The relation between organ anatomy and pre-existent vertebral rotation in the normal spine: magnetic resonance imaging study in humans with situs inversus totalis.
METHODS
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.


OBJECTIVE
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.


BACKGROUND
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.


METHODS
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.


RESULTS
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 degrees at level T7 (P < 0.001).


CONCLUSIONS
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.
Kouwenhoven
Jan-Willem M
JW
Department of Orthopedics, University Medical Center Utrecht, Utrecht, The Netherlands.
Bartels
Lambertus W
LW
Vincken
Koen L
KL
Viergever
Max A
MA
Verbout
Abraham J
AJ
Delhaas
Tammo
T
Castelein
René M
RM
D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008159:Lumbar Vertebrae / Q000002:abnormalities* / Q000033:anatomy & histology / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011859:Radiography; D012399:Rotation; D012600:Scoliosis / Q000000981:diagnostic imaging; D012857:Situs Inversus / Q000473:pathology*; D013904:Thoracic Vertebrae / Q000002:abnormalities* / Q000033:anatomy & histology / Q000473:pathology