In this cross-sectional magnetic resonance imaging study, vertebral rotation was measured in the transverse plane of the normal, nonscoliotic spine of persons with a complete mirror image reversal of the internal body organs, called situs inversus totalis.
To determine if a pattern of rotation exists in the normal spine of persons with situs inversus totalis, opposite of what was found in humans with normal organ anatomy.
In humans, as well as in quadrupeds, the mid and lower thoracic vertebrae of the normal, nonscoliotic spine show a pre-existent pattern of rotation to the right side. This rotational pattern is similar to what is seen in the most prevalent types of adolescent idiopathic scoliosis and, therefore, probably plays an important role in determining the direction of spinal curvature once scoliosis starts to develop. The cause of this pre-existent rotation, however, is unknown.
Magnetic resonance imaging scans of the thorax and abdomen of 37 persons with situs inversus totalis and a normal, nonscoliotic spine were acquired to measure axial vertebral rotation from T2 to L5 with a previously developed computer-based measurement method.
The results of this study showed a predominant rotation to the left side of the mid and lower thoracic vertebrae, and to the right side of the upper thoracic and lumbar vertebrae. The mean vertebral rotation angles differed significantly from zero degrees rotation at the mid and lower thoracic levels, with a maximum rotation of 2.7° at level T7 (P < 0.001).
The normal spine of humans with a situs inversus totalis shows a pre-existent pattern of vertebral rotation opposite of what is seen in humans with normal organ anatomy. This study shows a relation between the asymmetrical position of the thoracic organs and pre-existent vertebral rotation in the normal spine.
Vertebral rotation was analyzed in the transverse plane at level T2–L5 in the normal, nonscoliotic spine of persons with situs inversus totalis by using a previously developed measurement method. The results demonstrated a pre-existent rotational pattern, which is the opposite of what is seen in humans with normal organ anatomy.
From the *Department of Orthopedics and †Image Sciences Institute, University Medical Center Utrecht, Utrecht; ‡Department of Physiology, Maastricht University, Maastricht; and §Department of Paediatrics, University Hospital Maastricht, Maastricht, The Netherlands.
Acknowledgment date: July 11, 2006. First revision date: September 20, 2006. Acceptance date: September 22, 2006.
The manuscript submitted does not contain information about medical device(s)/drug(s).
Foundation and Other funds were received in support of this work. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript.
Address correspondence and reprint requests to R.M. Castelein, MD, PhD, Department of Orthopedics, G05.228, University Medical Center Utrecht, P.O. Box 85500, 3508 GA Utrecht, The Netherlands; E-mail: R.M.Castelein@umcutrecht.nl