Temporal dynamics of gait function in acute cervical spinal cord injury.

BACKGROUND: Following spinal cord injury (SCI), gait function reaches a post-recovery plateau that depends on the paralysis severity. However, the plateau dynamics during the recovery period are not known. This study aimed to examine the gait function temporal dynamics after traumatic cervical SCI (CSCI) based on paralysis severity. METHODS: This retrospective cohort study included 122 patients with traumatic CSCI admitted to a single specialized facility within 2 weeks after injury. The Walking Index for Spinal Cord Injury II (WISCI II) was estimated at 2 weeks and 2, 4, 6, and 8 months postinjury for each American Spinal Injury Association Impairment Scale (AIS) grade, as determined 2 weeks postinjury. Statistical analysis was performed at 2 weeks to 2 months, 2-4 months, 4-6 months, and 6-8 months, and the time at which no significant difference was observed was considered the time at which the gait function reached a plateau. RESULTS: In the AIS grade A and B groups, no significant differences were observed at any time point, while in the AIS grade C group, the mean WISCI II values continued to significantly increase up to 6 months. In the AIS grade D group, the improvement in gait function was significant during the entire observation period. CONCLUSIONS: The plateau in gait function recovery was reached at 2 weeks postinjury in the AIS grade A and B groups and at 6 months in the AIS grade C group.

Randomized double-blind placebo-controlled trial of hydrogen inhalation for Parkinson's disease: a pilot study.

BACKGROUND: Oxidative stress is involved in the progression of Parkinson's disease (PD). Recent studies have confirmed that molecular hydrogen (H2) functions as a highly effective antioxidant in animal models of PD. A placebo-controlled, randomized, double-blind, parallel-group clinical pilot study was conducted to assess the efficacy of hydrogen gas inhalation in Japanese patients with PD on treatment with levodopa. METHODS: Twenty participants fulfilling the Movement Disorder Society criteria were enrolled. Participants inhaled 6.5 (0.1) vol% hydrogen gas in 2 L/min of mixed air or placebo air for 16 weeks, twice a day for 1 h. RESULTS: Five participants were excluded due to deviation from the protocol of the total duration of inhalation < 112 h. No significant differences were seen in the change in the total Movement Disorder Society Unified Parkinson's Disease Rating Scale score from baseline to the 16th week between the group that inhaled hydrogen gas and the group that inhaled placebo air (Mann-Whitney U test, p > 0.05). No adverse events were seen. The compliance to the protocol-based duration of inhalation time in all participants decreased with the elderly participants, the higher daily dose of levodopa, and the higher PDQ-39 items on emotions (n = 20, p < 0.05). CONCLUSION: This pilot study revealed that the inhalation of molecular hydrogen gas was safe, but did not show any beneficial effects in patients with PD. TRIAL REGISTRATION: UMIN ID: 000,039,217 (October 6, 2018).

The time course of dysphagia following traumatic cervical spinal cord injury: a prospective cohort study.

STUDY DESIGN: Prospective cohort study. OBJECTIVES: To elucidate serial changes in dysphagia and elucidate the critical period for dysphagia following acute traumatic cervical spinal cord injury (CSCI). SETTING: Spinal Injuries Center, Fukuoka, Japan. METHODS: We prospectively examined individuals with acute traumatic CSCI admitted within 2 weeks after injury. Severity of dysphagia was evaluated using both the dysphagia severity scale (DSS) and functional oral intake scale (FOIS) at 2 weeks, 1 month, 2 months, and 3 months after injury. Condition of oral intake before injury was assessed by history taking. American Spinal Injury Association (ASIA) impairment scale grade and motor scores were also assessed at the same timepoints, and the correlation between dysphagia and paresis was analyzed. RESULTS: Sixty-five individuals with CSCI were assessed consecutively for 3 months after injury. Swallowing function, evaluated using both the DSS and FOIS, was significantly decreased at 2 weeks after injury, but significantly improved thereafter. Significant correlations between severity of dysphagia (DSS and FOIS scores) and motor scores were found at 2 weeks after injury (rs = 0.66 and 0.61; p < 0.001 and p < 0.001, respectively), indicating that individuals with lower motor scores had more severe swallowing dysfunction. CONCLUSIONS: Dysphagia occurred immediately after injury, but gradually improved over time. Individuals with more severe paralysis had significantly more severe dysphagia. Special attention for dysphagia should be paid to individuals with severe paralysis in acute phase.

A prediction model of functional outcome at 6 months using clinical findings of a person with traumatic spinal cord injury at 1 month after injury.

STUDY DESIGN: Retrospective statistical analysis of database. OBJECTIVES: Prediction of the Spinal Cord Independence Measure version III Total Score (SCIM-TS) at 6 months after injury based on physical findings at 1 month after injury is an important index for rehabilitation approach in the recovery phase. SETTING: Spinal Injuries Center, Fukuoka, Japan. METHODS: The study participants were selected from patients with traumatic spinal cord injuries who were registered in the Japan Single Center Study for Spinal Cord Injury Data Base (JSSCI-DB) of the Japan Spinal Injuries Center specializing in spine and spinal cord injuries. Of the 534 participants registered with the JSSCI-DB between January 2012 and October 2018, we retrospectively extracted 137 participants for 6 months after injury, and these participants were included in this study. RESULTS: According to multiple regression analysis, SCIM-TS at 6 months after injury could be predicted based on only six variables, i.e., age at injury, three key muscles (C6 wrist extensors, C8 finger flexors, and L3 knee extensors), and two mobility assessments (WISCI and SCIM-item13) (Adjusted R-Squared: 0.83). These six independent variables were significant factors reflecting SCIM-TS at 6 months. CONCLUSIONS: In rehabilitation after traumatic spinal cord injuries, a simple and reliable prognostic model can help accurately predict the achievable activity of daily living competency to set a goal. In addition, if the procedure is simple, evaluation can be completed in a short period of time, and the physical burden on both treating staff and patients can be reduced.

How much time is necessary to confirm the diagnosis of permanent complete cervical spinal cord injury?

STUDY DESIGN: Retrospective chart audits. OBJECTIVE: To investigate the optimal timing at which permanent complete cervical spinal cord injury (CSCI) can be confirmed when evaluating paralysis caused by traumatic CSCI. SETTING: Department of Orthopedic Surgery, Spinal Injuries Center, Japan. METHODS: Two-hundred and three patients with CSCI that was classified with an American Spinal Injury Association (ASIA) Impairment Scale (AIS) grade A (AIS A) within 72 h of the initial diagnosis of traumatic CSCI were included in the present study. Neurological data from the time of the initial diagnosis to 1 year after the injury were extracted. The number of those with recovery from AIS A and changes of AIS in the recovery were examined. RESULTS: Thirty-five of 203 (17%) patients whose injuries were initially classified with an AIS A showed recovery from AIS A. Thirty-four of 35 (97%) patients showed recovery from AIS A within 8 weeks after injury. CONCLUSION: If CSCI patients with AIS A have not recovered by 8 weeks, the likelihood that they will recover from AIS A is marginal. However, this conversely means that we must consider the possibility that a patient with a traumatic CSCI classified with an AIS A may still show recovery from AIS A within the first 8 weeks after injury.

The EQ-5D-5L in patients admitted to a hospital in Japan with recent spinal cord injury: a descriptive study.

STUDY DESIGN: Descriptive study. OBJECTIVE: To demonstrate Euro Quality of Life 5-dimensional 5-level (EQ-5D-5L) by severity level at the acute stage and discharge in patients with traumatic spinal cord injury (SCI). SETTING: Spinal Injuries Center, Fukuoka, Japan. METHODS: Patients with traumatic SCI who completed the EQ-5D-5L instrument at the acute stage and discharge were divided into four groups according to severity (severity group G1; C1-C4 ASIA Impairment Scale (AIS) A, B, and C, G2; C5-C8 AIS A, B, and C, G3; T1-S5 AIS A, B, and C, G4; all AIS D). All data were extracted from the Japan single-center study for spinal cord injury database (JSSCI-DB). RESULTS: Data were collected from 139 individuals at the acute stage and 164 individuals at discharge. In the comparison of utility score by severity in acute stage and discharge, G3 was significantly higher in discharge (0.325 versus 0.580). Utility scores by degree of severity were significantly higher in group G4 than those of G1, G2, and G3 at the acute stage. Utility scores at discharge were significantly higher in groups G3 and G4 than in G1, and there was a significant difference between groups G4 and G2. CONCLUSIONS: At each stage, the utility scores of group G4 were significantly higher than those of groups G1 and G2. Altogether, the utility scores for hospitalized patients with traumatic SCI that were indicated in this study will serve as basic data that can be used while performing spinal regeneration medical procedures in the future.

The dosage and administration of long-term intrathecal baclofen therapy for severe spasticity of spinal origin.

STUDY DESIGN: Retrospective chart audit. OBJECTIVE: To indicate the appropriate baclofen dosage to control severe spasticity of spinal origin and to develop the optimal administration protocol for long-term intrathecal baclofen (ITB) therapy. SETTING: Department of Orthopaedic Surgery, Spinal Injuries Center, Japan. METHODS: Thirty-four people with spasticity of various spinal origins who were consistently treated at our hospital were included. The median follow-up period was 6 years and 11 months. Measures of Ashworth score were taken before and after surgical implant of baclofen pump. We decided not to increase the baclofen dosage after the Ashworth score reached 1. We recorded the control of spasticity, changes in the baclofen dose, and the incidence of complications. RESULTS: The average Ashworth score was 3.31 (1.75-4.0) before implant surgery, 1.38 (1.0-2.25) after implant surgery, and 1.39 (1.0-2.25) at the final follow-up, while the average baclofen dose (therapeutic/optimal dose) was 230.6 µg/day (50-450). The incidence of each complication was as follows: 8.8% (n = 3) catheter-related, 2.9% (n = 1) pump-related and 5.9% (n = 2) drug tolerance. No patients experienced withdrawal syndrome. Dose fluctuation with changes in the pathology of the original disease was observed in three cases. CONCLUSIONS: The usage of the Ashworth score as a guide for dose adjustment was found to be a good objective indicator for ITB therapy. The administration based on this objective indicator made it possible to effectively manage patients with a relatively low dose of baclofen and a low rate of drug-related complications.

Effect of Modic changes on spinal canal stenosis and segmental motion in cervical spine.

PURPOSE: Few studies have reported the characteristics of Modic changes (MCs) in the cervical spine in contrast to the lumbar spine. The purpose of this study was to identify the prevalence of MCs in the cervical spine and to elucidate the relationship of MCs with spinal canal stenosis and angular motion. METHODS: 437 consecutive, symptomatic patients with neck pain with or without neurogenic symptoms were included in this study. MRI in multiple positions was performed with dynamic motion of the cervical spine in upright, weight-bearing neutral, flexion and extension positions. Type of MC, intervertebral disc degeneration grade, spinal cord compression grade and sagittal angular motion between flexion and extension for each segment from C2-3 to C6-7 were evaluated. RESULTS: MCs were observed in 84 out of 437 patients (19.2%) and in 109 out of 2,185 motion segments (5.0%) with type 2 changes predominating. Disc degeneration grades and spinal cord compression grades of segments with MCs were significantly higher than those without MCs. Sagittal angular motion of segments with MCs were significantly lower than those without MCs. Multiple logistic regression analysis revealed that significantly elevated odds ratios for MCs were observed in segments with severe disc degeneration, severe spinal canal compression and less angular motion. CONCLUSION: The cervical segments with MCs were significantly more likely to have disc degeneration and spinal canal stenosis. In addition, the segments with MCs had significantly less angular motion, which suggests MCs may correlate with loss of mobility.

[Team-Based Clinical Laboratory Testing in Nephrology and Urology--Chairmen's Introductory Remarks].

Recently, the Department of Clinical Examination has been extensively subdivided. When we perform examinations, we often require wide knowledge of other specialized fields. This symposium was planned to consider the procedure for examinations in the kidney urology field. Seven professionals gave lectures on the interpretation and adequacy of examinations involving the kidney urology field. Knowledge of not only specialized fields but also wide, basic, routine fields is required to perform more precise examinations. Therefore, we became aware that cooperation between examination departments is essential to improve our overall judgments.

Hypoperfusion in Supramarginal and Orbital Gyrus, Position Discrimination Test, and Microsaccades as a Predictor of Pisa Syndrome in Parkinson's Disease.

Patients with Parkinson's disease (PD) experience significantly reduced quality of life when PD is complicated with Pisa syndrome (PS). PS is a postural abnormality associated with a lateral bending of the trunk, causing the patient to lean to one side. Microsaccades during fixation are transmitted to the visual cortex, and this gaze movement may be impaired in PD. We aimed to detect presymptomatic signs of PS. We enrolled 50 patients with PD without dementia and investigated the visual systems in patients with concurrent PD and PS based on a Romberg ratio of<1.0. Gaze analysis, pupil diameter, stabilization tests, neuropsychological tests, and cerebral perfusion scintigraphy were reviewed and statistically analyzed. Two years later, we divided the patients into three groups as follows: PISA++ (patients who had PS at enrollment), PISA-+ (patients without PS that developed PS during the 2-year period), and PISA-- (patients without PS that did not develop PS during the 2-year period). The PISA-+ group exhibited a significantly higher daily levodopa dose and longer fixations, as well as lower position discrimination, Wechsler Adult Intelligence Scale-Third Edition blocking, and blood flow in the left supramarginal and orbital gyri than that in the PISA-- group. The PISA++ group showed a significantly longer fixation time and lower Mini-Mental State Examination score, Romberg ratio of area, amplitude, velocity of microsaccades, and blood flow in the left precuneus and cuneus than that in the PISA-+ group. Before the onset of PS, hypoperfusion occurred in the correlative visual cortex and the position discrimination test. Patients with PS have reduced saccades and slow microsaccades.

Erratum for Factors Affecting Home Discharge of Older Adults with Cervical Spinal Cord Injury in Japan Regional Population.

[This corrects the article DOI: 10.22603/ssrr.2023-0045.].

Effect of nutritional status on occurrence of pneumonia after traumatic cervical spinal cord injury.

Pneumonia after cervical spinal cord injury (CSCI) is a common and serious complication; however, its nutrition-related etiology has not yet been elucidated. This study aimed to elucidate the effects of nutritional factors on pneumonia after CSCI. Patients with acute traumatic CSCI who were admitted within 3 days after injury and followed up for at least 3 months were retrospectively examined. Occurrence of pneumonia, nutritional status, severity of dysphagia, vital capacity, use of respirators, and motor scores for paralysis were evaluated. Of 182 patients included in this study, 33 (18%) developed pneumonia. Multiple logistic regression analysis revealed that low nutritional status, severe paralysis, and low vital capacity were significant risk factors for pneumonia. The severity of paralysis, respiratory dysfunction, and poor nutritional status can affect the occurrence of pneumonia after CSCI. In addition to respiratory management, nutritional assessment and intervention may play key roles in preventing pneumonia associated with spinal cord injury-induced immune depression. Nutritional care should be provided as soon as possible when the nutritional status of a patient worsens after an injury.

Impact of the width and shape of the sliding board on design evaluation.

This study aimed to investigate how width affects the design evaluation of sliding boards with a new shape. Ten caregivers at a senior facility evaluated five types of boards every two weeks. The new shape board received high ratings as the width increased, with a SUS (System Usability Scale) score of 68.5 points (95% CI 60.6-76.4). Compared to the traditional rectangular board, which had a width of 250 mm and a thickness of 5 mm, the new shape board (with a central width of 163 mm and a thickness of 8 mm) received higher ratings by 0.68 points (95% CI 0.31-1.05)using a paired comparison method. The results of a quantitative study on the usability of sliding boards from the perspective of caregivers indicated that for similar board shapes with a length of 650 mm and a thickness of 8 mm, the evaluation increases as the width increases in the range of 130 mm to 163 mm at the center.

Halo vest fixation effectively maintains cervical alignment through intraoperative repositioning in patients with cervical spine instability.

Introduction: The objective of this study was to examine if halo vest fixation provides sufficient stabilization of cervical spine alignment to endorse its use through intraoperative positional changes in patients with cervical spine instability. Methods: The subjects of this study were 14 patients with cervical spine instability who were immobilized in halo vests until they underwent subsequent internal fixation surgery. After induction of anesthesia, the patients in halo vests were repositioned from the supine position to the prone position. The halo ring was fixed to the surgical table and the dorsal struts and vest were removed for surgery. Radiographs obtained in the preoperative sitting position and intraoperative prone position were compared for the following measures of cervical alignment: O-C2 angle, C2-C6 angle, pharyngeal inlet angle (PIA), atlantodental interval (ADI), Redlund-Johnell (R-J) value as a measure of O-C2 length, O-C6 length, and O-C2 length/O-C6 length (%). Results: There were no significant differences in O-C2 angle, C2-C6 angle, PIA, ADI, or O-C2 length/O-C6 length (%). However, the R-J value and O-C6 length were significantly higher in the intraoperative prone position than in the preoperative sitting position. None of the patients presented with any complications, including dysphagia or neurological deterioration. Conclusions: Our results suggest that when patients are repositioned to the prone position while immobilized in halo vests, the cervical spine is distracted in the cephalocaudal direction across all cervical segments but the cervical alignment is sufficiently maintained. Halo vests are a highly effective external fixation method for patients with cervical spine instability, allowing for a safe repositioning to the prone position for surgery while preserving cervical alignment and preventing neurological deterioration.

Verification of the Accuracy of Cervical Spinal Cord Injury Prognosis Prediction Using Clinical Data-Based Artificial Neural Networks.

BACKGROUND: In patients with cervical spinal cord injury (SCI), we need to make accurate prognostic predictions in the acute phase for more effective rehabilitation. We hypothesized that a multivariate prognosis would be useful for patients with cervical SCI. METHODS: We made two predictive models using Multiple Linear Regression (MLR) and Artificial Neural Networks (ANNs). We adopted MLR as a conventional predictive model. Both models were created using the same 20 clinical parameters of the acute phase data at the time of admission. The prediction results were classified by the ASIA Impairment Scale. The training data consisted of 60 cases, and prognosis prediction was performed for 20 future cases (test cohort). All patients were treated in the Spinal Injuries Center (SIC) in Fukuoka, Japan. RESULTS: A total of 16 out of 20 cases were predictable. The correct answer rate of MLR was 31.3%, while the rate of ANNs was 75.0% (number of correct answers: 12). CONCLUSION: We were able to predict the prognosis of patients with cervical SCI from acute clinical data using ANNs. Performing effective rehabilitation based on this prediction will improve the patient's quality of life after discharge. Although there is room for improvement, ANNs are useful as a prognostic tool for patients with cervical SCI.

Changing trends in traumatic spinal cord injury in an aging society: Epidemiology of 1152 cases over 15 years from a single center in Japan.

Traumatic spinal cord injury (TSCI) causes an insult to the central nervous system, often resulting in devastating temporary or permanent neurological impairment and disability, which places a substantial financial burden on the health-care system. This study aimed to clarify the up-to-date epidemiology and demographics of patients with TSCI treated at the largest SCI center in Japan. Data on all patients admitted to the Spinal Injuries Center with TSCI between May 2005 and December 2021 were prospectively collected using a customized, locally designed SCI database named the Japan Single Center Study for Spinal Cord Injury Database (JSSCI-DB). A total of 1152 patients were identified from the database. The study period was divided into the four- or five-year periods of 2005-2009, 2010-2013, 2014-2017, and 2018-2021 to facilitate the observation of general trends over time. Our results revealed a statistically significant increasing trend in age at injury. Since 2014, the average age of injury has increased to exceed 60 years. The most frequent spinal level affected by the injury was high cervical (C1-C4: 45.8%), followed by low cervical (C5-C8: 26.4%). Incomplete tetraplegia was the most common cause or etiology category of TSCI, accounting for 48.4% of cases. As the number of injuries among the elderly has increased, the injury mechanisms have shifted from high-fall trauma and traffic accidents to falls on level surfaces and downstairs. Incomplete tetraplegia in the elderly due to upper cervical TSCI has also increased over time. The percentage of injured patients with an etiology linked to alcohol use ranged from 13.2% (2005-2008) to 19% (2014-2017). Given that Japan has one of the highest aging populations in the world, epidemiological studies in this country will be very helpful in determining health insurance and medical costs and deciding strategies for the prevention and treatment of TSCI in future aging populations worldwide.

Factors Affecting Home Discharge of Older Adults with Cervical Spinal Cord Injury in Japan Regional Population.

Introduction: Older adults with cervical spinal cord injury (CSCI) often have a poor prognosis due to the high number of complications, decreased motivation to rehabilitation, and poor response to treatment. This study aimed to investigate the characteristics of CSCI in Japanese older adults and examined the factors influencing their discharge home. Methods: In this retrospective cohort study, we extracted data on consecutive cases with CSCI between 2005 and 2020 from the study hospital's database. Patients over 65 years old who were admitted to the hospital within 14 days of injury were selected. A univariate analysis was performed between the home discharge and out-of-home discharge groups. In addition, binary logistic regression analysis of admission findings and patient background was performed to examine independent factors influencing home discharge. Results: Of the 219 patients included, 90 (41.1%) were eventually discharged to home. Comparing home discharge and out-of-home discharge groups revealed significant differences in age at injury, length of hospital stay, neurological level of injury (NLI), percentage of American Spinal Injury Association (ASIA) Impairment Scale (AIS: A), percentage of living alone, ASIA motor score (AMS), and Spinal Cord Independence Measure (SCIM) at initial visit and discharge. Binary logistic regression analysis revealed that old age (over 75 years old) at injury (odds ratio [OR]: 0.31, 95% CI: 0.16-0.60, P<.001), living alone (OR: 0.22, 95% CI: 0.03-0.42, P<.01), high level of injury (i.e., NLI: C1-4; OR: 0.22, 95% CI: 0.09-0.53, P<.0001), and percentage of AIS: A at admission (OR: 0.09, 95% CI: 0.04-0.24, P<.001) were independent factors that influenced home discharge. Conclusions: More than 50% older adults with CSCI were discharged to a place other than their own home. Age, percentage of AIS: A, living alone, and high level of injury at admission were independent factors that influenced home discharge.

Correlation between Respiratory Dysfunction and Dysphagia in Individuals with Acute Traumatic Cervical Spinal Cord Injury.

Introduction: Aspiration pneumonia is one of the most frequent and fatal life-threatening complications among individuals with acute traumatic cervical spinal cord injury (CSCI). However, the mechanism of dysphagia among individuals with CSCI is not well understood. Morbidity and mortality associated with CSCI may result from the interplay between respiratory dysfunction and dysphagia. This study aimed to elucidate the effect of respiratory dysfunction on the swallowing function of individuals with acute traumatic CSCI. Methods: A prospective cohort study was conducted involving 54 individuals with acute traumatic CSCI who were admitted within 2 weeks following injury. Dysphagia was evaluated using the Dysphagia Severity Scale (DSS) and the Functional Oral Intake Scale (FOIS). Respiratory function was evaluated by measuring the cough peak flow (CPF), forced expiratory volume in 1 s (FEV1.0), FEV1.0/forced vital capacity (FEV1.0%), and percent vital capacity (%VC). We recorded these parameters at weeks 2, 4, 8, and 12 following injury and analyzed pertinent changes over time and significant correlations. Results: Among 54 individuals (46 men and 8 women) recruited in this study, 48 (88.9%) had restrictive ventilatory impairment and 17 (31.5%) had severe dysphagia (DSS level 1-4) 2 weeks following injury. However, respiratory function and swallowing function significantly improved thereafter. CPF, FEV1.0, and %VC were significantly correlated with the severity of dysphagia during each period. Conclusions: Restrictive ventilatory impairment, poor cough force, and dysphagia are closely related, and the evaluation of respiratory function plays an important role in evaluating dysphagia.

Intraoperative Radiation Exposure from O-arm-based 3D Navigation in Spine Surgery.

Introduction: Intraoperative three-dimensional (3D) imaging guide technology, such as the O-arm surgical imaging system, is a beneficial tool in spinal surgery that provides real-time 3D images of a patient's spine. This study aims to determine the exposure dose from intraoperative O-arm imaging. Methods: A consecutive retrospective review of all patients undergoing spinal surgery was conducted between June 2019 and August 2022. Demographic and operative data were collected from electronic medical records. Results: Intraoperative O-arm imaging was conducted in 206 (12.9%) of 1599 patients, ranging from one to 4 scans per patient (1.17±0.43 scans). Single O-arm imaging enabled navigation of seven vertebrae in the cervical spine, seven in the thoracic spine, five in the thoracolumbar spine, and four in the lumbar spine on average. The number of O-arm shots per surgery was 1.15±0.36, 1.06±0.24, 1.61±0.7, and 1.07±0.25 for cervical, thoracic, thoracolumbar, and lumbar spinal cases, respectively. The exposure doses represented by dose length products in single O-arm imaging were 377±19 mGy-cm, 243±22 mGy-cm, 378±38 mGy-cm, and 258±11 mGy-cm for cervical, thoracic, thoracolumbar, and lumbar spine cases, respectively. We observed a weak positive correlation between the number of fused spinal levels and the exposure dose. Conclusions: Intraoperative radiation exposure from O-arm imaging was lower than the national diagnostic reference levels in Japan established based on the International Commission on Radiological Protection publication, demonstrating its safety from the standpoint of radiological protection in most cases. In surgeries with a large range of fixations, such as corrective deformity surgery, the number of imaging sessions and the amount of intraoperative radiation exposure would increase, leading surgeons to pay attention to the risk of radiation in spinal surgery.