Abstract
Introduction
At the Zorab Symposium in Oxford, 2006, we showed that semicircular canal (SCC) anomalies occurring with posterior basicranium asymmetry affect the oculovestibular system in human beings. As a consequence, we proposed the hypothesis of a descending direct vestibulospinal and cognitive top-down effect on some scoliosis. We will show that some SCC anomalies detected with MRI modelling are malformations frequently found in scoliosis.
Methods
445 patients (323 women, mean age 21 years; 122 men, mean age 24 years) with instability, imbalance, and spatial disorientation were submitted to T2 MRI modelling. 95 of 445 patients had scoliosis: 57 thoracolumbar scoliosis, 24 thoracic scoliosis, and 14 lumbar deformation. We processed the data acquired with G.E.MRI (1.5T), T2- 3D Fiesta with a set of Brainvisa modules (http://brainvisa.info/).
Results
We detected abnormal connection between the lymphatic posterior and lateral duct (LPDC) in 67 of 445 (15%) patients. The frequency of LPDC was equal in men (18/122 [14·7%]) and women (nine of 323 [15·1%]). In patients with scoliosis, LPDC was more frequent (29/95 [30·5%]): these patients belonged to the thoracolumbar subgroup, but no correlation with the Cobb angle was established. Three patients with scoliosis with LPDC were submitted to threedimensional CT scan (figure 1): the modelling revealed that LPDC was also present on the bony canals. Aplasia (defined by Casselman [2009] as a partial interruption of the fluid-filled semicircular ducts) on lateral duct was detected in 129 of 445 patients (28·9%). In patients with scoliosis, lateral canal aplasia (LCA) was recorded in 40 of 95 (42·0%) patients (figure 2) and bilaterally in 25 of 40 (62·5%). LCA was specific of thoracolumbar scoliosis (Mann-Whitney U test: p=0·002). Aplasia of anterior and/or posterior ducts was present in 97 of 445 patients. In patients with scoliosis, bilateral aplasia of the anterior canal was the most frequent result (24/95), mainly in thoracolumbar scoliosis. We also discovered a lateral duct shaped as a saccule partially merged with the utricle in four patients with scoliosis (figure 3).
Conclusions
Lateral SCC malformations and highly suspected associated malformations of the otolithic chambers have been implicated in abnormal descending vestibulospinal output and potentially cause scoliosis in otherwise healthy individuals. In this study, through cross checked modelling (MRI/CT), LPDC abnormalities related to the ossification of the inner-ear canal structure were noted in a subgroup of individuals with a diagnosis of idiopathic scoliosis. A co-development of inner-ear structures with the molecular pathways of axial development is suggestive of an integrated molecular pathway that is related to individuals with idiopathic scoliosis.
