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Embed code for: BISS 2016 CCJ (White) SMITH
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Undiagnosed atlanto-axial injury in whiplash injury.
Francis W. Smith MD.
Medserena Upright MRI
Method and Materials :
40 patients 15 - 72 yrs. (Mean 48yrs),
All the patients previously investigated following hyperextension injury of the neck , who had reportedly normal MRI examination of the cervical spine were entered in to the study.
The previous MRI examinations had comprised :
Sagittal T1 & T2 weighted images
Axial T2 weighted images at all levels from C2 - T1
Previous MRI examinations had comprised :
Axial T2 weighted images at all levels from C2 to T1
This Scout view from a conventional Supine (Lying down) MRI Scan, shows the limited levels at which the axial sections are made
You will note the junction between the head and spine is not routinely scanned (The cranio-cervical junction)
Patients were studied in the seated upright position
Images were made as follows:
All patients were scanned seated in an Upright MRI scanner
Sagittal T1 & T2 weighted images together with axial T2 weighted images at all levels from C2/3 to C7/T1(The same as is routinely performed in supine position)
Sagittal T2 weighted images with the neck in flexion and extension.
Coronal and axial proton density images made from the skull base down to the C2/3 level.
Axial proton density images of the atlanto-axial joints made with head turned to the right and to the left
All studies were assessed for:
Integrity of the intervertebral discs
Integrity of the neck muscles
Facet joint alignment
Alignment of the atlanto-axial joints and atlanto-occipital joints
Integrity of the alar and cruciate ligaments
Cerebellar tonsillar ectopia
Views used to examine the cervical spine
Clivo-vertebral or Clivo-axial angle (normal range 150°-180°).
(The basion axial interval is the length of a line drawn between the tip of the basion and a line drawn along the posterior aspect of the odontoid peg. The basion dental interval is a distance measured between the tip of the basion and the tip of the dens. Both these measurements should be less than 12 mm. If they are greater than 12 mm, then occipito-atlantal disassociation has occurred. These measurements are often referred to as "The rule of 12")
(The Grabb-Oakes measurement is the perpendicular distance from the BpC2 line [Basion to posterior inferior C2 body] to the dura.
A value greater than or equal to 9 mm indicates ventral brainstem compression)
Specific coronal views of the cranio-cervical junction to show the position of the odontoid peg
Normal position of the odontoid peg
The alar ligaments are intact (arrows)
The odontoid peg is deviated to the right
The alar ligaments are not clearly seen due to them being damaged
Cranio –vertebral Ligaments
Normal Alar Ligaments
Normal Transverse band of the Cruciform Ligament
Specific views to assess the atlanto-axial joint
20o of dislocation at the atlanto-axial joint
Post-traumatic ectopia of the cerebellar tonsils
is best demonstrated when sitting
A case-control study of cerebellar tonsillar ectopia (Chiari) and cervical spine trauma.
Freeman MD, Rosa S, Harshfield D, Smith FW Bennett R, Centano CJ, Kornel E, Nystrom A, Heffez DS, & Kohles SS
Brain Inj. 24 (7-8):988-94. 2010
In over 50% of patients (22), no additional information was gained.
In the other 18 patients, 16 showed ligamentous damage at the atlanto-axial joint, of which 10 had dislocation, 2 of which showed instability on the rotation images. 2 had atlanto-occipital joint dislocation.
Cerebellar tonsillar ectopia was seen in 10 patients.
When cost implications of under diagnosis of mechanical damage at the cranio-cervical junction is very large, the current practice of limiting imaging to below C2 is inadequate and under-estimates the incidence of post traumatic ligamentous damage.
For thorough MRI examination, imaging of the cranio-cervical junction is important, to find or exclude ligamentous damage.
The cost implications of under diagnosis of mechanical damage at the cranio-cervical junction, both in terms of patient suffering and cost in insurance claims, is very large
We believe it is of paramount importance :
To show any dislocation and ligamentous damage when present
Also to exclude such damage when it is not present
(Unless it is specifically looked for, any damage at
the cranio-cervical junction cannot be excluded from a
limited cervical spine examination.)
Prof. Francis W. Smith MD
Tel +44 020 7370 6003
Cell +44 07967658027