Neurophysiological assessment of the feasibility and safety of neural tissue transplantation in patients with syringomyelia

The feasibility and safety of a procedure involving fetal spinal cord tissu e transplantation in patients with syringomyelia was assessed using a neuro physiological protocol designed to quantitate peripheral nerve function, sp inal cord reflex excitability, and spinal cord conduction pathways essentia l for somatosensory evoked potentials. We report here data obtained before and for 18 months following the transplantation procedure performed on the first two patients in this study. The neurophysiological assessment protoco ls included measures of cortical and spinal cord evoked potentials, H-refle x excitability, and peripheral nerve conduction. Prior to the procedure, bo th patients had significant deficits on some of the neurophysiological meas ures, for example, lower extremity cortical evoked potentials. However, rob ust measures of intact pathways, such as upper extremity cortical evoked po tentials, were also observed preoperatively in both patients. Thus, it was anticipated that conduction in these intact pathways could be at risk eithe r from complications from the transplantation procedure and/or from continu ed expansion of the syrinx. Following the transplantation procedure, no neg ative changes were observed in any of the neurophysiological measures in ei ther patient. In addition, patient I showed a decrease in the rate potentia tion of tibial H-reflexes on the right side and an increase in the response probability of left tibial H-reflexes. The results of this postoperative l ongitudinal assessment provide a first-level demonstration of the safety of the intraspinal neural tissue transplantation procedure. However, the cons ideration of safety is currently limited to the grafting procedure itself, since the long-term fates of the donor tissue in these two patients remain to be shown more definitively.