INTRAOPERATIVE MONITORING OF MOTOR PATHWAYS DURING OPERATIVE FIXATIONOF ACUTE ACETABULAR FRACTURES

Objective: To determine whether intra-operative spontaneous electromyo graphy (EMG) was superior to somatosensory evoked potentials (SSEP) in the prevention of iatrogenic sciatic nerve injury. Design: Prospectiv e, consecutive. Setting: Tertiary referral, teaching Hospital in New Y ork City. Patients: Seventy four patients with acutely displaced aceta bular fractures. Main Outcome Measure: Group A consisted of 24 patient s who underwent intraoperative sciatic nerve monitoring using SSEP onl y. Group B consisted of 50 patients who underwent monitoring using bot h SSEP and spontaneous EMG. Motor potentials were recorded from the ti bialis anterior. peroneus longus, abductor hallucis, and flexor halluc es longus muscles. All patients had independent Preoperative and posto perative evaluations by the same neurologist. Results: One iatrogenic sciatic nerve injury occurred in group A and none in group B. Prolonge d sciatic nerve compromise, demonstrated by significant intraoperative SSEP changes, occurred 2.4 times per case in group A and only 0.8 tim es per case in group B. In group B, spontaneous EMG noted compromise a n average of 3.6 times per case (p <0.0001). Conclusions: The results of this study support spontaneous EMG as feasible and superior to SSEP monitoring in detecting intraoperative sciatic nerve comprise in acut e acetabular fracture surgery. Spontaneous EMG permits earlier detecti on of intraoperative sciatic nerve comprise. allowing a more rapid res ponse of the surgical team to noxious nerve stimulu. This may prevent permanent neurologic sequellae.