title: Lateral Semicircular Canal Asymmetry in Idiopathic Scoliosis: An Early Link between Biomechanical, Hormonal and Neurosensory Theories?
abstract: BACKGROUND
  Despite its high incidence and severe morbidity, the physiopathogenesis of adolescent idiopathic scoliosis (AIS) is still unknown. Here, we looked for early anomalies in AIS which are likely to be the cause of spinal deformity and could also be targeted by early treatments. We focused on the vestibular system, which is suspected of acting in AIS pathogenesis and which exhibits an end organ with size and shape fixed before birth. We hypothesize that, in adolescents with idiopathic scoliosis, vestibular morphological anomalies were already present at birth and could possibly have caused other abnormalities.
  
  
  METHODS
  The vestibular organ of 18 adolescents with AIS and 9 controls were evaluated with MRI in a prospective case controlled study. We studied lateral semicircular canal orientation and the three semicircular canal positions relative to the midline. Lateral semicircular canal function was also evaluated by vestibulonystagmography after bithermal caloric stimulation.
  
  
  RESULTS
  The left lateral semicircular canal was more vertical and further from the midline in AIS (p = 0.01) and these two parameters were highly correlated (r = -0.6; p = 0.02). These morphological anomalies were associated with functional anomalies in AIS (lower excitability, higher canal paresis), but were not significantly different from controls (p>0.05).
  
  
  CONCLUSIONS
  Adolescents with idiopathic scoliosis exhibit morphological vestibular asymmetry, probably determined well before birth. Since the vestibular system influences the vestibulospinal pathway, the hypothalamus, and the cerebellum, this indicates that the vestibular system is a possible cause of later morphological, hormonal and neurosensory anomalies observed in AIS. Moreover, the simple lateral SCC MRI measurement demonstrated here could be used for early detection of AIS, selection of children for close follow-up, and initiation of preventive treatment before spinal deformity occurs.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, CHU de Caen, Caen, F-14000, France; Department of Anatomy, UNICAEN, Caen, 14032, France; Department of Pharmacology and Toxicology; School of Medical Sciences and Brain Health Research Center, University of Otago, Dunedin, New Zealand; U 1075 COMETE, INSERM, Caen, 14032, France.
authors.forename: Martin
authors.initials: M
authors.lastname: Hitier
authors.affiliation: Department of Neuroradiology, CHU de Caen, Caen, 14000, France.
authors.forename: Michèle
authors.initials: M
authors.lastname: Hamon
authors.affiliation: U 1075 COMETE, INSERM, Caen, 14032, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Denise
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, CHU de Caen, Caen, F-14000, France.
authors.forename: Julien
authors.initials: J
authors.lastname: Lacoudre
authors.affiliation: Department of Neuroradiology, CHU de Caen, Caen, 14000, France.
authors.forename: Marie-Aude
authors.initials: MA
authors.lastname: Thenint
authors.affiliation: Department of Paediatric surgery, CHU de Caen, Caen, 14000, France.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Mallet
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, CHU de Caen, Caen, F-14000, France; Department of Anatomy, UNICAEN, Caen, 14032, France.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Moreau
authors.affiliation: U 1075 COMETE, INSERM, Caen, 14032, France.
authors.forename: Gaëlle
authors.initials: G
authors.lastname: Quarck
mesh_terms: D000293:Adolescent; D001696:Biomechanical Phenomena; D016022:Case-Control Studies; D002531:Cerebellum / Q000473:pathology / Q000503:physiopathology; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D007031:Hypothalamus / Q000473:pathology / Q000503:physiopathology; D008279:Magnetic Resonance Imaging; D008297:Male; D009949:Orientation; D010812:Physical Stimulation; D011446:Prospective Studies; D012600:Scoliosis / Q000175:diagnosis / Q000473:pathology* / Q000503:physiopathology; D012665:Semicircular Canals / Q000473:pathology* / Q000503:physiopathology; D011984:Sensory Receptor Cells / Q000473:pathology; D013131:Spine / Q000473:pathology* / Q000503:physiopathology; D013696:Temperature; D014722:Vestibule, Labyrinth / Q000473:pathology* / Q000503:physiopathology