- See:
Atlanto-axial Subluxation:
- Discussion:
- a condition in which there is fixed rotation of C1 on C2;
- fixation may occur with in the range of normal rotation, may occur w/
subluxation, or may occur w/ dislocation;
- clinically patients will have ipsilateral rotation and contralateral tilt of the head
in relation to the lateral mass of C1;
- the contra-lateral sternocleidomastoid may be spastic;
- rotatory fixation may arise from neglected cases of
torticollis;
- often, the diagnosis is delayed by several months upto 1 year;
- key feature is that when head is rotated maximally to opposite side, the malaligned
relationship of
C1 to
C2 appears unchanged;
-
pertinent anatomy:
- anatomically, if the patient's head is turned to the right, then the right
lateral mass of C1 is rotated posteriorly;
- if transverse ligament is intact, only a severe amount of rotation can result in
facet dislocation and subsequent narrowing of the SAC;
- if
transverse ligament has ruptured, 5 mm of anterolithesis and 45 deg of
rotation will narrow the SAC to less than 12 mm;
- vertebral arteries are also at risk in this situation;
- Diff Dx:
-
Atlantoaxial Subluxation
-
Grissel's Syndrome
-
Torticollis
- will demonstrate spasm or fibrosis of the ipsilateral side, in contrast
to rotatory fixation which has spasm on contralateral side;
- Radiographs for Rotatory Fixation:
CT scan:
- dynamic CT scan is test of choice;
- CT is first taken with the head in its rotated position (injured position), and subsequently, the
the CT scan is taken with the head is rotated maximally to the opposite side;
- in rotatory fixation, the relationship between C1 and C2 is unchanged;
- Classification:
- Type I: (most common)
- rotary fixation is w/in the normal ROM and has no anterior displacement
(ie,
ADI is normal);
-
transverse ligament is intact and odontoid process acts as pivot;
- treated w/ soft collar and analgesics +/- halter traction;
- Type II:
- rotatory fixation w/ anterior displacement of 3 to 5 mm, w/ disruption
of the transverse ligament;
- one lateral mass is displaced where as the remaining mass is intact
and acts as a pivot;
- Type III:
- rotatory fixation w/ anterior displacement of more than 5 mm, which
implies disruption of both the
transverse and alar ligaments;
- both lateral masses are displaced;
- Type IV:
- rotatory fixation with posterior displacement;
- Treatment:
- pt requires special attention when any degree of anterior displacement is present;
- typically patients are placed in cervical halter traction in acute cases;
- w/ chronic fixation, it is first necessary to determine whether concomitant
atlanto-occipital subluxation is present;
- if not present, then procede w/
antanto-axial fusion;
- if atlanto-occipital subluxation is present, then consider fusion
from occiput to C2;
The management of rotatory atlanto-axial subluxation in children.
Atlanto-axial rotatory fixation. (Fixed rotatory subluxation of the atlanto-axial joint).
