10.14639/0392-100X-N1136
Object. The aim of this study was to evaluate the effectiveness of the Bow and Lean Test (BLT) based on nystagmus intensity and direction evaluation (NID-BLT) in the diagnosis of benign paroxysmal positional vertigo of the lateral semicircular canal (LSC-BPPV). We hypothesised that the presence of a pseudo-spontaneous nystagmus increases the diagnostic accuracy of the test. Methods. The BLT was performed in 32 subjects affected by LSC-BPPV. Results. BLT was positive in 27 cases with a sensitivity of 84.3% and an accuracy of 70.4%. In other words, it was possible to carry out a BPPV root canal diagnosis (LSC) with BLT in 27 patients, of whom 19 also received a diagnosis of side and form. Pseudo-spontaneous nystagmus was detected in 15 patients, all of whom were BLT positive. In these patients, a clear diagnosis of form and side was also obtained in 14 cases (accuracy 93.3%). In the 12 patients without pseudo-spontaneous nystagmus and BLT positive, a diagnosis of side and form was reached in 5 cases (accuracy 41.6%). The comparison between percentages (Chi square test) showed a significant difference (p = 0.038). Conclusions. The presence of a pseudo-spontaneous nystagmus, as an expression of more mobile debris within the canal or a more deflectable cupula, increases the accuracy of the BLT.
text/xml
1827-675X
1136
en
Vincenzo Marcelli
https://creativecommons.org/licenses/by-nc-nd/4.0
ACTA Otorhinolaryngologica Italica
Bow and Lean Test
Pseudo-spontaneous nystagmus increases Bow and Lean Test accuracy
Text.Serial.Journal
https://www.actaitalica.it/
41
Vestibology
2021-07-07
2020-09-24
2021-07-08
2021-07-08
270-276
1
Vincenzo Marcelli
2021/07/07
10.14639/0392-100X-N1136
270
ASL Napoli1 Centro, Ospedale del Mare, Naples, Italy
1827-675X
Bow and Lean Test
276
Pseudo-spontaneous nystagmus increases Bow and Lean Test accuracy
https://www.actaitalica.it/article/download/1136/626
41
ACTA OTORHINOLARYNGOLOGICA ITALICA 2021;41:270-276; doi: 10.14639/0392-100X-N1136




Vestibology


Pseudo-spontaneous nystagmus increases Bow
and Lean Test accuracy
La presenza di nistagmo pseudo-spontaneo incrementa l’accuratezza del Bow
and Lean Test
Mario Faralli1, Alfredo Di Giovanni1, Giacomo Ciacca1, Giulia Zambonini1, Erica De Bernardo2, Vincenzo Marcelli2
1
    Otorhinolaryngology Clinic, University of Perugia, Perugia, Italy; 2 A.S.L. Napoli1 Centro, Ospedale del Mare, Naples, Italy


SUMMARY
Object. The aim of this study was to evaluate the effectiveness of the Bow and Lean Test
(BLT) based on nystagmus intensity and direction evaluation (NID-BLT) in the diagnosis
of benign paroxysmal positional vertigo of the lateral semicircular canal (LSC-BPPV). We
hypothesised that the presence of a pseudo-spontaneous nystagmus increases the diagnostic
accuracy of the test.
Methods. The BLT was performed in 32 subjects affected by LSC-BPPV.
Results. BLT was positive in 27 cases with a sensitivity of 84.3% and an accuracy of 70.4%.
In other words, it was possible to carry out a BPPV root canal diagnosis (LSC) with BLT
in 27 patients, of whom 19 also received a diagnosis of side and form. Pseudo-spontaneous
nystagmus was detected in 15 patients, all of whom were BLT positive. In these patients, a
clear diagnosis of form and side was also obtained in 14 cases (accuracy 93.3%). In the 12
patients without pseudo-spontaneous nystagmus and BLT positive, a diagnosis of side and
form was reached in 5 cases (accuracy 41.6%). The comparison between percentages (Chi
square test) showed a significant difference (p = 0.038).                                          Received: September 24, 2020
Conclusions. The presence of a pseudo-spontaneous nystagmus, as an expression of more              Accepted: December 28, 2020
mobile debris within the canal or a more deflectable cupula, increases the accuracy of the
BLT.                                                                                               Correspondence
                                                                                                   Mario Faralli
KEY WORDS: benign paroxysmal positional vertigo, lateral semicircular canal, vestibular            Otorhinolaryngology Clinic, University of Perugia,
system, pseudo-spontaneous nystagmus, Bow and Lean Test                                            Perugia, Italy
                                                                                                   Tel. +39 075 5783236
RIASSUNTO                                                                                          E-mail: mario.far@hotmail.it
Obiettivo. Scopo dello studio è stato valutare l’efficacia del Bow and Lean Test (BLT) nella
diagnosi di vertigine posizionale parossistica benigna del canale semicircolare laterale           Funding
                                                                                                   None.
(LSC-BPPV). Nello specifico abbiamo ipotizzato che la presenza di nistagmo pseudo-spon-
taneo potesse incrementare l’accuratezza del BLT.
Metodi. Abbiamo eseguito il BLT in 32 pazienti affetti da LSC-BPPV.                                Conflict of interest
                                                                                                   The Authors declare no conflict of interest.
Risultati. Il BLT è risultato positivo, consentendo diagnosi di LSC-BPPV, in 27 casi; inol-
tre in 19 pazienti è stato possibile identificare il lato affetto e la forma (sensibilità 84,3%,
accuratezza 70,4%). Quindici dei pazienti presentavano nistagmo pseudo-spontaneo, que-               How to cite this article: Faralli M, Di Giovanni
sti sono risultati tutti positivi al BLT ed è stato inoltre possibile ottenere una diagnosi di       A, Ciacca G, et al. Pseudo-spontaneous nystag-
forma in 14 casi (accuratezza 93,3%). Nei 12 pazienti, positivi al BLT, che non presenta-            mus increases Bow and Lean Test accuracy. Acta
vano nistagmo pseudo-spontaneo è stato possibile fare diagnosi di lato e forma in 5 casi             Otorhinolaryngol Ital 2021;41:270-276. https://
(accuratezza 41,6%). Il confronto tra le percentuali (test del Chi quadro) ha mostrato una           doi.org/10.14639/0392-100X-N1136
differenza statisticamente significativa.
                                                                                                   © Società Italiana di Otorinolaringoiatria
Conclusioni. I risultati ottenuti permettono di affermare che la presenza di nistagmo pseu-
                                                                                                   e Chirurgia Cervico-Facciale
do-spontaneo, espressione di una maggiore mobilità intracanalare degli otoliti o di una più
ampia escursione della cupola, incrementa l’accuratezza del BLT.
                                                                                                                  OPEN ACCESS
PAROLE CHIAVE: vertigine posizionale parossistica benigna, canale semicircolare                    This is an open access article distributed in accordance with
laterale, sistema vestibolare, nistagmo pseudo-spontaneo, Bow and Lean Test                        the CC-BY-NC-ND (Creative Commons Attribution-Non-
                                                                                                   Commercial-NoDerivatives 4.0 International) license. The
                                                                                                   article can be used by giving appropriate credit and mentio-
                                                                                                   ning the license, but only for non-commercial purposes and
                                                                                                   only in the original version. For further information: https://
                                                                                                   creativecommons.org/licenses/by-nc-nd/4.0/deed.en




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Introduction                                                     “null-point” in the pitch plane 8,9, “bending nystagmus” 10,
                                                                 “Bow and Lean Choung’s Test” 11, “Head Shaking-Induced
Benign paroxysmal positional vertigo (BPPV) represents
                                                                 Nystagmus” (HSIN) 8, Sitting to Supine positioning Test
the most common vestibular disorder. It can affect all ages,     (SSPT) 12-15 and null point in supine position 9. On occa-
although the incidence increases progressively in the el-        sion, the psycho-physical conditions of the patient signifi-
derly. BPPV is about two to three times more common in           cantly affect the executability of diagnostic and therapeutic
women than in men 1. BPPV occurs due to the displace-            manoeuvers in clinical practice. The need for a diagnosis,
ment of otoconia within the fluid-filled semicircular canals     even timely in any case, requires the examiner to adhere
of the inner ear, which is capable of inducing significant       to a behaviour of minimum stress for the patient, in order
endolymphatic flows responsible for vertigo crises follow-       to collect useful semeiological information. The Bow and
ing head movements 2. The anamnesis strongly orientates          Lean Test (BLT) based on nystagmus intensity and direc-
towards a diagnosis which must, in any case, be confirmed        tion evaluation (NID-BLT) 16 for its dynamic characteristics
by bedside examination. Paroxysmal positional nystagmus,         seems to respond to these needs. The BLT was designed by
when it respects certain morphological and temporal char-        Choung to evaluate whether pitch movements (flexion and
acteristics, represents the typical semeiological element        hyperextension) of the head can generate or modify a sug-
for diagnosis of BPPV. The most frequent locations of the        gestive nystagmus of LSC-BPPV 11. The test is performed
dislodged otoconia are the ampullary arm of the posterior        with the patient seated with the head in axis with the trunk
semicircular Canal (PSC) and the non-ampullary arm of            (starting position). In this position, before execution of
the lateral semicircular canal (LSC) 2. In particular, LSC-      pitch head movements, horizontal pseudo-spontaneous
BPPV results from the movement of dense particles in the         nystagmus, generated by the slow slide of the dense par-
LSC. The diagnostic test is the supine roll test, also called    ticles along the LSC, may be present in subjects suffering
Pagnini-McClure manoeuver 3,4, showing, in the two posi-         from LSC-BPPV 8.
tions, a typical horizontal paroxysmal bipositional bidirec-     The purpose of this study was qualitative and quantita-
tional nystagmus which is apogeotropic in case of dense          tive analysis of the oculomotor responses obtained with
particles adherent to the cupula (cupulolithiasis) or free-      the application of the NID-BLT. For this purpose, a con-
floating in the LSC ampullary arm (canalolithiasis) and          secutive population of LSC-BPPV patients ascertained by
geotropic in case of dense particles free-floating in the LSC    Pagnini-McClure manoeuver was recruited. The sensitiv-
non-ampullary arm (canalolithiasis) 2,5,6. The identification    ity of the BLT in the diagnosis of LSC-BPPV and its ac-
of the affected ear is fundamental in order to perform the       curacy in identifying the intracanal location of the debris
right repositioning manoeuvre. In the apogeotropic form,         and the affected side were calculated. A comparative as-
the nystagmus is more intense when the affected ear is up,       sessment in terms of sensitivity and diagnostic accuracy
since this position provokes a direct (cupulolithiasis) or       was performed between patients affected from LSC-BPPV
indirect (canalolithiasis, endolymph-mediated) excitatory        with and without spontaneous nystagmus in sitting position
deflection of the cupula, according to Ewald’s 2nd law. On       before performing BLT. We hypothesised that the presence
the contrary, the nystagmus is less intense when the affect-     of a pseudo-spontaneous nystagmus, as an expression of
ed ear is down, since this position provokes an inhibitory       more mobile debris within the canal or a more deflectable
deflection of the cupula. In the geotropic form, the nystag-     cupula, increases the diagnostic accuracy of the BLT.
mus is more intense when the affected ear is down, since
this position provokes an indirect, endolymph-mediated
excitatory deflection of the cupula, while the nystagmus         Materials and methods
is less intense with the affected ear up, since this position    32 consecutive patients suffering from LSC-BPPV without
provokes an indirect, endolymph-mediated inhibitory de-          any other associated vestibular disease were enrolled in a
flection of the cupula. As a result, the affected ear can be     prospective study from January 2019 to February 2020. Pa-
determined as the side showing the less intense nystagmus        tients underwent vestibular examination using an infrared
in the apogeotropic form and the side showing the more           video-nystagmoscopic and video-nystagmographic instru-
intense nystagmus in the geotropic form 5,7. However, it is      ment (VNG Ulmer; Synapsys S.A., Marseille, France) to
sometimes difficult to identify the differences in nystagmus     confirm diagnosis of BPPV. Patients suffering from PSC-
intensity occurring during roll test that lead to diagnosis of   BPPV or Anterior Semicircular Canal (ASC) BPPV were
side. For this reason, secondary signs and several tests for     not recruited. Patients were initially selected in accordance
lateralisation, performed in both erect and supine positions,    with our protocol (see below) in which BPPV was speculat-
have been described: “pseudo-spontaneous” nystagmus 7,8,         ed, but not confirmed by bedside examination; patients in



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M. Faralli et al.




whom important neurovegetative symptoms prevented the             2nd step (Bow): the head is bowed 60° forward and the nys-
correct execution of diagnostic manoeuvers were excluded.         tagmus intensity assessed again. The head should be held in
                                                                  this position for 30 sec.
Study protocol                                                    The test is based on assumption that the nystagmus intensi-
132 consecutive patients with suggestive anamnesis for            ty, in the two BLT positions, may be equally compared only
BPPV were initially selected for the study from a popula-         if the magnitude of the LSC tilt (or head pitch) is identical.
tion of 290 patients who came to our observation in the pe-       Only in this case can one be certain that the dense particles
riod from 1 January 2019 to 28 February 2020. Patients un-        run through the affected LSC at the same speed and that the
derwent vestibular tests including BLT, Pagnini-McClure           difference in nystagmus intensity is solely due to Ewald’s
and Dix-Hallpike manoeuvers. The reliable diagnosis of            2nd law 16.
LSC-BPPV and PSC-BPPV was ascertained with the Pag-               The different “nystagmus intensity” in the bow and in the
nini-McClure and Dix-Hallpike manoeuvers, respectively.           lean positions was used to differentiate a geotropic form
Three operators belonging to the ENT Clinic of Perugia            from an apogeotropic one. “Direction nystagmus” evalua-
were involved in the study with specific vestibular skills.       tion allows identification of the affected side when associ-
In particular, the first was assigned to the collection of an-    ated with the “intensity nystagmus” evaluation.
amnestic data which allowed to formulate the hypothesis
of BPPV. The second performed the BLT for searching               Data collection and statistical evaluation
nystagmus evoked by cupulo-canalolitiasis of LSC. Subse-          The sensitivity and diagnostic accuracy of BLT in patients
quently, the third operator performed the Pagnini-McClure         suffering from LSC-BPPV with or without spontaneous
manoeuver, an indispensable procedure for the definitive          nystagmus in the primary head position was calculated. A
diagnosis of LSC-BPPV. The BLT was always performed               sensitive test was intended to be able to provide, on the
before Pagnini-McClure manoeuver. It is important to un-          basis of the semeiological findings that emerged during the
derline the time sequence of the tests, because the Pagnini-      examination, a diagnosis exclusively of root canal location.
McClure manoeuver, if performed before, can influence the         An accurate test was intended to provide a diagnosis not
BLT sensitivity and results. The second and third operators       only of root canal location, but also of intra-canal loca-
operated in a double-blind fashion.                               tion of debris (geotropic form, apogeotropic form) and the
                                                                  affected side. The comparison between percentages was
BLT                                                               made by chi-square test. Differences with p < 0.05 were
Before the BLT was performed, the patient was observed in         considered to be statistically significant.
two or three preliminary positions:                               The authors assert that all procedures contributing to this
A) Primary position: the patient, seated with the head in         work comply with the ethical standards of the relevant na-
    axis with the trunk, is assessed for a horizontal pseudo-     tional and institutional guidelines on human experimenta-
    spontaneous nystagmus.                                        tion and with the Helsinki Declaration of 1975, as revised
B) Null point position: the so-called null point position         in 2008. Informed consent was obtained from all partici-
    must be sought with a slow pitch movement of the head         pants in the study.
    (or LSC tilt) forward to determine the disappearance of
    the spontaneous nystagmus. When the LSC lies on a
                                                                  Results
    horizontal plane, in fact, the spontaneous sliding of the
    particles disappears and so does the nystagmus.               Of the 132 patients initially selected based on their history,
C) Starting position: once the null point is identified, which    16 were excluded as the diagnostic manoeuvers (Pagnini-
    is slightly different in each subject due to the inevitable   McClure and Dix-Hallpike) did not evoke paroxysmal po-
    anatomical differences, we bow the head of 30° with           sitional nystagmus. In all these patients, BLT did not evoke
    respect to the null point itself and wait for about 30 sec    nystagmus. In addition, 11 patients with a history sugges-
    (or wait for the disappearance of nystagmus if evoked).       tive of BPPV could not complete the bedside examination
The starting position can be reached directly, excluding the      due to onset of significant autonomic symptoms. A further
null point position, in the case that pseudo-spontaneous          8 patients were excluded as they presented down beat-
nystagmus was not detected in the primary position.               ing nystagmus to the diagnostic procedures, which led to
The next phase is the proper NID-BLT test:                        a hypothesis of an apogeotropic variant of PSC-BPPV 17
1st step (Lean): from the starting position the head is leant     or ASC-BPPV. Additionally, 61 patients affected by PSC-
60° backward, and the nystagmus is evaluated. The head            BPPV were not enrolled. Thirty-six patients were affected
should be held in this position for 30 sec.                       by LSC-BPPV. In 4 (3 apogeotropic, 1 geotropic) of the



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36 patients with LSC-BPPV it was not possible to make                           The diagnostic accuracy was 70.4%. In other words, it was
a side diagnosis, as no significant differences in the inten-                   possible to carry out a BPPV root canal diagnosis (LSC)
sity of the nystagmus evoked at the two Pagnini-McClure                         with BLT in 27 patients, of whom 19 also received a di-
manoeuvers were detectable. Therefore, 32 patients with                         agnosis of side and form (Tab. I). In the other 8 patients,
LSC-BPPV were definitively recruited in the study. In all                       the BLT did not show clinically appreciable differences in
these cases, the Pagnini-McClure manoeuver allowed with                         the intensity of the inverted nystagmus, evoked by the two
reasonable certainty a diagnosis of root canal involvement                      investigated head positions, in 6 cases (patients 4-10-12-
(LSC) and affected side (19 right, 13 left) and intracanal                      15-20-31). In the remaining 2 patients, the direction and
localisation (22 non-ampullary: geotropic form, 10 ampul-                       the intensity of the inverted nystagmus was in opposition
lary arm: apogeotropic form). The BLT was positive in 27                        with the clinical findings from Pagnini-McClure manouev-
cases with a sensitivity of 84.3%. In 5 patients (patients                      er (patients 9-18) (Tab. I). Pseudo-spontaneous nystagmus
5-7-13-26-29), BLT did not evoke any nystagmus (Tab. I).                        was detected in 15 patients (patients 1-2-3-6-8-11-14-16-


Table I. Semeiological findings in 32 patient affected by LSC-BPPV.
 Patient              Arm                  Form      Side          Bow             Lean              Bow              Lean        Sensivity   Accurancy
                                                              (ny direction)   (ny direction)   (ny intensity)   (ny intensity)     (BLT)       (BLT)
 1               Non ampullary             Geo       Right        Right            Left             +++                +            Yes          Yes
 2               Non ampullary             Geo       Right        Right            Left             +++                +            Yes          Yes
 3                 Ampullary              Apogeo     Right        Left             Right              +              +++            Yes          Yes
 4               Non ampullary             Geo       Left         Left             Right             ++              ++             Yes          No
 5                 Ampullary              Apogeo     Right       Absent           Absent           Absent           Absent          No           No
 6               Non ampullary             Geo       Right        Right            Left             +++                +            Yes          Yes
 7               Non ampullary             Geo       Left        Absent           Absent           Absent           Absent          No           No
 8               Non ampullary             Geo       Right        Right            Left             +++                +            Yes          Yes
 9                 Ampullary              Apogeo     Left         Left             Right            +++                +            Yes          No
 10              Non ampullary             Geo       Left         Left             Right             ++               ++            Yes          No
 11              Non ampullary             Geo       Right        Right            Left             +++                +            Yes          Yes
 12                Ampullary              Apogeo     Right        Left             Right             ++               ++            Yes          No
 13              Non ampullary             Geo       Left        Absent           Absent           Absent           Absent          No           No
 14              Non ampullary             Geo       Right        Right            Left             +++                +            Yes          Yes
 15              Non ampullary             Geo       Left         Left             Right             ++               ++            Yes          No
 16              Non ampullary             Geo       Right        Right            Left             +++                +            Yes          Yes
 17                Ampullary              Apogeo     Left         Right            Left               +              +++            Yes          Yes
 18                Ampullary              Apogeo     Right        Right            Left             +++                +            Yes          No
 19              Non ampullary             Geo       Right        Right            Left             +++                +            Yes          Yes
 20              Non ampullary             Geo       Left         Left             Right             ++               ++            Yes          No
 21              Non ampullary             Geo       Left         Left             Right            +++                +            Yes          Yes
 22                Ampullary              Apogeo     Right        Left             Right              +              +++            Yes          Yes
 23              Non ampullary             Geo       Right        Right            Left             +++               +             Yes          Yes
 24                Ampullary              Apogeo     Left         Right            Left               +              +++            Yes          Yes
 25              Non ampullary             Geo       Right        Right            Left             +++               +             Yes          Yes
 26              Non ampullary             Geo       Right       Absent           Absent           Absent           Absent          No           No
 27              Non ampullary             Geo       Right        Right            Left             +++               +             Yes          Yes
 28                Ampullary              Apogeo     Left         Right            Left               +              +++            Yes          Yes
 29                Ampullary              Apogeo     Right       Absent           Absent           Absent           Absent          No           No
 30              Non ampullary             Geo       Left         Left             Right            +++               +             Yes          Yes
 31              Non ampullary             Geo       Right        Right            Left              ++              ++             Yes          No
 32              Non ampullary             Geo       Left         Left             Right            +++               +             Yes          Yes




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M. Faralli et al.




20-22-23-24-25-30-32), all BLT positive and none of the 5                      side was also obtained in 14 cases (accuracy 93.3%), obvi-
cases of LSC-BPPV with negative BLT (Tab. II). The pres-                       ously confirmed at the subsequent Pagnini-McClure man-
ence of a pseudo-spontaneous nystagmus therefore implies                       ouever. In the 12 patients without pseudo-spontaneous nys-
a sensitivity and specificity of BLT of 100%. In 17 patients                   tagmus and positive BLT, a clear diagnosis of form and side
without pseudo-spontaneous nystagmus, BLT was posi-                            was reached in 5 cases (accuracy 41.6%). The comparison
tive in 12 cases (70.6%). The comparison between the two                       between percentages (Chi square test) showed a significant
groups of patients showed a statistically significant increase                 difference (p = 0.038) (Tab. II).
in BLT sensitivity in the presence of pseudo-spontaneous
nystagmus. Regarding the diagnostic accuracy of BLT in
presence of pseudo-spontaneous nystagmus, the data are as
                                                                               Discussion
follows: In the 15 patients with pseudo-spontaneous nys-                       The BLT is a simple method that may help to determine
tagmus and positive for BLT, a clear diagnosis of form and                     the affected ear in cases of LSC-BPPV. The limitation is


Table II. Sensitivity and accuracy of the BLT in LSC-BPPV patient with and without pseudo-spontaneous nystagmus.
 Patient                                 Diagnosis LSC-PPV                    Pseudo-spontaneous                 Sensivity   Accurancy
                                          (Pagnini-McClure)                            ny                          (BLT)       (BLT)
 1                                        Right geotropic                            Yes                           Yes          Yes
 2                                        Right geotropic                            Yes                           Yes          Yes
 3                                      Right apogeotropic                           Yes                           Yes          Yes
 4                                        Left geotropic                             No                            Yes          No
 5                                      Right apogeotropic                           No                            No            -
 6                                        Right geotropic                            Yes                           Yes          Yes
 7                                        Left geotropic                             No                            No            -
 8                                        Right geotropic                            Yes                           Yes          Yes
 9                                      Left apogeotropic                            No                            Yes          No
 10                                       Left geotropic                             No                            Yes          No
 11                                       Right geotropic                            Yes                           Yes          Yes
 12                                     Right apogeotropic                           No                            Yes          No
 13                                       Left geotropic                             No                            No            -
 14                                       Right geotropic                            Yes                           Yes          Yes
 15                                       Left geotropic                             No                            Yes          No
 16                                       Right geotropic                            Yes                           Yes          Yes
 17                                     Left apogeotropic                            No                            Yes          Yes
 18                                     Right apogeotropic                           No                            Yes          No
 19                                       Right geotropic                            No                            Yes          Yes
 20                                       Left geotropic                             Yes                           Yes          No
 21                                       Left geotropic                             No                            Yes          Yes
 22                                     Right apogeotropic                           Yes                           Yes          Yes
 23                                       Right geotropic                            Yes                           Yes          Yes
 24                                     Left apogeotropic                            Yes                           Yes          Yes
 25                                       Right geotropic                            Yes                           Yes          Yes
 26                                       Right geotropic                            No                            No            -
 27                                       Right geotropic                            No                            Yes          Yes
 28                                     Left apogeotropic                            No                            Yes          Yes
 29                                     Right apogeotropic                           No                            No            -
 30                                        Left geotropic                            Yes                           Yes          Yes
 31                                       Right geotropic                            No                            Yes          No
 32                                        Left geotropic                            Yes                           Yes          Yes




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represented by the need to always integrate the test with       flows generated by the new spatial relationships between
the Pagnini-McClure manoeuvre in order to know a priori         gravitational vector and LSC. On the contrary, in the ab-
which variant (geotropic vs. apogeotropic) the patient is       sence of nystagmus, where a lower spontaneous mobility
suffering from. Nystagmus intensity and direction evalua-       of the particles is conceivable, the energy applied to the
tion overcome this limitation, providing information with-      pitch movements would initially be dissipated, in part, to
out necessarily having to resort to other tests 16. Based on    overcome the counter-resistance forces. In all probabil-
semeiological findings, in both forms the direction of the      ity, these effects would be greater at the beginning of the
more intense nystagmus points to the affected side, while       first diagnostic positioning in lean (or bow). The amount
the different nystagmus intensity in the bow and in the lean    of stimulus and the extent of the responses evoked by the
position allow us to differentiate a geotropic form from        two pitch movements of the head could prove unequal and
an apogeotropic one. In our study the NID-BLT was ef-           lead to less accuracy in the interpretation of the NID-BLT.
fective in identifying the form and the side in the 70.4%       This model, proposed for canalolithiasis (ampullary and
of patients, a slightly lower value than that reported in a     non-ampullary arm) appears, however, less convincing to
previous study (76%) 16. Several reasons can explain the        explain the spontaneous nystagmus and the relative greater
lack of identification in some cases. First, a very minimal     accuracy of BLT in cupulolithiasis. An accurate BLT rep-
difference between the intensities in the two positions was     resents an undoubted therapeutic advantage. The ability
found, even during video-nystagmographic recordings. An-        to diagnose the form (geotropic vs apogeotropic) and the
other limitation is the occurrence of mixed forms in which      side of the BPPV by BLT allows to correctly orient Gu-
some otoconia are adherent to the cupula, but others are        foni’s manoeuver 18 towards the most suitable decubitus
free-floating within the semicircular canal. Finally, differ-   for the repositioning procedure, without the diagnostic aid
ent accelerations in the canal can be generated by unequal      provided by the Pagnini-McClure manoeuver. This advan-
amplitude in flexion and extension, and thus the different      tage appears further confirmed by the situation in which
nystagmus intensity may also be due to a slight difference      neurovegetative symptoms, possibly present, represent an
in head angle. The main data emerging from our study is         aggravating condition for the patient’s stress and limiting
the significant increase in the accuracy of the BLT when        the performance of traditional diagnostic manoeuvers. The
pseudo-spontaneous nystagmus was observed in the prima-         last consideration regards the appropriateness of resorting
ry position of the head, before performing the diagnostic       to additional measures such as gentle lateral head rotations
procedures. Such horizontal nystagmus, which may be pre-        in sitting position (low frequencies) to either side or the
sent in subjects suffering from LSC-BPPV, when present,         vibratory stimulus (high frequencies) that is capable of pro-
is generated by the slow slide of dense particles along the     moting the mobility of the particles and the appearance of a
LSC. Since the LSC is superiorly inclined by 30° forward        pseudo-spontaneous nystagmus that was previously absent.
relative to the horizontal plane, it behaves as a natural and   The BLT is a valid clinical approach, even in patients who
true inclined plane along which the dense particles slowly      do not show pseudo-spontaneous nystagmus. Despite the
slide, resulting in either an excitatory (dense particles ad-   low accuracy, the test is easy to perform and well toler-
herent to the cupula or free-floating in the ampullary arm)     ated. Undoubtedly, the induction of this semeiological data
or inhibitory (dense particles in non-ampullary arm) de-        may be useful in determining an increase in the accuracy
flection of the cupula and nystagmus 16. The reason why         of the BLT in cases in which the anamnesis strongly ori-
the aforementioned semeiological data is associated with        entates towards a diagnosis of BPPV and the presence of
a greater accuracy of the BLT is not easy to understand.        neurovegetative symptoms, or physical limitations, advise
It is conceivable that debris, more endowed with high-          against the execution of traditional diagnostic manoeuvers.
er mobilisation capacity for intrinsic root canal factors,
are more affected by gravitational effects and, therefore,
more predisposed to spontaneously induce endolymphatic
                                                                Conclusions
flows and significant ampullary deflections responsible for     Our study found that the presence of a pseudo-spontaneous
pseudo-spontaneous nystagmus before performing the text.        nystagmus, as an expression of more mobile debris within
These dynamic characteristics may influence the following       the canal or a more deflectable cupula, increases the diag-
responses evoked at BLT. In the presence of floating par-       nostic accuracy of the BLT. Additional measures such as
ticles, whose inertia is able to overcome the resistance of     gentle lateral head rotations to either side before BLT ex-
opposing forces by exploiting only the inclination of the       ecution, capable of promoting the mobility of the particles
LSC plane, the energy applied at the beginning of the pitch     and the appearance of a pseudo-spontaneous nystagmus
movements would be largely used to induce endolymphatic         previously absent are recommended.



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M. Faralli et al.




References                                                                          ing the horizontal canal. J Neurol Sci 2007;256:75-80 https://doi.
                                                                                    org/10.1016/j.jns.2007.02.026
1
     Bruintjes TD, van der Zaag-Loonen HJ, Eggelmeijer F, et al. The           11
                                                                                    Choung Y-H, Shin YR, Kahng H, et al. “Bow and Lean Test” to de-
     prevalence of benign paroxysmal positional vertigo in patients with            termine the affected ear of horizontal canal benign paroxysmal po-
     osteoporosis. Eur Arch Otorhinolaryngol 2018;275:3083-3086. htt-               sitional vertigo. Laryngoscope 2006;116:1776-1781. https://doi.
     ps://doi.org/10.1007/s00405-018-5164-4                                         org/10.1097/01.mlg.0000231291.44818.be
2
     Brandt T, Steddin S. Current view of the mechanism of benign parox-       12
                                                                                    Nuti D, Vannucchi P, Pagnini P. Benign paroxysmal positional ver-
     ysmal positioning vertigo: cupulolithiasis or canalolithiasis? J Vestib        tigo of the horizontal canal: a form of canalolithiasis with variable
     Res 1993;3:373-82.                                                             clinical features. J Vest Res 1996;6:173-184. https://doi.org/10.3233/
3
     McClure A. Lateral canal BPV. J Otolaryngol 1985;14:30-35.                     VES-1996-6303
4
     Pagnini P, Nuti D, Vannucchi P. Benign paroxysmal vertigo of the          13
                                                                                    Nuti D, Vannucchi P, Pagnini P. Lateral canal BPPV: which
     horizontal canal. ORL J Otorhinolaryngol Relat Spec 1989;51:161-               is the affected side? Audiol Med 2005;3:16-20. https://doi.
     170. https://doi.org/10.1159/000276052                                         org/10.1080/16513860510028275
5
     Brandt T. Benign paroxysmal positional vertigo. In: Brandt T, editor
                                                                               14
                                                                                    Han BI, Oh HJ, Kim JS. Nystagmus while recumbent in horizontal
     Vertigo: its multisensory syndrome. Second Edition. Berlin: Springer-          canal benign paroxysmal positional vertigo. Neurology 2006;66:706-
     Verlag; 1999. pp. 269-279.                                                     710. https://doi.org/10.1212/01.wnl.0000201184.69134.23
6
     Baloh RW, Jacobson KM, Honrubia V. Horizontal semicircular vari-
                                                                               15
                                                                                    Koo JW, Moon IJ, Shim WS, et al. Value of lying-down nystagmus
     ant of benign positional vertigo. Neurology 1993;43:2542-2549. htt-            in the lateralization of horizontal semicircular benign paroxys-
     ps://doi.org/10.1212/wnl.43.12.2542                                            mal positional vertigo. Otol Neurotol 2006;27:367-371. https://doi.
                                                                                    org/10.1097/00129492-200604000-00013
7
     Asprella-Libonati G. Diagnostic and treatment strategy of lat-            16
                                                                                    Marcelli V. Nystagmus intensity and direction in bow and lean test: an
     eral semicircular canal canalolithiasis. Acta Otorhinolaryngol Ital
                                                                                    aid to diagnosis of lateral semicircular canal benign paroxysmal po-
     2005;25:277-283.
                                                                                    sitional vertigo. Acta Otorhinolaryngol Ital 2016;36:520-526. https://
8
     Asprella-Libonati G. Pseudo-spontaneous nystagmus: a new sign to               doi.org/10.14639/0392-100X-795
     diagnose the affected side in lateral semicircular canal benign parox-    17
                                                                                    Vannucchi P, Pecci R, Giannoni B, et al. Apogeotropic posterior sem-
     ysmal positional vertigo. Acta Otorhinolaryngol Ital 2008;28:73-78.            icircular canal benign paroxysmal positional vertigo: some clinical
9
     Bissdorff AR, Debatisse D. Localizing signs in positional vertigo due          and therapeutic considerations. Audiol Res 2015;5:130. https://doi.
     to lateral cupulolithiasis. Neurology 2001;57:1085-1088. https://doi.          org/10.4081/audiores.2015.130.
     org/10.1212/wnl.57.6.1085                                                 18
                                                                                    Gufoni M, Mastrosimone L. Trattamento con manovra di riposiziona-
10
     Lee S-H, Choi K-D, Jeong S-H, et al. Nystagmus during neck flex-               mento per la canalolitiasi orizzontale. Acta Otorhinolaryngol Ital
     ion in the pitch plane in benign paroxysmal positional vertigo involv-         1998;18:363-367.




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