Lateral Semicircular Canal Benign Paroxysmal Positional Vertigo diagnostic signs

I read with interest the article entitled Converting apo-geotropic into geotropic lateral canalolithiasis by head-pitching manoeuvre in the sitting position by Califano et al. 1. The Authors describe their experience in transforming the apogeotropic LSC BPPV (Lateral Semicircular Canal Benign Paroxysmal Positional Vertigo) into a geo-tropic one performing " a quick 60° forward exion and a slow maximal backward-extension of the head " in the sitting position. Furthermore, many diagnostic tests and clinical signs concerning the diagnosis of the affected side in LSC BPPV are mentioned. I would like to clarify some points regarding a few statements in the above-mentioned paper. The Authors refer to the converting technique from apo to geo either as a " manoeuvre " or as a " test " , but it would be more correct to call " test " , the clinical procedure used to dene clinical diagnostic signs and " manoeuvre " , the therapeutic procedure. Besides, there is a clear difference between the Head Pitch Test already described 2 to make the differential diagnosis between the Pseudo-Spontaneous Nystagmus and the Spontaneous Nystagmus, and the Head Pitch Manoeuvre described by the Authors as a procedure to reach the conversion of LSC BPPV from apo to geo. The former is performed by slowly bending the head 60° forward and then 30° backward, the latter is performed by a " a quick 60° forward exion and a slow maximal backward-extension of the head ". As far as concerns the diagnosis of the affected side, in LSC BPPV, a misleading list of clinical signs, improperly called " accessory signs of laterality " is given. In this regard, I should like to elucidate the following points: 1. The nystagmus observed in the upright position in LSC BPPV, known as Pseudo-Spontaneous Nystagmus (PSN), was rst described in 2003 (Asprella-Libonati personal communication, cited by Nuti et al. 3) and it was observed in a large series of patients in 2005 4. This latter article pointed out the clinical value of this sign in diagnosing the affected side and identied a pathophysiological theory, attributing the PSN to the slow oating of the otoliths along the LSC bent 30° compared to the horizontal plane, so that it acts as an inclined plane on which the otoliths can gravitate following the same direction as the gravitational vector. The nystagmus (PSN) direction changes, induced by exing and extending the patient's head in …