the effects from lumbar nerve root transection in rats on spinal somatosensory and motorevoked potentials study design spinal somatosensoryevoked potentials sseps elicited by mixed nerve and dermatomal stimulation and compound evoked muscle potentials cmaps elicited by lower thoracic interspinous space stimulation were recorded in rats that underwent single nerve root transectionobjectives to investigate and compare the effects of single nerve root transection using various electrophysiological models and to define a monitoring strategy that can easily and accurately predict compromise caused by a single lumbosacral nerve root injurysummary of background data neuromonitoring is an important and effective preventive measure against neurologic complications during spinal surgery but monitoring the lumbosacral nerve roots is not well establishedmethods rats received group i a sham operation or had the group ii left l4 group iii l5 or group iv l6 nerve root transected ssep were recorded at the thoracolumbar junction following stimulation of the sciatic nerve mssep and the l5 dermatome dssep cmap was recorded at the intrinsic muscles of the foot by electrical stimulation in the lower thoracic spinal cord potentials recorded before and after a single nerve root transection were compared and correlated with clinical status by walkingtrack analysis 1 week laterresults relative amplitudes in group ii were 541 mssep 846 dssep and 855 cmap 252 mssep 665 dssep and 858 cmap in group iii and 665 mssep 955 dssep and 232 cmap in group iv mssep is sensitive but not specific to single nerve root injury dssep and cmap are less sensitive but more specificconclusions injury to a single lumbosacral nerve root is diagnosed more easily with mssep with dssep and cmap it was possible to differentiate the lesioned nerve root by stimulating the primary dermatome or recording from the innervated muscle mssep is an easysampling and appropriate tool for screening nerve root injury its poor specificity may be overcome by using dssep and cmap in addition optimal monitoring of the lumbosacral nerve roots during lumbar spinal surgery requires the administration of mssep dssep and cmap to provide independent verification of lumbosacral nerve root integrity and to allow detection of the occasional injuries that selectively affect either the sensory or motor system