Robotic technology (ROBERT®) to enhance muscle strength in the hip flexor muscles following spinal cord injury: a feasibility study.

STUDY DESIGN: Feasibility study. OBJECTIVE: To determine the feasibility of conducting a large trial designed to determine whether the ROBERT® can be used to increase the strength of the hip flexor muscles after spinal cord injury (SCI). The ROBERT® is a robotic device that provides assisted active movement while supporting the weight of the leg. Focus was on recruitment capability, suitability, and acceptability of the intervention and outcome measure. SETTING: Specialised SCI centre in Denmark. METHODS: All first-time admitted patients were screened to assess participant recruitment capability. Four people with SCI < 3 months tested a protocol consisting of 60 repetitions of hip flexion in supine conducted with the assistance of the ROBERT® three times a week for 4 weeks. Feasibility was assessed based on adherence to the protocol and completion rate and from the participants' perspectives. Maximal voluntary contraction (MVC) was accessed at baseline and four weeks. RESULTS: The recruitment rate was 8% (7 months). The four participants completed 44 out of 48 sessions (92%). No adverse events occurred. One physiotherapist was required to set-up and supervise each session. The active exercise time varied from 7.5 to 17 min. The participants found the ROBERT® a good supplement to their usual rehabilitation. We were able to measure MVC in even very weak hip flexor muscles with a dynamometer MicroFET2 fixed to a frame. CONCLUSION: The ROBERT® was feasible and acceptable. The participants perceived it as a supplement, not a replacement to usual physiotherapy. However, recruitment to the study was slow. TRIAL REGISTRATION: ClinicalTrials.gov NCT05558254. Registered 28th September 2022.

Acquired Brain Injury Among Adolescents and Young Adults: A Nationwide Study of Labor Market Attachment.

Purpose Young patients represent a particularly vulnerable group regarding vocational prognosis after an acquired brain injury (ABI). We aimed to investigate how sequelae and rehabilitation needs are associated with vocational prognosis up to 3 years after an ABI in 15-30-year-old patients. Methods An incidence cohort of 285 patients with ABI completed a questionnaire on sequelae and rehabilitation interventions and needs 3 months after the index hospital contact. They were followed-up for up to 3 years with respect to the primary outcome "stable return to education/work (sRTW)", which was defined using a national register of public transfer payments. Data were analyzed using cumulative incidence curves and cause-specific hazard ratios. Results Young individuals reported a high frequency of mainly pain-related (52%) and cognitive sequelae (46%) at 3 months. Motor problems were less frequent (18%), but negatively associated with sRTW within 3 years (adjusted HR 0.57, 95% CI 0.39-0.84). Rehabilitation interventions were received by 28% while 21% reported unmet rehabilitation needs, and both factors were negatively associated with sRTW (adjusted HR 0.66, 95% CI 0.48-0.91 and adjusted HR 0.72, 95% CI 0.51-1.01). Conclusions Young patients frequently experienced sequelae and rehabilitation needs 3 months post ABI, which was negatively associated with long-term labor market attachment. The low rate of sRTW among patients with sequelae and unmet rehabilitation needs indicates an untapped potential for ameliorated vocational and rehabilitating initiatives targeted at young patients.

Vocational/educational prognosis in adolescents and young adults with acquired brain injury: a nationwide cohort study.

OBJECTIVE: To determine prognostic factors for work ability and employment/educational status among young patients referred to outpatient neurorehabilitation clinics after an acquired brain injury. METHODS: A nationwide cohort study of 471 15-30-year-old patients who attended an interdisciplinary clinical assessment and provided questionnaire data at baseline and after one year. The outcomes were the Work Ability Score (WAS, 0-10 (best)) and employment/educational status after one year. Prognostic performance was analyzed using univariable regression and multivariable Ridge regression in a five-fold cross-validated procedure. RESULTS: Preinjury, 86% of the patients were employed, while the percentage had decreased to 55% at baseline and 52% at follow-up. The model, which included clinical measures of function, showed moderate prognostic performance with respect to WAS (R2=0.29) and employment/educational status (area under the curve (AUC)=0.77). Glasgow Outcome Scale Extended (R2=0.15, AUC=0.68) and the cognitive subscale of the Functional Independence Measure (R2=0.09, AUC=0.64), along with fatigue measured with the Multidimensional Fatigue Inventory (R2=0.15, AUC=0.60) were the single predictors with the highest predictive performance. CONCLUSION: Despite generally high scores in motor and cognitive tests, only about half of the patients were employed at baseline and this proportion remained stable. Global disability, cognitive sequelae and fatigue had the highest prognostic performance.

Attachment and symptom reporting in adolescents and young adults after a concussion.

BACKGROUND: The incidence of hospital-treated concussion is 100-300/100,000 person years. Reporting of long-lasting post-concussion symptoms (PCS) is estimated at 5-15%. Attachment insecurity is a potential vulnerability factor for physical illness and poorer disease outcomes in general. This study aimed to explore associations between attachment insecurity and PCS in young people sustaining a concussion. METHODS: This cross-sectional study was embedded in a cohort of 15-30-year-old patients (n = 3080) 3 months after sustaining a concussion. Data were obtained from a database and questionnaires. PCS were measured by the Rivermead Post-Concussion Symptoms Questionnaire and attachment dimensions (anxiety and avoidance) by the Experiences in Close Relationships-Relationship Structures Questionnaire. Multiple linear regression models were performed to investigate the association between the attachment dimensions and PCS with adjustment for demographic, injury-related and psychological factors and with additional testing for interaction between the attachment dimensions. RESULTS: In the final study sample, comprising 973 patients (31.6%), we found an interaction between the attachment dimensions. Hence, the effect of attachment anxiety on PCS was statistically insignificant at low avoidance (25th percentile) but significant at high avoidance (75th percentile, ß = 0.64 (95%CI: 0.02; 1.26)), whereas the effect of attachment avoidance was significant regardless of level of attachment anxiety (25th percentile, ß = 1.09 (95%CI: 0.18; 2.01); 75th percentile, ß = 2.71 (95%CI: 1.80; 3.61)). CONCLUSION: Attachment insecurity, especially characterised by high avoidance in combination with high anxiety, also called fearful attachment, is associated with PCS. Considering the attachment perspective can potentially improve health care for this patient group.

Predictors of disability in adolescents and young adults with acquired brain injury after the acute phase.

AIM: To develop and validate a prediction model for disability among young patients with acquired brain injury (ABI) after the acute phase. METHODS: Within a nationwide cohort of 446 15-30-year-old ABI-patients, we predicted disability in terms of Glasgow Outcome Scale - Extended (GOS-E) <7 12 months after baseline assessment in outpatient neurorehabilitation clinics. We studied 22 potential predictors covering demographic and medical factors, clinical tests, and self-reported fatigue and alcohol/drug consumption. The model was developed using multivariable logistic regression analysis and validated by 5-fold cross-validation and geographical validation. The model's performance was assessed by receiver operating characteristic curves and calibration plots. RESULTS: Baseline assessment took place a median of 12 months post-ABI. Low GOS-E (range 1-8 (best)) and Functional Independence Measure (range 18-126 (best)) along with high mental fatigue (range 4-20 (worst)) predicted disability. The model showed high validity and performance with an area under the curve of 0.82 (95% confidence interval (CI) 0.77, 0.87) in the cross-validation and 0.81 (95% CI 0.73, 0.88) in the geographical validation. CONCLUSION: We developed and validated a parsimonious model which effectively predicted disability. The model may be useful to guide decision-making in outpatient neurorehabilitation clinics treating young patients with ABI.

Return to work predictors after traumatic brain injury in a welfare state.

OBJECTIVE: To identify predictors of return to work (RTW) and stable labour market attachment (LMA) after severe traumatic brain injury (TBI) in Denmark. MATERIALS & METHODS: Patients aged 18-64 years, admitted to highly specialized neurorehabilitation after severe TBI 2004-2012 were included and followed up for ≤6 years. Weekly LMA data were retrieved from a national register of public assistance benefits. Weeks without or with supplemental public assistance benefits were defined as LMA weeks. Time of RTW was defined as first week with LMA. Stable LMA was defined as weeks with LMA ≥75% first year after RTW. Multivariable regressions were used to identify predictors of RTW and stable LMA among preinjury characteristics, injury severity, functional ability and rehabilitation trajectories. RESULTS: For the analyses of RTW and stable LMA, 651 and 336 patients were included, respectively. RTW was significantly associated with age (adjusted subhazard ratio 0.98, 95% CI 0.97-0.99), education (1.83, 95% CI 1.16-2.89), supplemental benefits (3.97, 95% CI 2.04-7.71), no benefits (4.86, 95% CI 2.90-8.17), length of stay in acute care (0.77, 95% CI 0.60-0.99) and time period of injury (1.56, 95% CI 1.15-2.10). The only significant predictor of stable LMA was age (adjusted odds ratio 0.97, 95% CI 0.95-0.99). CONCLUSION: RTW after severe TBI was associated with several socio-economic factors, whereas maintaining LMA depended on age only. We suggest that RTW rates could be improved by extensive rehabilitation targeting people that are older and low-educated, as these were less likely to RTW.

Reliability of surface electromyography measurements from the suprahyoid muscle complex.

Assessment of swallowing musculature using motor evoked potentials (MEPs) can be used to evaluate neural pathways. However, recording of the swallowing musculature is often invasive, uncomfortable and unrealistic in normal clinical practice. To investigate the possibility of using the suprahyoid muscle complex (SMC) using surface electromyography (sEMG) to assess changes to neural pathways by determining the reliability of measurements in healthy participants over days. Seventeen healthy participants were recruited. Measurements were performed twice with one week between sessions. Single-pulse (at 120% and 140% of the resting motor threshold (rMT)) and paired-pulse (2 ms and 15 ms paired pulse) transcranial magnetic stimulation (TMS) were used to elicit MEPs in the SMC which were recorded using sEMG. ≈50% of participants (range: 42-58%; depending on stimulus type/intensity) had significantly different MEP values between day 1 and day 2 for single-pulse and paired-pulse TMS. A large stimulus artefact resulted in MEP responses that could not be assessed in four participants. The assessment of the SMC using sEMG following TMS was poorly reliable for ≈50% of participants. Although using sEMG to assess swallowing musculature function is easier to perform clinically and more comfortable to patients than invasive measures, as the measurement of muscle activity using TMS is unreliable, the use of sEMG for this muscle group is not recommended and requires further research and development.

Effect of transcranial direct current stimulation on neuroplasticity in corticomotor pathways of the tongue muscles.

The aim of this study is to investigate effects of transcranial direct current stimulation (tDCS) on neuroplasticity in corticomotor pathways related to tongue muscles evoked by a training task using the tongue drive system (TDS). Using a crossover design, 13 healthy participants completed two sessions of tDCS while performing 30 min of TDS training. Sessions were spaced at least 2 weeks apart and participants randomly received anodal and sham tDCS stimulation in the first session and the other condition in the second session. Single and paired pulse transcranial magnetic stimulation was used to elicit motor evoked potentials (MEPs) of the tongue at three time-points: before, immediately after and 30 min after training. Participant-based reports of fun, pain, fatigue and motivation, level of difficulty and effort were evaluated on numerical rating scales. There was no consistent significant effect of anodal and sham stimulation on single or paired pulse stimulation MEP amplitude immediately or 30 min after TDS training. Irrespective of tDCS type, training with TDS induced cortical plasticity in terms of increased MEP amplitudes for higher stimulus intensities after 30 min compared with before and immediately after training. Participant-based reports revealed no significant difference between tDCS conditions for level of fun, fatigue, motivation, difficulty and level of effort but a significant increase in pain in the anodal condition, although pain level was low for both conditions. In conclusion, tongue MEP amplitudes appear to be sensitive to training with the tongue using TDS; however, anodal tDCS does not have an impact on training-evoked neuroplasticity of tongue corticomotor pathways.

Pain, spasticity and quality of life in individuals with traumatic spinal cord injury in Denmark.

STUDY DESIGN: Cross-sectional survey. OBJECTIVES: To estimate the prevalence, predictors and impact of self-reported pain and spasticity and examine variables affecting quality of life in individuals with a traumatic spinal cord injury (SCI). SETTING: Nationwide, Denmark. METHODS: An anonymous questionnaire was sent out to individuals with a traumatic SCI. The questionnaire included questions about demographics and SCI characteristics, pain, spasticity and quality of life. RESULTS: In total, 537 questionnaires were completed. Seventy-three percent reported chronic pain of which 60% used descriptors suggestive of neuropathic pain. The average pain intensity and interference were 5.6 (s.d. 2.3) and 5.0 (s.d. 2.8), respectively, on a 0-10 numeric rating scale (NRS), and 28.1% reported severe pain. Seventy-one percent reported spasticity. Average interference of spasticity was 2.9 (s.d. 2.7). Quality of life scores were 6.5 (s.d. 2.5) for life and life situation, 5.5 (s.d. 2.6) for physical health and 6.7 (s.d. 2.6) for mental health on the NRS (0-10). Female gender was associated with lower mental health scores and tetraplegia with lower physical health scores, and high pain interference and shorter time since injury were associated with lower quality-of-life scores for all three parameters. Pain with descriptors suggestive of neuropathic pain was associated with lower quality-of-life scores than pain without such descriptors. CONCLUSION: Chronic pain and spasticity are common problems after SCI, and in particular, high pain interference is associated with lower quality of life.

Additive genetic variance and developmental plasticity in growth trajectories in a wild cooperative mammal.

Individual variation in growth is high in cooperative breeders and may reflect plastic divergence in developmental trajectories leading to breeding vs. helping phenotypes. However, the relative importance of additive genetic variance and developmental plasticity in shaping growth trajectories is largely unknown in cooperative vertebrates. This study exploits weekly sequences of body mass from birth to adulthood to investigate sources of variance in, and covariance between, early and later growth in wild meerkats (Suricata suricatta), a cooperative mongoose. Our results indicate that (i) the correlation between early growth (prior to nutritional independence) and adult mass is positive but weak, and there are frequent changes (compensatory growth) in post-independence growth trajectories; (ii) among parameters describing growth trajectories, those describing growth rate (prior to and at nutritional independence) show undetectable heritability while associated size parameters (mass at nutritional independence and asymptotic mass) are moderately heritable (0.09 ≤ h(2) < 0.3); and (iii) additive genetic effects, rather than early environmental effects, mediate the covariance between early growth and adult mass. These results reveal that meerkat growth trajectories remain plastic throughout development, rather than showing early and irreversible divergence, and that the weak effects of early growth on adult mass, an important determinant of breeding success, are partly genetic. In contrast to most cooperative invertebrates, the acquisition of breeding status is often determined after sexual maturity and strongly impacted by chance in many cooperative vertebrates, who may therefore retain the ability to adjust their morphology to environmental changes and social opportunities arising throughout their development, rather than specializing early.

Social structure mediates environmental effects on group size in an obligate cooperative breeder, Suricata suricatta.

Population dynamics in group-living species can be strongly affected both by features of sociality per se and by resultant population structure. To develop a mechanistic understanding of population dynamics in highly social species we need to investigate how processes within groups, processes linking groups, and external drivers act and interact to produce observed patterns. We model social group dynamics in cooperatively breeding meerkats, Suricata suricatta, paying attention to local demographic as well as dispersal processes. We use generalized additive models to describe the influence of group size, population density, and environmental conditions on demographic rates for each sex and stage, and we combine these models into predictive and individual-based simulation models of group dynamics. Short-term predictions of expected group size and simulated group trajectories over the longer term agree well with observations. Group dynamics are characterized by slow increases during the breeding season and relatively sharp declines during the pre-breeding season, particularly after dry years. We examine the demographic mechanisms responsible for environmental dependence. While individuals appear more prone to emigrate after dry years, seasons of low rainfall also cause reductions in reproductive output that produce adult-biased age distributions in the following dispersal season. Adult subordinates are much more likely to disperse or be evicted than immature individuals, and demographic structure thus contributes to crashes in group size. Our results demonstrate the role of social structure in characterizing a population's response to environmental variation. We discuss the implications of our findings for the population dynamics of cooperative breeders and population dynamics generally.

Training-induced cortical plasticity compared between three tongue-training paradigms.

The primary aim of this study was to investigate the effect of different training types and secondary to test gender differences on the training-related cortical plasticity induced by three different tongue-training paradigms: (1) therapeutic tongue exercises (TTE), (2) playing computer games with the tongue using the Tongue Drive System (TDS) and (3) tongue-protrusion task (TPT). Forty-eight participants were randomized into three groups with 1h of TTE, TDS, or TPT. Stimulus-response curves of motor evoked potentials (MEPs) and motor cortex mapping for tongue muscles and first dorsal interosseous (FDI) (control) were established using transcranial magnetic stimulation at three time-points: (1) before tongue-training, (2) immediately after training, (3) 1h after training. Subject-based reports of motivation, fun, pain and fatigue were evaluated on 0-10 numerical rating scales after training. The resting motor thresholds of tongue MEPs were lowered by training with TDS and TPT (P<0.011) but not by TTE (P=0.167). Tongue MEP amplitudes increased after training with TDS and TPT (P<0.030) but not with TTE (P=0.302). Men had higher MEPs than women in the TDS group (P<0.045) at all time-points. No significant effect of tongue-training on FDI MEPs was observed (P>0.335). The tongue cortical motor map areas were not significantly increased by training (P>0.142). Training with TDS was most motivating and fun (P<0.001) and TTE was rated the most painful (P<0.001). Fatigue level was not different between groups (P>0.071). These findings suggest a differential effect of tongue-training paradigms on training-induced cortical plasticity and subject-based scores of fun, motivation and pain in healthy participants.

Mating strategies in dominant meerkats: evidence for extra-pair paternity in relation to genetic relatedness between pair mates.

Rates of extra-pair paternity (EPP) have frequently been associated with genetic relatedness between social mates in socially monogamous birds. However, evidence is limited in mammals. Here, we investigate whether dominant females use divorce or extra-pair paternity as a strategy to avoid the negative effects of inbreeding when paired with a related male in meerkats Suricata suricatta, a species where inbreeding depression is evident for several traits. We show that dominant breeding pairs seldom divorce, but that rates of EPP are associated with genetic similarity between mates. Although extra-pair males are no more distantly related to the female than social males, they are more heterozygous. Nevertheless, extra-pair pups are not more heterozygous than within-pair pups. Whether females benefit from EPP in terms of increased fitness of the offspring, such as enhanced survival or growth, requires further investigations.

Short-latency crossed spinal responses are impaired differently in sub-acute and chronic stroke patients.

OBJECTIVE: Investigate if patients with supraspinal lesions have impaired interlimb spinal reflex pathways. The short-latency crossed spinal response will be investigated during sitting from the non-paretic to paretic and paretic to non-paretic extremities at different stimulation intensities in chronic and sub-acute stroke patients. METHODS: The ipsilateral tibial nerve of the paretic and non-paretic extremities were stimulated at motor threshold, 35% M-max and 85% M-max of the ipsilateral soleus while the contralateral soleus was contracted from 5% to 15% of the maximum voluntary contraction of the paretic soleus. RESULTS: Chronic patients (from both extremities) had significantly less prominent inhibitory responses than healthy controls (post hoc tests: P<.01-P<.05). The responses were significantly modulated by stimulus intensity in healthy controls and chronic patients (P<.001-P<.05) but not sub-acute patients (P>.05). Some sub-acute patients had significantly more variable responses than chronic patients and healthy controls (P<.001-P⩽.05). CONCLUSIONS: Short-latency interlimb reflexes are impaired differently in sub-acute vs. chronic patients, are impaired from the non-paretic and paretic extremity, and abnormal when compared to healthy controls. SIGNIFICANCE: The inappropriate coordination could result in an inability to quickly avoid obstacles following a mechanical disturbance to the ipsilateral extremity. It also indicates that bilateral descending projections affect the response.

Intra-cortical excitability in healthy human subjects after tongue training.

Training of specific muscles causes plastic changes in corticomotor pathways which may underlie the effect of various clinical rehabilitation procedures. The paired pulse transcranial magnetic stimulation (ppTMS) technique can be used to assess short interval intra-cortical inhibitory (SICI) and intra-cortical facilitatory (ICF) networks. This study examined changes in SICI and ICF in tongue motor cortex after tongue training in 11 healthy volunteers using ppTMS. Paired pulse TMS was applied to the 'hot-spot' for the tongue motor cortex and motor-evoked potentials (MEPs) were recorded from tongue muscles. In tongue motor cortex, bilateral SICI (P < 0.019) and ICF (P < 0.001) was detected before and after training. There were no significant effects of training on single MEPs or SICI/ICF (P > 0.063). The success rate improved during training (P < 0.001) and changes in success were correlated to changes in single MEP amplitude (P < 0.006) but not to SICI/ICF (P > 0.113). This first study of SICI/ICF after tongue training showed no training-related changes in intra-cortical inhibitory or facilitatory networks. However, there was an association between task performance and changes in corticomotor excitability. Further studies are required to determine the clinical utility of muscle specific training for oral rehabilitation purposes.

Image-matching as a medical diagnostic support tool (DST) for brain diseases in children.

Imaging-matching is an important research area in imaging informatics. We have developed and evaluated a novel diagnostic support tool (DST) based on medical image matching using MR brain images. The approach consists of two steps, database generation and image matching. The database contains pre-diagnosed MR brain images. As the images are added to the database, they are registered to the 3D Talairach coordinate system. In addition, regions of interests (ROI) are generated, and image-processing techniques are used to extract relevant image parameters related to the brain and diseases from the ROIs and from the entire MR image. The second step is to retrieve relevant information from the database by performing image matching. In this step, the physician first submits a query image. The DST computes the similarity between the query image and each of the images in the database, and then presents the most similar images to the user. Since the database contains pre-diagnosed images, the retrieved cases tend to contain relevant diagnostic information. To evaluate the usefulness of the DST in a clinical setting, pediatric brain diseases were used. The database contains 2500 pediatric patients between ages 0 and 18 with brain Magnetic Resonance (MR) images of known brain lesions. A testbed was established at the Children's Hospital Los Angeles (CHLA) for acquiring MR images from the PACS server of patients with known lesions. These images were matched against those in the DST pediatric brain MR database. An expert pediatric neuroradiologist evaluated the matched results. We found that in most cases, the image-matching method was able to quickly retrieve images with relevant diagnostic content. The evaluation method and results are given.

No correlation between number of MRI-evident lesions in cerebrum and the soleus stretch reflex in multiple sclerosis patients.

The aim of the study was to investigate if the stretch reflex of the soleus muscle was useful in quantifying upper motor neuron lesions. The soleus stretch reflex was recorded in 10 healthy subjects and 20 patients with active relapsing-remitting multiple sclerosis and correlated to the number of MRI lesions in cerebrum and clinical scores (expanded disability status scale and regional functional scoring system). The short latency stretch reflex was elicited by rotating the left ankle joint 4 degrees with a rise time in the interval of 40-640 ms. The amplitude of the stretch was larger in multiple sclerosis patients being 88.5 microV in patients and 12.8 microV in controls, P = 0.007. The sensitivity of the stretch reflex expressed as the slope of the best linear fit was increased in MS patients to 2.6 microVs/degree compared with 0.6 microVs/degree (0.1-2.2) in controls, P = 0.009. There was no correlation between amplitude of the stretch reflex and number of MRI lesions (r = -0.03). In conclusion, the soleus stretch reflex might be useful to quantify spasticity but is not useful in detecting dysfunction of upper motor neurons in MS.