- C1 / C2
- AtlantoAxial Rotatory Subluxation in Down's Syndrome:
- Atlantooccipital Disassociation:
- Atlantoaxial Rotatory Fixation:
- Atlantoaxial Subluxation in R.A.:
- Cross Table Lateral:
- Occipital-Atlanto-Axial Anomalies:
- Posterior Atlanto-Axial Arthrodesis
- Torticollis:
- Discussion:
- refers to loss of ligamentous stability between atlas and axis;
- occurs most often in older children and adolescents;
- mechanism of injury in atlantoaxial rotatory subluxation is unknown, but is usually due to forced rotation of the neck along w/
some element of lateral tilt;
- it can occur spontaneously or after trauma;
- complete C1-C2 dislocation is a known complication of football spearing;
- pts complain of neck pain, occipital neuralgia, and occassionally symptoms of vertebrobasilar artery insufficiency;
- prognosis:
- significant potential for continued displacement of atlas on axis w/ resultant pressure on spinal cord;
- vertebrobasilar artery insufficiency may lead to cerebral infarcts;
- Atlanto-Axial Articulation:
- approx 50 % of cervical rotation takes place between atlas and axis, around laterally central but anteriorly eccentric odontoid
process;
- lateral wall of atlas rotates to across canal of axis, physiologically decreasing opening between these 2 segments;
- spinal canal of the atlas is large compared w/ that of other segments, which rotation around axis along w/ translational
displacement without pressure on the spinal cord;
- Steele's Rule of Thirds:
- canal of atlas is about 3 cm in its AP diameter;
- spinal cord, odontoid process, and free space for cord are each about 1 cm in diameter;
- anterior displacement of the atlas that exceeds one centimeter may jeopardize the adjacent segment of the spinal cord;
- Associated Conditions:
- Down syndrome (25% of patients);
- Rheumatiod Arthritis (adults);
- Grisel's syndrome:
- atlantoaxial instability may be noted in nl child in association w/ pharyngeal infection (Grisel's syndrome);
- hyperemia causes demineralization of attachment of transverse ligament to anterior arch of atlas, with subsequent rotary
subluxation of atlas on axis or anterior atlantoaxial subluxation;
- Klippel Feil;
- Morquio syndrome;
- Spondyloepiphyseal dysplasia:
- Achondroplasia:
- Larsen's syndrome:
- Diff Dx:
- Torticollis;
- Atlantoaxial Rotatory Fixation:
- Odontoid Fractures
- Congenital Anomalies:
- os odontoideum:
- congenital absence of the odontoid process;
- Radiographs:
- Lateral View:
- ADI < 3.5 mm in flexion, implies that the transverse ligament is intact;
- ADI 3-5 mm, transverse ligament is insufficient; (this is a type II injury);
- in children upto 4.5 mm may be normal;
- ADI > 5 mm:
- indicates failure of the alar ligaments;
- consistent w/ type III rotatory subluxation;
- Non Operative Treatment:
- Grissel's syndrome
- vast majority of pts w/ this form of torticollis improve spontaneously;
- w/ the subluxation does not resolve, the child should be admited for Halter traction (in order to avoid rotatory fixation);
- in those few cases in which persistent instability is present, stabilization by posterior atlantoaxial arthrodesis is required;
- Children:
- children w/ radiographic evidence of transverse ligament disruption can be treated non operatively in acute cases (less than 3
wks) in which there is no indication of transient or permanent neurological deficit;
- requires treatment in halter or skull traction (NSAIDS and muscle relaxants may be given as necessary);
- following reduction, pt is kept in traction or a halo 3 months;
- recurrence of deformity is possible, even with this treatment, and therefore flexion-extension radiographs are needed after halo
has been removed;
- ref: The delayed presentation of atlantoaxial rotatory fixation in children
- Adults: should not be treated non operatively, since ligament healing potential is unreliable;
- Elderly Patient: in some cases, can be managed non-operatively, because few demands are made on neck;
- Arthrodesis:
- indications for fusion:
- children:
- fusion is indicated w/ neurologic involvement;
- persistent anterior displacement;
- deformity present for more than 3 months;
- recurrence of deformity following 6 wks of immobilization;
- young adults:
- instability, w/ or w/o pain, is treated w/ arthrodesis, because trivial trauma might lead to catastrophic cord injury;
- w/ moderate displacement that minimally shifts on flexion & extension views may undergo further gradual displacement of
atlas over time which again places the cord at risk;
- considerations for fusion:
- fusion should be proceded by 2 to 3 weeks of skeletal traction
- after skeletal traction is continued for 6 wks or use a halo cast
- extension reduction and surgical stabilization followed by 8-12 weeks in halo jacket;
- w/ chronic subluxation, operative reduction should not be attempt, and rather the surgeon should accept a fusion in situ or
should perform occiput to C2 fusion;
- posterior C1-C2 arthrodesis:
Atlanto-axial instability and spinal cord compression in children--diagnosis by computerized tomography.