Retrospective analysis of radiology reports of conventional MRI in 100 patients with definite spinal stenosis to determine the incidence of reported “foraminal stenosis”.

Prospective study of MRI including T2 coronal and T2 STIR coronal sequences in 57 patients with suspected stenosis. Three surgeons and one radiologist independently compared the diagnoses on conventional and coronal scans.

Patients with suspected spinal stenosis undergoing MRI.

Incidence of “foraminal stenosis” on radiologists' reports.

Diagnoses obtained by different scanning methods.

Retrospective analysis: “foraminal stenosis” called by radiologists in 46% using conventional axial and sagittal sequences.

Prospective study - 57 patients: conventional sequences diagnosed lateral recess stenosis well but also suggested foraminal stenosis in 33%. However, coronal sequences clearly showed no foraminal nerve compression.

In degenerative spondylolisthesis conventional scans suggested foraminal stenosis in 8 of 11 cases. Coronals showed no foraminal stenosis.

Excellent correlation was found in normal spines and in disc herniation. In far lateral disc herniation and isthmic spondylolisthesis, true foraminal stenosis was confirmed by conventional and coronal imaging.

Additional coronal MRI sequences prove that foraminal stenosis is over-diagnosed and is rare in spinal stenosis, but true foraminal nerve compression occurs in isthmic spondylolisthesis and far lateral disc herniation.