Transcranial Motor Evoked Potential Monitoring for the Detection of Nerve Root Injury during Adult Spinal Deformity Surgery

Hiroki Ushirozako,Go Yoshida,Sho Kobayashi,Tomohiko Hasegawa,Yu Yamato,Tatsuya Yasuda,Tomohiro Banno,Hideyuki Arima,Shin Oe,Yuki Mihara,Daisuke Togawa,Yukihiro Matsuyama 대한척추외과학회 2018 Asian Spine Journal Vol.12 No.4

Study Design: Retrospective study. Purpose: We aimed to determine the utility of transcranial motor evoked potential (TcMEP) monitoring for the detection of intraoperative nerve root injury. Overview of Literature: Intraoperative neuromonitoring is important for the prediction of neurological injuries or postoperative paralysis. Nerve root injury can develop as a complication of adult spinal deformity (ASD) surgery. Methods: We analyzed 295 patients who underwent ASD surgery using multi-channel TcMEP monitoring between 2010 and 2016 (58 men, 237 women; median age, 68 years; follow-up period ≥1 year). We defined the alarm point as a TcMEP amplitude <30% of that at baseline, and nerve root injury as meeting the focal TcMEP alerts shortly following surgical procedures with the presence of postoperative motor deficits in the selected muscles. Patients were classified into two groups, as those with nerve root injury and those with true-negatives. Results: Seven patients (2.4%) exhibited neurological events related to nerve root injury, comprising six true-positive and one falsenegative cases. TcMEP monitoring from multiple myotomes was effective in detecting nerve root injury. Compared to the 248 truenegative cases, the seven cases of nerve root injury were associated with significantly different preoperative pelvic tilt (PT) values, sacral slope values, and degree of change in PT. The cutoff for the degree of change in PT for predicting nerve root injury, with the best sensitivity and specificity, was 17.5°. Multivariate logistic analyses revealed that a change of >17.5° in PT (odds ratio, 17.5; 95% confidence interval, 1.994–153.560; p =0.010) was independently associated with intraoperative nerve root injury. Conclusions: Multi-channel TcMEP monitoring may be useful for detecting nerve root injuries. A change in PT of >17.5° may be a significant risk factor for neurological events related to intraoperative nerve root injury.

Impact of Spinal Correction Surgeries with Osteotomy and Pelvic Fixation in Patients with Kyphosis Due to Osteoporotic Vertebral Fractures

Hasegawa Tomohiko,Ushirozako Hiroki,Yamato Yu,Yoshida Go,Yasuda Tatsuya,Banno Tomohiro,Arima Hideyuki,Oe Shin,Yamada Tomohiro,Ide Koichiro,Watanabe Yuh,Matsuyama Yukihiro 대한척추외과학회 2021 Asian Spine Journal Vol.15 No.4

Study DesignCombination of retrospective and prospective study.PurposeWe aimed to compare the clinical outcomes between local fixation surgery and spinopelvic fixation surgery for the treatment of kyphosis secondary to osteoporotic vertebral fractures with spinopelvic malalignment.Overview of LiteratureThe clinical characteristics of patients with rigid kyphosis due to osteoporotic vertebral fracture differ from that of middle-aged patients with vertebral fractures in terms of bone fragility and presence of spinopelvic malalignment. Little is known about the surgical strategies for these deformities, most especially the extent of fusion of vertebra involved.MethodsWe analyzed 24 patients with vertebral osteotomy at the level of the fracture and spinal fixation without pelvic fixation (local group), and 22 patients with vertebral osteotomy and pelvic fixation (pelvic group). Radiographic parameters, the incidence of proximal junctional kyphosis (PJK), distal junctional kyphosis (DJK), rod fractures, and the Oswestry Disability Index (ODI) were compared between the two groups over a 2-year follow-up period.ResultsIn the pelvic group, postoperative spinopelvic parameters significantly improved, with the improvements maintained. No remarkable changes in spinopelvic parameters were seen in the local group. The mean ODI scores 2 years after surgery were 45.3 and 33.0 in the local and pelvic group, respectively (p-value <0.05). There was no significant difference in the incidence of PJK in the local and pelvic groups, but there was a higher rate of DJK (41.7%) in the local group. In contrast, rod fractures were more common in the pelvic group (45.5%). Patients with DJK had higher ODI scores 2 years after surgery (52.0 in DJK patients vs. 34.8 in non-DJK patients; p-value <0.05).ConclusionsFor patients with rigid kyphosis due to osteoporotic vertebral fractures, better spinopelvic alignment and health-related quality of life can be achieved through extensive corrective surgery with pelvic fixation.

Selective Angiography to Detect Anterior Spinal Artery Stenosis in Thoracic Ossification of the Posterior Longitudinal Ligament

Yoshida Go,Ushirozako Hiroki,Hasegawa Tomohiko,Yamato Yu,Yasuda Tatsuya,Banno Tomohiro,Arima Hideyuki,Oe Shin,Mihara Yuki,Yamada Tomohiro,Ide Koichiro,Watanabe Yuh,Ushio Takasuke,Matsuyama Yukihiro 대한척추외과학회 2022 Asian Spine Journal Vol.16 No.3

Study Design: Single-center prospective study.Purpose: To investigate anterior spinal artery (ASA) status using preoperative selective angiography in patients undergoing surgery for thoracic ossification of the posterior longitudinal ligament (T-OPLL).Overview of Literature: Surgery for T-OPLL has a high risk of neurological complications, which might be associated with insufficient spinal cord blood flow.Methods: This study prospectively examined nine T-OPLL patients who underwent posterior thoracic decompression with kyphosis correction and instrumented fusion at Hamamatsu University School of Medicine between 2017 and 2019. All underwent preoperative selective angiography to detect and evaluate the Adamkiewicz artery and ASA. Intraoperative neuromonitoring and Doppler ultrasonography were performed to analyze neurological complications and spinal cord blood flow.Results: All nine patients showed ASA stenosis in the area of T-OPLL. In all patients, the Adamkiewicz artery was located between T7 and L2 and the area of ASA stenosis corresponded to the level of T-OPLL and greatest spinal cord compression; intraoperative Doppler ultrasonography confirmed the ASA defect at the same spinal level. The number of spinal levels from the Adamkiewicz artery to the most compressive OPLL lesion was greater in the two patients who developed postoperative neurological deficit compared to those who did not (5.5 vs. 2.3, p=0.014).Conclusions: This is the first study to report detection of ASA stenosis in patients with T-OPLL. Maintaining spinal cord blood flow is important in these patients to avoid neurological deterioration.

How Is Degenerative Lumbar Scoliosis Associated with Spinopelvic and Lower-Extremity Alignments in the Elderly

Wang Jili,Ushirozako Hiroki,Yamato Yu,Ide Koichiro,Hasegawa Tomohiko,Yoshida Go,Banno Tomohiro,Oe Shin,Arima Hideyuki,Mihara Yuki,Watanabe Yuh,Nakai Keiichi,Kurosu Kenta,Hoshino Hironobu,Matsuyama Yuk 대한척추외과학회 2023 Asian Spine Journal Vol.17 No.2

Study Design: A retrospective cohort study.Purpose: Our aim is to investigate the relationship between degenerative lumbar scoliosis (DLS), and whole-body alignment, including spinopelvic and lower extremity alignments. Overview of Literature: DLS is a deformity commonly associated with aging. However, the correlation between whole-body alignment and DLS remains controversial.Methods: Adult volunteers aged over 50 years were included in the study after participating in the screening program. Characteristic data and standing radiographic parameters were assessed. A propensity score model was established with adjustments for age and sex after a preliminary analysis, and cases were divided into DLS (Cobb angle >10°) and non-DLS (Cobb angle ≤10°) groups.Results: There were significant differences in age, sex, C2 sagittal vertical axis (C2-SVA), C7-SVA, T1 pelvic angle (TPA), lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), PI minus LL (PI–LL), knee angle, ankle angle, pelvic shift, C7-center sacral vertical line, L4 tilt, femur-tibia angle, and hip-knee-ankle angle (all p <0.05) using a preliminary analysis of 261 cases (75 DLS and 186 non-DLS). A one-to-one propensity score-matched analysis was used after 70 pairs of cases were selected. There were no significant differences in the characteristic data for lower extremity parameters. There were still significantly higher values of C2-SVA, TPA, PI, PT, and PI–LL in DLS group than in non-DLS group (all p <0.05).Conclusions: This study showed an important relationship between DLS and sagittal spinal deformity. However, DLS was not associated with the sagittal and coronal lower extremity alignments.

Spinal Sagittal Alignment, Hospital Anxiety and Depression Scale Scores, and Patient-Reported Outcome among People with Sporting Activity

Oe Shin,Yamato Yu,Hasegawa Tomohiko,Yoshida Go,Kobayashi Sho,Yasuda Tatsuya,Banno Tomohiro,Arima Hideyuki,Mihara Yuki,Ushirozako Hiroki,Yamada Tomohiro,Ide Koichiro,Watanabe Yuh,Haruo Niwa,Matsuyama Y 대한척추외과학회 2020 Asian Spine Journal Vol.14 No.3

Study Design: Retrospective cohort study.Purpose: This study aimed to investigate how participation in sporting activity affects patient-reported outcome (PRO), including Neck Disability Index (NDI), in males and females.Overview of Literature: Previously, our study reported that factors with a negative influence on the NDI in females were a lack of sporting activities. However, it was still unclear why it affected poor scores of NDI.Methods: The subjects were 473 volunteers. They were divided into two groups (activity and non-activity) according to participation or non-participation in sporting activities using a self-filled questionnaire. The evaluation items were height, weight, grip strength, bone density, Hospital Anxiety and Depression Scale (HADS) score, standing radiographic parameters, PRO (evaluated by EuroQol-5 dimension [EQ-5D], Oswestry Disability Index [ODI]), and NDI.Results: There were 101 males in the non-activity group and 69 in the activity group and 178 females in the non-activity group and 125 in the activity group. For the males, the evaluation items with significant influence were cervical lordosis (non-activity group:activity group, 17°:22°) and T1 slope minus cervical lordosis (10°:6°, <i>p</i> <0.05). For the females, the evaluation items with significant influence were sagittal vertical axis (28:14 mm), HADS (10.4:8.4), EQ-5D (0.79:0.86), ODI (17:12), and NDI (12:9, <i>p</i> <0.01). HADS and PRO in the females were significantly correlated with the EQ-5D (−0.40), ODI (0.43), and NDI (0.55).Conclusions: Males who participated in sporting activities had better cervical spine alignment but no effect on PRO. Females with sporting activities had better spinal global alignment and less mental stress. It is suggested that sporting activity in females might be associated with PRO because HADS highly correlates with PRO.

Revision Surgery for a Rod Fracture with Multirod Constructs Using a Posterior-Only Approach Following Surgery for Adult Spinal Deformity

Yamato Yu,Hasegawa Tomohiko,Yoshida Go,Banno Tomohiro,Oe Shin,Arima Hideyuki,Mihara Yuki,Ushirozako Hiroki,Yamada Tomohiro,Watanabe Yuh,Ide Koichiro,Nakai Keiichi,Kurosu Kenta,Matsuyama Yukihiro 대한척추외과학회 2022 Asian Spine Journal Vol.16 No.5

Study Design: Single-center retrospective case series.Purpose: We aimed to evaluate the clinical results of revision surgery for a rod fracture using a posterior-only approach and determine the best procedure to prevent refracture in patients with adult spinal deformity (ASD).Overview of Literature: ASD affects the thoracolumbar spine and often requires surgical correction. However, surgery for extensive spinal fusion causes rod fracture, a major mechanical complication. Few studies have described the treatment methods for rod fractures. Furthermore, the clinical outcomes of revision surgery for rod fractures in patients with ASD are currently unclear.Methods: We retrospectively reviewed the medical records of 404 patients who underwent corrective fusion surgery for ASD with a minimum 2-year follow-up. We studied cases of reoperation for postoperative rod fractures and investigated surgical procedure, intraoperative findings, clinical course, and rod refracture following revision surgery.Results: Rod fracture was observed in 88 patients (21.8%). Fifty-three patients (average age, 68.3 years; average blood loss, 502.2 mL [% estimated blood volume=16.4%]; and operation time, 203.3 minutes) who suffered from a rod fracture at an average of 28.3 months after the primary operation underwent reoperation. Surgical invasiveness had no significant differences in total or partial rod replacement; however, the procedures with and without an anterior bone graft significantly differed. The replaced rod refractured at an average of 35.3 months after the revision surgery of five patients. The rod also refractured at a level outside multiple rods in two patients and with traumatic episodes in three patients. Three patients had bone grafts in the anterior column.Conclusions: Revision surgery involving a multirod with a posterior-only approach for a rod fracture that occurred after ASD was performed successfully. Bone grafting in the anterior column is unnecessary for patients without massive bone defects.

Change in Line of Sight after Corrective Surgery of Adult Spinal Deformity Patients: A 2-Year Follow-up

Magcalas Ken Jeffrey,Oe Shin,Yamato Yu,Hasegawa Tomohiko,Yoshida Go,Banno Tomohiro,Arima Hideyuki,Mihara Yuki,Ushirozako Hiroki,Yamada Tomohiro,Ide Koichiro,Watanabe Yuh,Matsuyama Yukihiro 대한척추외과학회 2023 Asian Spine Journal Vol.17 No.2

Study Design: Cohort study.Purpose: There is currently no published study that focuses on the spinal corrective surgery effects with cranial parameters in adult spinal deformity (ASD) patients. It is an important factor to measure since it plays a critical role in maintaining the line of sight. The objective is to determine the change in cranial parameters using the slope of McGregor’s line (McGS) after ASD surgery after 2 years of follow-up.Overview of Literature: A study concluded that cervical spine alignment (C2–C7 lordosis) is strongly affected by thoracic kyphosis (TK). Another study showed that patients with ascending gaze had significantly more thoracolumbar malalignment.Methods: This retrospective study includes 295 corrective surgery patients with ASD. Subjects were divided into two groups after propensity age matching analysis: cranial malalignment (McGS <−8 or >13) and normal cranial alignment (−8≤ McGS ≤13). Lumbar lordosis (LL), pelvic tilt (PT), TK, cervical lordosis (CL), and sagittal vertical axis (SVA) were evaluated between the two groups.Results: SVA (95–56 mm) and PT (34°–25°) decreased and LL (19°–41°) increased 2 years after surgery (p <0.05), but McGS (−1.1° to −0.5°) and CL (21°–19°) did not change. Conversely, in the group with cranial malalignment, SVA (120–64 mm), PT (35°–26°), and LL (12°–41°) showed similar results to the normal cranial parameter group 2 years after surgery, but in contrast, McGS (−13° to −2°) and CL (24°–18°) improved significantly.Conclusions: Severe ASD adversely affects to maintain horizontal gaze but can be improved by spinal corrective surgery.

Association between Pelvic Parameters and Vaginal Delivery

Yamada Tomohiro,Yamato Yu,Hasegawa Tomohiko,Yoshida Go,Yasuda Tatsuya,Banno Tomohiro,Arima Hideyuki,Oe Shin,Mihara Yuki,Ushirozako Hiroki,Ide Koichiro,Watanabe Yuh,Hosino Hironobu,Matsuyama Yukihiro 대한척추외과학회 2022 Asian Spine Journal Vol.16 No.2

Study Design: Cross-sectional study. Purpose: To investigate the association between vaginal delivery and pelvic parameters and clarify the effect of parity on parameter fluctuations. Overview of Literature: During vaginal delivery, the sacroiliac joint widens and the sacrum nutates (nods). However, the association between these pelvic parameters and parity is unknown. Methods: As part of a 2016 health screening, 320 female volunteers underwent whole-spine radiographs. Age-matched healthy women were grouped according to the number of vaginal deliveries (0, 1–2, or ≥3). Demographic variables and spinopelvic parameters were compared among the three groups. Results: Of the 320 volunteers, 213 were enrolled (mean age, 71.1±7.2 years). The mean number of vaginal deliveries was 2.2. The average pelvic incidence (PI) was 55.6°±11.1° and was significantly higher in the 90 women with three or more vaginal deliveries than in the other two groups (p<0.001). The average sacral slope was 33.4°±11.1° and was significantly higher in the women with three or more vaginal deliveries than in the 18 who did not deliver vaginally (p<0.001). The 105 women with one or two vaginal deliveries had significantly higher PIs and sacral slopes than did those who did not deliver vaginally (p<0.001). Conclusions: This is the first study documenting an association between vaginal delivery and pelvic parameters. Bony birth canal realignment during vaginal delivery can affect postnatal PI. Our study helps in understanding the PI changes over a woman’s life span.

Minimum Clinically Important Differences in Oswestry Disability Index Domains and Their Impact on Adult Spinal Deformity Surgery

Go Yoshida,Tomohiko Hasegawa,Yu Yamato,,Sho Kobayashi,Oe Shin,Tomohiro Banno,Yuuki Mihara,Hideyuki Arima,Hiroki Ushirozako,Tatsuya Yasuda,Daisuke Togawa,Yukihiro Matsuyama 대한척추외과학회 2019 Asian Spine Journal Vol.13 No.1

Study Design: Retrospective study. Purpose: To calculate the minimum clinically important difference (MCID) for total and individual domains of the Oswestry Disability Index (ODI) and assess score distribution and changes over time in surgically treated adult spinal deformity (ASD) patients. Overview of Literature: Despite the common use of ODI for assessing ASD, there are no robust studies defining MCID values for this index. Methods: This study included 240 consecutive ASD patients with a minimum of 2 years of follow-up. We calculated MCID values for total and individual ODI domains using all or part of the Scoliosis Research Society-22R questionnaire as anchors. Using current MCID values, we measured the acquisition rates in patients who acquired MCID at follow-up in both total and individual ODI domains. Differences in pathology, age, and locations of the upper and lower instrumented vertebrae were analyzed. Results: MCID of the total ODI score was 11%, with an area under the curve of 0.737. Each domain ranged from 0 to 2, with 1 being the most common value. In the pain and standing domains, >60% of the patients acquired MCID, although acquisition rates of the personal care, lifting, sleep, and sexual activity domains were relatively low (20%–35%). Patients with MCID had more radiographic improvement in lumbar lordosis, sagittal vertical axis, and T1 pelvic angle than those without MCID (p <0.05). Conclusions: To our knowledge, this is the first study to describe MCID of ODI (11%) after ASD surgery. In the pain and standing domains, most patients acquired MCID although the rates of acquisition of MCID in the personal care, lifting, sleep, and sexual activity domains were low. Spine surgeons should counsel their patients regarding the benefits and setbacks of ASD surgery.

Multi-Rod Constructs Can Increase the Incidence of Iliac Screw Loosening after Surgery for Adult Spinal Deformity

Tomohiro Banno,Tomohiko Hasegawa,Yu Yamato,Daisuke Togawa,Go Yoshida,Sho Kobayashi,Tatsuya Yasuda,Hideyuki Arima,Shin Oe,Yuki Mihara,Hiroki Ushirozako,Yukihiro Matsuyama 대한척추외과학회 2019 Asian Spine Journal Vol.13 No.3

Study Design: A retrospective study. Purpose: To investigate the incidence of iliac screw loosening with a two-rod vs. multi-rod construct and the effect on clinical and radiographic outcomes after surgery for adult spinal deformity (ASD). Overview of Literature: Multi-rod construct is useful for preventing rod fracture in ASD surgery. However, limited information is available regarding the incidence of iliac screw loosening after corrective fusion surgery using a multi-rod construct. Methods: Total 106 patients with ASD (24 men and 82 women; mean age, 68 years) who underwent corrective fusion surgery using bilateral iliac screws and were followed up for at least 1 year were reviewed. The following variables were compared between patients who underwent surgery with a two-rod and multi-rod construct: age, sex, bone mineral density (BMD), fusion level, high-grade osteotomy, L5/S interbody fusion, screw loosening (upper instrumented vertebra [UIV], S1, and iliac), rod fracture, proximal junctional kyphosis, spinopelvic parameters, and Oswestry Disability Index (ODI) score. We also compared patients with and without iliac screw loosening in the multi-rod construct group. Results: Of the 106 patients, 55 underwent surgery with a conventional two-rod construct and 51 with a multi-rod construct (three rods in 16, four rods in 35). Iliac and UIV screw loosening was observed in 24 patients (21%) and 35 patients (33%), respectively. The multi-rod group showed significantly higher incidence of iliac and UIV screw loosening and lower incidence of rod fracture. Patients with iliac screw loosening had a lower BMD than those without screw loosening; however, no significant differences were observed in the spinopelvic parameters or the ODI score. Conclusions: The use of multi-rod constructs led to a higher incidence of junctional screw loosening than the use of conventional two-rod constructs, especially in patients with osteoporosis. Iliac screw loosening did not affect sagittal alignment or clinical outcome in the short term.