Experimental Brain Research (2018) 236:1725–1734
Verticality perception reveals a vestibular deﬁcit in adolescents
with idiopathic scoliosis
· Vassilia Hatzitaki
· Stavros Ι Stavridis
· Eythimios Samoladas
Received: 28 August 2017 / Accepted: 7 April 2018 / Published online: 10 April 2018
© Springer-Verlag GmbH Germany, part of Springer Nature 2018
Adolescent idiopathic scoliosis (AIS) is a three-dimensional spine deformation with elusive aetiopathogenesis. One appeal-
ing hypothesis points to its neurologic origin with an emphasis on a vestibular impairment. In the present study, we explored
the hypothesis of a vestibular deﬁcit accompanying AIS by assessing diﬀerences in the subjective estimation of the gravi-
tational vertical between adolescents with idiopathic scoliosis (n = 10, age 11–16 years, Cobb’s angle > 15°) and healthy
age-matched controls (n = 10). Group participants actively controlled the verticality of a visual line in two visual conditions
(eyes open-visual feedback and eyes closed-no visual feedback) and using three diﬀerent segments (hand, head, and trunk).
An electromagnetic tracking sensor (Nest of Birds, Ascension Ltd., USA, 60 Hz), attached either to a hand-held rod, the
head, or the upper trunk, measured the line’s deviation from the gravitational vertical that was reﬂected in two measures, the
mean absolute and variable error. The head’s medio-lateral tilt when estimating verticality with the hand was also registered.
Analysis revealed that adolescents with idiopathic scoliosis made a greater error than control participants when estimat-
ing verticality with the head and eyes closed. In addition, they adopted a signiﬁcantly greater head tilt when estimating the
vertical by controlling the hand-held rod, regardless of the availability of vision. The error in the earth vertical was greater
when the estimate was performed in the absence of vision. Results suggest a malfunction of the vestibular system and/or a
sensorimotor integration impairment in patients with AIS, while vision compensates for the observed deﬁcit in estimating
the earth vertical.
Keywords Spine · Gravity · Labyrinth · Proprioception · Vision · Sensory integration
Adolescent idiopathic scoliosis (AIS) is a three-dimensional
spine deformation that develops in, otherwise healthy, ado-
lescents with a prevalence of 0.47–5.2% approximately at
an age between 11 and 16 years. The female-to-male ratio is
1.4:1 in curves between 10° to 20° and soars to 7.2:1 when
the spinal curvature exceeds 40° (Konieczny et al. 2013).
Despite intensive research, the aetiopathogenesis of AIS
remains elusive. Several hypotheses have been proposed to
identify its origin, including inner ear anomalies (Rousie
et al. 2009; Patten and Moldovan 2011; Hitier et al. 2015),
abnormalities in brain development (Domenech et al. 2011;
Wang et al. 2012, 2013; Shi et al. 2013), hormonal deﬁcien-
cies (Moreau et al. 2004; Azeddine et al. 2007; Wai et al.
2014), and genetics (Kesling and Reinker 1997; Justice et al.
2003; Wajchenberg et al. 2010; Aulisa et al. 2013).
Research has lately focused on the neurological origins
of AIS suggesting a possible malfunction of the vestibu-
lar system (Wiener-Vacher and Mazda 1998; Lambert et al.
2009; Pialasse et al. 2013, 2015a; Catanzariti et al. 2014;
Hawasli et al. 2014). Experimental evidence from animal
studies has shown that peripheral vestibular lesions in the
larval Xenopus frog lead to an asymmetric vestibulo-spinal
drive to the axial muscles of the trunk, which results in the
rapid development of scoliosis (Lambert et al. 2009, 2013).
A vestibular tone imbalance is possibly compensated by
* Vassilia Hatzitaki
Laboratory of Motor Behavior and Adapted Physical
Activity, Department of Physical Education and Sports
Sciences, Aristotle University of Thessaloniki,
546 24 Thessaloníki, Greece
Orthopeadics Division of Genimatas Hospital, Faculty
of Medicine, Aristotle University of Thessaloniki,
Spine Clinic, Agios Loukas Hospital, Thessaloníki, Greece