Comparison between somatosensory-evoked potential parameters in patients with nonspecific versus specific chronic low back pain

Background: Modern pain neuroscience has revolutionized our understanding about pain, including the role of central sensitization in amplifying pain experiences with increased neuronal response to central nervous system stimuli. During external upper and lower limb perturbation, it has been shown that Chronic low back pain (CLBP) was associated with longer reflex response latencies of trunk muscles. One theoretic but rarely examined possibility for longer reflex latencies is related to modulated somatosensory information processing. Objectives: The objective of the study was to compare the somatosensory-evoked potential (SSEP) parameters of the right median and left tibial nerves between patients with nonspecific and specific CLBP. Materials and Methods: The study includes 102 CLBP patients, clinically and radiologically confirmed and divided into two groups: 48 patients with nonspecific pathology and 54 patients with specific pathology. During this SSEP study the right median and left tibial nerves of all patients were examined. Recorded parameters include the latency and amplitudes. Results: The means of the latencies of all the SSEP waves of the right median and left tibial nerves were only significant in the peripheral SSEP waves in the upper and lower limbs (N9 and N10, respectively) and highly significant in cortical right median N20 SSEP wave. Regarding the central sensory conduction time values, both in the median and tibial SSEP study, The significant differences was noted only in the median nerve SSEP study. Regarding the means of the amplitudes of differently studied SSEP components of the right median and left tibial nerves, it was only significant in the peripheral SSEP (N9) wave of the right median nerve and in the subcortical and cortical (P37 and N45) waves in the tibial nerve SSEP study. Conclusions: Results showed a significantly higher SSEP amplitude and latency in nonspecific CLBP patients as compared to their counterpart CLBP patients. This could reflect a higher excitability of sensory cortex and sensory pathways in patients with nonspecific CLBP as compared to their counterpart patients.