Open functional magnetic resonance imaging of structural defects of the alar ligaments
E. Volle;A. Montazem;
To investigate longstanding cervicocephalic symptoms after trauma to the atlanto- occipital joint – applying exclusion criteria – 95 patients, 56 females (n = 59 %), 39 males (n = 41 %) with an average age of 39 years – between 21 and 55 years of age – were investigated on an open 0.2 Tesla magnet MAGNETOM OPEN using a special coil device. Functional dynamic MRI studies of the upper cervical spine were conducted between November 1995 and December 1996. Two continuous functional studies were performed, tilting of the upper China magnets cervical spine to the right and left and then axial rotation in dorsal decubitus position also to the right and left. The types of rupture were classified as Type I: Complete rupture – 3 %; Type II a: Incomplete rupture with an extensive structural lesion – 20 %; Type II b: Intraligamentous rupture of fibres with resulting scar formation and local bulging – 11 %; Type III-lesion: a central intraligamentous alteration of signal – 39 %. With the presently available diagnostic methods no demonstrable lesion could be recognized in 27 % patient involving the liagments of the atlanto-occipital region. This study clearly shows that type I and type II a lesions are accompanied by injuries to the ypsilateral transverse ligament of the atlas. The functional MRI-examination of the atlanto-occipital joint in an open system is an appropriate modality to document morphological alterations. With the MRI-studies, until the end point of rotation was reached, a deviation of the dens could be demonstrated in the presence of ligamentous pathology. Instability of the atlanto-occipital joints was documented as a result. The frequency of structural lesions in the vicinity of the dens offer an argument for the assumption that overstretching by mechanical shear- and forces of overheating become effective at the point of contact between the periosteum of the dens and the alar ligaments as a result of excessive rotation of the atlanto-occipital region.http://www.chinamagnets.biz
