Background: Magnetic resonance imaging is commonly used to diagnose
lumbar spinal stenosis. Some persons without symptoms have a small lumbar
spinal canal. Electrodiagnosis has been used to diagnose spinal stenosis for
over sixty years, but we are aware of no masked, controlled trials of the use
of electrodiagnosis for that purpose. This study was performed to evaluate the
relationships of magnetic resonance imaging measures and electrodiagnostic
data with the clinical syndrome of spinal stenosis.
Methods: One hundred and fifty persons between the ages of
fifty-five and eighty years old, including asymptomatic volunteers and persons
referred for lumbar magnetic resonance imaging, underwent clinical
examination, electrodiagnosis, and magnetic resonance imaging. Subjects were
excluded if they had neuromuscular disease, sacral cancer, or inadequate test
results, which left 126 subjects for the final analysis. The final cohort was
divided into three groups—no back pain, mechanical back pain, and
clinical spinal stenosis—on the basis of the impression of the examining
physician, for whom the results of the magnetic resonance imaging and
electrodiagnostic testing were masked. A spine surgeon also reviewed both the
imaging and clinical examination data.
Results: The examining physician's diagnosis of clinical spinal
stenosis was significantly related to the neurological findings on examination
(p < 0.05) and to the spine surgeon's diagnosis (p < 0.001). The
diagnosis of clinical spinal stenosis was also significantly related to the
presence of fibrillations on electrodiagnostic testing (p = 0.003), the
minimum anteroposterior diameter of the spinal canal on the magnetic resonance
images (p = 0.016), and the average of the two smallest spinal canal diameters
(p = 0.008) on the images. Measurements on magnetic resonance imaging did not
differentiate subjects with clinical spinal stenosis from controls better than
chance, whereas paraspinal mapping electrodiagnosis scores did.
Conclusions: This prospective, controlled, masked study of
electrodiagnosis and magnetic resonance imaging for older subjects showed that
imaging does not differentiate symptomatic from asymptomatic persons, whereas
electrodiagnosis does. We believe that radiographic findings alone are
insufficient to justify treatment for spinal stenosis.
Level of Evidence: Diagnostic Level IV. See Instructions
to Authors for a complete description of levels of evidence.