Tatsuya Yasuda, Tomohiko Hasegawa, Yu Yamato, Daisuke Togawa, Sho Kobayashi, Go Yoshida, Tomohiro Banno, Hideyuki Arima, Shin Oe and Yukihiro Matsuyama
The purpose of this study was to evaluate the effect of position on lumbar lordosis (LL) in adult spinal deformity (ASD) patients.
The authors evaluated the radiographic data of ASD patients who underwent posterior corrective fusion surgery from the thoracic spine to L5, S1, or the ilium for the treatment of ASD of the lumbar spine. The spinopelvic parameters were measured in the standing position preoperatively. LL was also evaluated in the supine position preoperatively and in the prone position on the surgical frame. Changes in LL were compared between groups.
Eighty-five patients were included. The average LL in standing, supine, and prone positions was 11.8°, 24.3°, and 24.0°, respectively. LL increased significantly from standing to supine or prone position (p < 0.001). In 80 patients (94.1%), the difference between supine LL and prone LL was within 5°. Change in LL from standing to prone position was significantly higher in the severe deformity group.
The lordotic effect of intraoperative prone positioning was remarkable in patients with severe deformities. LL in the supine position was approximately the same as that in the prone position. Therefore, assessing preoperative supine lateral lumbar radiographs enables one to plan corrective spinal surgeries in ASD patients.
Hiroki Ushirozako, Go Yoshida, Sho Kobayashi, Tomohiko Hasegawa, Yu Yamato, Tatsuya Yasuda, Tomohiro Banno, Hideyuki Arima, Shin Oe, Yuki Mihara, Daisuke Togawa and Yukihiro Matsuyama
Intraoperative neuromonitoring may be valuable for predicting postoperative neurological complications, and transcranial motor evoked potentials (TcMEPs) are the most reliable monitoring modality with high sensitivity. One of the most frequent problems of TcMEP monitoring is the high rate of false-positive alerts, also called “anesthetic fade.” The purpose of this study was to clarify the risk factors for false-positive TcMEP alerts and to find ways to reduce false-positive rates.
The authors analyzed 703 patients who underwent TcMEP monitoring under total intravenous anesthesia during spinal surgery within a 7-year interval. They defined an alert point as final TcMEP amplitudes ≤ 30% of the baseline. Variations in body temperature (maximum − minimum body temperature during surgery) were measured. Patients with false-positive alerts were classified into 2 groups: a global group with alerts observed in 2 or more muscles of the upper and lower extremities, and a focal group with alerts observed in 1 muscle.
False-positive alerts occurred in 100 cases (14%), comprising 60 cases with global and 40 cases with focal alerts. Compared with the 545 true-negative cases, in the false-positive cases the patients had received a significantly higher total propofol dose (1915 mg vs 1380 mg; p < 0.001). In the false-positive cases with global alerts, the patients had also received a higher mean propofol dose than those with focal alerts (4.5 mg/kg/hr vs 4.2 mg/kg/hr; p = 0.087). The cutoff value of the total propofol dose for predicting false-positive alerts, with the best sensitivity and specificity, was 1550 mg. Multivariate logistic analysis revealed that a total propofol dose > 1550 mg (OR 4.583; 95% CI 2.785–7.539; p < 0.001), variation in body temperature (1°C difference; OR 1.691; 95% CI 1.060–2.465; p < 0.01), and estimated blood loss (500-ml difference; OR 1.309; 95% CI 1.155–1.484; p < 0.001) were independently associated with false-positive alerts.
Intraoperative total propofol dose > 1550 mg, larger variation in body temperature, and greater blood loss are independently associated with false-positive alerts during spinal surgery. The authors believe that these factors may contribute to the false-positive global alerts that characterize anesthetic fade. As it is necessary to consider multiple confounding factors to distinguish false-positive alerts from true-positive alerts, including variation in body temperature or ischemic condition, the authors argue the importance of a team approach that includes surgeons, anesthesiologists, and medical engineers.
Tadayoshi Kurita and Yoshiki Nakajima