Assessment of dorsal nerve root and spinal cord dorsal horn function in clinically normal dogs by determination of cord dorsum potentials

Objective-To establish normal predictive values for cord dorsum potential ( CDP) onset latency after thoracic and pelvic limb sensory or mixed nerve st imulation in adult dogs. Animals-26 clinically normal adult dogs. Procedure-Sensory nerve action potentials (SNAP) were recorded proximally f rom tibial and lateral superficial radial nerves after distal stimulation. The CDP were recorded from the L-4-L-5 interarcuate ligament for the tibial nerve and from the CT-TI interarcuate ligament for the radial nerve. Linea r regression analyses were performed for CDP onset latency, and mean +/- SD was calculated for CDP onset to peak latency differences and sensory nerve conduction velocities (SNCV). Results-For the tibial nerve, expected CDP onset latency (CDPOL) = -1.194 0.014 X pelvic limb length (mm; R-e = 0.912); CDPOL = -2.156 + 0.011 x pel vic limb/spinal length (mm; R-e = 0.911); and CDPOL = 0.941 + 2.197 X tibia l nerve SNAP latency (milliseconds; R-e = 0.903). For the radial nerve, CDP OL = -0.9 + 0.014 X thoracic limb length (mm; R-e = 0.873); and CDPOL = 1.4 54 + 1.874 X radial nerve SNAP latency (milliseconds; R-e = 0.903). Mean +/ - SD for CDP onset to peak latency difference for tibial and radial nerves was 3.1 +/- 0.3 and 3.0 +/- 0.4 milliseconds, respectively. Conclusions-Strong linear associations exist between CDPOL and a number of easily measured peripheral independent variables in dogs. There is also a n arrow range of normal values for CDP onset to peak latency differences that is independent of limb length. Clinical Relevance-CDP evaluation can be used to accurately assess function al severity and distribution of abnormalities in proximal sensory nerves, d orsal nerve roots, and spinal cord dorsal horns in dogs with suspected neur opathy, radiculopathy, or myelopathy involving the brachial or lumbosacral intumescences.