Cervical Stenosis

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.