A method for objectively verifying the efficacy of manipulative therapy is provided. The method includes performing a first dermatomal somatosensory evoked potentials test �82! on a patient �12! to establish a baseline response of the nerve latency period. A manipulative therapy technique �88! is then performed on the patient to relieve nerve root compression. A second dermatomal somatosensory evoked potentials test �90! is then performed, to establish a post-manipulation nerve latency period.