Christian Schuld

Computer implementation of the international standards for neurological classification of spinal cord injury for consistent and efficient derivation of its subscores including handling of data from not testable segments.

The International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI), defined by the American Spinal Injury Association (ASIA), and particularly the ASIA Impairment Scale (AIS) are widely used for research and clinical purposes. Although detailed procedures for scaling, scoring, and classification have been defined, misclassifications remain a major problem, especially for cases with missing (i.e., not testable [NT]) data. This work aimed to implement computer-based classification algorithms that included rules for handling NT data. A consistent and structured algorithmic scoring, scaling, and classification scheme, and a computerized application have been developed by redefining logical/mathematical imprecisions. Existing scoring rules are extended for handling NT segments. Design criterion is a pure logical approach so that substitution of non-testability for all valid examination scores leads to concordant results. Nine percent of 5542 datasets from 1594 patients in the database of the European Multicenter Study of Human Spinal Cord Injury (EM-SCI) contained NT segments. After adjusting computational algorithms, the classification accuracy was equivalent between clinical experts and the computational approach and resulted in 84% valid AIS classifications within datasets containing NT. Additionally, the computational method is much more efficient, processing approximately 200,000 classifications/sec. Computational algorithms offer the ability to classify ISNCSCI subscores efficiently and without the risk of human-induced errors. This is of particular clinical relevance, since these scores are used for early predictions of neurological recovery and functional outcome for patients with spinal cord injuries.

A vibrational technique for diagnosing loosened total hip endoprostheses: An experimental sawbone study

Aseptic loosening of hip implants is a severe orthopaedic problem and a valid diagnosis is often difficult. A potential method to determine loosening of the prosthesis is a swing analysis of the bone-implant interface using a vibrational technique. In this study, hip models were constructed to assess the vibration behaviour of the stem and cup components. Four different states of implant loosening were simulated: (1) stem and cup stable, (2) stem loosened and cup stable, (3) stem and cup loosened, and (4) stem stable and cup loosened. The model was excited at the lateral condyle of the femur between 100 Hz and 2000 Hz. Resonance spectra were recorded using an optical laser vibrometer and an accelerometer-based system. Analysis of the spectra revealed shifts of the resonances towards lower frequencies, especially in the case of a loosened stem component. The integral value of the spectra was a second parameter that was sensitive to a stem loosening. In the case of a loosened cup, a peak count analysis resulted in a significantly higher number of counts. In our model, different states of implant loosening could be determined with a vibrational technique and the localisation of the loosened component could be distinguished as well.

International standards for neurological classification of spinal cord injury: classification skills of clinicians versus computational algorithms.

Study design:This is a retrospective analysis.Objectives:The objective of this study was to describe and quantify the discrepancy in the classification of the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) by clinicians versus a validated computational algorithm.Settings:European Multicenter Study on Human Spinal Cord Injury (EMSCI).Methods:Fully documented ISNCSCI data sets from EMSCI’s first years (2003–2005) classified by clinicians (mostly spinal cord medicine residents, who received in-house ISNCSCI training by senior SCI physicians) were computationally reclassified. Any differences in the scoring of sensory and motor levels, American Spinal Injury Association Impairment Scale (AIS) or the zone of partial preservation (ZPP) were quantified.Results:Four hundred and twenty ISNCSCI data sets were evaluated. The lowest agreement was found in motor levels (right: 62.1%, P=0.002; left: 61.8%, P=0.003), followed by motor ZPP (right: 81.6%, P=0.74; left 80.0%, P=0.27) and then AIS (83.4%, P=0.001). Sensory levels and sensory ZPP showed the best concordance (right sensory level: 90.8%, P=0.66; left sensory level: 90.0%, P=0.30; right sensory ZPP: 91.0%, P=0.18; left sensory ZPP: 92.2%, P=0.03). AIS B was most often misinterpreted as AIS C and vice versa (AIS B as C: 29.4% and AIS C as B: 38.6%).Conclusion:Most difficult classification tasks were the correct determination of motor levels and the differentiation between AIS B and AIS C/D. These issues should be addressed in upcoming ISNCSCI revisions. Training is strongly recommended to improve classification skills for clinical practice, as well as for clinical investigators conducting spinal cord studies.Sponsorship:This study is partially funded by the International Foundation for Research in Paraplegia, Zurich, Switzerland.

International standards for neurological classification of spinal cord injury: impact of the revised worksheet (revision 02/13) on classification performance.

Study Design: Prospective cohort study. Objectives: Comparison of the classification performance between the worksheet revisions of 2011 and 2013 of the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI). Settings: Ongoing ISNCSCI instructional courses of the European Multicenter Study on Human Spinal Cord Injury (EMSCI). For quality control all participants were requested to classify five ISNCSCI cases directly before (pre-test) and after (post-test) the workshop. Participants: One hundred twenty-five clinicians working in 22 SCI centers attended the instructional course between November 2011 and March 2015. Seventy-two clinicians completed the post-test with the 2011 revision of the worksheet and 53 with the 2013 revision. Interventions: Not applicable. Outcome Measures: The clinicians’ classification performance assessed by the percentage of correctly determined motor levels (ML) and sensory levels, neurological levels of injury (NLI), ASIA Impairment Scales and zones of partial preservations. Results: While no group differences were found in the pre-tests, the overall performance (rev2011: 92.2% ± 6.7%, rev2013: 94.3% ± 7.7%; P = 0.010), the percentage of correct MLs (83.2% ± 14.5% vs. 88.1% ± 15.3%; P = 0.046) and NLIs (86.1% ± 16.7% vs. 90.9% ± 18.6%; P = 0.043) improved significantly in the post-tests. Detailed ML analysis revealed the largest benefit of the 2013 revision (50.0% vs. 67.0%) in a case with a high cervical injury (NLI C2). Conclusion: The results from the EMSCI ISNCSCI post-tests show a significantly better classification performance using the revised 2013 worksheet presumably due to the body-side based grouping of myotomes and dermatomes and their correct horizontal alignment. Even with these proven advantages of the new layout, the correct determination of MLs in the segments C2–C4 remains difficult.

MotionTherapy@Home – First results of a clinical study with a novel robotic device for automated locomotion therapy at home

Abstract In incomplete spinal cord injured subjects, task-oriented training regimes are applied for enhancement of neuroplasticity to improve gait capacity. However, a sufficient training intensity can only be achieved during the inpatient phase, which is getting shorter and shorter due to economic restrictions. In the clinical environment, complex and expensive robotic devices have been introduced to maintain the duration and the intensity of the training, but up to now only a few exist for continuation of automated locomotion training at home. For continuation of the automated locomotion training at home prototypes of the compact, pneumatically driven orthosis MoreGait have been realized, which generate the key afferent stimuli for activation of the spinal gait pattern generator. Artificial pneumatic muscles with excellent weight-to-force ratio and safety characteristics have been integrated as joint actuators. Additionally, a Stimulative Shoe for generation of the appropriate foot loading pattern has been developed without the need for verticalization of the user. The first results of the pilot study in eight chronic incomplete spinal cord injured subjects indicate that the home-based therapy is safe and feasible. The therapy related improvements of the walking capacity are in the range of locomotion robots used in clinical settings.

Neurological and functional recovery in multiple injured patients with paraplegia: outcome after 1 year.

BACKGROUND Injuries of thoracic vertebrae in multiple trauma patients are often accompanied by severe thoracic injuries and sensorimotor deficits. However, until now, it is not clear whether and how the severity of trauma influences the neurologic and functional outcome in paraplegic patients during the first year after the trauma. The aim of the study was to compare two cohorts of multiple injured paraplegic patients with and without conversion in the American Spinal Injury Association Impairment Scale (AIS) with regard to the severity of spinal trauma, the severity of thorax trauma, the type of fracture, and the functional outcome 1 year after the date of injury. METHODS Twenty-one traumatic paraplegic patients (neurologic level T1-T12) were included in the study based on a retrospective analysis of the Heidelberg European Multicenter Study about Spinal Cord Injury database (www.emsci.org) from 2002 to 2007. In all patients, the Polytraumaschluessel (PTS), the AO classification, the AIS, and the Spinal Cord Independence Measure were collected. Patients with no change in the AIS (group 1, n=14) were compared with patients with AIS changes (group 2, n=7), and t test and χ test were performed (p<0.05). RESULTS Differences in both groups concerning fracture classification were confirmed (p=0.046). A relation between neurologic improvement in the AIS and the severity of trauma (p=0.058) after 1 year was not found. The subitem PTST in the thoracic area showed statistical significance comparing the two groups (p=0.005). Both groups significantly improved functionally (Spinal Cord Independence Measure, p=0.035) during the first year but with no significant difference between the groups after 1 year. CONCLUSIONS Our data suggest that functional improvement is achieved independently from neurologic recovery. The combined assessment of the PTS, the AO classification, and the AIS in multiple-injured paraplegic patients can contribute to provide a better prognostication of the neurologic changes during rehabilitation and the outcome after 1 year than the AIS alone.

Tibial Cementing in UKA: A Three-Dimensional Analysis of the Bone Cement Implant Interface and the Effect of Bone Lavage

Loosening is a common cause for revision in cemented UKA. In a cadaver study, we analyzed the three-dimensional cement distribution under the tibial implant and the effect of bone lavage (pulsed lavage, syringe lavage) on maximum cement penetration and penetration volume. Analyses were determined by performing bone cuts in medio-lateral direction and converting this data into a 3D model. Pulsed lavage led to an increased mean maximum cement penetration 5.79 ± 2.63 mm and penetration volume 6471.34 ± 1156.43 mm(3) compared to syringe lavage 4.62 ± 2.61 mm, 5069.81 ± 1177.09 mm(3) (P<0.001; P<0.001). Our results show a complete cement mantle for both investigated lavage techniques. Cleansing the cancellous tibial bone bed using pulsed lavage is more effective than conventional syringe lavage and leads to a deeper cement penetration and lager cement penetration volume under the tibial component.

Motor levels in high cervical spinal cord injuries: Implications for the International Standards for Neurological Classification of Spinal Cord Injury

Context/Objective: To verify the hypothesis that motor levels (ML) inferred from sensory levels in the upper cervical segments C2–C4 according to the current version of the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) are counterintuitive in cases where the most rostral myotomes C5 and C6 are graded as intact. Design: Prospective cohort study of ISNCSCI instructional course participants completing a post-test after the workshop to determine the MLs in two variants of a complete, high cervical spinal cord injury (SCI) case scenario. Both variants were based on the same ISNCSCI sensory and MLs of C2. In the first variant myotomes C5 and C6 were bilaterally graded as intact, while in variant 2 only active movements against gravity were possible (grade 3). Setting: Eight ISNCSCI instructional courses conducted during the study period from November 2012 until March 2015 in the framework of the European Multicenter Study on Human Spinal Cord Injury (EMSCI— http//emsci.org). Participants: Ninety-two clinicians from twenty-two SCI centers. Most of the attendees were physicians (58.7%) or physical therapists (33.7%) and had less than one year (44.6%) experience in SCI medicine. Interventions: Not applicable. Outcome Measure: The classification performance described as percentage of correctly determined MLs by the clinicians. Results: Variant 2 (89.13%) was significantly (P < 0.0001) better classified than variant 1 (65.76%). In variant 1 with intact myotomes at C5 and C6, C6 was incorrectly classified as the ML by the clinicians in 33.15% of all cases, whereas in variant 2 with non-intact C5 / C6 myotomes, C6 was rarely chosen (2.17%). Conclusions: Sensory level deferred MLs in the high cervical region of C2–C4 are counterintuitive whenever the most rostral cervical myotomes are intact. An adjustment of the ML definition in ISNCSCI may be needed.

Sensory Feedback Interferes with Mu Rhythm Based Detection of Motor Commands from Electroencephalographic Signals

Background: Electroencephalogram (EEG)-based brain-computer interfaces (BCI) represent a promising component of restorative motor therapies in individuals with partial paralysis. However, in those patients, sensory functions such as proprioception are at least partly preserved. The aim of this study was to investigate whether afferent feedback interferes with the BCI-based detection of efferent motor commands during execution of movements. Methods: Brain activity of 13 able-bodied subjects (age: 29.1 ± 4.8 years; 11 males) was compared between a motor task (MT) consisting of an isometric, isotonic grip and a somatosensory electrical stimulation (SS) of the fingertips. Modulation of the mu rhythm (8–13 Hz) was investigated to identify changes specifically related to the generation of efferent commands. A linear discriminant analysis (LDA) was used to investigate the activation pattern on a single-trial basis. Classifiers were trained with MT vs. REST (periods without MT/SS) and tested with SS and vice versa to quantify the impact of afferent feedback on the classification results. Results: Few differences in the spatial pattern between MT and SS were found in the modulation of the mu rhythm. All were characterized by event-related desynchronization (ERD) peaks at electrodes C3, C4, and CP3. Execution of the MT was associated with a significantly stronger ERD in the majority of sensorimotor electrodes [C3 (p < 0.01); CP3 (p < 0.05); C4 (p < 0.01)]. Classification accuracy of MT vs. REST was significantly higher than SS vs. REST (77% and 63%; p < 10-8). Classifiers trained on MT vs. REST were able to classify SS trials significantly above chance even though no motor commands were present during SS. Classifiers trained on SS performed better in classifying MT instead of SS. Conclusion: Our results challenge the notion that the modulation of the mu rhythm is a robust phenomenon for detecting efferent commands when afferent feedback is present. Instead, they indicate that the mu ERD caused by the processing of afferent feedback generates ERD patterns in the sensorimotor cortex that are masking the ERD patterns caused by the generation of efferent commands. Thus, processing of afferent feedback represents a considerable source of false positives when the mu rhythm is used for the detection of efferent commands.