This document discusses evaluation and management of craniocervical dissociation and atlantoaxial injuries. It covers anatomy of the craniocervical junction, mechanisms of injury, classification systems, diagnosis using imaging, and treatment considerations including traction, fusion techniques. Key points are stability from skull to axis ligaments, most common injury is hyperextension with lateral flexion, and treatment depends on injury type and may involve traction or anterior-posterior fusion.

1. Neurosurgery department, Vajira hospital
Evaluation and Management
Craniocervical Dissociation
Atlantoaxial Rotatory Subluxation
Transverse Ligament Injury
Chapter 313 and 314
YOUMANS Neurological Surgery sixth edition

2. Craniocervical Dissociation

3. Anatomy of craniovertebral junction
✤ Ligaments of craniovertebral junction (CVJ)
✤ Skull to atlas group
✤ Articular capsule ligaments
✤ Anterior and posterior atlanto-occipital ligament
✤ Lateral atlanto-occipital ligament
✤ Cruciate ligament

4. Skull to atlas group

5. Anatomy of craniovertebral junction
✤ Ligaments of craniovertebral junction (CVJ)
✤ Skull to axis group
✤ Alar ligament
✤ Tectorial membrane
✤ Apical dental ligament
✤ Ligamentum nuchae

6. Skull to axis group

7. Stability of CVJ
✤ Mainly from skull to axis group of ligaments
✤ Alar ligament
✤ Connect odontoid process to occipital condyles and lateral mass of atlas
✤ Control axial rotation of neck and limit lateral flexion and AP translation
✤ Tectorial membrane (continuation of PLL)
✤ Connect dorsal surface of odontoid process to ventral surface of foramen
magnum
✤ Limit hyperextension of neck
✤ Odontoid process to foramen magnum limits hyperflexion of neck

8. Stability of CVJ

9. Stability of CVJ

10. Mechanism of injury
✤ Mechanisms
✤ Hyperextension
✤ Hyperflexion
✤ Lateral flexion
✤ Combined forces

11. Mechanism of injury
✤ Most common is hyperextension combined with extreme lateral flexion
✤ Hyperextension cause rupture of tectorial membrane
✤ Extreme lateral flexion cause alar ligament injury
✤ Anterior dislocation of cranium to cervical spine
✤ Children are susceptibility to AOD because of
✤ Less stiffness of ligaments
✤ Larger head to body ratio

12. Clinical findings
✤ Most common causes are high-speed motor vehicles accident and
pedestrians injury
✤ Wide range of injury from dead to minor injury
✤ Brainstem injury
✤ Cranial nerve deficit
✤ Spinal cord injury
✤ Cervical nerve roots injury
✤ Anterior spinal a., vertebral a. or carotid a. injury

13. Clinical findings
✤ Steel rules of third at C1 spinal canal
✤ Odontoid process
✤ Spinal cord
✤ CSF space
✤ Cruciate paralysis
✤ Weakness of hands and arms with sparing of lower extremities
✤ True mechanism is still unknown but there are theories
✤ Selective damage to neural areas
✤ Injury to ventral corticospinal tracts

14. Radiology
✤ Assessment of lateral C-spine
plain film for AOD
✤ Basilar line of Wackenheim
✤ Line from posterior surface
of clivus to caudal extension
✤ Normal line is attached to
posterior tip of odontoid
process and not altered by
flexion and extension
Wackenheim’s line

15. Radiology
✤ Assessment of lateral C-spine
plain film for AOD
✤ Dens-basion interval
✤ Normal range is below 5mm
in adult and 10mm in infant
✤ Unreliable due to wide
range of variability in
normal population

16. Radiology
✤ Assessment of lateral C-spine
plain film for AOD
✤ Craniovertebral relationships
distances (Powers ratio)
✤ BC/OA ratio more than 1.0
indicate AOD (normal is 0.77)
✤ Unreliable in congenital
anomaly or atlas fracture
Basion
Posterior arch of C1
Opisthion
Anterior arch of C1
Powers ratio

17. Radiology
✤ Assessment of lateral C-spine plain film for
AOD
✤ Basion-posterior axial line interval (BAI)
and basion-dental interval (BDI) (Harris
rule-of-12)
✤ Abnormal is more than 12mm (~95%)
✤ Universally acceptable and most
accuracy
✤ BDI is unreliable in age below 13
years
BAI
BDI
Harris rule-of-12

18. Children atlantooccipital dissociation (AOD)
By Pang and colleagues
✤ Condylar-C1 interval (CCI)
✤ Distance between occipital condyle to lateral mass of C1
✤ Assess by CT scan
✤ Normal value is 1.28mm (sensitivity 100%)
PANG ET AL. NEUROSURGERY | VOLUME 61 | NUMBER 5 | NOVEMBER 2007

19. Classification of craniocervical dissociation
✤ Assess by lateral C-spine plain film or CT scan
✤ 3 types
✤ Type I : Anterior displacement of occiput to atlas
✤ Type II : Longitudinal distraction with seperation of
occiput to atlas
✤ Type III : Posterior displacement of occiput to atlas

20. Classification of craniocervical dissociation
Type I Type II Type III

21. Treatment considerations
✤ Emergency considerations
✤ Awareness of craniocervical dissociation
✤ Cardiopulmonary support
✤ Spinal immobilisation
✤ Surgical removal of hematoma at CVJ (rare condition)
if hematoma associated with neurological deficit

22. Treatment considerations
✤ Skull traction
✤ Recommended in patients of Type I and III dislocation with
neurological deficit
✤ Fluoroscopic-guided for applied traction is recommended
✤ Traction weight below 5 lb.
✤ If clinical improved >> decrease weight to 1-2 lb. or halo vest
applied
✤ Contraindication in Type II dislocation and rotatory subluxation

23. Treatment considerations
✤ Surgical management
✤ Posterior fusion of occiput to C2 is recommended in most
cases of AOD
✤ Main injury is ligaments and stability cannot maintain
after external fixation
✤ Should be done after medically stable
✤ Some surgeon recommended posterior fusion without skull
traction first

25. Atlantoaxial Rotatory Subluxation and
Transverse Ligament Injury

26. Anatomy and Biomechanics of
Atlantoaxial joint
✤ Atlantoaxial joint is mainly functionally as neck rotation
✤ Facet joint of C1-2 is horizontal
✤ Stability of C1-2 joint is from ligamentous structures
✤ Transverse ligament : Prevent excessive translation of atlas to
axis
✤ Alar ligament : Limit rotation of atlas on axis and secondary
translation stabiliser (from transverse ligament)
✤ Vertebral artery runs in transverse foramen
Schmidek & Sweet operative neurosurgical techniques

27. Diagnosis
✤ Sign and symptom of AARS
✤ “Cock-robin” position of neck : head tilted one side
and rotated to contralateral side with flexion of neck
✤ Occipital pain from compression of occipital nerve or
C2 nerve root
✤ Posterior fossa syndrome from stretching or kinking
of vertebral arteries

28. Diagnosis
tidsskriftet.no

29. Diagnosis
✤ Imaging
✤ Open-mouth plain film show
asymmetrical of lateral of
C1 to odontoid process
✤ Lateral plain film show
lateral mass of C1
projecting anterior to
odontoid process >> “wink”
sign

30. Diagnosis
✤ Imaging
✤ Cervical spine CT is recommended for diagnosis of
AARS
✤ Contrast injection for evaluating of vertebral artery
✤ MRI can be used for evaluating of transverse ligament
and cord compression

31. Diagnosis

32. Classification system
✤ Fielding system (1977)
✤ Type I : Intact odontoid and transverse ligament with disrupt of alar
ligament
✤ Type II : Anterior translation of atlas on axis 3-5mm with disrupt of
transverse ligament
✤ Type III : Anterior translation of atlas on axis > 5mm with disrupt of
transverse ligament
✤ Type IV : Posterior displacement of atlas on axis and odontoid
process is injured

33. Classification system
✤ White and Panjabi system (1978)

34. Classification system

35. Grisel’s Syndrome
✤ Nontraumatic atlantoaxial subluxation (rare condition)
✤ Caused by infection process or head and neck procedure
✤ Edema (inflammation process) and relaxation of ligamentous structures
✤ In children with Down’s syndrome and Klippel-Feil syndrome increase risk of
Grisel’s syndrome
✤ Management
✤ Reduction by cervical traction with muscle relaxant
✤ Antibiotic prophylaxis in high risk group
✤ Surgical fusion if failed conservative treatment

36. Management of AARS
✤ Conservative treatment
✤ Cervical traction by Gardner-Wells tong or halo ring with
conscious sedation
✤ Bone fracture must be ruled out before traction application
✤ Patient with minor ligamentous injury should be placed in
halo vest for 3 months
✤ Failure of conservative treatment or gross instability,
surgical fusion should be done

37. Management of AARS
✤ Surgical treatment
✤ Reducible deformity >> only posterior fixation with fusion
✤ Irreducible deformity >> Anterior decompression with
posterior fusion
✤ Anterior decompression
✤ Transoral route with soft tissue and longus colli muscles
stripped from bone with/without anterior arch of C1
resection

38. Posterior C1-2 fusion techniques
✤ Magerl and Seemann
technique (1979)
✤ Transarticular screw fixation
technique
✤ No need for halo
immobilisation
postoperative
✤ High risk for vertebral
artery injury

39. Posterior C1-2 fusion techniques
✤ Harms and Melcher
technique
✤ Lateral mass screw in
C1
✤ Pedicular screw in C2
✤ Connect with rod

40. Posterior C1-2 fusion techniques
✤ Wright technique
✤ Translaminar fixation
technique of C2
✤ Low risk for vertebral
artery injury
C1
C2