Functional testing in lumbar nerve root compression syndromes. An evaluation in patients with normal neurological findings.

A functional test using downhill walking was evaluated in relation to the myelographical examination in 33 patients with a suspected lumbar nerve root compression syndrome despite normal neurological findings. Any changes of motor or reflex signs or of straight leg raising were accepted as test results. They were noted in a decision matrix and the positive and negative predictive value (PPV and NPV, respectively) calculated. The PPV of any deterioration of the neurological status resulting from the test as a sign of abnormal myelographical findings was calculated to be approximately 85 per cent, the corresponding NPVs being approximately 50 per cent. In its present form, this functional test is inadequate as a screening procedure in these patients.