RECENT C1-C2 ROTATION DISLOCATION BY TRAUMA IN ADULTS: DIAGNOSTIC CRITERIA

Abstract

Purpose: Rotation dislocation of C1-C2 subsequent to trauma is not often described in adults. The clinical, radiological and computed tomographic diagnostic criteria are not well known and can lead to false positive diagnosis. The Fielding classification was described for children. We report five cases of traumatic rotation dislocation of C1-C2 in adults and propose computed tomographic criteria for diagnosis. The Fielding classification is discussed.

Material and methods: In two cases, the diagnosis was suggested by the clinical presentation and the plain x-rays. In three cases, it was revealed by the systematic CT performed in multiple trauma patients. In three cases, MRI enabled visualisation of ligament tears (transverse ligament, alaire ligament). Finally, the C1-C2 relations in neutral position and in rotation were studied on the CT scans in the study patients and in ten healthy subjects to establish diagnostic criteria. The patients were treated with cervical traction until reduction was achieved (checked with CT) then with an “Indian”collar for 45 days. One patient did not wear the collar and experienced a recurrent dislocation.

Results and discussion: In patients who can be examined, the diagnosis is suggested by suboccipital pain, slight rotation inclination of the head to the contralateral side, impossibility of turning the head to the opposite side beyond the mid line. The open-mouth x-ray can be a source of false positive diagnosis but can be suggestive. The CT scan must be performed under precise conditions: patient positioned without rotation or inclination of the head (false positive); superposition of the two slices passing through the C1 and C2 faces (unilateral loss of congruency); sagittal reconstruction. In case of doubt, homo and contralateral rotation slices can provide more sensitive images. The five dislocations were uin-lateral (Fielding type II) with posterior displacement in two cases, a finding not described in this classification. In addition, type I could be a variant of the normal (as seen in control scans). Treatment in the early phase is conservative with reduction by simple cervical traction (verification on CT), followed by complementary immobilisation until ligament healing.

Conclusion: The diagnosis of traumatic rotation dislocation of C1-C2 in adults is based on CT evidence. Certain injuries should be added to complete the Fielding classification. When recognised early, this rotation dislocations can be treated conservatively.