The scalp recorded posterior tibial nerve somatosensory evoked potential(SEP) is used in evaluation of the tibial nerve somatosensory pathway dysfunction. In that the posterior tibial nerve has less muscle afferent nerve fibers than the tibial nerve in popliteal fossa and central amplification influence on the scalp recorded cortical SEP, this evoked potential is not always proper for the evaluation of the tibial nerve somatosensory pathway. We compared the amplitudes of tibial nerve and posterior tibial nerve SEP stimulated at popliteal fossa and ankle each, and recorded at scalp and T-L junction.

The results showed that the tibial nerve SEP stimulated at popliteal fossa and recorded at T-L junction has greater amplitude and better correlation with muscle afferent fiber composition. The tibial nerve SEP study, stimulated at popliteal fossa and recorded at T-L junction, is also recommended in evaluation of tibial nerve somatosensory pathway dysfunction.

Keywords :Tibial nerve SEP, Posterior tibial nerve SEP, T-L junction, Popliteal fossa