Recording of cord dorsum potentials in calves

Cord dorsum potentials are sensory evoked potentials being used to assess proximal sensory nerve, dorsal nerve root and spinal cord dorsal horn function. The purpose of the present study was to establish normal values for onset latency, peak latency and peak-to-peak amplitude of cord dorsum potentials after saphenous nerve stimulation in 15 healthy calves. Under general anesthesia, the saphenous nerve was stimulated in the periphery and cord dorsum potentials were recorded from the interarcuate space L3-L4, L4-L5, L5-L6 and L6-S1. Cord dorsum potentials were easily recorded at the different recording sites and consisted of a large negative peak followed by a long latency positive phase. The largest responses were recorded at the L5-L6 interarcuate space. Body temperature significantly influenced peak-to-peak amplitude. Onset latency prolonged with increasing limb length.