can be generated. We observed that such a sign, when elicited, has a very good prognostic meaning for healing purposes, even better than that of liberating nystagmus. Therefore, congruous torsional down beating nystagmus should always be checked when performing Semont's maneuver because it could help in predicting success of physical treatment and in managing patients.

Highlights

Posterior semicircular canal (PSC) benign paroxysmal positional vertigo (BPPV) is the most frequently diagnosed peripheral vestibular pathology [1,2,3,4]
The prototype of maneuvers exploiting the sharp deceleration imposed to the otoconial cluster is the Semont’s liberatory maneuver (SLM) [8]: a series of three rapid movements is performed in order to free the PSC from the mass of heavy particles, carrying the latter into the utriculus
Our work deals with a logistic regression study, conducted at the Audiology Unit of Careggi University Hospital in Florence on a series of 55 selected outpatients suffering from PSC BPPV

Summary

Introduction

Posterior semicircular canal (PSC) benign paroxysmal positional vertigo (BPPV) is the most frequently diagnosed peripheral vestibular pathology [1,2,3,4]. After the second movement of SLM, performed carrying the patient from the pathological onto the healthy side, a “Liberating Nystagmus” (LNy) with the same direction as the LoNy can be generated; this finding has been proved to be a good prognostic sign [9,10,11]. Our hypothesis was that patients who manifest this finding have overall a faster resolution than those who do not or those who only have LNy. The purpose of our work was to verify the presence of nystagmus when taking the third position of the SLM in a cohort of patients treated for PSC canal lithiasis, to describe it, to hypothesize the mechanism by which it is generated, to quantify its impact and, above all, to evaluate its prognostic value for the resolution of PSC BPPV. A secondary objective of our study was to investigate the existence of other factors that may change the outcome of SLM and to evaluate the weight of each of them, in particular that of the time elapsed between the onset of the symptoms and the execution of the maneuver

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Conclusion