  Citation: Carmona, S.; Zalazar, G.J.; Fernández, M.; Grinstein, G.; Lemos, J. Atypical Positional Vertigo: Definition, Causes, and Mechanisms. Audiol. Res. 2022, 12, 152–161. https://doi.org/10.3390/ audiolres12020018 Academic Editor: Giacinto Asprella Libonati Received: 31 January 2022 Accepted: 7 March 2022 Published: 14 March 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). Review Atypical Positional Vertigo: Definition, Causes, and Mechanisms Sergio Carmona 1,2, *, Guillermo Javier Zalazar 1,3 , Martin Fernández 1 , Gabriela Grinstein 2 and João Lemos 4 1 Fundación San Lucas Para la Neurociencia, Rosario 2000, Argentina; guille.zalazar87@gmail.com (G.J.Z.); fmartingabriel@gmail.com (M.F.) 2 Instituto de Neurociencias de Buenos Aires INEBA, Buenos Aires 1192, Argentina; gabrielagrin@gmail.com 3 Department of Neurology, Hospital Central Dr. Ramón Carrillo, San Luis 5700, Argentina 4 Department of Neurology, Coimbra University Hospital Centre, 3004-561 Coimbra, Portugal; merrin72@hotmail.com * Correspondence: sergiocarmona57@gmail.com Abstract: Paroxysmal positional vertigo is a frequent cause for consultation. When approaching these patients, we try to differentiate central from peripheral causes, but sometimes we find manifestations that generate diagnostic doubts. In this review, we address atypical paroxysmal positional vertigo, reviewing the literature on the subject and giving a provisional definition of atypical positional vertigo as well as outlining its causes and pathophysiological mechanisms. Keywords: APV (atypical positional vertigo); heavy cupula; light cupula; vestibular migraine; apogeotropic PV; vertigo in childhood 1. Introduction Benign paroxysmal positional vertigo is the most frequent cause of vertigo [1]. As its name indicates, it is characterized by vertigo episodes of sudden onset and end, triggered by changes in head’s position with regard to gravity. It is located in the labyrinth, and its cause is mechanical [2]. However, this is an etiologic diagnosis, reached after questioning and examining the patient. Based on what patients report, the duration of symptoms lasts seconds; however, many overestimate the duration of the vertiginous sensation. The trigger effect of positional changes is a key issue to be addressed [2]. A great variability of autonomic symptoms, including nausea and vomiting, can accompany BPPV. Gait instability, headache, and additional neurologic complaints are potential red flags in the differential diagnosis [1]. With a defined position trigger effect, it is the neurologist’s job to perform an examination to confirm the diagnosis of paroxysmal positional vertigo (PPV), and by virtue of the vertigo duration and nystagmus characteristics, to determine lesion localization (peripheral versus central) and to design a management plan. Therefore, we may define PPV as a condition characterized by sudden-onset and -end vertigo episodes, triggered by changes in the head’s position with regard to gravity. If, after questioning, the diagnosis is PPV, there is an attempt to find the cause of these symptoms by performing a physical examination and, in certain cases, supplementary tests. The causes may be divided in two main groups: Peripheral, as in the case of Benign Paroxysmal Positional Vertigo (BPPV), in its typical and atypical forms [3], and positional alcohol nystagmus [4]; and Central (Central Paroxysmal Positional Vertigo, or CPPV), due to multiple causes, for instance, vascular, demyelinating, degenerative, or nutritional [5]. In 1999, Büttner et al. published criteria to help differentiate between BPPV and CPPV [6]. Soto-Varela et al. proposed an update of the previous differentiation criteria [7], as follows: • PPV associated to neurological disorder signs and symptoms; Audiol. Res. 2022, 12, 152–161. https://doi.org/10.3390/audiolres12020018 https://www.mdpi.com/journal/audiolres