Experimental fetal neurosurgery: effects of in-utero manipulations on somatosensory evoked potentials

Somatosensory evoked potentials (SEP) were used to objectively evaluate sen sory function in neonatal sheep after experimental fetal surgery. Posterior tibial (PTN) and ulnar (UN) nerves were stimulated electrically and averag ed SEP were recorded from scalp electrodes placed over the somatosensory co rtex. Animals with experimentally-created myelomeningocele (MMC) showed no SEP to PTN stimulation, but normal SEP to UN stimulation. In-utero repair o f the MMC resulted in preservation of neurologic function and normal PTN SE P. In-utero thoracic spinal-cord transection resulted in no regeneration, a nd no SEP to PTN stimulation. In-utero unilateral transection of the sciati c nerve, even with attempted repair, resulted in little or no regeneration and absent or grossly abnormal PTN SEP from the affected side. In summary, the SEP technique provides valuable information concerning preservation of sensory function in a variety of experimentally created neurologic abnormal ities and can aid in functional evaluation of experimental therapeutic feta l interventions.