Importancia del registro neurofisiológico evocado durante la colocación de un neuromodulador sacro

Abstract

Sacral neuromodulation is a new treatment option in patients with urge incontinence, urgency-frequency and urinary retention refractory to the pharmacological therapy. The electrophysiological monitoring provides direct and immediate feedback about the function of nerves. We evaluated the utility of the electrophysiological monitoring to assert the correct position of the lead at the third sacral root (S3). We registered the sacral-vesicourethral and sacral plantar evoked potentials in two patients (a 55 years old man and a 37-year-old woman) during the implant of a sacral neuromodulator (Interstim, Medtronic, MN USA). We registered vesico-urethral and sacroplantar potentials in response to sacral stimulation. We found vesical evoked potentials after the stimulation of S3 and S4 and plantar responses after the stimulation of S2 and S3. The vesico-urethral evoked potentials had a latency of 25.10 mseg in our first case and 28.52 mseg in the second. The sacroplantar evoked potentials had a latency of 20.80 mseg and 22.46 mseg respectively. We observed the evoked potential register during the surgery prior to the visual motor and sensory responses with a lower intensity of stimulation (average 3.5 mAmp). The only sacral root in which we could find both responses was in S3. The electrophysiological monitoring was helpful in identifying the right position of the lead at the correct sacral root. It avoided the necessity of high stimulation intensity during the procedure.