MRI of the cervical spine with neck extension: is it useful?

Abstract

Objectives: Standard MRI of the cervical spine is performed in a different anatomical position to that utilised for traditional contrast myelography. Those well practised in myelography are familiar with the considerable changes in configuration of the bony and soft tissues of the cervical spine that may occur with changes in the degree of neck flexion and extension. We set out to compare the findings in a select group of patients with myeloradiculopathy who had undergone myelography and MRI in both standard and neck-extended positions. These findings were correlated with the clinical status.

Methods: 29 patients underwent myelography with CT (CTM) and MRI in neutral and neck-extended positions. The imaging was assessed for the degree of cord compression and neural foraminal narrowing, quantified using a simple grading scheme suitable for routine clinical practice. The degree of neck extension was assessed using an angular measurement.

Results: For both CTM and MRI, scanning with the neck extended significantly increases the severity of cord compression compared with the standard supine position, to a degree similar to that shown during conventional prone myelography. The degree of perceived cord compression is related to the degree of neck extension achieved. Correlation of standard MRI findings and the clinical level of radiculopathy is poor. This correlation improves when the neck is extended.

Conclusions: The most appropriate position for routine MRI of the cervical spine in degenerative disease remains unknown, but in selected patients imaging with the neck extended may provide important additional information.

Figure 1

Comparison of neutral and extended CT myelography studies. Top row: prone post-myelography CT sagittal reconstruction; and reconstructed axial at C4/5. Bottom row: supine study. Obvious cord compression only shown on extended imaging.

Figure 2

Patient position for extended MRI. Shoulders are elevated with robust foam padding and patient attempts to look down the bore of the scanner.

Figure 3

Left: standard (neutral) MRI; mid-sagittal and axial at C6/7. Right: images at same locations obtained 10 days later, with 17° greater extension. There is increased disc bulging and buckling of the ligamentum flavum at two levels.

Figure 4

In this case angle of extension is 39°.

Figure 5

Angle between C2 and C7, neutral and extended studies. 17 patients, each with a different colour coding.

Figure 6

Perceived cord compression on neutral and extended studies. Same patients and colour coding as in Figure 5.

Figure 7

Difference in perceived cord compression versus change in angle between neutral and extended MRI.