Don't Lose Your Head
Mr Angus Don
Outline
Don’t Lose Your Head
Internal decapitation or Atlanto-occipital Dislocation
Angus Don
Pre op CT
Right Parasagittal
Upper Cervical Spine Fractures
• Epidemiology
• Anatomy
• Radiology
• Management Issues
Upper Cervical Spine Fractures
• Epidemiology
– Cause
• MVC 42%
• Fall 20%
• GSW 16%
– Gender
• Male 81%
• Female 19%
Upper Cervical Spine Fractures
• Epidemiology
– Level of Education
• To 8th Grade: 10%
• 9th to 11th: 26%
• High School: 48%
• College: 16%
Upper Cervical Anatomy
• Biomechanically Specialized
– Support of “large” Cranial mass
– Large range of motion
• Flexion/extension
• Axial rotation
• Unique osteological characteristics
C1 - Atlas
• No body
• 2 articular pillars
– Flat articular surface
– Vertebral artery foramen
• 2 arches
– Anterior
– Posterior
• Vertebral artery groove
Anatomy – The Atlas
• Transition zone between head and c-spine
• Important anatomical points
– Superior articular processes allow flex/ext
– Inferior articular processes are important for rotation
– Notch for vertebral artery is a common fracture site
Anatomy – The Ligaments
• Allow for the wide ROM of upper C-spine while maintaining stability
• Classified according to location with respect to vertebral canal
– Internal:
• Tectorial membrane
• Cruciate ligament – including transverse ligament
• Alar and apical ligaments
– External
• Anterior and posterior atlanto-occipital membranes
• Anterior and posterior atlanto-axial membranes
• Articular capsules and ligamentum nuchae
AtlantoAxial Anatomy
Radiographic Evaluation
Plain Radiographic Evaluation
Radiographic Lines
Powers' Lines
• BC/OA
– >1 considered abnormal
• Limited Usefulness
• Positive only in Anterior Translational injuries
• False Negative with pure distraction
Powers et al, Neurosurg, 1979
Harris Rule of 12
• Better measurement
• Adults and kids >13yo
• Three landmarks
– Basion
– Odontoid tip
– Posterior axial line
• 1) Basion-axial interval
• 2) Basion-dental interval
Radiographic Lines
• Basion-Dental Interval (BDI)
• Basion to Tip of Dens
• <12 mm in 95%
• >12 mm ABNORMAL
• Basion-Axial Interval (BAI)
• Basion to Posterior Dens
• -4-12 mm in 98%
• >12 mm Anterior Subluxation
• >4 mm Posterior Subluxation
Harris et al, Am J Radiol, 1994
Radiographic Diagnosis
CT Scan
Same rules as with plain films
Better visualization of craniocervical junction
Subluxation
Focal hematomas
Occ condyle fx
Dens fx
MRI
Increased Signal Intensity in :
Occ-C1Joint
C1-2 Joint
Spinal Cord
Craniocervical ligaments
Prevertebral soft tissues
Warner et al, Emerg Radiol, 1996
Dickman et al, J Neurosurg, 1991
Classification
Traynelis
OccipitoAtlantal Dissociation (OAD)
Commonly Fatal
- Present 6-20% of post mortem studies
Alker et al, 1978
Bucholz & Burkhead,1979
Adams et al, 1992
50% missed injury rate
1/3 Neurological Worsening
Davis et al, 1993
Clinical findings
• Clinical findings range from mild to catastrophic
– Death by medulla oblongata transection and respiratory failure
• Cranial nerve injuries
– Abducens (VI) most often
• Vertebral artery injuries
– ALC, nystagmus, ataxia, diplopia, dysarthria
OAD - Treatment
• Emergency Room
• Collar/sandbag
• Halo vest
• Respiratory support
OAD - Treatment
• Traction – NOT
• Immobilisation – Maybe
– Halo Jacket
• Reduction and fusion – Yes
– Posterior occipital cervical fusion
• Non-op tx rarely results in stability
Type 1
Pre op CT
Right Parasagittal
Post Op
C0/C1 Dislocation - Type II - Acute Rx
Rx - Occipitocervical Fusion
C0/C1 Dislocation - Type III - Missed
The course of the vertebral artery through C1 and C2 determines the possibility of placing screws for fixation of fractures and dislocations
• C1 lateral mass screws
• C1-2 transarticular screws
• C2 pedicle/pars screws
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Ministry of Health
