Amino acids in spinal dorsal horn of patients during surgery for neuropathic pain or spasticity

A specific microdialysis probe combined with high performance liquid chroma tography analysis was used to compare the basal levels of extracellular ami no acids (AAs) in the dorsal horn (DH) between two groups of patients under going spinal surgery for the treatment of peripheral neuropathic pain (n = 5) or disabling spasticity (n = 5). A stabilized concentration was reached in the dialysates 45 min after probe implantation for excitatory AAs (gluta mate and aspartate) and inhibitory AAs (GABA and glycine). A significant in crease in the ratios aspartate/GABA and aspartate/glycine was found in the group of patients suffering from neuropathic pain. This study shows the fea sibility of a microdialysis investigation in the DH of patients during a ne urosurgical operation and supports in humans the hypothesis of an imbalance between excitatory AAs and inhibitory AAs within the DH in neuropathic pai n states, as suggested by previous animal studies. NeuroReport 11:1795-1798 (C) 2000 Lippincott Williams & Wilkins.