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Hiroki Ushirozako, Go Yoshida, Tomohiko Hasegawa, Yu Yamato, Tatsuya Yasuda, Tomohiro Banno, Hideyuki Arima, Shin Oe, Tomohiro Yamada, Koichiro Ide, Yuh Watanabe, Tadayoshi Kurita, and Yukihiro Matsuyama

OBJECTIVE

Transcranial motor evoked potential (TcMEP) monitoring may be valuable for predicting postoperative neurological complications with a high sensitivity and specificity, but one of the most frequent problems is the high false-positive rate. The purpose of this study was to clarify the differences in the risk factors for false-positive TcMEP alerts seen when performing surgery in patients with pediatric scoliosis and adult spinal deformity and to identify a method to reduce the false-positive rate.

METHODS

The authors retrospectively analyzed 393 patients (282 adult and 111 pediatric patients) who underwent TcMEP monitoring while under total intravenous anesthesia during spinal deformity surgery. They defined their cutoff (alert) point as a final TcMEP amplitude of ≤ 30% of the baseline amplitude. Patients with false-positive alerts were classified into one of two groups: a group with pediatric scoliosis and a group with adult spinal deformity.

RESULTS

There were 14 cases of false-positive alerts (13%) during pediatric scoliosis surgery and 62 cases of false-positive alerts (22%) during adult spinal deformity surgery. Compared to the true-negative cases during adult spinal deformity surgery, the false-positive cases had a significantly longer duration of surgery and greater estimated blood loss (both p < 0.001). Compared to the true-negative cases during pediatric scoliosis surgery, the false-positive cases had received a significantly higher total fentanyl dose and a higher mean propofol dose (0.75 ± 0.32 mg vs 0.51 ± 0.18 mg [p = 0.014] and 5.6 ± 0.8 mg/kg/hr vs 5.0 ± 0.7 mg/kg/hr [p = 0.009], respectively). A multivariate logistic regression analysis revealed that the duration of surgery (1-hour difference: OR 1.701; 95% CI 1.364–2.120; p < 0.001) was independently associated with false-positive alerts during adult spinal deformity surgery. A multivariate logistic regression analysis revealed that the mean propofol dose (1-mg/kg/hr difference: OR 3.117; 95% CI 1.196–8.123; p = 0.020), the total fentanyl dose (0.05-mg difference; OR 1.270; 95% CI 1.078–1.497; p = 0.004), and the duration of surgery (1-hour difference: OR 2.685; 95% CI 1.131–6.377; p = 0.025) were independently associated with false-positive alerts during pediatric scoliosis surgery.

CONCLUSIONS

Longer duration of surgery and greater blood loss are more likely to result in false-positive alerts during adult spinal deformity surgery. In particular, anesthetic doses were associated with false-positive TcMEP alerts during pediatric scoliosis surgery. The authors believe that false-positive alerts during pediatric scoliosis surgery, in particular, are caused by “anesthetic fade.”

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Hideyuki Arima, Yu Yamato, Tomohiko Hasegawa, Daisuke Togawa, Go Yoshida, Tatsuya Yasuda, Tomohiro Banno, Shin Oe, Hiroki Ushirozako, Tomohiro Yamada, Yuh Watanabe, Koichiro Ide, and Yukihiro Matsuyama

OBJECTIVE

Extensive corrective fusion surgery was performed on elderly patients with adult spinal deformity (ASD) to improve abnormal posture. Varying improvements in postoperative walking function were expected owing to differences in muscular strength and bone quality between patients in their 40s and those over 75 years of age. The purpose of this study was to compare preoperative and postoperative gait posture and physical functionality in elderly patients with ASD who underwent extensive corrective fusion to the thoracic spine.

METHODS

A prospectively maintained surgical database was reviewed for patients with ASD who underwent corrective fusion surgery (thoracic spine to pelvis) between 2011 and 2016. The cohort was divided into three age groups: nonelderly (40–64 years), young-old (65–74 years), and old-old (> 75 years). Patients underwent a 4-m walk test preoperatively and 2 years postoperatively to measure gait-trunk tilt angle and walking speed (meters per minute).

RESULTS

Among 291 patients with ASD who underwent corrective fusion surgery, 56 patients (14 men and 42 women; mean age 68.8 years) were included. Mean preoperative gait-trunk tilt angle (12.9° vs 5.2°, p < 0.01) and walking speed (41.2 m/min vs 45.7 m/min, p < 0.01) significantly improved postoperatively. Intergroup analysis revealed that the mean preoperative gait-trunk tilt angles in the nonelderly (n = 13), young-old (n = 28), and old-old (n = 15) groups were 11.9°, 10.0°, and 19.3°, respectively; postoperatively, these improved to 4.5°, 4.5°, and 7.2°, respectively. Mean preoperative walking speeds of 47.9, 40.0, and 37.7 m/min improved to 52.4, 44.8, and 41.5 m/min postoperatively in the nonelderly, young-old, and old-old groups, respectively. There were no statistically significant differences in degree of improvement in gait-trunk tilt angle and walking speed among groups.

CONCLUSIONS

Extensive corrective fusion surgery improved the postoperative walking posture of patients with ASD. Statistical analysis of gait measurements demonstrated intergroup equivalence, indicating comparable improvement in physical functionality in elderly and middle-aged patients after corrective fusion surgery.

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Shin Oe, Yu Yamato, Tomohiko Hasegawa, Go Yoshida, Sho Kobayashi, Tatsuya Yasuda, Tomohiro Banno, Hideyuki Arima, Yuki Mihara, Hiroki Ushirozako, Tomohiro Yamada, Koichiro Ide, Yuh Watanabe, and Yukihiro Matsuyama

OBJECTIVE

Many complications are likely to occur in patients with malnutrition. The prognostic nutritional index (PNI) is often used when evaluating a patient’s nutritional condition. However, no studies have investigated the association between nutritional status and postoperative medical complications or prognosis by using the PNI in the field of spinal surgery. The purpose of this retrospective study was to investigate postoperative medical complications and prognoses of patients who had undergone adult spinal deformity (ASD) surgery, according to their preoperative nutritional status.

METHODS

All patients aged ≥ 40 years who had undergone scheduled ASD surgery in the authors’ hospital between March 2010 and June 2017 were eligible for study inclusion and were divided into groups according to their PNI (< 50, group L; ≥ 50, group H). Medical complications diagnosed within 30 days postoperatively were evaluated; however, surgical site infection and death were evaluated until 1 and 5 years after surgery, respectively.

RESULTS

Among the 285 eligible patients, groups L and H consisted of 118 and 167 patients, whose mean ages were 68.6 and 68.3 years, respectively. There was a significant difference in body mass index (22 vs 24 mg/kg2, respectively, p = 0.000), PNI (46 vs 55, p = 0.000), comorbidity of osteoporosis (50% vs 32%, p = 0.005) and autoimmune disease (13% vs 5%, p = 0.036), medical history of malignant disorder (17% vs 6%, p = 0.007), and medical complications (49% vs 23%, p = 0.000) between groups L and H. Multiple logistic regression analysis suggested that significant risk factors for postoperative medical complications were male sex (p = 0.000, OR 3.5, 95% CI 1.78–6.96), PNI < 50 (p = 0.000, OR 2.9, 95% CI 1.69–4.93), and days to ambulation (p = 0.003, OR 1.1, 95% CI 1.02–1.09).

CONCLUSIONS

Medical complication rates are significantly higher in patients with PNI < 50, those with delayed ambulation, and male patients. In malnourished patients scheduled for ASD surgery, improvement of preoperative nutritional status and postoperative early ambulation are important to avoid medical complications.

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Hiroki Ushirozako, Tomohiko Hasegawa, Yu Yamato, Go Yoshida, Tatsuya Yasuda, Tomohiro Banno, Hideyuki Arima, Shin Oe, Yuki Mihara, Tomohiro Yamada, Koichiro Ide, Yuh Watanabe, Keichi Nakai, Takaaki Imada, and Yukihiro Matsuyama

OBJECTIVE

Surgical site infection (SSI) after posterior spinal surgery is one of the severe complications that may occur despite administration of prophylactic antibiotics and the use of intraoperative aseptic precautions. The use of intrawound vancomycin powder for SSI prevention is still controversial, with a lack of high-quality and large-scale studies. The purpose of this retrospective study using a propensity score–matched analysis was to clarify whether intrawound vancomycin powder prevents SSI occurrence after spinal surgery.

METHODS

The authors analyzed 1261 adult patients who underwent posterior spinal surgery between 2010 and 2018 (mean age 62.3 years; 506 men, 755 women; follow-up period at least 1 year). Baseline and surgical data were assessed. After a preliminary analysis, a propensity score model was established with adjustments for age, sex, type of disease, and previously reported risk factors for SSI. The SSI rates were compared between patients with intrawound vancomycin powder treatment (vancomycin group) and those without (control group).

RESULTS

In a preliminary analysis of 1261 unmatched patients (623 patients in the vancomycin group and 638 patients in the control group), there were significant differences between the groups in age (p = 0.041), body mass index (p = 0.013), American Society of Anesthesiologists classification (p < 0.001), malnutrition (p = 0.001), revision status (p < 0.001), use of steroids (p = 0.019), use of anticoagulation (p = 0.033), length of surgery (p = 0.003), estimated blood loss (p < 0.001), and use of instrumentation (p < 0.001). There was no significant difference in SSI rates between the vancomycin and control groups (21 SSIs [3.4%] vs 33 SSIs [5.2%]; OR 0.640, 95% CI 0.368–1.111; p = 0.114). Using a one-to-one propensity score–matched analysis, 444 pairs of patients from the vancomycin and control groups were selected. There was no significant difference in the baseline and surgical data, except for height (p = 0.046), between both groups. The C-statistic for the propensity score model was 0.702. In the score-matched analysis, 12 (2.7%) and 24 (5.4%) patients in the vancomycin and control groups, respectively, developed SSIs (OR 0.486, 95% CI 0.243–0.972; p = 0.041). There were no systemic complications related to the use of vancomycin.

CONCLUSIONS

The current study showed that intrawound vancomycin powder was useful in reducing the risk of SSI after posterior spinal surgery by half, without adverse events. Intrawound vancomycin powder use is a safe and effective procedure for SSI prevention.