Abstract|Pain 1| Volume 357, SUPPLEMENT 1, e91-e92, October 15, 2015

Somatosensory evoked potentials after painful electrical stimulation in patients with central and peripheral somatosensory pathology with and without neuropathic pain

      Background: The potential clinical use of somatosensory evoked potentials after painful electrical stimulation (SSEPs) has not been systematically explored.
      Objective: To compare SSEPs in controls and patients with central nervous system (CNS) lesions and Polyneuropathies (PNP) affecting the somatosensory pathway with and without neuropathic pain (NP).
      Methods: Healthy adults n = 24. Patients (n = 77), mean age 55.8 ± 14.9 (20 to 83 years), grouped as with(+) and without(−) NP. CNS(+), n = 14/26, CNS(−), n = 12/26; PNP(+), n = 35/51, PNP(−), n = 16/51. 10 double pulse stimuli, 1 ms duration ISI 5 ms at 0.1Hz were applied twice (ring electrodes) in the middle finger and second toe. The electrical intensity was such to evoke pain (VAS 4 or more). Two superimposed averages were recorded at Cz-A1/A2. N1, P1 latencies and N1-P1 amplitude were measured. Patient consent were obtained.
      Results: SSEPs were recorded in all controls subjects. Absent SSEPs in arms or legs(n): CNS(+) 8/14, CNS(−) 4/12, PNP(+)17/35 PNP(−) 8/16. There were no significant differences in the proportions of absent SSEPs between CNS and PNP, or their subgroups, nor between all with and without NP (Fisher’s exact test). P1 latency was prolonged only in arms in both groups of CNS and PNP patients. N1-P1 amplitudes in legs were significantly smaller only compared to controls in both subgroups of CNS and PNP patients (P < 0.0001).
      Conclusions: SSEPs may be useful in the assessment of patients with central or peripheral somatosensory pathways pathology but did not appear to distinguish between CNS and PNS pathology or between presence or absence of NP.
      *Fondecyt 1120339: LAcevedo, GBarraza, MCampero, JLCastillo, GCavada, RGuiloff, JHoneyman, RHughes, JMMatamala, EMullins, POrellana, CRamirez, HRojas, ISazuni, RVerdugo, YWang.