Vertical atlantoaxial distraction injuries: radiological criteria and clinical implications.
OBJECTIVE
The authors sought to establish radiological criteria for the diagnosis of C1-2 vertical distraction injuries.


METHODS
Conventional radiography, computerized tomography (CT), and magnetic resonance (MR) imaging findings in five patients with a C1-2 vertical distraction injury were correlated with their clinical history, operative findings, and autopsy findings. The basion-dens interval (BDI) and the C-1 and C-2 lateral mass interval (LMI) were measured in 93 control patients who underwent CT angiography; these measurements were used to define the normal BDI and LMI. The MR imaging results obtained in 30 healthy individuals were used to characterize the normal signal intensity of the C1-2 joint. The MR imaging results were compared with MR images obtained in five patients with distraction injuries. In the 93 patients, the BDI averaged 4.7 mm (standard deviation [SD] 1.7 mm, range 0.6-9 mm) and the LMI averaged 1.7 mm (SD 0.48 mm, range 0.7-3.3 mm). Based on CT scanning in the five patients with distraction injuries, the BDIs (mean 11.9 mm, SD 3.2 mm; p < 0.001) and LMIs (mean 5.5 mm, SD 2 mm; p < 0.0001) were significantly greater than in the control group. Fast-spin echo inversion-recovery MR images obtained in these five patients revealed markedly increased signal distributed throughout the C1-2 lateral mass articulations bilaterally.


CONCLUSIONS
In 95% of healthy individuals, the LMI ranged between 0.7 and 2.6 mm. An LMI greater than 2.6 mm indicates the possibility of a distraction injury, which can be confirmed using MR imaging. Patients with a suspected C1-2 distraction injury may be candidates for surgical fusion of C1-2.
Division of Neurological Surgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona 85013-4496, USA.
L Fernando
LF
Gonzalez
David
D
Fiorella
Neil R
NR
Crawford
Robert C
RC
Wallace
Iman
I
Feiz-Erfan
Denise
D
Drumm
Stephen M
SM
Papadopoulos
Volker K H
VK
Sonntag
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D000704:Analysis of Variance; D000792:Angiography; D001268:Atlanto-Axial Joint / Q000293:injuries*; D001269:Atlanto-Occipital Joint / Q000293:injuries*; D002648:Child; D002675:Child, Preschool; D003952:Diagnostic Imaging; D005260:Female; D006801:Humans; D004204:Joint Dislocations / Q000175:diagnosis* / Q000628:therapy; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D014057:Tomography, X-Ray Computed