- See:
-
Cross Table Lateral
-
Spondylosis
- Discussion:
- risk of
spinal cord injury with damage to cervical vertebrae is greater in individuals who have narrow spinal-canal diameters;
- narrow mid-sagittal spinal-canal diameter increases risk of severe neurological injury from spinal frx or dislocation compared w/ pts
w/ large mid-sagittal canal diameter;
- in the study by JR Blackley et al (JBJS Vol 81-B, Jan 1999), the authors studied the reliability of using radiographs to determine the true
diameter of the cervical canal;
- they noted a poor correlation between the true diameter of the canal and the ratio of its saggital diameter to that of the vertebral body;
- the authors felt that other types of ratios were equally ineffective in predicting true saggital canal diameter;
-
Torg ratio:
- diameter of cervical canal
: to width of cervical body;
- less than
0.80 as seen on the lateral view, cervical stenosis is present;
-
Pavlov's ratio (canal-vertebral body width):
- should be 1.0, with < 0.85 indicating stensosis;
- ratio of < 0.80 is a significant risk factor for lateral neurologic injury;
- this identifies a congenitally narrow canal;
- absolute (AP canal
diameter < 10 mm) or relative (10-13 mm canal diameter) stenosis are risk factors for myeopathy, radiculopathy, or both
due to relatively minor spondylosis pathology or trauma;
- normal is about 17 mm;
- minor trauma such as hyperextension may lead to
central cord syndrome, even without an overt injury;
-
hyperextension:
- cord increases in diameter;
- anteriorly: roots are pinched between discs & adjacent spondylitic bars;
- posteriorly: hypertrophic facets & infolded ligamentum flavum posteriorly;
-
hyperflexion:
- neural structures are tethered anteriorly across discs or spondylitic bars;
-
vetebral collapse:
- collapse of lordotic cervical discs results in loss of normal lordosis of the cervical spine and chronic anterior cord compression;
-
soft disc herniation w/ radiculopathy;
- usually posterolateral, between the posterior edge of uncinate process and the lateral edge of posterior longitudinal ligament;
-
ossificaition of posterior longitudinal ligament:
- causes cervical stenosis &
myelopathy;
- common in Orientals;
Cervical spinal stenosis: determination with vertebral body ratio method.
Cervical spinal stenosis with cord neurapraxia and transient quadriplegia.
