10.14639/0392-100X-N1233
Objectives. Benign paroxysmal positional vertigo (BPPV) is a disorder of the inner ear with a high rate of recurrence. Vascular disorders, migraine and autoimmune disorders have been considered facilitating factors for relapsing episodes. Our aim was to assess the role of vascular disorders, migraine and anti-thyroid antibodies in patients with recurrences.Methods. We retrospectively analysed records of 3042 patients treated for BPPV without other lifetime vertigo. Clinical data included previous vascular disorders of the central nervous system, heart disorders, migraine and recent head trauma. The presence of anti-thyroid autoantibodies was assessed in all patients.Results. Mean age of the first BPPV was 52.8 ± 14.5 years; there were 2339 females (76.9%), while 2048 (67.3%) of patients presented recurrences within two years of followup. Previous disorders of the central nervous system, presence of anti-thyroid antibodies, head trauma and migraine showed an association with recurrences. Above all, in subjects having the first BPPV while aged between 40 and 60 years, anti-thyroid antibodies were predictive for recurrences.Conclusions. Our data are consistent with the hypothesis that anti-thyroid autoantibodies may play a role in recurrences in subjects with initial manifestations between 40 and 60 years.
text/xml
1827-675X
1233
en
Giorgio Guidetti
http://creativecommons.org/licenses/by-nc-nd/4.0
ACTA Otorhinolaryngologica Italica
vascular disorders of the central nervous system
Recurrence of benign paroxysmal positional vertigo: experience in 3042 patients
Text.Serial.Journal
https://www.actaitalica.it/
41
Vestibology
2021-11-05
2020-11-10
2021-11-02
2021-11-02
461-466
1
Giorgio Guidetti
2021/11/05
10.14639/0392-100X-N1233
461
Vertigo Centre, Poliambulatorio Chirurgico Modenese, Italy
1827-675X
vascular disorders of the central nervous system
466
Recurrence of benign paroxysmal positional vertigo: experience in 3042 patients
https://www.actaitalica.it/article/download/1233/682
41
ACTA OTORHINOLARYNGOLOGICA ITALICA 2021;41:461-466; doi: 10.14639/0392-100X-N1233




Vestibology


Recurrence of benign paroxysmal positional vertigo:
experience in 3042 patients
Le recidive della vertigine parossistica posizionale benigna: dati su un campione
di 3042 soggetti
Roberto Teggi1, Riccardo Guidetti2, Omar Gatti1, Giorgio Guidetti2
1
 Division of Otolaryngology, IRCCS San Raffaele Scientific Institute, Milan, Italy; 2 Vertigo Centre, Poliambulatorio Chirurgico
Modenese, Italy


SUMMARY
Objectives. Benign paroxysmal positional vertigo (BPPV) is a disorder of the inner ear
with a high rate of recurrence. Vascular disorders, migraine and autoimmune disorders have
been considered facilitating factors for relapsing episodes. Our aim was to assess the role
of vascular disorders, migraine and anti-thyroid antibodies in patients with recurrences.
Methods. We retrospectively analysed records of 3042 patients treated for BPPV without
other lifetime vertigo. Clinical data included previous vascular disorders of the central nerv-
ous system, heart disorders, migraine and recent head trauma. The presence of anti-thyroid
autoantibodies was assessed in all patients.
Results. Mean age of the first BPPV was 52.8 ± 14.5 years; there were 2339 females
(76.9%), while 2048 (67.3%) of patients presented recurrences within two years of follow-
up. Previous disorders of the central nervous system, presence of anti-thyroid antibodies,
head trauma and migraine showed an association with recurrences. Above all, in subjects
having the first BPPV while aged between 40 and 60 years, anti-thyroid antibodies were              Received: November 10, 2020
predictive for recurrences.                                                                         Accepted: May 10, 2021
Conclusions. Our data are consistent with the hypothesis that anti-thyroid autoantibodies
may play a role in recurrences in subjects with initial manifestations between 40 and 60            Correspondence
years.                                                                                              Roberto Teggi
                                                                                                    San Raffaele Hospital, via Olgettina 60, 20132
KEY WORDS: benign paroxysmal positional vertigo, bppv, anti-thyroids autoantibodies,                Milan, Italy
migraine, vascular disorders of the central nervous system                                          Tel. +39 02 26433522. Fax +39 02 26433508
                                                                                                    E-mail: teggi.roberto@hsr.it
RIASSUNTO
Obiettivi. La vertigine parossistica posizionale benigna (VPPB) è una patologia con nume-           Funding
                                                                                                    None.
rose recidive. Disordini vascolari, emicrania, traumi cranici e patologie autoimmuni sono
stati considerati come fattori facilitanti. Scopo del nostro lavoro è stato stabilire il ruolo di
                                                                                                    Conflict of interest
tali fattori e la presenza di anticorpi anti tiroide come facilitanti le recidive.
                                                                                                    The Authors declare no conflict of interest.
Metodi. Retrospettivamente abbiamo analizzato i dati di 3042 soggetti trattati per VPPB
con storia negativa per altri tipi di vertigine. I dati clinici includevano la presenza di di-
sordini vascolari del sistema nervoso centrale, del miocardio, emicrania, traumi cranici              How to cite this article: Teggi R, Guidetti R, Gat-
recenti. Era inoltre stato chiesto di effettuare un dosaggio degli anticorpi anti tiroide.            ti O, et al. Recurrence of benign paroxysmal po-
Risultati. L’età media del primo episodio era di 52,8; i soggetti di sesso femminile erano            sitional vertigo: our experience in 3042 patients.
2339 (76,9%), mentre 2048 (67,3%) hanno presentato una ricorrenza nei 2 anni successi-                Acta Otorhinolaryngol Ital 2021;41:461-466.
                                                                                                      https://doi.org/10.14639/0392-100X-N1233
vi. Precedenti vascolari del sistema nervoso centrale, positività per anticorpi anti tiroide
(soprattutto nel soggetti tra 40 e 60 anni), traumi cranici ed emicrania erano correlati con
                                                                                                    © Società Italiana di Otorinolaringoiatria
recidive.                                                                                           e Chirurgia Cervico-Facciale
Conclusioni. I nostri dati sono compatibili con l’ipotesi che gli anticorpi anti tiroide pos-
sano giocare un ruolo favorente le recidive nei soggetti la cui prima manifestazione sia
                                                                                                                   OPEN ACCESS
avvenuta tra i 40 e 60 anni.
                                                                                                    This is an open access article distributed in accordance with
PAROLE CHIAVE: vertigine parossistica posizionale benigna, vppb, anticorpi anti tiroide,            the CC-BY-NC-ND (Creative Commons Attribution-Non-
emicrania, disordini vascolari del sistema nervoso centrale                                         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                                                      Clinical history was collected by a senior neurotologist and
                                                                  subjects were included if they did not refer previous long
Benign paroxysmal positional vertigo (BPPV) is the most
                                                                  lasting (more than 5 minute) episodes of vertigo possibly
common vestibular disorder, and its lifetime incidence in
                                                                  related to Menière’s disease, vestibular migraine or unilat-
the general population has been estimated at around 10% 1.
                                                                  eral vestibular loss. Regarding clinical history, we collected
Its prevalence normally increases with age and presents a
                                                                  the following data:
female-to-male ratio of 2:1 or 3:1 2. The commonly ac-
                                                                  • Migraine: subjects were considered migraineurs if re-
cepted pathophysiological mechanism is displacement of
                                                                     porting typical headaches according to IHS criteria 11
otoconial debris from the utricular macula, floating freely
                                                                     and cautiously if they had a confirmatory neurological
in the semicircular canals or attached to the cupola; grav-
                                                                     consultation.
ity acting on the debris during head movements leads to
                                                                  • Vascular disorders of the central nervous system: we
an abnormal stimulation of the cupola thus provokes short
                                                                     considered mainly previous ischaemic or haemorrhagic
lasting paroxysmal vertigo mainly when lying in bed in a
                                                                     episodes or transitory ischaemic attacks.
specific head position 3. In most cases BPPV can be sus-
                                                                  • Heart disorders including ischaemic episodes, previous
pected by collecting clinical history and is easily diag-
                                                                     myocardial infarction or atrial fibrillation.
nosed by performing positional provocative manoeuvres;
                                                                  • Recent (in the previous month) head trauma; we also in-
it can be treated with repositioning manoeuvres which are
                                                                     cluded mild traumatic brain injuries not provoking loss
specific for each single canal and the positions of the de-
                                                                     of consciousness.
bris. Recently, the Barany Society published diagnostic
criteria for BPPV based on the onset of a short-lasting
                                                                  Clinical intervention
canal-specific nystagmus 4. BPPV has been classified in
                                                                  All subjects underwent a bedside examination including
primary and secondary (to head trauma, Menière’s Dis-
                                                                  head impulse test, head shaking and stepping test. All clini-
ease, otologic surgery, prolonged bed rest) 5. Recurrence
                                                                  cal tests were performed with the aid of video Frenzel (In-
of BPPV is far from being rare and according to previous
                                                                  teracoustics – Assens – Denmark).
authors about 50% of BPPV subjects present new epi-
sodes after successful repositioning manoeuvres 6. Differ-        In a second moment, we performed diagnostic manoeu-
ent clinical conditions have been proposed as facilitating        vres for BPPV, Semont or Dix-Hallpike to assess poste-
factors for recurrence, including diabetes, osteoporosis          rior or superior canal BPPV, supine head roll test for the
and vascular disorders 7,8. Other authors have focused on         lateral canal; final diagnosis of BPPV was made when
a possible role of low levels of vitamin D as a predispos-        patients referred vertigo in the diagnostic position and we
ing factor for recurrent BPPV 9 or high plasma levels of          observed a nystagmus presenting latency, duration and
anti-thyroid autoantibodies 10.                                   typical characteristics for the stimulated canal. Semont
The aim of this work was to assess the clinical conditions        or Epley repositioning manoeuvres were performed for
and anti-thyroid autoantibody positivity possibly associ-         the posterior canal, Yacovino for the superior canals and
ated with an increased rate of recurrences in a large sample      head shaking, barbecue or Gufoni for apogeotropic and
of patients with BPPV.                                            geotropic variants of the lateral canal. We normally prefer
                                                                  to firstly treat vertical canals and lateral canals at a later
                                                                  time. Patients were evaluated after 2 days; complete re-
Materials and methods                                             covery was considered when all diagnostic manoeuvres
Study cohort                                                      were negative and patients referred no vertigo during trig-
In this retrospective study we included 3042 patients treated     gering manoeuvres. Patients were considered to have a
for BPPV from 2014 and 2018; clinical data were obtained          history of previous BPPV only if this was explicitly docu-
from our records. All patients found in our clinical records      mented 13-15.
were included if they fulfilled criteria for single or multiple   We considered recurrent BPPV when patients presented
canal BPPV according to the Barany Society guidelines 4           typical signs after at least 2 months from complete re-
and performed an analysis for thyroid autoantibodies (anti-       covery. Data regarding recurrence were also collected by
thyroglobulin and anti-thyroid peroxidase autoantibodies)         phone interview in patients who were not evaluated in our
and if positive for hormone dosage; since data were col-          clinics after the first successful repositioning manoeuvre
lected from different centres, we were able only to assess        for another vestibular disorder. Before being considered
if they had normal or elevated thyroid hormone values. A          non-recurrent, a time of at least 2 years (in many cases until
retrospective analysis of data confirmed the diagnosis of         4 years) had to have been observed.
BPPV according to these recent guidelines.                        These patients were excluded if reporting clinical history



462
                                                                                                       Recurrence of BPPV and anti-thyroid autoantibodies




or presenting any sign possibly related to a vestibular dys-                    were migraineurs (10.6%), heart disorders were present in
function different from BPPV. A few cases with intractable                      269 subjects (8.8%) and a recent head trauma was reported
BPPV were not included.                                                         by 212 subjects (6.9%). Only 442 subjects with positivity
In order to exclude cerebellar disorders leading to posi-                       for thyroid autoantibodies (55.2%) presented increased thy-
tional vertigo, all relapsing episodes underwent an MRI or                      roid hormonal levels. Among patients with recurrent BPPV,
CT scan of the central nervous system and subjects were                         positivity for thyroid autoantibody was present in 599 sub-
included only if they had negative imaging.                                     jects (29.2%), central nervous system vascular disorders
Since previous works reported an overlap with autoimmune                        in 306 (14.9%), migraine in 234 (11.4%), heart disorders
thyroiditis, we routinely suggested that anti-thyroglobulin                     in 181 (8.8%) and head trauma in 158 subjects (7.7%). A
and peroxidase antibodies be assessed in all patients and,                      linear regression model demonstrated that all these factors
when positive, blood hormonal values were assessed; in the                      with the exclusion of cardiological disorders were predic-
present sample we included only subjects completing all                         tive of recurrence of BPPV (Tab. I).
diagnostic pathways.                                                            In the sample of 703 males, 439 (62.5%) reported recurrent
                                                                                BPPV, 72 (10.2%) had anti-thyroid antibodies, 41 (5.8%)
Statistical analysis                                                            were migraineurs, heart disorders were reported in 118
Continuous variables are reports as mean and standard de-                       (16.8%) subjects, while 130 (18.5%) had CNS vascular
viation. Categorical variables are presented as total number                    disorders and 78 (11.1%) had head trauma. Among 2339
and percentage. A p value ≤ 0.05 was considered statisti-                       females, recurrent BPPV was found in 1609 (68.8%) of
cally significant. A linear regression model was calculated                     cases. Thyroid antibodies were present in 731 (31.2%), 284
to assess the independent role of migraine, head trauma,                        (12.2%) were migraineurs, heart disease was found in 152
vascular disorders of the central nervous system, heart dis-                    (6.5%) cases and CNS vascular disorders in 253 (10.8%)
orders and positivity for thyroid antibodies on recurrence                      subjects; finally, a head trauma was reported by 134 (5.8%)
of BPPV. An identical analysis was performed in the sub-                        cases.
groups of subjects aged below 40, between 40 and 60 and                         Moreover, we studied the frequency of migraine, thyroid
over 60. Finally, a Pearson test was performed to corre-                        antibodies positivity, heart disorders, CNS vascular dis-
late age of onset of BPPV and recurrence. We used SPSS                          orders and head trauma separately in the subgroups of
software version 22.0 (SPSS, Inc., Chicago, IL, USA) for                        patients with onset of the first BPPV below 40, between
statistical analyses.                                                           40 and 60 and over 60 years. In Tables II-IV the results
                                                                                of a linear model considering migraine, thyroid antibod-
                                                                                ies positivity, heart disorders, CNS vascular disorders and
Results                                                                         head trauma as independent variables and recurrences as
The sample was composed of 3042 subjects; there were                            dependent variable are reported. Recent head trauma was
2339 females (76.9%). Age at inclusion was 63.3 ± 13.3                          the main causal factor for recurrence, while positivity for
years. The age of the first episode of BPPV was 52.8 ± 14.5                     thyroid autoantibodies was correlated with relapsing epi-
years (range 10-90). Recurrent episodes were demonstrated                       sodes only in the subgroup of subjects aged between 40
in 2048 subjects (67.3%). A strong correlation was found                        and 60 years.
between age and recurrences (r = -0.14, 95% CI -0.17 -0.10,                     In order to assess anti-thyroid autoantibodies as a causal
p < 0.0001), with the elderly having more frequent recur-                       factor for recurrence, we selected 1981 subjects not pre-
rences. In order of frequency, thyroid autoantibodies were                      senting migraine, head trauma or a clinical history of vas-
demonstrated in 801 subjects (26.3%), vascular disorders                        cular disorders of the heart/CNS. Among them, 683 had
of the central nervous system in 382 subjects (12.5%), 324                      positive while 1298 negative autoantibodies. No difference


Table I. Linear regression model in the total sample considering the recurrence of BPPV as dependent variable and the presence of thyroid autoantibody, mi-
graine, heart disorders, CNS disorders and head trauma as independent variables.
                                        Coefficient                      95% CI                          SE              t statistic            p
 Thyroid antibody                      0.03656                    0.02119 to 0.05194                   0.007842            4.66             < 0.0001
 Migraine                              0.05663                    0.00265 to 0.11061                   0.027531            2.06               0.04
 Heart disorder                       -0.005523                 -0.064358 to 0.053311                 0.0300064            -0.18              0.85
 CNS vascular disorders                0.07905                    0.05387 to 0.10423                  0.012842             6.16             < 0.0001
 Head trauma                            0.1907                     0.1280 to 0.2534                    0.03199             5.96             < 0.0001




                                                                                                                                                     463
R. Teggi et al.




Table II. Linear regression model in the sample with BPPV onset below 40, considering the recurrence of BPPV as dependent variable and the presence of thy-
roid autoantibody, migraine, heart disorders, CNS disorders and head trauma as independent variables.
                                           Coefficient                       95% CI                       SE            t statistic             p
 Thyroid antibody                        0.02165                     -0.01041 to 0.05370                0.016316              1.33               0.18
 Migraine                                0.04502                     -0.03940 to 0.12945                0.042975              1.05               0.29
 Heart disorders                         -0.05833                    -0.32045 to 0.20379                0.133435              -0.44              0.66
 CNS vascular disorders                  0.03717                     -0.06881 to 0.14314                0.053946              0.69               0.49
 Head trauma                              0.2396                       0.0961 to 0.3832                 0.07306               3.28               0.001



Table III. Linear regression model in the sample with BPPV onset between 40 and 60 considering the recurrence of BPPV as dependent variable and the pres-
ence of thyroid autoantibody, migraine, heart disorders, CNS disorders and head trauma as independent variables.
                                          Coefficient                         95% CI                        SE          t statistic            p
 Thyroid antibody                         0.04569                     0.02459 to 0.06678               0.010753                4.25             < 0.0001
 Migraine                                0.008642                   -0.068450 to 0.085733              0.0393008               0.22               0.82
 Heart disorders                            0.121                        0.017 to 0.225                  0.0530                2.28               0.02
 CNS vascular disorders                    0.1161                      0.0748 to 0.1573                 0.02102                5.52             < 0.0001
 Head trauma                               -0.267                       -0.369 to -0.165                 0.0522               -5.11             < 0.0001



Table IV. Linear regression model in the sample with BPPV onset over 60 considering the recurrence of BPPV as dependent variable and the presence of thyroid
autoantibody, migraine, heart disorders, CNS disorders and head trauma as independent variables.
                                          Coefficient                        95% CI                       SE             t statistic             p
 Thyroid antibody                        0.02741                     -0.00179 to 0.05661                0.014882              1.84                0.06
 Migraine                                -0.03125                    -0.17399 to 0.11148                0.072739              -0.43               0.66
 Heart disorders                         0.02074                     -0.05859 to 0.10007                0.040428              0.51                0.61
 CNS vascular disorders                  0.09822                     0.06246 to 0.13397                 0.018220              5.39              < 0.0001
 Head trauma                             -0.09042                    -0.18561 to 0.00477                0.048508              1.86                0.06



was detected for the age of the first vertigo between the 2                     Table V. Total number, percentages (between parentheses), and statistical
groups (51.1 ± 12.8 and 51.3 ± 13.4 respectively). Among                        significance of BPPV recurrency and thyroid autoantibodies in the entire sam-
                                                                                ple and in subsamples of males (M) and females (F) with onset of the first BPPV
683 subjects with positive autoantibodies 511 (74.8%) had                       below 40, between 40 and 60 and over 60.
more than one episode of BPPV, while 810 (62.4%) pa-                                                       Recurrent BPPV               Autoantibodies
tients with negative autoantibodies had relapsing episodes
                                                                                 Mtot (n = 703)               439 (62.5%)                 72 (10.2%)
(chi-square statistic with Yates correction 30.4827, p-val-
                                                                                 Ftot (n = 2339)             1609 (68.8%)                 731 (31.2%)
ue < 0.00001). In the group of 683 subjects with positive
                                                                                 p                               0.001                     < 0.00001
autoantibodies, 287 (42%) presented elevated hormonal
                                                                                 M<40 (n = 98)                 67 (68.4%)                   8 (8.1%)
values and 396 (58%) had normal values; 208 (72.5%) out
                                                                                 F<40 (n = 443)               346 (78.1%)                 135 (30.5%)
of 287 with hyperthyroidism while 303 (76.5%) of 396 (chi
                                                                                 p                                0.04                     < 0.00001
squared, p = 0.23) had recurrent episodes.
                                                                                 M40-60 (n = 306)              205 (67%)                    49 (16%)
Finally, in the entire sample, we found a higher rate of re-
                                                                                 F40-60 (n = 1172)            823 (70.2%)                 386 (32.9%)
currences in females, mainly in the subsample of younger
                                                                                 p                                 ns                      < 0.00001
subjects; moreover, in females we found a higher rate of
                                                                                 M≥60 (n = 299)               167 (55.8%)                   49 (16%)
thyroid autoantibodies in the entire sample and subsam-
ples. In Table V, the rates and statistical significance are                     F≥60 (n = 724)               440 (60.8%)                  210 (29%)
summarised.                                                                      p                                 ns                       0.00002




464
                                                                                    Recurrence of BPPV and anti-thyroid autoantibodies




Discussion                                                       The prevalence of positive anti-thyroid autoantibodies in
                                                                 the general population has been estimated to range between
Some of our results are mainly confirmatory; for example,        3% and 17%, and differences may be due to genetic, envi-
we found a female to male ratio that was increased three-fold,   ronmental factors or methods applied for antibody meas-
which is in the range of previously published studies 1,5,16.    urement 25. Anti-thyroid antibodies have been correlated
Moreover, BPPV presents a high rate of recurrences, which        with different inner ear disorders, including autoimmune
were present in our study in 67.3% of subjects, and espe-        inner ear disorders and Ménière’s disease 26. As far as we
cially in females. Previous authors estimated the value at a     know, the present study reports on the largest sample of
lower range between 35 and 50% 17,18; this difference might      BPPV subjects tested for anti-thyroid autoantibodies to
in our opinion be justified with our longer period of ob-        date, although two previous investigations have been pub-
servation of these patients (up to five years); on the other     lished on the topic 10,27. Although not all authors reported
hand, it should be considered the probability that a bias in     an overlapping between anti-thyroid autoantibodies and
our work may result from the fact that we excluded subjects      BPPV 28, regarding the overlap between anti thyroid anti-
that we were unable to contact by phone, possibly without        bodies and BPPV, several hypotheses can be made. Some
recurrences, leading to an overestimation of the value.          authors postulated a cross reaction mechanism; according
On the whole, even if small differences can be noted, our        to this theory, the inner ear would share common antigens
results are in line with previous works regarding head trau-     with potentially harmful organisms such as viruses or bac-
ma as an important causal factor predisposing to recurrent       teria. Other authors have postulated mechanical stimulation
episodes 19. Since some authors found an increased rate of       by immune complexes and the possible co-existence of a
VEMP dysfunction in BPPV patients occurring after head           micro-angiotis in the inner ear in the context of an autoim-
trauma compared to idiopathic BPPV, they proposed that           mune multi-organ disease. In both cases a primary vascular
the trauma may provoke a macular disorder leading to oto-        disorder of the macula could be the triggering factor lead-
conia detachment.                                                ing to the detachment of otoconia 26,27. Moreover, our data
Migraine per se has a strong association with different ver-     support the possibility that recurrence may be linked to au-
tigo, including BPPV; a recent survey study reported a cor-      toantibodies per se rather than increased plasma levels of
relation between BPPV and migraine that was two times            hormones; our data are not different with those of previous
more frequent in migraineurs 20, and, more recently, a meta-     works reporting that in the recurrence the hormonal situa-
analysis of literature data included migraine among the fac-     tion is less important than the hormonal status 27,29, while,
tors predisposing to recurrences of BPPV 21.                     on the opposite, a recent work based on data obtained by
Risk factors for vascular disorders have been widely stud-       the Korean public register demonstrated an association be-
ied in BPPV and its recurrences, and a general consensus         tween hormonal status and BPPV 30.
has been reached on the fact that hyperlipidaemia, hyper-        Some limitations of our work should be underlined. Firstly,
tension, low vitamin D plasma levels and diabetes may play       in our sample we were unable to retrieve complete data on
a role in predisposing to BPPV 8,21,22. In a previous work,      other variables possibly related to relapsing episodes, such
BPPV was correlated with an increased risk of ischaemic          as diabetes, hypertension, hypercholesterolaemia and hy-
stroke during 9-year follow-up; however, controversial re-       perlipidaemia. Moreover, the strict diagnostic criteria we
sults have been published on CNS vascular disorders as a         applied possibly led to an underestimated proportion of pa-
predisposing factor for recurrences 21. The different inclu-     tients with migraine or vascular disorders. Finally, in sub-
sion criteria may justify the different results.                 jects with negative anti-thyroid autoantibodies, the plasma
Probably the most interesting finding of our work regards        levels of thyroid hormone were not assessed, and thus a
the high rate of subjects with positivity for anti-thyroid       role of plasma thyroid hormonal levels in recurrencies of
autoantibodies (26.3% in the entire sample and 29.2% in          VPPB cannot be excluded.
recurrent BPPV with a female preponderance in both co-
horts), which strongly correlates with recurrences above all
in subjects presenting the first episode of BPPV while aged
                                                                 Conclusions
between 40 and 60 years. A possible overlapping between          We believe that our data are not inconsistent with the hy-
autoimmune disorders and BPPV has already been postu-            pothesis that among others, positivity for anti-thyroid au-
lated by previous papers 23,24.                                  toantibodies may play a role as predisposing factor for
It could be speculated that other factors may play a major       recurrence of BPPV. If confirmed, our data support the pos-
role in patients aged below 40 (head trauma) and over 60         sibility that they should be routinely evaluated above all in
(vascular disorders of the central nervous system) years.        middle-aged subjects with frequent recurrences.



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