Recording of ventral posterior lateral thalamus neuron response to contact heat evoked potential in patient with neurogenic pain.

Microrecording of single unit response to contact heat-evoked potential (CHEP) were performed in right ventral posterior lateral (VPL) thalamus during deep brain stimulation (DBS) surgery in a patient with chronic neurogenic pain. In our patient, neurons (n = 10) recorded in the ventral thalamus fired at a higher rate of 40 Hz compared to neurons recorded in Parkinsonian patients (24 Hz). Contact heat was applied by a fast heating and cooling probe of 5 cm2 area on the dermatome C6 territory of the left hand. One out of four thalamic cells located in the VPL responded repetitively 325 ms after the peak temperature was reached with a burst of action potential, suggesting A-delta fibre activation. This observation supports the use of CHEP for mapping nociceptive neurons location during DBS surgery for intractable pain.