Intraoperative neuromonitoring using motor evoked potentials (MEP) satisfactorily detects motor tract integrity changes during spinal surgery. However, monitoring is affected by “anesthetic fade,” in which the stimulation threshold increases because the waveform amplitude decreases with the accumulation of propofol. Therefore, the purpose of this study was to clarify the effect of anesthetic fade on transcranial MEPs by investigating the time-dependent changes of amplitude during spinal deformity surgeries. We retrospectively reviewed medical records of 142 spinal deformity patients (66 patients with idiopathic scoliosis, 28 with adult spinal deformities, 19 with neuromuscular scoliosis, 17 with syndromic scoliosis, and 12 with congenital scoliosis). The average age was 28 years (range, 5 to 81 years). MEPs were recorded bilaterally from the abductor digiti minimi (ADM) and abductor hallucis (AH) muscles during spinal deformity surgeries. The Wilcoxon signed-rank test was used to investigate the time-dependent changes of amplitude after propofol infusion to evaluate anesthetic fade effects. The average time to baseline from initial propofol infusion was 113 min (range, 45 to 182 min). In the ADM, the amplitude was 52% at 1 h after initial propofol infusion, 102% at 2 h, 105% at 3 h, 101% at 4 h, 86% at 5 h, and 81% at 6 h. Compared to the 2-h time point, MEP decreased significantly by 16% at 5 h (P < 0.0005) and by 21% at 6 h (P < 0.05). In the AH, the amplitude was 49% at 1 h after initial infusion of propofol, 102% at 2 h, 102% at 3 h, 92% at 4 h, 71% at 5 h, and 63% at 6 h. Compared to the 2-h time point, MEP decreased significantly by 10% at 4 h (P < 0.005), by 31% at 5 h (P < 0.0000005), and by 39% at 6 h (P < 0.05). MEP amplitude significantly decreased in the upper limbs at 5 and 6 h and in the lower limbs at 4, 5, and 6 h after the initial infusion of propofol, respectively. The influence of anesthetic fade could influence false positive MEPs during long spinal surgeries.

We report two cases of combined lumbar vertebral and sacral fractures treated with minimally invasive reconstructive surgery comprising transiliac-transsacral (TITS) screws and spinopelvic fixation (SPF). Case 1 involved a 32-year-old Japanese male patient who fell and sustained multilevel vertebral and sacral fractures with anterior displacement and kyphosis and right pubic fracture. The patient was placed in the supine position and underwent closed reduction in the hyperextended supine position. A TITS screw was inserted at S1 and a cannulated screw was inserted in the right pubic ramus under navigation. The patient's body was then changed to the prone position. Two iliac screws were inserted on each side and percutaneous pedicle screws (PPS) were inserted from Th11 to L4 under navigation. We performed percutaneous rod placement and connected the screws. Postoperative computed tomography (CT) showed no deviation of the screws from the bone and acceptable sacral deformity reduction. Case 2 involved an 83-year-old Japanese female patient who fell and sustained L5 vertebral and fragile sacral fractures. The patient was placed in the prone position, and TITS screw insertion was performed at S1 and S2 under navigation. Iliac screws were inserted on each side and PPS were inserted at the L3 and L4 vertebrae under navigation. Postoperative CT revealed no deviation of the screws from the bone. TITS screw placement and SPF allow minimally invasive reduction and reconstruction of unstable pelvic ring injuries with lower lumbar vertebral and sacral fractures.

Background and Objectives: Diffuse idiopathic skeletal hyperostosis (DISH)-related spinal fractures with marked anterior distraction are highly unstable and pose substantial surgical challenges. The transdiscal screw for diffuse idiopathic skeletal hyperostosis (TSD) technique has been proposed to enhance fixation strength by penetrating adjacent vertebral endplates; however, its clinical utility in large-displacement cases remained unclear. Materials and Methods: In this retrospective study, we reviewed 21 patients with thoracolumbar DISH-related fractures and an anterior fracture gap ≥ 15 mm, who underwent posterior fixation between 2010 and 2024. 11 patients underwent TSD fixation (TSD group), and 10 underwent conventional fixation without bilateral TSD (control group). Results: The mean number of fused segments did not differ significantly between the groups (5.0 ± 1.4 vs. 5.0 ± 1.3, p = 0.43). Operative time was comparable (164 ± 57 vs. 168 ± 60 min, p = 0.90). Blood loss tended to be lower in the TSD group (306 ± 334 vs. 528 ± 658 mL, p = 0.33). For fracture-gap reduction, the TSD group improved from 17.4 ± 2.3 mm preoperatively to 13.8 ± 4.4 mm postoperatively and 2.0 ± 3.6 mm at final follow-up, while the control group showed less reduction (16.8 ± 2.2, 15.4 ± 1.4, and 7.0 ± 9.1 mm, respectively). Screw loosening occurred in three TSD patients and six controls (p = 0.13). All patients in the TSD group achieved bone union without reoperation, whereas four controls experienced implant backout, three required reoperation, and two failed to achieve bone union (p = 0.035). Conclusions: Posterior fixation using TSD provided reliable stability, maintained reduction, and reduced the risk of implant failure compared with conventional fixation in highly unstable DISH-related fractures with anterior distraction. Although larger prospective studies are needed, TSD may represent a valuable surgical option for this challenging patient population.

Background/Objectives: Rigid internal fixation and early mobilization using pedicle screws have become a standard treatment option for vertebral fractures in patients with diffuse idiopathic skeletal hyperostosis. Poor bone quality and a long lever arm may result in a high rate of screw loosening, screw pullout, and implant failure in these patients. Therefore, researchers have developed various techniques to enhance fixation strength, including cement-augmented fenestrated pedicle screw (CAFPS) and transdiscal screw (TDS) fixation. This study compared the clinical and radiological outcomes of CAFPS and TDS fixation techniques for treating diffuse idiopathic skeletal hyperostosis (DISH)-associated thoracolumbar vertebral fractures. This study compared the clinical and radiological outcomes of CAFPS and TDS fixation techniques for DISH-associated thoracolumbar vertebral fractures. Methods: Retrospective comparative cohort study. An evaluation was conducted of patients who underwent posterior instrumentation for vertebral fractures accompanied by DISH, using CAFPS or TDS techniques, at our hospital between August 2019 and March 2025. We assessed preoperative, operative, and postoperative data, outcomes, and radiographic parameters. Results: We included 40 patients; 11 received CAFPS, and 29 received TDS fixation. Operative time (104 ± 19.6 min vs. 115 ± 29.4 min, p = 0.32), blood loss (87.7 ± 69.4 mL vs. 88.3 ± 64.8 mL, p = 0.95), and bone union rate (100% vs. 89.7%, p = 0.27) did not differ significantly. The incidence of screw loosening number was higher in the TDS group (5.68% vs. 13.4%, p = 0.049). However, patient-level analysis showed no difference (4/11 vs. 7/29, p = 0.455). Neither group had implant backouts, failures, or reoperations. Conclusions: Transdiscal screws and transdiscal and cement-augmented pedicle screws are useful techniques for treating thoracolumbar vertebral fractures in patients with DISH. These techniques can reduce the level of fixation in vulnerable patient populations.