Spatio-temporal modulation of cortical activity during motor deadaptation depends on the feedback of task-related error

Motor adaptations are responsible for recalibrating actions and facilitating the achievement of goals in an ever-changing environment. Once consolidated, the decay of motor adaptation is a process affected by available sensory information during deadaptation. However, the cortical response to task error feedback during the deadaptation phase has received little attention. Here, we explored changes in brain cortical responses due to feedback of task-related error during deadaptation. Twelve healthy volunteers were recruited for the study. Right hand movement and EEG were recorded during repetitive trials of a hand reaching movement. A visuomotor rotation of 30° was introduced to induce motor adaptation. Volunteers participated in two experimental sessions organized in baseline, adaptation, and deadaptation blocks. In the deadaptation block, the visuomotor rotation was removed, and visual feedback was only provided in one session. Performance was quantified using angle end-point error, averaged speed, and movement onset time. Non-parametric spatiotemporal cluster-level permutation test was used to analyze the EEG recordings. During deadaptation, participants experienced a greater error reduction when feedback of the cursor was provided. The EEG responses showed larger activity in the left centro-frontal parietal areas during the deadaptation block when participants received feedback, as opposed to when they did not receive feedback. Centrally distributed clusters were found for the adaptation and deadaptation blocks in the absence of visual feedback. The results suggest that visual feedback of the task-related error activates cortical areas related to performance monitoring, depending on the accessible sensory information.

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.

Disability and physical activity in people with chronic disease receiving physiotherapy. A prospective cohort study

Chronic disease affects patients' disability and participation in activities of daily living. Longitudinal information on disability and physical activity is generally scarce in patients with chronic disease. The current study aimed to investigate if self-reported disability and physical activity changed in patients with chronic disease receiving physiotherapy. Furthermore, the aim was to assess if an improvement in self-reported disability was related to an increase in objectively measured physical activity and if an aggravation in self-reported disability was related to a decrease in physical activity. Seventy patients with either multiple sclerosis, Parkinson's disease, rheumatoid arthritis or stroke receiving free of charge physiotherapy were tested at baseline and 1 year later. Disability was measured with the self-reported modified Ranking Scale-9 Questionnaire and physical activity was objectively measured using tri-axial accelerometry. Neither self-reported disability nor physical activity changed among patients receiving 1 year of free of charge physiotherapy at group level. Furthermore, self-reported change of disability was not expressed with changes in objectively measured physical activity, indicating that the two measures represent two different constructs.

Effectiveness of Standard Oral Care Plan During Hospital Stay in Individuals With Brain Injury

Objective: To investigate the effectiveness of an existing standard oral care program (SOCP) and factors associated with it during hospitalization in individuals with acquired brain injury (ABI).

Material and Methods: A total of 61 individuals underwent a SOCP for 4 weeks in a longitudinal observational study. Rapidly noticeable changes in oral health were evaluated by performing plaque, calculus, bleeding on probing (BOP) and bedside oral examination (BOE) at weeks 1 and 5. Individuals' brushing habits, eating difficulties, and the onset of pneumonia were retrieved from their medical records. Association between oral-health outcomes to systemic variables were investigated through multilevel regression models.

Results: Dental plaque (P = 0.01) and total BOE score (P &lt; 0.05) decreased over time but not the proportion of dental calculus (P = 0.30), BOP (P = 0.06), and tooth brushing frequency (P = 0.06). Reduction in plaque and BOE over time were negatively associated with higher periodontitis scores at baseline (coef. −6.8; −1.0), respectively, which in turn were associated with an increased proportion of BOP (coef. ≈ 15.0). An increased proportion of calculus was associated with eating difficulties (coef. 2.3) and the onset of pneumonia (coef. 6.2).

Conclusions: Nursing care has been fundamental in improving oral health, especially reducing dental plaque and BOE scores. However, our findings indicate a need for improving the existing SOCP through academic-clinical partnerships.

Clinical Relevance: Early introduction of oral care program to brain-injured individuals is beneficial in reducing plaque accumulation and improving oral health.

Analysis of 15 different pelvis marker protocols during sit-to-stand

Sit-to-stand (STS) is a common transition movement needed to perform daily tasks. Previously, the kinematics of the STS movement has been investigated using optical motion capture. This method uses cameras and reflective markers on the body to capture movements. During STS, these markers can be difficult to measure due to blocked vision from the chair's arm- and backrest. This can result in poor data quality. The aim of this study was to investigate 15 different marker protocols and compare them in terms of visibility and selected outcome measures: hip flexion mean angle and range of motion (ROM). Fourteen healthy subjects completed five successful trials of STS. Marker protocols consisted of three anterior marker protocols and five posterior marker protocols, combined into a total of 15 marker protocols. For visibility, the traditional pelvis marker protocol proved unsuitable for STS tracking. Marker pins or additional markers anteriorly, and sacrum markers posteriorly, proved to be more suitable alternatives. For hip flexion mean angle and ROM, the estimates had similar tendencies. Hence, marker protocols were not outcome measure specific. Anteriorly, marker pins resulted in similar estimates as the traditional pelvis marker protocol. Posteriorly, sacrum markers estimated a smaller hip flexion angle, compared to the traditional pelvis marker protocol. In conclusion, marker pins can be used instead of regular ASIS markers at anterior pelvis. Posteriorly, sacrum markers can be used instead of PSIS markers.

Internal structure and validity of the bedside oral examination tool in patients with brain injury at neurorehabilitation setting

OBJECTIVES

To assess the internal structure and validity of the 'bedside oral examination' (BOE) instrument in individuals with acquired brain injury (ABI).

METHODS

Ninety ABI individuals were examined using BOE in their first week of neurorehabilitation. BOE measures oral health within eight categories including: swallow, tongue, odour, teeth, lips, saliva, mucosa and gingiva. To assess the validity of BOE, full-mouth clinical examination (gold standard) was performed. The internal structure of BOE was assessed using exploratory and confirmatory factor analyses. To measure the validity, the BOE scores were dichotomised into excellent oral health and altered oral health. Sensitivity, specificity and area under the receiver operating characteristic (ROC) curve of the six/eight BOE items were compared with their related clinical oral examination tool.

RESULTS

Overall, the patients had poor oral health irrespective of the oral examination tool used. Factor analyses indicated two factors within BOE: 'oral hygiene' (teeth, gingiva and mucosa) and 'orofacial health' (lips, swallow and saliva). BOE tongue and odour items loaded in neither factor. BOE items showed low validity since the highest area under the ROC curve was 0.60. Findings on the sensitivity value ranged from 35.0 to 74.2, while specificity from 44.4 to 83.3, depending on the item evaluated.

CONCLUSION

Bedside oral examination does not seem to be an ideal 'single' outcome tool in a neurorehabilitation setting as it lacks validity. BOE evaluates oral health as two independent but correlated components and treat them separately indicating precision treatment depending on their oral health dysfunction. It is advisable to use BOE as a screening tool. However, it should be complimented by proper clinical examination before establishing a treatment plan for oral health in patients with ABI.

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, β = 0.64 (95%CI: 0.02; 1.26)), whereas the effect of attachment avoidance was significant regardless of level of attachment anxiety (25th percentile, β = 1.09 (95%CI: 0.18; 2.01); 75th percentile, β = 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.

Externally validated model predicting gait independence after stroke showed fair performance and improved after updating

OBJECTIVE

To externally validate recent prognostic models that predict independent gait following stroke.

STUDY DESIGN AND SETTING

A systematic search identified recent models (<10 years) that predicted independent gait in adult stroke patients, using easily obtainable predictors. Predictors from the original models were assigned proxies when required, and model performance was evaluated in the validation cohort (n = 957). Models were updated to determine if performance could be improved.

RESULTS

Three prognostic models met our criteria, all with high Risk of Bias. Validation data was only available for the Australian model. This model used National Institute of Health Stroke Scale (NIHSS) and age to predict independent gait, using Motor Assessment Scale (MAS) walking item. For validation, Scandinavian Stroke Scale (SSS) was a proxy for NIHSS, and Functional Independence Measure (FIM) locomotion item was a proxy for MAS. The Area Under the Curve was 0.77 (0.74-0.80) and had good calibration in the validation dataset. Adjustment of the intercept and regression coefficients slightly improved discrimination. By adding paretic leg strength, the model further improved (AUC 0.82).

CONCLUSION

External validation of the Australian model with proxies showed fair discrimination and good calibration. Updating the model by adding paretic leg strength further improved model performance.

Changes in oral health related quality of life and its associated factors in individuals with brain injury

Purpose: To evaluate changes in oral health-related quality of life (OHRQoL) and associated factors in individuals with acquired brain injury (ABI) during hospitalization.Methods: Forty-six individuals with ABI were examined at week 1 and 5 of hospitalization. OHRQoL was recorded through Oral Health Impact Profile-14 (OHIP-14), clinical oral examinations were conducted, while orofacial health-related 'motor' and 'cognitive' scores were retrieved from patients' e-journal. Association between variables were investigated using factor analysis and multilevel regression modeling.Results: There were no significant differences in the OHIP-14 scores between week 1 and 5. Factors analysis revealed two OHIP-14 domains, 'psychosocial' and 'physica'. Individuals who improved their cognitive skills over study period and those with 'severe' periodontitis at baseline had increased scores of OHIP-14 'psychosocial' domain. Individuals who improved orofacial health-related 'motor' skills over study period had decreased 'physical' domain scores. Increased cognition over study period, current smoking and dental calculus were associated with increased 'physical' domain.Conclusions: The OHRQoL was poor both at week 1 and 5. Individual's cognitive and motor skills as well as their oral health status influenced their OHRQoL. Thus, individual's awareness and involvement in addition to oral care seem to be imperative in improving the OHRQoL in neurorehabilitation setting.

Periodontitis and orofacial health-related systemic impairment in patients with brain injury: a factor analysis approach

Aim: To investigate the association of periodontitis to orofacial health-related systemic impairment in patients with acquired brain injury (ABI).Methods: Ninety individuals with ABI were included. Full mouth periodontal examination was performed. Orofacial health-related 'motor' and 'cognitive' scores, dysphagia and feeding status, onset of pneumonia were retrieved from e-journal. Factor analysis dubbed periodontal data as 'moderate' and 'severe' periodontitis while orofacial health-related brain injury scores were dubbed into 'motor' and 'cognitive' domains. Association between periodontal findings and systemic impairments were analyzed using multivariable linear regression models.Results: Higher scores of 'moderate' periodontitis were significantly associated with lower scores of motor impairment (β = -0.2), feeding tube dependency (β = 0.2) and dysphagia (β = 1.21), whereas higher scores of 'severe' periodontitis were associated with lower scores of cognition (β = -0.2) and reduced dental visits (β = -0.2). Both periodontal domains were significantly associated with aging (β = 0.02) and onset of pneumonia (β = 0.5-0.7).Conclusions: Robust association between 'moderate' periodontitis and motor impairment, feeding problems and dysphagia, reflects an acute clinical condition, demanding cross-disciplinary intervention. Periodontal examination can be an early indicator tool for systemic chronic conditions, as ABI and periodontitis share a common environmental, social and biological background. Periodontitis majorly affects ageing population and are prone to pneumonia, compromising rehabilitation plan.

Epilepsy after severe traumatic brain injury: frequency and injury severity

Objective: To estimate national frequency of posttraumatic epilepsy (PTE) after severe traumatic brain injury (TBI) and assess injury severity (Glasgow Coma Scale (GCS) and posttraumatic amnesia (PTA)) as prognostic factors for PTE.

METHODS

Data on patients ≥18 years surviving severe TBI 2004-2016 were retrieved from the Danish Head Trauma Database (n = 1010). The cumulative incidence proportion (CIP) was estimated using death as competing event. The association between injury severity and PTE was assessed using multivariable competing risk regressions.

RESULTS

CIP of PTE 28 days and one year post-TBI was 6.8% (95% confidence interval (CI) 5.4-8.5) and 18.5% (95% CI 16.1-21.1%), respectively. Injury severity was not associated with PTE within 28 days post-TBI but indicated higher PTE-rates in less severely injured patients. PTA-duration >70 days was associated with PTE 29-365 days post-TBI (Adjusted sub-hazard ratio 4.23 (95% CI 1.79-9.99)). GCS was not associated with PTE 29-365 days post-TBI.

CONCLUSION

The PTE frequency was higher compared to previous estimates. Increasing injury severity was associated with PTE 29-365 days post-TBI when measured with PTA, but not with GCS. Though nonsignificant, the increased PTE-risk within 28 days in lower severity suggests an underdiagnosing of PTE.

Gastrointestinal transit time and heart rate variability in patients with mild acquired brain injury

Background

Constipation is suspected to occur frequently after acquired brain injury (ABI). In patients with ABI, heart rate variability (HRV) is reduced suggesting autonomic dysfunction. Autonomic dysfunction may be associated with prolonged gastrointestinal transit time (GITT). The primary aim of this study was to investigate if GITT is prolonged in patients with ABI. Secondarily, HRV and its correlation with GITT was investigated.

Methods

We included 25 patients with ABI (18 men, median age: 61.3 years, range [30.7-74.5]). GITT was assessed using radio-opaque markers and HRV was calculated from 24-hour electrocardiograms. Medical records were reviewed for important covariates, including primary diagnosis, time since injury, functional independence measure, and use of medication. The GITT assessed in patients was compared to a control group of 25 healthy subjects (18 men, median age: 61.5 years, range [34.0-70.9]).

Results

In ABI patients, the mean GITT was significantly longer than in healthy controls (2.68 days, 95% CI [2.16-3.19] versus (1.92 days, 95% CI [1.62-2.22], p = 0.011)). No correlation was found between HRV and GITT.

Conclusion

Patients with mild to moderate ABI have prolonged GITT unrelated to the HRV.

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.

Assessment of primary rehabilitation needs in neurological rehabilitation: translation, adaptation and face validity of the Danish version of Rehabilitation Complexity Scale-Extended

BACKGROUND

Assessing primary rehabilitation needs in patients with acquired brain injury is a challenge due to case complexity and the heterogeneity of symptoms after brain injury. The Rehabilitation Complexity Scale-Extended (RCS-E) is an instrument used in assessment of rehabilitation complexity in patients with severe brain injury. The aim of the present study was to translate and test the face validity of the RCS-E as a referral tool for primary rehabilitation. Face validity was tested in a sample of patients with acquired brain injury.

METHODS

Ten clinicians and records from 299 patients with acquired brain injury were used in the translation, cross-cultural adaptation and face validation study of the RCS-E. RCS-E was translated into Danish by a standardized forward-backward translation by experts in the field. Face validity was assessed by a multi-professional team assessing 299 patients. The team was asked their opinion on whether the RCS-E presents a sufficient description of the patients.

RESULTS

The RCS-E was translated according to international guidelines and tested by health professionals; some adaptations were required due to linguistic problems and differences in the national health system structures. The patients in the study had a mean age of 63.9 years (SD 14.7); 61 % were male. We found an excellent face validity with a mean score of 8.2 (SD 0.34) assessed on a 0-10 scale.

CONCLUSIONS

The RCS-E demonstrated to be a valid assessment of primary rehabilitation needs in patients with acquired brain injury. Excellent face validity indicates that the RCS-E is feasible for assessing primary rehabilitation needs and the present study suggests its applicability to the Danish health care system.

Referral decision support in patients with subacute brain injury: evaluation of the Rehabilitation Complexity Scale - Extended

PURPOSE

To test if the Rehabilitation Complexity Scale Extended (RCS-E) can be used as decision support for patient referral to primary rehabilitation as either complex specialized services (CSS) or district specialist services (DSS).

METHOD

Two independent expert teams analyzed medical records on 299 consecutive patients admitted for CSS or DSS rehabilitation. One team provided a golden standard for the patient referrals, and the other team provided RCS-E scores. Models for predicting referrals from RCS-E scores were developed on data for 149 patients and tested on the remaining 150 patients.

RESULTS

The optimal RCS-E sum score threshold for referral prediction was 11, predicting the golden standard for patient referral with sensitivity 88%, specificity 78% and correct classification rate 81%. Improved referral prediction performance was achieved by using RCS-E item-wise score thresholds (sensitivity 81%, specificity 89%, correct classification rate 87%). The RCS-E sum score range for patients referred CSS and DSS by the item-wise model was, respectively, 0-12 and 2-22 suggesting strong non-linear interaction of the RCS-E items.

CONCLUSIONS

We found excellent referral decision support in the RCS-E and the item specific threshold model, when patients with acquired brain injury are to be referred to CSS or DSS as their primary rehabilitation. Implications for Rehabilitation Efficient rehabilitation after acquired brain injury requires rehabilitation settings that meet patient needs. Validated tools for referral decision support make the process more transparent. Patient rehabilitation complexity can be stratified by the RCS-E with high sensitivity, specificity and predictive value of positive test. RCS-E is an excellent tool for referral decision support.

Guided intrathecal baclofen administration by using soleus stretch reflex in moderate-severe spastic multiple sclerosis patients with implanted pump

We tested the hypothesis that changes in soleus stretch reflex was correlated to changes in intrathecal baclofen dose in 12 multiple sclerosis patients with moderate-severe spasticity treated with intrathecal baclofen pump. Twice patients were evaluated clinically and biomechanically. The short-latency soleus stretch reflex was elicited by rotating the ankle joint 48 with a velocity from 3.1 to 1808/s. There was a strong correlation between changes in intrathecal baclofen dose and amplitude of the short-latency stretch reflex (r=- 0.88, PB < 0.001), which means that with an increase in baclofen dose there is a decrease in the amplitude. In contrast, no correlation exists between changes in intrathecal baclofen dose and clinical assessment of spasticity by using the Ashworth scale. The amplitude of the stretch reflex was very small (5 mV) compared with previous findings (> 50 μV), which indicates an effective antispastic effect of intrathecal baclofen. We suggest that clinical evaluation of spasticity using Ashworth scale is insensitive to detect minor changes in moderate-severe spasticity and consequently might not be very useful in evaluating spasticity in relation to ambulatory filling of baclofen pumps. The soleus stretch reflex might be useful in situations when there is doubt about the effect of intrathecally administered baclofen.

Feasibility of Using Lokomat Combined with Functional Electrical Stimulation for the Rehabilitation of Foot Drop

This study investigated the clinical feasibility of combining the electromechanical gait trainer Lokomat with functional electrical therapy (LokoFET), stimulating the common peroneal nerve during the swing phase of the gait cycle to correct foot drop as an integrated part of gait therapy. Five patients with different acquired brain injuries trained with LokoFET 2-3 times a week for 3-4 weeks. Pre- and post-intervention evaluations were performed to quantify neurophysiological changes related to the patients' foot drop impairment during the swing phase of the gait cycle. A semi-structured interview was used to investigate the therapists' acceptance of LokoFET in clinical practice. The patients showed a significant increase in the level of activation of the tibialis anterior muscle and the maximal dorsiflexion during the swing phase, when comparing the pre- and post-intervention evaluations. This showed an improvement of function related to the foot drop impairment. The interview revealed that the therapists perceived the combined system as a useful tool in the rehabilitation of gait. However, lack of muscle selectivity relating to the FES element of LokoFET was assessed to be critical for acceptance in clinical practice.

The effect of age on rehabilitation outcome after traumatic brain injury assessed by the Functional Independence Measure (FIM)

BACKGROUND

The impact of age on rehabilitation outcome after traumatic brain injury (TBI) as measured by changes in the Functional Independence Measure (FIM) has been addressed in several seemingly conflicting reports. Differences may be explained by different study populations and different ways of analyzing data.

OBJECTIVE

To investigate the role of data analysis in the interpretation of the age effect on rehabilitation outcome after TBI by comparing classical analyses of the total FIM score with a new item-wise analysis that unfolds the comprehensive amount of information contained in the FIM measurement otherwise concealed by the total score.

METHODS

We analyzed admission and discharge FIM data from 411 consecutive TBI patients admitted to inpatient rehabilitation during 1998-2011 by both methods.

RESULTS

The classical analysis indicated similar rehabilitation outcome in the 18 to 39, 40 to 64, and 65+ years age groups, which could be explained by selection of strong elderly patients and/or methodological problems with classical data analyses, whereas the item-wise analysis demonstrated profound age effect on most FIM items throughout the age interval covered.

CONCLUSIONS

The item-wise analysis meets requirements of proper data analysis, avoids concealing diversity in rehabilitation outcome behind the total FIM score, and provides a flexible, informative, and clinically relevant data analysis.

Statistical Considerations When Assessing Short Latency Stretch Reflexes in the Human Soleus Muscle

The aim was to investigate trial-by-trial response characteristics in the short-latency stretch reflex (SSR). Fourteen dorsiflexion stretches were applied to the ankle joint with a pre-contracted soleus muscle on two days. The magnitude and variability of trial-by-trial responses of the SSR were assessed. The SSR was log-normally distributed and variance heterogeneous between subjects. For some subjects, the magnitude and variance differed between days and stretches. As velocity increased, variance heterogeneity tended to decrease and response magnitude increased. The current study demonstrates the need to assess trial-by-trial response characteristics and not averaged curves. Moreover, it provides an analysis of SSR characteristics accounting for log-normally distributed and variance heterogeneous trial-by-trial responses.

Input-output properties of the soleus stretch reflex in spastic stroke patients and healthy subjects during walking

The input-output properties of the soleus stretch reflex during walking and sitting were examined in 11 spastic stroke patients and 10 healthy subjects. In the early swing phase, the threshold of the input-output relation was significantly lower in the patient group - on average 108°/s compared to 309°/s in the control group (P=0.02). The slope of the input-output properties was unchanged in patients and in control subjects (P=0.39). In stroke patients we found a minor, but significant, difference in threshold with 108°/s in the early swing phase compared to 74°/s in sitting position at matched TA EMG activity (P=0.01). Furthermore, we found an unchanged slope of 0.25μVs/° during walking and 0.28μVs/° in the sitting position (P=0.21). In contrast, control subjects showed a large difference in the threshold in the early swing phase during walking (309°/s) compared with findings in the sitting position at a matched TA EMG activity (71°/s, P=0.004). The slope was unchanged during walking and when the subject was sitting (P=0.22). There was a significant correlation between clinical spasticity score and stretch reflex threshold in the early swing phase (P=-0.61, P=0.04) and between clinical spasticity score and the slope in the early swing phase (P=0.72, P=0.009). It is concluded that in the early swing phase, the markedly reduced soleus stretch reflex threshold was preventing the stroke patients from making fast dorsiflexion of the foot at the ankle joint and thereby impairing the walking speed.

Left/right judgement does not influence the effect of mirror therapy after stroke

PURPOSE

To investigate the correlation between left/right judgement and the effect of mirror therapy (MT). A partial aim was to describe adverse effects of MT.

METHODS

This prospective follow-up study included 36 stroke patients, mean time since stroke was 33 d, SD 23. Left/right judgement is the ability to judge a pictured hand as belonging to one side of the body or the other. In this study, left/right judgement was established before the onset of MT by asking the patient to recognise left and right hands in photographs. Patients were tested before and after the intervention with the motor assessment scale (MAS) and two-point discrimination (2PD). The correlation between left/right judgement and the change of effect measured on the MAS and 2PD were tested by Spearman's rank correlation.

RESULTS

The ability to perform left/right judgement before the onset of MT had no significant correlation with change of effect measured on the MAS and 2PD (rho -0.169, p = 0.363 and rho = -0.227, p = 0.219). Thirty-one patients completed the intervention without adverse effects.

CONCLUSION

Left/right judgement does not influence the effect of MT. There seems to be no reason to test the ability to perform left/right judgement before the onset of MT. MT is an intervention without major adverse effects. Implications for Rehabilitation Mirror therapy (MT) is a method for treating sensory and motor disturbances post-stroke. It is important to clarify whether the ability to perform left/right judgement influences the effect of MT. In this study, left/right judgement does not influence the effect of MT. Based on the results of this study, testing and training left/right judgement before commencing MT cannot be recommended.

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.

Crossed spinal soleus muscle communication demonstrated by H-reflex conditioning

INTRODUCTION

A conditioning volley to the ipsilateral tibial nerve (iTN) inhibits contralateral soleus (cSOL) electromyographic activity at latencies of 37-41 ms. This is evidence for spinal muscular communication in opposing limbs. The aim of our study was to determine whether the cSOL H-reflex would be inhibited in a similar manner.

METHODS

Thirteen subjects participated in two experiments: (1) stimuli delivered to the iTN at 85% of the maximal peak-to-peak M-wave (85% M-max) with a pre-contracted cSOL; (2) 510 stimuli delivered at 85% M-max to the iTN with a test volley delivered to the contralateral tibial nerve at interstimulus intervals of -6 to 100 ms.

RESULTS

Significant inhibition was observed in the cSOL H-reflex when conditioning stimuli were delivered 3-33 ms before the test H-reflex.

CONCLUSIONS

The activity of this spinal pathway can be quantified using H-reflex conditioning to provide a controlled model for further studies of this response.

Phase Modulation of the Short-Latency Crossed Spinal Response in the Human Soleus Muscle

Short-latency spinally mediated interlimb reflex pathways were recently reported between the left and right soleus muscles in the human lower-limb during sitting. The aim of the current study was to establish if these pathways were observed during a functional motor task such as human gait and modulated by the gait cycle phase and/or electrical stimulation intensity. The second aim was to elucidate on the afferents involved. Two interventions were investigated. First was ipsilateral tibial nerve (iTN) stimulation at motor threshold (MT), 35% of the maximal peak-to-peak M-wave (M-Max) and 85% M-Max (85M-Max) with stimuli applied at 60×, 70×, 80×, 90×, and 100% of the gait cycle of the ipsilateral leg. Second was ipsilateral sural nerve (SuN) and medial plantar nerve (MpN) stimulation at 1, 2, and 3 perceptual threshold at 90% of the gait cycle. The root mean squared (RMS) of the contralateral soleus (cSOL) responses were analyzed in a time window, 40–55 ms (or 45–60 ms for subjects >50 y/o) following iTN stimulation. The most consistent responses occurred at 90 and 100% of the gait cycle at higher stimulation intensities of the iTN. Significantly inhibitory responses ( P = 0.006) were reported at 60 versus 80% ( P = 0.03), 90% ( P = 0.006), and 100% ( P = 0.002) and 70 versus 90% ( P = 0.02) and 100% ( P = 0.009) of the gait cycle at 85M-Max. The responses became more inhibitory with increasing stimulation intensities at 80% ( P = 0.01), 90% ( P = 0.001), and 100% ( P = 0.004) of the gait cycle. Stimulation of the MpN and SuN at all stimulation intensities demonstrated no short-latency responses. Therefore, it is unlikely that afferents within these nerves contribute to the response. This is the first study to show short-latency spinally mediated responses in the cSOL following iTN stimulation, during walking. It provides evidence for a new spinal pathway contributing to motor control and demonstrates that the response likely has functional relevance.

Quantification of hyperreflexia in amyotrophic lateral sclerosis (ALS) by the soleus stretch reflex

The aim of this study was to quantify upper motor neuron (UMN) involvement in amyotrophic lateral sclerosis (ALS) by the soleus stretch reflex.

METHODS

In a group of 24 ALS patients and ten healthy controls the soleus stretch reflex was elicited by a four degree rotation at the ankle joint. Amplitude of the short-latency stretch reflex, threshold, and sensitivity were determined. Peripheral excitation/contraction properties were evaluated by supramaximal stimulation of the tibial nerve. Clinical scores of upper motor neuron involvement were applied.

RESULTS

A highly significant correlation between threshold and sensitivity of the stretch reflex and clinical score of upper motor neuron involvement was found; patients with a low threshold and a high sensitivity in general had a high upper motor neuron score.

CONCLUSION

It is suggested that upper motor neuron involvement in ALS can be evaluated by using the soleus stretch reflex. This may be useful in monitoring progression of the disease and evaluating new therapies.

Cortical and spinal excitability changes after robotic gait training in healthy participants

BACKGROUND

Recent studies have proposed a role for robotic gait training in participants with acquired brain injury, but the effects on the excitability of cortical and spinal neurons even in healthy participants are uncertain.

OBJECTIVE

To investigate changes in corticospinal excitability in healthy participants after active and passive robotic gait training in a driven gait orthosis (DGO), the Lokomat.

METHODS

Thirteen healthy participants took part in 2 experiments. Each participant performed 20 minutes of active and passive gait training in a DGO. Motor evoked potentials (MEP), short-interval intracortical inhibition (SICI), intracortical facilitation (ICF), F-wave frequency, and Mmax were measured in the right tibialis anterior muscle before and after training.

RESULTS

Active training led to a decline in MEP amplitude and F-wave frequency. The MEP decline was associated with subjective muscle fatigue. Passive training induced a decrease in SICI lasting for 20 minutes after training.

CONCLUSIONS

The decline in MEP after active training is most likely because of central fatigue, whereas the decreased F-wave frequency might represent short-term plastic changes in the spinal cord. The decrease in SICI after passive training probably reflects a decrease in intracortical GABA activity, which could benefit the acquisition of new motor skills.

Motor cortical excitability remains unaffected of short-term hyperglycemia in Type 1 diabetic patients

BACKGROUND

In diabetic patients, hyperglycemia may precipitate seizures, and in experimental diabetes, indications for an increased neuronal excitability have been found. In this study, the excitability of the motor cortex and conduction of the central motor pathways were studied in diabetic patients in relation to the glycemic level.

METHODS

Using a double-blind study protocol, transcranial magnetic stimulation (TMS) was performed in five Type 1 diabetic patients during normo- and hyperglycemia, using a hyperglycemic clamp technique. Single and paired-pulse transcranial magnetic and single root stimulations were applied before and after 3 h of a fixed glucose level of 5 and 16 mmol/l. The percentage of change from baseline at the two glycemic levels was calculated and compared.

RESULTS

No difference in central motor conduction time was found comparing the change following normo- and hyperglycemia. Furthermore, no difference was observed for the changes in latency and amplitude following double stimulation with interstimulation intervals (ISIs) of 0-125 ms comparing normo- and hyperglycemia.

CONCLUSIONS

The excitability of motor cortex and central motor nerve conduction in Type 1 diabetic patients are unaffected by short-term moderate hyperglycemia as compared with normoglycemia.

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.

Effects of subanaesthetic and anaesthetic doses of sevoflurane on regional cerebral blood flow in healthy volunteers. A positron emission tomographic study

BACKGROUND

We tested the hypothesis that escalating drug concentrations of sevoflurane are associated with a significant decline of cerebral blood flow in regions subserving conscious brain activity, including specifically the thalamus.

METHODS

Nine healthy human volunteers received three escalating doses using 0.4%, 0.7% and 2.0% end-tidal sevoflurane inhalation. During baseline and each of the three levels of anaesthesia one PET scan was performed after injection of . Cardiovascular and respiratory parameters were monitored and electroencephalography and bispectral index (BIS) were registered.

RESULTS

Sevoflurane decreased the BIS values dose-dependently. No significant change in global cerebral blood flow (CBF) was observed. Increased regional CBF (rCBF) in the anterior cingulate (17-21%) and decreased rCBF in the cerebellum (18-35%) were identified at all three levels of sedation compared to baseline. Comparison between adjacent levels sevoflurane initially (0 vs. 0.2 MAC) decreased rCBF significantly in the inferior temporal cortex and the lingual gyrus. At the next level (0.2 MAC vs. 0.4 MAC) rCBF was increased in the middle temporal cortex and in the lingual gyrus, and decreased in the thalamus. At the last level (0.4 MAC vs. 1 MAC) the rCBF was increased in the insula and decreased in the posterior cingulate, the lingual gyrus, precuneus and in the frontal cortex.

CONCLUSION

At sevoflurane concentrations at 0.7% and 2.0% a significant decrease in relative rCBF was detected in the thalamus. Interestingly, some of the most profound changes in rCBF were observed in structures related to pain processing (anterior cingulate and insula).

Decreased stiffness at the ankle joint in patients with long-term Type 1 diabetes

AIMS

To evaluate contractile and reflex properties of the soleus muscle together with ankle joint stiffness in long-term Type 1 patients.

METHODS

Stretch reflex and muscle function of the soleus muscle was tested in 15 Type 1 diabetes mellitus patients and 15 controls. M-wave amplitude and maximal twitch torque was elicited by supramaximal stimulation of the tibial nerve. The stretch reflex was elicited by a 4 degree rotation of the ankle.

RESULTS

Rise time and fall time of the maximal twitch torque were increased compared with controls. The amplitude of the short latency stretch reflex was significantly reduced in patients at contraction levels of 5-30 Nm. At a contraction level of 5 Nm the median stretch reflex threshold was 10 degrees/s in patients and 6 degrees/s in controls (P = 0.03). Stiffness was decreased in diabetic patients, especially at lower contraction levels. There was no significant correlation between the clinical neuropathy score and stiffness. In contrast, high neuropathy score was correlated with low amplitude of the reflex amplitude (rho = -0.51, P = 0.05).

CONCLUSIONS

We demonstrate altered contractile properties, a decrease in stretch reflex of the soleus muscle, and a reduced stiffness at the ankle joint in patients with long-term Type 1 diabetes. These changes may cause delayed muscle contraction and impaired reflex modulation which could contribute to gait disturbances and increased number of falls in diabetic patients.

Enhanced terrace stability for preparation of step-free Si(001)-(2 x 1) surfaces

We show that depositing Si while annealing patterned Si(001)-(2 x 1) substrates at sublimation temperatures enhances terrace stability, permitting larger step-free areas to be produced in a given time than possible by annealing alone. We confirm this enhanced terrace stability using real-time low-energy electron microscopy observations, and quantitative microscopic modeling of step dynamics. Our measurements can be used to estimate the lateral variation in adatom concentration across large terraces, and to estimate an adatom diffusion length lambda approximately 10-30 microm at 1000 degrees C.

Post-exercise facilitation of compound muscle action potentials evoked by transcranial magnetic stimulation in healthy subjects

Post-exercise facilitation (PEF) of motor evoked potentials (MEPs) was studied by transcranial magnetic stimulation in 15 healthy subjects following standardized and controlled isometric contraction of the biceps brachii muscle. PEF was highly dependent on the time delay (TD) from muscle relaxation to delivery of the magnetic stimulus and only to a minor degree on the duration of the maintained muscular contraction of 2, 4, and 6 s. In addition, PEF was unaffected by the contraction levels of 25%, 50%, and 100% of maximal voluntary contraction (MVC). There was a linear relationship between the log amplitude of the post-exercise MEPs and the TD. The time point at which PEF had vanished was calculated to be 15.2 s. In order to challenge the question whether segmental and/or suprasegmental mechanisms are primarily responsible for PEF, MEPs and H-reflexes were recorded from the soleus muscle following a sustained plantar flexion at the ankle joint in three healthy subjects. PEF of MEPs was present at a TD of 1000 ms following a sustained contraction of 6 s at a level of 50% of MVC. It was accompanied by a pronounced decrease in the soleus H-reflex amplitude at a TD of 1000 ms.

Baclofen increases the soleus stretch reflex threshold in the early swing phase during walking in spastic multiple sclerosis patients

The effect of baclofen on walking performance was examined in nine spastic multiple sclerosis patients. In addition, nine healthy subjects were tested as controls. The modulation of the short latency soleus stretch reflex was closer to normal with baclofen compared to the recordings without baclofen, the modulation index being 74% (range: 60 - 100) with baclofen and 62% (range: 20 - 100) without baclofen, P=0.03. In healthy subjects the modulation index was 100% (range: 52 - 100). In the early swing phase the threshold of the soleus stretch reflex was significantly higher during baclofen medication being 139 deg/s (range: 63 - 302) compared with 93 deg/s (range: 37 - 187) without baclofen, P=0.004. The relation between the stretch velocity (input) and the amplitude of the stretch reflex (output) in early swing phase was unchanged being 0. 27 microVs/deg (range: 0.1 - 1.51) in patients with baclofen and 0. 24 microVs/deg (range: 0.08 - 0.79) without baclofen, P=0.25. Baclofen induced no change in input - output properties of the stretch reflex during walking compared with findings in a sitting position at matched EMG activity. There was a significant correlation between clinical spasticity score and stretch reflex threshold in the early swing phase (rho=-0.61, P=0.04) and between clinical spasticity score and the slope of the best linear fit in the early swing phase (rho=0.72, P=0.009).

Effect of ischemia and cooling on the response to high frequency stimulation in rat tail nerves

In normal rat tail nerves the effect of temperature and ischemia on the response to long-term high frequency stimulation (HFS) (143 Hz) was studied. The effect of temperature was studied in two consecutive tests at 14 degrees C and 35 degrees C. Prior to the HFS the peak-to-peak amplitude (PP-amp) of the compound nerve action potential was 139 +/- 20 microV (mean +/- SD) and 127 +/- 37 microV at 35 degrees C and 14 degrees C, respectively (NS). After 15 min of HFS the PP-amp was reduced to 45.3 +/- 20.5% of baseline level at 14 degrees C as compared with 80.8 +/- 10.2% at 35 degrees C (p < 0.001). Applying ischemia to the rat tail, an additional fall of the PP-amp was seen after 15-20 min of HFS at both low (20 Hz) and high (143 Hz) stimulation frequencies. In conclusion, ischemia and cooling result in an impaired ability to transmit high frequency impulses.

Peripheral and central effect of baclofen on ankle joint stiffness in multiple sclerosis

The effect of baclofen on the soleus stretch reflex and peripheral muscle function was tested in 10 multiple sclerosis (MS) patients with spasticity in the lower extremities. Peroral baclofen (15-60 mg daily) induced a decrease in the twitch torque of the soleus muscle elicited by supramaximal nerve stimulation. The torque was 15.1 +/- 5.5 Nm with baclofen and 17.1 +/- 5.0 Nm without baclofen (P = 0.03). The slope of the background torque/EMG relation was also changed from 1.53 Nm/microV with baclofen to 1.13 NM/microV without it (P = 0.03), and the soleus stretch reflex threshold decreased from 11.4 degrees /s (3.1-62.8) to 6.2 degrees /s (3.1-25.1) without baclofen medication (P = 0.03) in the relaxed muscle. Furthermore, baclofen induced an approximately 20% decrease in the total stiffness at the ankle joint at all contraction levels due to a decrease in the short-latency stretch reflex. From a clinical point of view, the peripheral action of baclofen may be unfortunate. Spasticity is often accompanied by weakness, which may be the major cause of any disability. Consequently, reduction in spasticity by the central effect of baclofen may be counteracted by its influence on muscle properties. In addition, treatment of spasticity by baclofen may unmask weakness.

Soleus long-latency stretch reflexes during walking in healthy and spastic humans

The present study was carried out to investigate the long-latency soleus stretch reflexes M2 (peak latency of approximately 85 ms) and M3 (peak latency of approximately 115 ms) during walking in healthy and spastic multiple sclerosis (MS) patients. An 8 degrees stretch was applied to the ankle extensors of the left leg in 8 healthy subjects during normal walking speed and 9 spastic MS patients and 10 age-matched healthy subjects during slow walking. When present in walking healthy subjects, M2 and M3 were modulated in a similar way and with the same amplitudes as previously described for the short latency soleus stretch reflex (M1). The spastic patients' soleus M1 was significantly less modulated during walking. The patients' M2 long-latency response was modulated in the same way as the age-matched healthy subjects. All patients' M3 responses were absent or much suppressed during walking. The origin and functional importance of the short- and long-latency stretch reflexes in healthy and spastic persons are discussed in relation to the above findings and the behaviour of the stretch reflexes during matched isometric contractions. M3 is argued to be part of a transcortical reflex in healthy subjects.

Frequency-dependent conduction delay of motor-evoked potentials in multiple sclerosis

Paired transcranial magnetic stimulation was applied in 33 multiple sclerosis (MS) patients and in 21 healthy controls. A major abnormality was found in latency of the second motor-evoked potential in MS patients. At interstimulus intervals of 75, 100, and 150 ms the central motor conduction time (CMCT) was significantly prolonged in MS patients to 139%, 150%, and 125% of the CMCT of a single magnetic stimulation (P=0.02, P=0.004, P=0.03), respectively. Voluntary contraction of the target muscle abolished the difference in latency independent of the degree of contraction. Stimulation intensity influenced the length of the interstimulus interval during which the maximal conduction delay was obtained. In MS patients there was no correlation between prolonged CMCT to a single magnetic stimulus and the frequency-dependent conduction delay to paired magnetic stimuli. It is hypothesized that the conduction delay of the conditioned response of paired magnetic stimuli in MS is of cortical origin and induced by abnormalities of the ascending volley to the neocortex.

Long-lasting depression of soleus motoneurons excitability following repetitive magnetic stimuli of the spinal cord in multiple sclerosis patients

The effect of repetitive magnetic stimulation at the spinal level on the soleus H-reflex amplitude was evaluated in II MS patients with lower limb spasticity and in nine healthy subjects. In MS patients stimulation with a train of 16 stimuli at 25 Hz induced a decrease in amplitude to 61.2 +/- 25.7% of the unconditioned H-reflex amplitude at interstimulus interval (ISI) of 10-1000 ms (P < 0.01). The amount of decrease in H-reflex amplitude was highly dependent on the stimulation intensity and the placement of the coil, and to a lesser extent influenced by the stimulation frequency. No decrease in motor evoked potentials (MEPs) evoked by transcranial magnetic stimulation was seen following trains of 16 stimuli at mid-thoracic in contrast to the post-stimulation depression in H-reflex amplitude which could imply that mechanisms acting at presynaptic level were involved. In response to repetitive magnetic stimuli for 5 min, a long-lasting decrease in H-reflex amplitude to a level of about 70% of the pre-stimulation H-reflex amplitude occurred in MS patients (P < 0.01). A similar although not significant decrease was observed in healthy subjects. We propose that long-lasting depression of the soleus H-reflex amplitude after repetitive magnetic stimuli is due to long-term depression of the synaptic transmission.

Treatment of spasticity with repetitive magnetic stimulation; a double-blind placebo-controlled study

The effect of repetitive magnetic stimulation on spasticity was evaluated in 38 patients with multiple sclerosis in a double-blind placebo-controlled study. One group was treated with repetitive magnetic stimulation (n = 21) and the other group with sham stimulation (n = 17). Both groups were treated twice daily for 7 consecutive days. Primary end-points of the study were changes in the patients self-score, in clinical spasticity score, and in the stretch reflex threshold. The self-score of ease of daily day activities improved by 22% (P = 0.007) after treatment and by 29% (P = 0.004) after sham stimulation. The clinical spasticity score improved -3.3 +/- 4.7 arbitrary unit (AU) in treated patients and 0.7 +/- 2.5 AU in sham stimulation (P = 0.003). The stretch reflex threshold increased 4.3 +/- 7.5 deg/s in treated patients and -3.8 +/- 9.7 deg/s in sham stimulation (P = 0.001). The data presented in this study supports the idea that repetitive magnetic stimulation has an antispastic effect in multiple sclerosis. Future studies should clarify the optimal treatment regimen.

Improvement of amplitude variability of motor evoked potentials in multiple sclerosis patients and in healthy subjects

Variability of the amplitude of motor evoked potentials was studied in 33 multiple sclerosis (MS) patients and 21 healthy subjects. Normal probability plots revealed skewness of the distribution of amplitudes obtained from the abductor pollicis brevis (APB) muscle during muscle relaxation, muscle contraction, and by paired magnetic stimulation. Natural logarithmic transformation of amplitude data resulted in normal distribution. Negative first-order autocorrelations were established for consecutive recordings independent of the repetition rate tested (5 s, 8 s, 12 s, and 20 s). A given measurement had a tendency to be systematically followed by a measurement of a lower value, indicating that magnetic stimulations induce a long-lasting inhibitory effect on the excitability of the motor pathways. A significant decrease in amplitude variability was achieved by a controlled muscle contraction of the target muscle compared with an uncontrolled muscle contraction in MS patients. Paired magnetic stimulation halved the coefficient of variation of amplitude data compared with amplitude obtained during muscle relaxation, and is introduced to reduce amplitude variability in conditions where no collaboration is possible.