Trigeminal somatosensory evoked potentials: technical parameters, reliability and potential in clinical dentistry

Various parameters of the short-latency trigeminal somatosensory evoked potential (TSEP) waveform were investigated in 12 healthy volunteers. The waveform was found to comprise two principal components at 23 (N1) and 39 (P1) ms and to show a significant contralateral dominance. Varying the stimulus strength significantly affected the amplitudes but not the peak latencies. The waveform pattern was maintained irrespective of whether the reference site was Fpz or Cv7. The peak latencies of N1 and P1 were found to be very reproducible. To a lesser extent, N1-P1 amplitude was also reproducible. The results show that clear and reliable TSEPs can be conveniently generated at the pain threshold intensity, and that they could be suitable for clinical investigations of lesions involving the trigeminal pathway. The clinical application of TSEPs has helped in treatment planning for patients with lesions of branches of the trigeminal nerve. Three cases are presented in which the TSEP confirmed the presence of the lesion, and was used to forecast its prognosis.