Equivocal plantar responses: a clinical and electromyographic study.

Thirty patients in whom others found equivocal plantar reflexes were studied clinically and electromyographically (EMG-og flexor hallucis brevis, extensor hallucis longus, and tibialis anterior), during mechanical stimulation of the sole. Bias of recording or interpretation of EMG was excluded. The study was repeated after one week; the EMG outcome was reproducible in 26 patients (87%). Of these 26, a pathological reflex was suspected by the clinician in 17, but shown by EMG in only six patients. Compared with the 'final' diagnosis, false-pathological EMG results did not occur; conversely, EMG criteria were wide enough to demonstrate expected, but clinically unconvincing, Babinski signs. Various factors that cause false impressions in the routine situation could be identified. Provided one has some experience with reference groups, EMG can improve clinical interpretation of equivocal plantar responses.