The Accuracy of Patient-Specific Spinal Drill Guides Is Non-Inferior to Computer-Assisted Surgery: The Results of a Split-Spine Randomized Controlled Trial.

In recent years, patient-specific spinal drill guides (3DPGs) have gained widespread popularity. Several studies have shown that the accuracy of screw insertion with these guides is superior to that obtained using the freehand insertion technique, but there are no studies that make a comparison with computer-assisted surgery (CAS). The aim of this study was to determine whether the accuracy of insertion of spinal screws using 3DPGs is non-inferior to insertion via CAS. A randomized controlled split-spine study was performed in which 3DPG and CAS were randomly assigned to the left or right sides of the spines of patients undergoing fixation surgery. The 3D measured accuracy of screw insertion was the primary study outcome parameter. Sixty screws inserted in 10 patients who completed the study protocol were used for the non-inferiority analysis. The non-inferiority of 3DPG was demonstrated for entry-point accuracy, as the upper margin of the 95% CI (−1.01 mm−0.49 mm) for the difference between the means did not cross the predetermined non-inferiority margin of 1 mm (p < 0.05). We also demonstrated non-inferiority of 3D angular accuracy (p < 0.05), with a 95% CI for the true difference of −2.30°−1.35°, not crossing the predetermined non-inferiority margin of 3° (p < 0.05). The results of this randomized controlled trial (RCT) showed that 3DPGs provide a non-inferior alternative to CAS in terms of screw insertion accuracy and have considerable potential as a navigational technique in spinal fixation.

What can we learn from long-term studies on chronic low back pain? A scoping review.

PURPOSE: A scoping review was conducted with the objective to identify and map the available evidence from long-term studies on chronic non-specific low back pain (LBP), to examine how these studies are conducted, and to address potential knowledge gaps. METHOD: We searched MEDLINE and EMBASE up to march 2021, not restricted by date or language. Experimental and observational study types were included. Inclusion criteria were: participants between 18 and 65 years old with non-specific sub-acute or chronic LBP, minimum average follow-up of > 2 years, and studies had to report at least one of the following outcome measures: disability, quality of life, work participation, or health care utilization. Methodological quality was assessed using the Effective Public Health Practice Project quality assessment. Data were extracted, tabulated, and reported thematically. RESULTS: Ninety studies met the inclusion criteria. Studies examined invasive treatments (72%), conservative (21%), or a comparison of both (7%). No natural cohorts were included. Methodological quality was weak (16% of studies), moderate (63%), or strong (21%) and generally improved after 2010. Disability (92%) and pain (86%) outcomes were most commonly reported, followed by work (25%), quality of life (15%), and health care utilization (4%). Most studies reported significant improvement at long-term follow-up (median 51 months, range 26 months-18 years). Only 10 (11%) studies took more than one measurement > 2 year after baseline. CONCLUSION: Patients with persistent non-specific LBP seem to experience improvement in pain, disability and quality of life years after seeking treatment. However, it remains unclear what factors might have influenced these improvements, and whether they are treatment-related. Studies varied greatly in design, patient population, and methods of data collection. There is still little insight into the long-term natural course of LBP. Additionally, few studies perform repeated measurements during long-term follow-up or report on patient-centered outcomes other than pain or disability.

Accuracy of Patient-Specific 3D-Printed Drill Guides for Pedicle and Lateral Mass Screw Insertion: An Analysis of 76 Cervical and Thoracic Screw Trajectories.

STUDY DESIGN: Single-center retrospective case series. OBJECTIVE: The purpose of this study was to assess the safety and accuracy of three-dimensional (3D)-printed individualized drill guides for pedicle and lateral mass screw insertion in the cervical and upper-thoracic region, by comparing the preoperative 3D surgical plan with the postoperative results. SUMMARY OF BACKGROUND DATA: Posterior spinal fusion surgery can provide rigid intervertebral fixation but screw misplacement involves a high risk of neurovascular injury. However, modern spine surgeons now have tools such as virtual surgical planning and 3D-printed drill guides to facilitate spinal screw insertion. METHODS: A total of 15 patients who underwent posterior spinal fusion surgery involving patient-specific 3D-printed drill guides were included in this study. After segmentation of bone and screws, the postoperative models were superimposed onto the preoperative surgical plan. The accuracy of the realized screw trajectories was quantified by measuring the entry point and angular deviation. RESULTS: The 3D deviation analysis showed that the entry point and angular deviation over all 76 screw trajectories were 1.40 ±â€Š0.81 mm and 6.70 ±â€Š3.77°, respectively. Angular deviation was significantly higher in the sagittal plane than in the axial plane (P = 0.02). All screw positions were classified as "safe" (100%), showing no neurovascular injury, facet joint violation, or violation of the pedicle wall. CONCLUSIONS: 3D virtual planning and 3D-printed patient-specific drill guides appear to be safe and accurate for pedicle and lateral mass screw insertion in the cervical and upper-thoracic spine. The quantitative 3D deviation analyses confirmed that screw positions were accurate with respect to the 3D-surgical plan.Level of Evidence: 4.

Can We Change Health Care Costs in Patients With Complex Back Pain?: Results From a 5-year Before and After Study.

STUDY DESIGN: A before and after study cohort study. OBJECTIVES: The aim of this study was to examine changes in health care costs after multidisciplinary spine care in patients with complex chronic back pain (CBP), to analyze the predictive value of patient and disease characteristics on health care costs, and to study the potential impact of biases concerning the use of real world data. SUMMARY OF BACKGROUND DATA: Due to high direct and indirect societal costs of back pain there is a need for interventions that can assist in reducing the economic burden on patients and society. METHODS: All patients referred to a university-based spine center insured at a major health care insurer in the Netherlands were invited. Personal and disease-related data were collected at baseline. Health care costs were retrieved from the health care insurer from 2 years before to 2 years after intervention. Repeated measures analysis of variances were calculated to study changes in health care costs after intervention. Multivariable regression analyses and cluster robust fixed effect models were applied to predict characteristics on health care costs. To study regression to the mean, a fixed effect model was calculated comparing 2 years before and 2 years post-intervention. RESULTS: In total 428,158 declarations during 4.6 years were filed by 997 participants (128,666 considered CBP-related). CBP-related costs significantly increased during the intervention period and reduced 2 years after the intervention. Total health care costs kept rising. The intervention was associated with a 21% to 34% (P < 0.01) reduction in costs depending on the model used. Reduction in costs was related to being male and lower body mass index. CONCLUSION: This study suggests that reduction in CBP-related health care utilization in patients with complex CBP can be achieved after a multidisciplinary spine intervention. The results are robust to controlling for background characteristics and are unlikely to be fully driven by regression to the mean. LEVEL OF EVIDENCE: 4.

Personal and Societal Impact of Low Back Pain: The Groningen Spine Cohort.

STUDY DESIGN: Cross-sectional study. OBJECTIVE: The aim of this study was to study the personal and societal impact of low back pain (LBP) in patients admitted to a multidisciplinary spine center. SUMMARY OF BACKGROUND DATA: The socioeconomic burden of LBP is very high. A minority of patients visit secondary or tertiary care because of severe and long-lasting complaints. This subgroup may account for a major part of disability and costs, yet could potentially gain most from treatment. Currently, little is known about the personal and societal burden in patients with chronic complex LBP visiting secondary/tertiary care. METHODS: Baseline data were acquired through patient-reported questionnaires and health insurance claims. Primary outcomes were LBP impact (Impact Stratification, range 8-50), functioning (Pain Disability Index, PDI; 0-70), quality of life (EuroQol-5D, EQ5D; -0.33 to 1.00), work ability (Work Ability Score, WAS; 0-10), work participation, productivity costs (Productivity Cost Questionnaire), and healthcare costs 1 year before baseline. Healthcare costs were compared with matched primary and secondary care LBP samples. Descriptive and inferential statistics were applied. RESULTS: In total, 1502 patients (age 46.3 ±â€Š12.8 years, 57% female) were included. Impact Stratification was 35.2 ±â€Š7.5 with severe impact (≥35) for 58% of patients. PDI was 38.2 ±â€Š14.1, EQ5D 0.39 (interquartile range, IQR: 0.17-0.72); WAS 4.0 (IQR: 1.0-6.0) and 17% were permanently work-disabled. Mean total health care costs (&OV0556;4875, 95% confidence interval [CI]: 4309-5498) were higher compared to the matched primary care sample (n = 4995) (&OV0556;2365, 95% CI: 2219-2526, P < 0.001), and similar to the matched secondary care sample (n = 4993) (&OV0556;4379, 95% CI: 4180-4590). Productivity loss was estimated at &OV0556;4315 per patient (95% CI: 3898-4688) during 6 months. CONCLUSION: In patients seeking multidisciplinary spine care, the personal and societal impact of LBP is very high. Specifically, quality of life and work ability are poor and health care costs are twice as high compared to patients seeking primary LBP care. LEVEL OF EVIDENCE: 3.

Accuracy Assessment of Pedicle and Lateral Mass Screw Insertion Assisted by Customized 3D-Printed Drill Guides: A Human Cadaver Study.

BACKGROUND: Accurate cervical screw insertion is of paramount importance considering the risk of damage to adjacent vital structures. Recent research in 3-dimensional (3D) technology describes the advantage of patient-specific drill guides for accurate screw positioning, but consensus about the optimal guide design and the accuracy is lacking. OBJECTIVE: To find the optimal design and to evaluate the accuracy of individualized 3D-printed drill guides for lateral mass and pedicle screw placement in the cervical and upper thoracic spine. METHODS: Five Thiel-embalmed human cadavers were used for individualized drill-guide planning of 86 screw trajectories in the cervical and upper thoracic spine. Using 3D bone models reconstructed from acquired computed tomography scans, the drill guides were produced for both pedicle and lateral mass screw trajectories. During the study, the initial minimalistic design was refined, resulting in the advanced guide design. Screw trajectories were drilled and the realized trajectories were compared to the planned trajectories using 3D deviation analysis. RESULTS: The overall entry point and 3D angular accuracy were 0.76 ± 0.52 mm and 3.22 ± 2.34°, respectively. Average measurements for the minimalistic guides were 1.20 mm for entry points, 5.61° for the 3D angulation, 2.38° for the 2D axial angulation, and 4.80° for the 2D sagittal angulation. For the advanced guides, the respective measurements were 0.66 mm, 2.72°, 1.26°, and 2.12°, respectively. CONCLUSION: The study ultimately resulted in an advanced guide design including caudally positioned hooks, crosslink support structure, and metal inlays. The novel advanced drill guide design yields excellent drilling accuracy.

Anterior Thoracic Spinal Cord Herniation: Surgical Treatment and Postoperative Course. An Individual Participant Data Meta-Analysis of 246 Cases.

BACKGROUND: Anterior thoracic spinal cord herniation (ATSCH) is a rare cause of progressive myelopathy. Early surgery is essential, but there is no agreement about the best surgical approach. OBJECTIVE: To identify factors that determine surgical results and to find evidence for the most favorable technique to correct ATSCH. METHODS: To find relevant literature, computed databases of PubMed, EMBASE, and ISI Web of Science were searched. The study comprised case reports published between 1974 and 2018, and the data set was completed with 12 cases treated in our own institute. Patient characteristics were analyzed following the principles of an individual participant data meta-analysis. RESULTS: Brown-Séquard-like neurologic deficit before surgery was associated with postoperative motor function improvement compared with patients with paraparesis (P = 0.04). In the univariate analysis, widening of the dura defect (WDD) was more prevalent among improved patients, whereas anterior dura patch and application of intraoperative neurophysiologic monitoring were not. In the multivariate analysis, the favorable association with WDD disappeared, which is explained by the dominant influence of a Brown-Séquard-like deficit on outcome. CONCLUSIONS: In general, postoperative results after surgery for ATSCH are favorable, with a high percentage of patients experiencing postoperative improvement. Postoperative motor function improvement is more likely to occur in patients with a Brown-Séquard-like neurologic deficit. The WDD should be favored above the application of a patch as the technique of choice in surgical treatment of ATSCH.

Can Patients With Low Back Pain Be Satisfied With Less Than Expected?

STUDY DESIGN: A prospective cohort study within care as usual. OBJECTIVE: (1) To explore the psychometric properties of a baseline disability questionnaire designed to collect patients' expectation. (2) To analyze relations between satisfaction with care and treatment success in patients with chronic low back pain (CLBP). (3) To determine the chances of being satisfied with the received care in absence of treatment success. SUMMARY OF BACKGROUND DATA: There is a lack of evidence on determinants of treatment satisfaction in patients with CLBP, specifically the role of patient's expectation of disability reduction after treatment. METHODS: Treatment expectation was measured with questions inspired by the Pain Disability Index (PDI) at baseline. Treatment success was considered if disability at the end of therapy was lower than, or equal to pretreatment expectation. An exploratory factor analysis was performed on the new questionnaire. Binary logistic regression models were used to analyze how much variance of satisfaction with care was explained by treatment success, pain disability at baseline, sex, age, duration of complaints, and pain intensity. The odds ratio of being satisfied when treatment was successful was calculated. RESULTS: Six hundred nine patients were included. The factor structure of the PDI-expectancy had optimal fit with a one factor structure. There were low correlations between the expected and baseline disability, pain intensity, and duration of pain. Correlation between treatment success and satisfaction with care was low (χ = 0.13; P < 0.01). Treatment success had a low contribution to satisfaction with care. Of all participating patients, 51.4% were satisfied with care even when treatment was not successful. The odds ratio for being satisfied was 2.42 when treatment was successful compared to when treatment was not successful. CONCLUSION: The PDI-expectancy is internally consistent. Pretreatment expectation contributes uniquely but slightly to satisfaction with care; patients whose treatment was considered successful have 1.38 to 4.24 times higher chance of being satisfied at the end of treatment. Even when treatment was not successful, 51.4% of the patients with CLBP are satisfied with care. LEVEL OF EVIDENCE: 2.

Prediction of Quality of Life and Survival After Surgery for Symptomatic Spinal Metastases: A Multicenter Cohort Study to Determine Suitability for Surgical Treatment.

BACKGROUND: Surgery for symptomatic spinal metastases aims to improve quality of life, pain, function, and stability. Complications in the postoperative period are not uncommon; therefore, it is important to select appropriate patients who are likely to benefit the greatest from surgery. Previous studies have focused on predicting survival rather than quality of life after surgery. OBJECTIVE: To determine preoperative patient characteristics that predict postoperative quality of life and survival in patients who undergo surgery for spinal metastases. METHODS: In a prospective cohort study of 922 patients with spinal metastases who underwent surgery, we performed preoperative and postoperative assessment of EuroQol EQ-5D quality of life, visual analog score for pain, Karnofsky physical functioning score, complication rates, and survival. RESULTS: The primary tumor type, number of spinal metastases, and presence of visceral metastases were independent predictors of survival. Predictors of quality of life after surgery included preoperative EQ-5D (P = .002), Frankel score (P < .001), and Karnofsky Performance Status (P < .001). CONCLUSION: Data from the largest prospective surgical series of patients with symptomatic spinal metastases revealed that tumor type, the number of spinal metastases, and the presence of visceral metastases are the most useful predictors of survival and that quality of life is best predicted by preoperative Karnofsky, Frankel, and EQ-5D scores. The Karnofsky score predicts quality of life and survival and is easy to determine at the bedside, unlike the EQ-5D index. Karnofsky score, tumor type, and spinal and visceral metastases should be considered the 4 most important prognostic variables that influence patient management.

Reference Values of the Pain Disability Index in Patients With Painful Musculoskeletal and Spinal Disorders: A Cross-national Study.

STUDY DESIGN: Cross-sectional study. OBJECTIVE: To examine reference data for the Pain Disability Index (PDI) in Dutch and Canadian patient samples with a variety of musculoskeletal pain disorders and to test which potential factors are independently associated with the PDI score. SUMMARY OF BACKGROUND DATA: The PDI is a widely used generic instrument for measuring disability related to pain. It is unknown whether patients with spinal and other musculoskeletal diagnoses have different levels of disability when scored on the PDI. METHODS: Patients were referred to secondary and tertiary care centers in the Netherlands and Alberta, Canada, between 2009 and 2013. All patients filled out a baseline questionnaire including demographics and the PDI. After first consultation with a medical doctor, diagnoses were set by the medical specialist. Univariate general linear models were used to examine correlations between PDI scores and age, sex, country of residence, diagnosis, and work status. RESULTS: In total 6997 patients were included in this study: 1302 Canadian and 5695 Dutch patients. Mean PDI score of the total group was 37.8 ± 14.2. Reference values are presented and clustered into the following diagnostic groups: spinal nerve and intervertebral disc disorders; nonspecific back pain; rheumatic soft-tissue pain (widespread pain or fibromyalgia); spinal stenosis; and whiplash-associated disorder. The PDI score was significantly and relevantly associated with pain intensity (η explained variance from 20% to 25%), but not relevantly associated with age, sex, country of residence, and diagnostic group (η<3%). In the working subgroup, adding "current sick leave" as covariate increased the explained variance to 34%. CONCLUSION: Reference values of the PDI are presented. Patient ratings of disability on the PDI are relevantly associated with pain intensity and work status, but not with nationality or diagnostic group. Only minimal differences were identified between the various musculoskeletal diagnoses included. LEVEL OF EVIDENCE: N/A.

Surgery on spinal epidural metastases (SEM) in renal cell carcinoma: a plea for a new paradigm.

BACKGROUND CONTEXT: Prediction models for outcome of decompressive surgical resection of spinal epidural metastases (SEM) have in common that they have been developed for all types of SEM, irrespective of the type of primary tumor. It is our experience in clinical practice, however, that these models often fail to accurately predict outcome in the individual patient. PURPOSE: To investigate whether decision making could be optimized by applying tumor-specific prediction models. For the proof of concept, we analyzed patients with SEM from renal cell carcinoma that we have operated on. STUDY DESIGN/SETTING: Retrospective chart analysis 2006 to 2012. PATIENT SAMPLE: Twenty-one consecutive patients with symptomatic SEM of renal cell carcinoma. OUTCOME MEASURES: Predictive factors for survival. METHODS: Next to established predictive factors for survival, we analyzed the predictive value of the Motzer criteria in these patients. The Motzer criteria comprise a specific and validated risk model for survival in patients with renal cell carcinoma. RESULTS: After multivariable analysis, only Motzer intermediate (hazard ratio [HR] 17.4, 95% confidence interval [CI] 1.82-166, p=.01) and high risk (HR 39.3, 95% CI 3.10-499, p=.005) turned out to be significantly associated with survival in patients with renal cell carcinoma that we have operated on. CONCLUSIONS: In this study, we have demonstrated that decision making could have been optimized by implementing the Motzer criteria next to established prediction models. We, therefore, suggest that in future, in patients with SEM from renal cell carcinoma, the Motzer criteria are also taken into account.

Extensive validation of the pain disability index in 3 groups of patients with musculoskeletal pain.

STUDY DESIGN: A cross-sectional study design was performed. OBJECTIVE: To validate the pain disability index (PDI) extensively in 3 groups of patients with musculoskeletal pain. SUMMARY OF BACKGROUND DATA: The PDI is a widely used and studied instrument for disability related to various pain syndromes, although there is conflicting evidence concerning factor structure, test-retest reliability, and missing items. Additionally, an official translation of the Dutch language version has never been performed. METHODS: For reliability, internal consistency, factor structure, test-retest reliability and measurement error were calculated. Validity was tested with hypothesized correlations with pain intensity, kinesiophobia, Rand-36 subscales, Depression, Roland-Morris Disability Questionnaire, Quality of Life, and Work Status. Structural validity was tested with independent backward translation and approval from the original authors. RESULTS: One hundred seventy-eight patients with acute back pain, 425 patients with chronic low back pain and 365 with widespread pain were included. Internal consistency of the PDI was good. One factor was identified with factor analyses. Test-retest reliability was good for the PDI (intraclass correlation coefficient, 0.76). Standard error of measurement was 6.5 points and smallest detectable change was 17.9 points. Little correlations between the PDI were observed with kinesiophobia and depression, fair correlations with pain intensity, work status, and vitality and moderate correlations with the Rand-36 subscales and the Roland-Morris Disability Questionnaire. CONCLUSION: The PDI-Dutch language version is internally consistent as a 1-factor structure, and test-retest reliable. Missing items seem high in sexual and professional items. Using the PDI as a 2-factor questionnaire has no additional value and is unreliable.

Design of COSMIC: a randomized, multi-centre controlled trial comparing conservative or early surgical management of incomplete cervical cord syndrome without spinal instability.

BACKGROUND: Incomplete cervical cord syndrome without spinal instability is a very devastating event for the patient and the family. It is estimated that up to 25% of all traumatic spinal cord lesions belong to this category. The treatment for this type of spinal cord lesion is still subject of discussion. From a biological point of view early surgery could prevent secondary damage due to ongoing compression of the already damaged spinal cord. Historically, however, conservative treatment was propagated with good clinical results. Proponents for early surgery as well those favoring conservative treatment are still in debate. The proposed trial will contribute to the discussion and hopefully also to a decrease in the variability of clinical practice. METHODS/DESIGN: A randomized controlled trial is designed to compare the clinical outcome of early surgical strategy versus a conservative approach. The primary outcome is clinical outcome according to mJOA. This also measured by ASIA score, DASH score and SCIM III score. Other endpoints are duration of the stay at a high care department (medium care, intensive care), duration of the stay at the hospital, complication rate, mortality rate, sort of rehabilitation, and quality of life. A sample size of 36 patients per group was calculated to reach a power of 95%. The data will be analyzed as intention-to-treat at regular intervals, but the end evaluation will take place at two years post-injury. DISCUSSION: At the end of the study, clinical outcomes between treatments attitudes can be compared. Efficacy, but also efficiency can be determined. A goal of the study is to determine which treatment will result in the best quality of life for the patients. This study will certainly contribute to more uniformity of treatment offered to patients with a special sort of spinal cord injury. TRIAL REGISTRATION: Gov: NCT01367405.

Clinimetric properties of the EuroQol-5D in patients with chronic low back pain.

BACKGROUND CONTEXT: Clinimetric properties of the EuroQol-5D (EQ-5D) in patients with nonspecific chronic low back pain (CLBP) are largely unknown. PURPOSE: To study the criterion validity, responsiveness, and minimal clinically important change (MCIC) of EQ-5D in patients with CLBP. STUDY DESIGN: Prospective study design carried out in a multispecialist Spine Center in The Netherlands. PATIENT SAMPLE: One hundred fifty-one patients with CLBP. OUTCOME MEASURES: Quality of life (QOL) was measured with EQ-5D, consisting of two scales: one scale measuring QOL with five categorical questions and the other measuring health state on a visual analog scale (0-100). Criterion measures were disability, measured with the Pain Disability Index (PDI) and the Roland Morris Disability Questionnaire (RMDQ), and pain intensity, measured with a numeric rating scale (NRS). METHODS: Pearson correlation coefficients between the EQ-5D and RMDQ, PDI, and NRS were calculated to test the criterion validity. Correlations were interpreted based on predefined criteria. Responsiveness of the EQ-5D was calculated with area under the receiver operating characteristics (ROC) curve. Minimal clinically important change was calculated with the optimal cutoff point under the ROC curve, and sensitivity and specificity were also calculated. RESULTS: Correlations between EQ-5D and criterion measures ranged between 0.39 and 0.59 and were considered moderate to good. Areas under the ROC curve ranged from 0.59 to 0.72 depending on the external criterion and EQ-5D subscale. The MCIC was 0.03 points for the categorical scales of the EQ-5D and 10.5 points for the EQ-5D visual analog scale. CONCLUSIONS: The EQ-5D is a valid and responsive QOL scale in patients with CLBP.

Posterior transdural discectomy: a new approach for the removal of a central thoracic disc herniation.

BACKGROUND: The optimal surgical approach for thoracic disc herniation remains a matter of debate, especially for central disc herniation. In this paper, we present a new technique to remove central thoracic disc herniation, the posterior transdural approach, and report a series of 13 cases operated on in this way at our institute. METHODS: Between September 2004 and October 2010, 13 patients with symptomatic central thoracic disc herniation were operated on, utilising this posterior transdural approach. All patients underwent magnetic resonance imaging (MRI) of the thoracic spine before surgery. All patients were followed at our outpatient department for at least 3 months. In addition, all patients were interviewed in April 2009 and February 2011 to evaluate the final results. A seven-point Likert scale was applied and the Frankel score was determined preoperatively and postoperatively. Additionally, a postoperative MRI was obtained for all but two patients. RESULTS: The most frequently involved levels were T10-11 and T12-L1. Median operative time was 210 min (range 140-360). Three patients experienced reversible complications. No patient required spinal fixation. The median duration of hospitalisation was 6 days (range 4-20 days). With a median follow-up of 18 months, symptoms improved in 12 patients (92%), including the three patients with complications. One patient was unchanged (8%), while none of the patients experienced worsening of symptoms. CONCLUSIONS: The posterior transdural approach is well tolerated by the patient and has a relatively high success rate. It is a relatively simple and safe procedure, suitable for the operative treatment of almost all types of thoracic disc herniation, but especially the centrally located disc herniation.

Responsiveness and minimal clinically important change of the Pain Disability Index in patients with chronic back pain.

STUDY DESIGN: Prospective cohort study. OBJECTIVE: The objective of this study was to test the responsiveness and minimal clinically important change (MCIC) of the Pain Disability Index (PDI) in patients with chronic back pain (CBP). SUMMARY OF BACKGROUND DATA: Treatment of patients with CBP is primarily focused on reduction of disability. For disability measurement, the PDI is a widely used questionnaire. There are, however, no data available on responsiveness and MCIC. METHODS: Two hundred forty-two patients with CBP were included in this study. Patients filled in the PDI at baseline and at discharge. The PDI consists of 2 subscales: 1 measuring voluntary activities and 1 measuring obligatory activities. PDI was anchored at 2 self-reported global perceived effect (GPE) scales for complaints and self-care, respectively. Responsiveness was considered sufficient when Area Under the Receiver Operating Characteristics (ROC) Curve (AUC) was higher than 0.70. To test interpretability, change scores and MCIC were calculated. MCIC was tested by determination of optimal cut-off point of the ROC curve and determination of specificity and sensitivity of the optimal cut-off point. RESULTS: AUCs were 0.76 and 0.77 depending on the external criterion. The subscale obligatory activities did not meet the criteria for responsiveness (AUC: 0.63-0.69). MCIC of the PDI was 9.5 points for GPE "complaints" and 8.5 for GPE "self-care." CONCLUSION: The total score of the PDI as well as the subscale of voluntary activities is responsive. Partly because of floor effects, the subscale obligatory activities are not sufficiently responsive in patients with CBP. However, the responsiveness of this subscale in other patient groups should be further tested. In patients with CBP, change can be considered clinically important when PDI score has decreased 8.5 to 9.5 points.

Cervical cystic swelling in an adolescent: unusual association of a cervical mature teratoma with vertebral anomalies and a history of gastric duplication cyst.

A 14-year-old girl presented with a cervical cystic swelling in association with deformity of cervical vertebrae. As a child, she had been treated for gastric duplication. Pathologic examination of the resected cervical swelling revealed a mature teratoma. We discuss possible embryologic associations, which could explain the unusual combination of a mature teratoma with vertebral anomalies and gastric duplication.

Cauda equina entrapment in a pseudomeningocele after lumbar schwannoma extirpation.

Incidental or intentional durotomy causing cerebrospinal fluid (CSF) leakage, leading to the formation of a pseudomeningocele is a known complication in spinal surgery. Herniation of nerve roots into such a pseudomeningocele is very rare, but can occur up to years after initial durotomy and has been described to cause permanent neurologic deficit. However, cauda equina fiber herniation and entrapment into a pseudomeningocele has not been reported before. Here, we present a case of symptomatic transdural cauda equina herniation and incarceration into a pseudomeningocele, 3 months after extirpation of a lumbar Schwannoma. A 59-year-old man, who previously underwent intradural Schwannoma extirpation presented 3 months after surgery with back pain, sciatica and loss of bladder filling sensation caused by cauda equina fiber entrapment into a defect in the wall of a pseudomeningocele, diagnosed with magnetic resonance imaging. On re-operation, the pseudomeningocele was resected and the herniated and entrapped cauda fibers were released and replaced intradurally. The dura defect was closed and the patient recovered completely. In conclusion, CSF leakage can cause neurological deficit up to years after durotomy by transdural nerve root herniation and subsequent entrapment. Clinicians should be aware of the possibility of this potentially devastating complication. The present case also underlines the importance of meticulous dura closure in spinal surgery.