In terms of myelography, what anterior-posterior diameter indicates absolute stenosis?

• A. Greater than 10 mm
• B. 8 mm or less
• C. Between 9-10 mm
• D. Less than 12 mm

Answer: (B)

Absolute stenosis is diagnosed when there is significant narrowing of the spinal canal, which can lead to compression of the neural structures within. In the context of myelography, an anterior-posterior diameter of 8 mm or less is considered indicative of absolute stenosis. This threshold is critical because it correlates with clinical symptoms and the likelihood of neurologic compromise.

A diameter of 8 mm or less suggests that the space available for the spinal cord and nerve roots is severely limited, which is associated with a higher risk of conditions such as myelopathy or radiculopathy. This is particularly important in evaluating patients presenting with symptoms related to spinal stenosis, where effective diagnosis through imaging techniques such as myelography is essential for planning treatment options.

The other choices represent measurements that are not considered indicative of absolute stenosis. For example, values greater than 10 mm or between 9-10 mm indicate a more open canal, thus suggesting that the neural structures are less likely to be impinged upon, and the risk of significant neurological issues is reduced. Understanding these measurements assists in the proficient evaluation of spinal conditions and emphasizes the importance of myelography in diagnosing and managing spinal stenosis.