The effect of COVID-19 lockdowns on exercise and the role of online exercise in Australians with multiple sclerosis

INTRODUCTION

Regular exercise is beneficial for people with Multiple Sclerosis (MS), regardless of disability level. The previously reported differential effect of COVID-19-related lockdowns on exercise levels in this population remains unexplained. We examined effects of lockdowns on exercise in Australians with MS according to disability levels, lockdown severity and health technology use.

METHODS

A cross-sectional survey of people with MS in Australia (22 April-23 September 2021) collected demographic and clinical information as well as exercise patterns before and during lockdowns. Mann-Whitney was used to compare ordinal data and Likelihood Ratio to compare dichotomous data.

RESULTS

151 people completed the survey. 72.2% had mild disability and 25.2% moderate disability. Extended lockdowns were associated with significantly decreased sedentary behaviour (31.5% to 25.9%) but also with decreased exercise frequency in frequent exercisers (≥3 times/week; 53.7% to 22.2%). The latter occurred significantly more in those with mild disability (-22.7%) than with moderate disability (-3.5%). More people with mild disability walked for exercise pre-pandemic (LR 8.6, p=.004) and during lockdowns (LR 6.6, p=.010). Walking during lockdowns was positively associated with working from home. People with moderate disability were more likely to engage in home exercise both pre-pandemic (LR 5.5, p=.019) and during lockdown (LR 5.2, p=.023). Engagement in home exercise rose for both groups during lockdowns and was facilitated by on-line exercise classes.

CONCLUSION

Lockdowns differentially affected exercise patterns according to disability level. The proportion of people achieving exercise recommendations decreased more in those with mild but not moderate disability. Incidental physical activity was disproportionately impacted in people with moderate disability.

Implementing education: Personal communication with a healthcare professional is a critical step to address vaccine hesitancy for people with multiple sclerosis

Background

People with Multiple Sclerosis (PwMS) were first able to access COVID-19 vaccines in Australia from March 2021, when vaccine hesitancy in the general population was high (14–43%). High uptake of vaccination is important globally and critical to protect this vulnerable population. We conducted an on-line survey to examine factors influencing COVID-19 vaccination willingness among PwMS in Australia.

Methods

149 PwMS living in Australia completed the on-line survey (April-September 2021) examining demographic, environmental and clinical factors with respect to vaccine willingness, including attitudes towards COVID-19 illness and vaccines. Additional items explored the influence of different information sources on vaccination decisions. Continuous and ordinal data were compared using the Mann-Whitney U test. All tests were two-tailed, with alpha set at 0.5.

Results

A majority of the respondents were female (87.2%) with relapsing-remitting MS (77.5%) treated by a neurologist (94.0%). A majority were on high efficacy disease-modifying therapies (DMTs) (64.9%), while 19.9% were on no DMTs. About one third of respondents (32.9%) had had two doses, 20.8% had received their first dose, and 22.1% were unvaccinated, while 24.2% of responses were missing. When asked about vaccine intentions, 60.6% of the unvaccinated indicated they were likely to extremely likely to get vaccinated, while 15.2% were very unlikely or extremely unlikely to do so and 24.2% were undecided. Unvaccinated people were significantly more concerned about vaccine side effects (mean 5.3 versus 3.1/10; p < .001). Only 53.3% of people on DMTs were vaccinated, compared to 75% of those who were not. People on ocrelizumab therapy (n = 35) had a lower vaccination rate (39%) than those on other medications (n = 86, 59%). Vaccine willingness in the unvaccinated was most highly correlated with knowledge regarding the vaccine (r_s²=.709), agreement with the statement that COVID-19 vaccination is “too new for me to be confident about getting vaccinated” (r_s²= -.709), anticipation of regret due to side effects of vaccination (r_s²= -.642), and lack of knowledge regarding interactions between COVID-19 vaccines and DMTs (r_s²= -.570).

Almost two thirds had read MS-specific information about COVID-19 vaccinations and found it easy to understand (67.6%) and applicable to their situation (53.6%). However, less than half (47.8%) reported the information helped them make a personal vaccination decision. Over two-thirds (64.9%) had discussed vaccinations with their healthcare professional and 31.1% had not. Those who had not, were significantly more uninformed about the interactions of the vaccine with MS medications (mean 3.9 versus 2.9/10; p = .044) and significantly lower intention of vaccine uptake than those who had (mean 5.8 versus 7.9/10; p = .009).

Conclusion

Our study highlights that vaccination efforts should be delivered by healthcare professionals, focus on educating those who are managed with DMTs, and include individual recommendations related to specific DMTs, how the vaccines work, expectations regarding potential side-effects, potential exacerbation of MS symptoms, likelihood of recovery from any exacerbation, and the relative risks of side effects versus COVID-19 infection. Specific recommendations are provided.

Speech metrics, general disability, brain imaging and quality of life in multiple sclerosis

BACKGROUND AND PURPOSE

Objective measurement of speech has shown promising results to monitor disease state in multiple sclerosis. In this study, we characterize the relationship between disease severity and speech metrics through perceptual (listener based) and objective acoustic analysis. We further look at deviations of acoustic metrics in people with no perceivable dysarthria.

METHODS

Correlations and regression were calculated between speech measurements and disability scores, brain volume, lesion load and quality of life. Speech measurements were further compared between three subgroups of increasing overall neurological disability: mild (as rated by the Expanded Disability Status Scale ≤2.5), moderate (≥3 and ≤5.5) and severe (≥6).

RESULTS

Clinical speech impairment occurred majorly in people with severe disability. An experimental acoustic composite score differentiated mild from moderate (P < 0.001) and moderate from severe subgroups (P = 0.003), and correlated with overall neurological disability (r = 0.6, P < 0.001), quality of life (r = 0.5, P < 0.001), white matter volume (r = 0.3, P = 0.007) and lesion load (r = 0.3, P = 0.008). Acoustic metrics also correlated with disability scores in people with no perceivable dysarthria.

CONCLUSIONS

Acoustic analysis offers a valuable insight into the development of speech impairment in multiple sclerosis. These results highlight the potential of automated analysis of speech to assist in monitoring disease progression and treatment response.

Multidimensional evaluation of changes in limb function following botulinum toxin injection in persons with stroke

BACKGROUND

There are limited evidence of instrumented measures of gait and balance to determine the functional effects of botulinum toxin injections (BoNT-A) in spasticity after stroke.

OBJECTIVE

To evaluate the functional changes in gait and balance following upper limb and lower limb BoNT-A in persons with stroke.

METHODS

A pre-post prospective study of 35 stroke patients with upper and/or lower limb spasticity after focal treatment with BoNT-A. Assessments were at baseline (T0), 6-weeks (T1) and 12-weeks (T2), using validated subjective and objective physical activity measures.

RESULTS

After BoNT-A injections, significant improvements in most measures of impairments, activity and participation domains were found at T1 (p < 0.05, effect sizes (r) = 0.5-0.9). There was a significant increase in low intensity physical activity (at T1) and sedentary time reductions at both follow-up periods. Instrumented gait/balance measures showed a significant increase in cadence and turn velocity, but no changes in sway measures were found using posturography. Improvements in most outcome measures were maintained at 12-weeks.

CONCLUSION

BONT-A improved scores in most clinical measures but only in some of the objective gait/balance and physical activity measures. Further robust studies should utilize a larger sample size to better determine the benefits of BoNT-A for stroke-related spasticity.

A preliminary investigation on the effect of extracorporeal shock wave therapy as a treatment for neurogenic heterotopic ossification following traumatic brain injury. Part I: Effects on pain

INTRODUCTION

Neurogenic heterotopic ossification (NHO) is a complication of a neurological injury following traumatic brain injury (TBI) and may be present around major synovial joints. It is often accompanied by severe pain, which may lead to limitation in activities of daily living. Currently, a common intervention for NHO is surgery, which has been reported to carry many additional risks. This study was designed to assess the effect of extracorporeal shock wave therapy (ESWT) on pain in patients with TBI with chronic NHO.

METHODS

A series of single-case studies (n = 11) was undertaken with patients who had TBI and chronic NHO at the hip or knee. Each patient received four applications of high-energy EWST delivered to the affected joint over 8 weeks. Two-weekly follow-up assessments were carried out, and final assessments were made 3 and 6 months post-intervention. Pain was measured using the Faces Rating Scale, and X-rays were taken at baseline and 6-months post-intervention to physiologically measure the size of the NHO.

RESULTS

The application of high-energy ESWT was associated with significant overall reduction of pain in patients with TBI and NHO (Tau-0.412, 95% confidence interval -0.672 to -0.159, p = 0.002).

CONCLUSIONS

ESWT is a novel non-invasive intervention for reducing pain resulting from NHO in patients with TBI.

A preliminary investigation on the effect of extracorporeal shock wave therapy as a treatment for neurogenic heterotopic ossification following traumatic brain injury. Part II: Effects on function

INTRODUCTION

Neurogenic heterotopic ossification (NHO) occurs as a complication of traumatic brain injury (TBI). Management of clinically significant NHO remains variable. Complications of mature NHO include limitation of mobility. The effect of the extracorporeal shock wave therapy (ESWT) on range of motion at hip and knee, and function in patients with TBI with chronic NHO was investigated.

METHODS

A series of single-case studies applying ESWT to chronic NHO at the hip or knee of 11 patients with TBI were undertaken at a rehabilitation hospital. Participants received four applications of high-energy EWST delivered to the affected hip or knee over a period of 8 weeks. Two-weekly follow- up assessments were carried out; final assessments were made 3 and 6 months post-intervention. Range of motion (ROM) and Functional Reach (FR) or Modified Functional Reach (MFR) were measured.

RESULTS

Application of high-energy ESWT was associated with significant improvement in ROM (flexion) of the NHO-affected knee (Tau = 0.833, 95% CI 0.391-1.276, p = 0.002) and significant improvement of FR (Overall Tau 0.486, 95% CI 0.141-0.832, p = 0.006); no significant improvement in hip ROM or MFR.

CONCLUSIONS

ESWT may improve mobility and balance of patients with TBI who have chronic NHO.

Does early exercise attenuate muscle atrophy or bone loss after spinal cord injury?

OBJECTIVES

To systematically identify and assess the evidence on the efficacy of exercise initiated early after traumatic spinal cord injury (SCI).

METHODS

A comprehensive search (Any-2014) of eleven databases identified studies evaluating exercise interventions initiated within 12 weeks after SCI on muscle and bone loss in paralyzed limbs and comparing with standard care or immobilization. Two reviewers assessed methodological quality. One reviewer extracted data and critiqued results according to the Spinal Cord Injury Rehabilitation Evidence body of evidence framework.

RESULTS

A total of 2811 titles were screened. Eleven studies were included: five randomized controlled trials, four cohort studies and two within-subject control studies. All provided level II evidence with a moderate risk of bias. Two studies found significant positive effects of high-load FES-resisted stance on physiological measures of muscle. Three reported positive effects of 3 months of Functional Electrical Stimulation (FES) on muscle size. Two studies found positive effects of 6-month body-weight supported treadmill training or FES on trabecular bone using pQCT.

CONCLUSION

We found consistent evidence of positive effects of early exercise on muscle, possibly related to load intensity of the protocol. However, the heterogeneity of interventions and outcomes makes this determination speculative. Evidence for the effectiveness of early exercise on bone is scant and confined to measures of trabecular bone mineral density via pQCT. Transparent reporting of methods and variability of data, combined with standardization of valid and sensitive measures of muscle atrophy and bone loss, could facilitate future meta-analysis on this topic.

Telerehabilitation for persons with multiple sclerosis. A Cochrane review

A wide range of telerehabilitation interventions are trialled in persons with multiple sclerosis (pwMS). However, the evidence for their effectiveness is unclear. Aim of the review was to systematically assess the effectiveness and safety of telerehabilitation intervention in pwMS, the types of approaches that are effective (setting, type, intensity) and the outcomes (impairment, activity limitation and participation) that are affected. The search strategy comprised: Cochrane Multiple Sclerosis and Rare Diseases of the Central Nervous System Review Group Specialised Register (up to 9 July, 2014). Relevant journals and reference lists of identified studies were screened for additional data. Selected studies included randomized and controlled clinical trials that compared telerehabilitation intervention/s in pwMS with a control intervention (such as lower level or different types of intervention, minimal intervention; waiting-list controls, no treatment or usual care; interventions given in different settings). Best evidence synthesis was based on methodological quality using the GRADEpro software. Nine RCTs (N.=531 participants, 469 included in analyses) investigated a variety of telerehabilitation interventions in adults with MS. The interventions evaluated were complex, with more than one rehabilitation component and included physical activity, educational, behavioural and symptom management programmes. All studies scored "low" on the methodological quality assessment. Evidence from included studies provides 'low-level' evidence for reduction in short-term disability (and symptoms) such as fatigue. There was also "low-level" evidence supporting telerehabilitation in the longer term for improved functional activities, impairments (such as fatigue, pain, insomnia); and participation. There were limited data on process evaluation (participants'/therapists' satisfaction) and no data available for cost effectiveness. There were no adverse events reported as a result of telerehabilitation intervention. There is limited evidence to date, on the efficacy of telerehabilitation in improving functional activities, fatigue and quality of life in adults with MS. There is also insufficient evidence to support what types of telerehabilitation interventions are effective, and in which setting. More robust trials are needed to build evidence for the clinical and cost effectiveness of these interventions.

Functional changes in deep dorsal horn interneurons following spinal cord injury are enhanced with different durations of exercise training

KEY POINTS

Exercise training after spinal cord injury (SCI) enhances collateral sprouting from axons near the injury and is thought to promote intraspinal circuit reorganisation that effectively bridges the SCI. The effects of exercise training, and its duration, on interneurons in these de novo intraspinal circuits are poorly understood. In an adult mouse hemisection model of SCI, we used whole-cell patch-clamp electrophysiology to examine changes in the intrinsic and synaptic properties of deep dorsal horn interneurons in the vicinity of a SCI in response to the injury, and after 3 and 6 weeks of treadmill exercise training. SCI alone exerted powerful effects on the intrinsic and synaptic properties of interneurons near the lesion. Importantly, synaptic activity, both local and descending, was preferentially enhanced by exercise training, suggesting that exercise promotes synaptic plasticity in spinal cord interneurons that are ideally placed to form new intraspinal circuits after SCI. Following incomplete spinal cord injury (SCI), collaterals sprout from intact and injured axons in the vicinity of the lesion. These sprouts are thought to form new synaptic contacts that effectively bypass the lesion epicentre and contribute to improved functional recovery. Such anatomical changes are known to be enhanced by exercise training; however, the mechanisms underlying exercise-mediated plasticity are poorly understood. Specifically, we do not know how SCI alone or SCI combined with exercise alters the intrinsic and synaptic properties of interneurons in the vicinity of a SCI. Here we use a hemisection model of incomplete SCI in adult mice and whole-cell patch-clamp recording in a horizontal spinal cord slice preparation to examine the functional properties of deep dorsal horn (DDH) interneurons located in the vicinity of a SCI following 3 or 6 weeks of treadmill exercise training. We examined the functional properties of local and descending excitatory synaptic connections by recording spontaneous excitatory postsynaptic currents (sEPSCs) and responses to dorsal column stimulation, respectively. We find that SCI in untrained animals exerts powerful effects on intrinsic, and especially, synaptic properties of DDH interneurons. Plasticity in intrinsic properties was most prominent at 3 weeks post SCI, whereas synaptic plasticity was greatest at 6 weeks post injury. Exercise training did not markedly affect intrinsic membrane properties; however, local and descending excitatory synaptic drive were enhanced by 3 and 6 weeks of training. These results suggest exercise promotes synaptic plasticity in spinal cord interneurons that are ideally placed to form new intraspinal circuits after SCI.

Prevalence and risk-factors of neurogenic heterotopic ossification in traumatic spinal cord and traumatic brain injured patients admitted to specialised units in Australia

OBJECTIVES

To identify the prevalence and risk factors in the development of Neurogenic Heterotopic Ossification (NHO) in traumatic brain and spinal cord injured patients admitted to specialised units.

METHODS

An audit protocol was used to gather all clinically relevant data, in specific patient groups, relating to the prevalence of NHO, and was statistically analysed to identify traumatic brain injury (TBI) and traumatic spinal cord injury (TSCI) patients at high risk of developing NHO.

RESULTS

262 TBI and 151 TSCI patients were identified. NHO was diagnosed in 10 and 16 patients with TBI and TSCI, respectively; 18 clinically relevant characteristics were analysed for association with NHO in these patient groups. The only common variables associated with NHO in both neurological conditions were deep vein thrombosis and/or pulmonary emboli (DVT/PE).

CONCLUSIONS

The prevalence of NHO in TBI patients is less than one-third of that found in TSCI patients, ~4% and 11%, respectively. This study also suggests that the risk factors associated with NHO in TBI patients are distinct from those identified as risk factors in TSCI patients.

Listing on MEDLINE: A new milestone for the Australian Journal of Physiotherapy

The Editorial Board is pleased to announce that, commencing with the first issue of Volume 47, the Australian Journal of Physiotherapy will now be listed in the prestigious MEDLINE database. It has long been a goal of past and current Editorial Boards to achieve listing with MEDLINE because of the international exposure that such listing brings. Of the estimated 13,000 to 14,000 biomedical titles currently published throughout the world, about 4,500 titles are indexed and included in the MEDLINE database. MEDLINE is the principal online bibliographic citation database of MEDLARS system of the National Library of Medicine (USA) and includes all the citations published in Index Medicus as well as the citations published in two other indices, the Index to Dental Literature (IDL) and the International Nursing Index (INI).

Spinal cord injury and physical activity: preservation of the body

SETTING

Spinal cord injury (SCI) causes devastating loss of function and can result in serious secondary complications. Although significant advances are being made to develop cellular and molecular therapies to promote regeneration, it is important to optimize physical interventions.

OBJECTIVES

The objective of this review was to examine the evidence for the effects of physical rehabilitation strategies on health and fitness, and maintenance of target systems below the level of injury (for example, muscle, bone, circulation).

RESULTS

Exercise appears to be a potent means of achieving these goals, using a variety of strategies.

CONCLUSION

Physical rehabilitation after SCI needs to move beyond the goal of maximizing independence to focus on maintenance of optimum health and fitness as well as maintenance of target system function below the level of injury. Issues requiring further investigation include identification of the optimum dosage of interventions to achieve specific goals, for example, prevention of muscle atrophy and osteoporosis, and development and validation of simple clinical measures to monitor the changes in body composition. Adoption of a classification system for physical interventions and standardized outcome measures would facilitate large-scale observational studies to identify the critical variables contributing to better outcomes.

The AsTex: clinimetric properties of a new tool for evaluating hand sensation following stroke

OBJECTIVES

To investigate the clinimetric properties and clinical utility of the AsTex((R)), a new clinical tool for evaluation of hand sensation following stroke.

DESIGN

The AsTex((R)) was administered on two occasions separated by a week to appraise test-retest reliability, and by three assessors on single occasion to establish inter-rater reliability. Pilot normative values were collected in an age-stratified sample. Clinical utility was evaluated based on ease of administration, ceiling and floor effects, and responsiveness to sensory recovery.

PARTICIPANTS

Test-retest (n = 31) and inter-rater (n = 31) reliability and normative values (n = 95) for the AsTex((R)) were established in neurologically normal participants aged 18-85 years. Test-retest reliability was investigated in 22 individuals a mean of 46 months (range 12-125) post stroke and clinical utility was evaluated in an additional 24 subacute stroke participants a mean of 29.4 days (range 12-41) post stroke.

MAIN MEASURE

The AsTex((R)).

RESULTS

The AsTex((R)) demonstrated excellent test-retest (intraclass correlation coefficient (ICC) = 0.98, 95% confidence interval (95% CI) = 0.97-0.99) and inter-rater reliability (ICC = 0.81, 95% CI = 0.73-0.87) in neurologically normal participants. Test-retest reliability of the AsTex((R)) in individuals following stroke was excellent (ICC = 0.86, 95% CI = 0.68-0.94). The AsTex((R)) was simple to administer, demonstrated small standard error of measurement (0.14 mm), minimal floor and ceiling effects (12.5% and 8.3%) and excellent responsiveness (standardized response mean = 0.57) in subacute stroke participants.

CONCLUSION

The AsTex((R)) is a reliable, clinically useful and responsive tool for evaluating hand sensation following stroke.

Gait and balance impairment in early multiple sclerosis in the absence of clinical disability

This study evaluated the gait and balance performance of two clinically distinct groups of recently diagnosed and minimally impaired multiple sclerosis (MS) patients (Expanded Disability Status Scale range 0-2.5), compared to control subjects. Ten MS patients with mild pyramidal signs (Pyramidal Functional Systems 1.0), 10 MS patients with no pyramidal signs (Pyramidal Functional Systems 0) and 20 age- and gender-matched control subjects were assessed using laboratory-based gait analysis and clinical balance measures. Both MS groups demonstrated reduced speed and stride length (P < 0.001), and prolonged double limb support (P <0.02), compared to the control group, along with alterations in the timing of ankle muscle activity, and the pattern of ankle motion during walking, which occurred independent of gait speed. The pyramidal MS group walked with reduced speed (P = 0.03) and stride length (P = 0.04), and prolonged double limb support (P =0.01), compared to the non-pyramidal group. Both MS groups demonstrated concomitant balance impairment, performing poorly on the Functional Reach Test compared to the control group (P <0.05). The identification of incipient gait and balance impairment in MS patients with recent disease onset suggests that motor function may begin to deteriorate in the early stages of the disease, even in the absence of clinical signs of pyramidal dysfunction.

Correction of severe crouch gait in patients with spastic diplegia with use of multilevel orthopaedic surgery

BACKGROUND

Severe crouch gait in patients with spastic diplegia causes excessive loading of the patellofemoral joint and may result in anterior knee pain, gait deterioration, and progressive loss of function. Multilevel orthopaedic surgery has been used to correct severe crouch gait, but no cohort studies or long-term results have been reported, to our knowledge.

METHODS

In order to be eligible for the present retrospective cohort study, a patient had to have a severe crouch gait, as defined by sagittal plane kinematic data, that had been treated with multilevel orthopaedic surgery as well as a complete clinical, radiographic, and instrumented gait analysis assessment. The surgical intervention consisted of lengthening of contracted muscle-tendon units and correction of osseous deformities, followed by the use of ground-reaction ankle-foot orthoses until stable biomechanical realignment of the lower limbs during gait was achieved. Outcome at one and five years after surgery was determined with use of selected sagittal plane kinematic and kinetic parameters and valid and reliable scales of functional mobility. Knee pain was recorded with use of a Likert scale, and all patients had radiographic examination of the knees.

RESULTS

Ten subjects with severe crouch gait and a mean age of 12.0 years at the time of surgery were studied. After surgery, the patients walked in a more extended posture, with increased extension at the hip and knee and reduced dorsiflexion at the ankle. Pelvic tilt increased, and normalized walking speed was unaltered. Knee pain was diminished, and patellar fractures and avulsion injuries healed. Improvements in functional mobility were found, and, at the time of the five-year follow-up, fewer patients required the use of wheelchairs or crutches in the community than had been the case prior to intervention.

CONCLUSIONS

Multilevel orthopaedic surgery for older children and adolescents with severe crouch gait is effective for relieving stress on the knee extensor mechanism, reducing knee pain, and improving function and independence.

Segmental degeneration in the cervical spine and associated changes in dorsal root ganglia

Degenerative change in cervical segments C5-C7 was documented to determine whether osteo-ligamentous adaptations were age-related. In addition, companion morphological studies were carried out to determine whether parallel changes occurred in related soft tissues, including DRG. Independent of the provoking stimulus, aberrant soft tissue change may be expected with segmental degeneration. Two associations were identified: between the incidence of segmental degeneration and severity of DRG distortion, and between segmental degeneration and DRG inflammatory mast cell density. Peripheral type C cells seemed more susceptible to compression in circumstances of DRG distortion. In light of neuropeptide expression in these cell types, predominant type C cell compression may be clinically relevant in the noxious cascade contributing to the sensation of pain.

Sagittal gait patterns in spastic diplegia

Classifications of gait patterns in spastic diplegia have been either qualitative, based on clinical recognition, or quantitative, based on cluster analysis of kinematic data. Qualitative classifications have been much more widely used but concerns have been raised about the validity of classifications, which are not based on quantitative data. We have carried out a cross-sectional study of 187 children with spastic diplegia who attended our gait laboratory and devised a simple classification of sagittal gait patterns based on a combination of pattern recognition and kinematic data. We then studied the evolution of gait patterns in a longitudinal study of 34 children who were followed for more than one year and demonstrated the reliability of our classification.

Digital nerve anaesthesia decreases EMG-EMG coherence in a human precision grip task

There is increasing evidence that the primary motor cortex is involved in the generation of electromyographic (EMG) oscillations at frequencies in the range of 15-30 Hz that are observed during performance of a precision grip task. Since the level of the corticomuscular coherence varies according to the nature of the object that is gripped, it seemed possible that somatosensory inputs from the hand might affect this coherence. The aim of this study was to investigate whether interrupting cutaneous inputs from the digits would affect the coherence between hand muscles during precision grip of a compliant object. Subjects performed a precision grip hold-ramp-hold task before, during and after digital nerve anaesthesia of the index finger and thumb. There were marked deficits in the performance of the task, particularly during the initial formation of the grip and first hold period. Local digital nerve anaesthesia reduced but did not abolish 14-31 Hz coherence between EMG activity recorded from different hand and forearm muscles. Coherence was measured during the second hold phase of the task. Digital nerve anaesthesia did not affect the predominant frequencies in the EMG power spectra compiled from the same phase of the task. We conclude that during a precision grip task, cutaneous input enhances oscillatory synchrony between pairs of hand muscles.

Muscle spindle distribution, morphology, and density in longus colli and multifidus muscles of the cervical spine

STUDY DESIGN

Tissue blocks comprising muscle and bone from C5 to C7 segments were harvested at autopsy from 16 individuals ranging in age from 4 to 77 years. The prevertebral longus colli and postvertebral multifidus muscle pairs from one side in each individual were randomly selected for this study of muscle spindles.

OBJECTIVES

To determine muscle spindle distribution, morphology, and density for the longus colli and multifidus in caudal segments of the human cervical spine, and to assess whether changes are evident from infancy to old age.

SUMMARY OF BACKGROUND DATA

Age-related changes to the osteoligamentous framework of the cervical spine have been well documented. Postural modification accompanies these structural alterations, but there have been limited attempts to document whether muscle sustains a comparable level of morphologic alteration. Previous studies have examined muscle spindles in the neck muscles of various animal models and in a variety of isolated human muscles. However, most of these studies incurred bias through sampling and methodologic assumptions.

METHODS

The longus colli and multifidus were resected between C5 and C7, and between left and right pairs selected randomly for spindle analysis. These vertebral segments were selected deliberately because they form the apex of the cervical lordosis and the site at which the greatest age-related modification occurs. The tissue was processed in paraffin, sectioned, and then stained by Masson's trichrome. Spindle characteristics were examined using light microscopy and analyzed by unbiased stereologic methods. A one-sample paired t test was used to ascertain whether the differences in spindle density between the two muscles were statistically significant.

RESULTS

The longus colli has a high density of muscle spindles, which appear clustered and concentrated anterolaterally, away from the vertebral body. The multifidus has a low density of muscle spindles, which are found predominantly as single units concentrated closely to the vertebral lamina. No change in spindle distribution, morphology, and density were observed with age.

CONCLUSIONS

The current study examined spindle characteristics for an intrinsic neck muscle pair whose coactivation contributes to segmental stability of the cervical spine. The distribution and morphology of muscle spindles differ between the longus colli and the multifidus. In addition, these muscles have significant differences in terms of mean spindle density. Spindle characteristics represent one of many factors that govern proprioceptive regulation in skeletal muscle, and in neck muscles, the central connectivity of these receptors remains undefined. Therefore, although there are anatomic differences between the neck flexor and extensor, the functional implications of these differences are not clear. It is also of interest that spindle characteristics remain unchanged in these intrinsic muscles whose underlying segments are subject to age-related osteoligamentous changes.

Comparing the efficacy of two fluorescent retrograde tracers in labeling the motor and sensory neuron populations of the rat sciatic nerve

We compared the efficacy with which the fluorescent tracers Fast Blue (FB) and Diamidino Yellow (DY) retrogradely label neutrons. Trace crystals were applied to the sciatic nerve exclusively (single label) or serially (double label). Unbiased cell counts showed that FB and DY label similar numbers of motoneurons (P=1.00, df 5) or DRG neurons (P=0.95, df 5) when applied exclusively. Plotting of motoneurons revealed a similar pattern of distribution of FB and DY labeled neurons. When the tracers were applied serially, 79% of labeled motoneurons and 77% of labeled DRG neurons were double-labeled irrespective of which tracer was applied first. Equal proportions of the remaining labeled neurons were single-labeled with FB or DY. These data show that FB and DY label equal numbers of motor and sensory neurons of the sciatic nerve following exclusive or serial application of tracers. These findings support the use of FB and DY together in serial fluorescent labeling experiments.

What is the functional outcome for the upper limb after stroke?

The Motor Assessment Scale (MAS) and the Functional Independence Measure (FIM) are commonly used in Australian rehabilitation centres but there have been few systematic studies using them to measure recovery after stroke, especially with regard to upper limb function. The aims of this study were to provide a profile of upper limb recovery in a non-surgical stroke population using measures of impairment and disability. The records of 153 subjects were audited for upper limb MAS sub-scores, the FIM sub-score for upper body dressing, and the total FIM score at admission and discharge from rehabilitation. Significant improvement occurred for all outcome measures. There was no relationship between the MAS scores and the functional task of upper body dressing. The results emphasize the importance of using outcome measures that assess both impairment and disability, and indicate that substantial improvements in upper limb function frequently occur after stroke. Although the MAS has limitations, it is a valuable tool for measuring upper limb outcome after stroke because it provides a more accurate profile of true upper limb recovery than the FIM.

Development and reorganization of corticospinal projections in EphA4 deficient mice

The Eph family of receptor tyrosine kinases and their ligands, the ephrins, are important regulators of axon guidance and cell migration in the developing nervous system. Inactivation of the EphA4 gene results in axon guidance defects of the corticospinal tract, a major descending motor pathway that originates in the cortex and terminates at all levels of the spinal cord. In this investigation, we report that although the initial development of the corticospinal projection is normal through the cortex, internal capsule, cerebral peduncle, and medulla in the brain of EphA4 deficient animals, corticospinal axons exhibit gross abnormalities when they enter the gray matter of the spinal cord. Notably, many corticospinal axons fail to remain confined to one side of the spinal cord during development and instead, aberrantly project across the midline, terminating ipsilateral to their cells of origin. Given the possible repulsive interactions between EphA4 and one of its ligands, ephrinB3, this defect could be consistent with a loss of responsiveness by corticospinal axons to ephrinB3 that is expressed at the spinal cord midline. Furthermore, we show that EphA4 deficient animals exhibit ventral displacement of the mature corticospinal termination pattern, suggesting that developing corticospinal axons, which may also express ephrinB3, fail to be repelled from areas of high EphA4 expression in the intermediate zone of the normal spinal cord. Taken together, these results suggest that the dual expression of EphA4 on corticospinal axons and also within the surrounding gray matter is very important for the correct development and termination of the corticospinal projection within the spinal cord.

Thumb invariance during prehension movement: effects of object orientation

The aim of the present study was to examine the contribution of the thumb and index finger during the task of reaching to grasp a cylinder positioned at different orientations. To this end an axis was defined between a marker positioned on the subjects' wrist and the target. For each frame the perpendicular distances of the thumb and index finger from this axis were determined. The perpendicular distance was greater for the index finger than the thumb, confirming a relative stability of the thumb during natural prehension and supporting the notion of the thumb as a guide for the transport component of reaching. Further, index finger perpendicular distance was varied according to object orientation. When the object was positioned at an angle that requires hand pronation, the perpendicular distance for the index finger was the greatest. It is concluded that changes in the index finger distance are necessary to allow the thumb to maintain stability in order to provide appropriate movement guidance.

Monitoring age-related changes of collagen content and vascularity in ganglia using unbiased stereological methods

We describe for the first time application of unbiased stereological techniques to estimate total volume and volume fractions of interest in individual dorsal root ganglia (DRG). Volume estimates were obtained using a two-stage sampling design. Sections were systematically sampled following a random start, from DRG which were embedded in methacrylate and exhaustively sectioned. We further examined the efficiency of point counting irregular volume fractions housed in a regular reference volume. We found that the precision of volume estimates was relatively unaffected by exhaustive sampling, and that the magnitude of error was, in large part, determined by object shape.

Requirements for obtaining unbiased estimates of neuronal numbers in frozen sections

The use of frozen sectioning is a convenient and rapid means of observing the results obtained using fluorescent retrograde tracers. Quantitation of these results using the biased stereological methods currently available can be associated with large errors. A recently developed stereological tool, the optical dissector, provides unbiased and efficient results, however, the requirements for its use in frozen sections has not previously been established. In this study, a comparison was made of neuron numbers, estimated using the optical dissector method, in the motoneuron pool retrogradely labelled from the rat sciatic nerve with either Fast Blue or Tetramethylrhodamine dextran (fluoro-ruby) in methacrylate embedded and frozen spinal cord specimens. Despite over 50% shrinkage in the frozen sections, compared with virtually no shrinkage in the methacrylate sections, no significant difference in labelled motoneuron numbers was observed, provided this shrinkage was taken into account. Correction for section shrinkage is therefore essential in order to use the optical dissector with confidence to count fluorescent labelled neurons in frozen tissue.

A method for processing fluorescent labelled tissue into methacrylate: a qualitative comparison of four tracers

A technique for preserving fluorescence in retrogradely labelled neurons embedded in resin was developed. Four retrograde tracers were tested, Fast Blue (FB); Diamidino Yellow (DY); tetramethylrhodamine dextran (fluoro-ruby) (TMRD) and fluorescein dextran (fluoro-emerald) (FD). These tracers were applied to the cut end of the sciatic nerves in rats either by: (a) direct application of tracer crystals, or (b) dipping the nerve into an aqueous solution containing the tracer. Each lumbar spinal cord was removed and dehydrated by one of two methods: (a) conventional alcohol dehydration, or (b) dehydration through a graded series of aqueous methacrylate infiltration solutions (inert dehydration). Specimens were embedded in methacrylate and horizontal sections cut. The location of labelled motoneurons was mapped using a fluorescence microscope. Direct application of tracer crystals labelled more motoneurons than dipping. Fast Blue labelled considerably more motoneurons than tetramethylrhodamine. Labelling by all tracers was retained following methacrylate embedding. Fast Blue and Diamidino Yellow required inert dehydration, while tetramethylrhodamine dextran and fluorescein dextran were preserved using conventional dehydration. These results indicate that tissue labelled with commonly used fluorescent tracers can be processed and embedded in methacrylate, thereby permitting quantitative analysis by modern stereological methods.

Prediction of gait velocity in ambulatory stroke patients during rehabilitation

OBJECTIVE

To quantify prediction of gait velocity in ambulatory stroke patients during rehabilitation.

DESIGN

Single group (n = 42) at the beginning of rehabilitation (Test 1) and 8 weeks later (Test 2).

SETTING

Inpatient rehabilitation.

PATIENTS

Unilateral first stroke; informed consent; able to walk 10 meters.

MEASURES

INDEPENDENT VARIABLES

Gait velocity at Test 1, age, time from stroke to Test 1, side of lesion, neglect.

DEPENDENT VARIABLES

Gait velocity at Test 2, gait velocity change.

RESULTS

The correlation between initial gait velocity and gait velocity outcome at Test 2 was of moderate strength (r2 = .62, p<.05). However, even at its lowest, the standard error of prediction for an individual patient was 9.4 m/min, with 95% confidence intervals extending over a range of 36.8 m/min. Age was a weak predictor of gait velocity at Test 2 (r2 = -.10, p<.05). Gait velocity change was poorly predicted. The only significant correlations were initial gait velocity (r2 = .10, p<.05) and age (r2 = .10, p<.05).

CONCLUSION

While the prediction of gait velocity at Test 2 was of moderate strength on a group basis, the error surrounding predicted values of gait velocity for a single patient was relatively high, indicating that this simple approach was imprecise on an individual basis. The prediction of gait velocity change was poor. A wide range of change scores was possible for patients, irrespective of their gait velocity score on admission to rehabilitation.

Corticospinal projection patterns following unilateral section of the cervical spinal cord in the newborn and juvenile macaque monkey

Immediately following a unilateral section of the midcervical spinal cord that interrupts the dorsolateral, lateral, and ventral columns, the macaque monkey has a severe flaccid paralysis on the side of the lesion. Recovery of hand function is rapid, and, although it is incomplete, within a few months, the monkey uses the initially disabled hand and fingers with considerable skill. We examined the accompanying changes in the pattern of projection of corticospinal neurons to the cervical spinal cord that occurred following such a lesion. Spinal section was done both in newborn and juvenile macaques, and the postlesion period was followed for up to 150 weeks. Corticospinal neuron populations were visualized by using both anterogradely and retrogradely transported labels, and their origins, spinal pathways, and terminations were examined at intervals during the period of recovery of hand function. Immediately following unilateral section of the spinal cord at C3, sampled counts of soma profiles of retrogradely labeled neurons indicated that there was a profound reduction in the corticospinal projection to the hemicord caudal to the lesion. The few labeled corticospinal axons spared by the lesion bypassed the spinal lesion by descending in the contralateral cord and then crossing the midline caudal to the lesion. A few corticospinal axons may also have bypassed the lesion in the ipsilateral ventromedial column when this was not fully interrupted by the lesion. In every monkey, we observed a similar, profound reduction in the corticospinal (and rubrospinal) projections to the hemicord caudal to the lesion: This pattern did not alter significantly over an extended recovery period. An unchanging corticospinal projection to the cervical spinal cord contralateral to the lesion was also visualized in each monkey and resembled that seen in the normal macaque. Although the resolution of the labeling and counting procedures used precluded the identification of small increases in the numbers of corticospinal neurons projecting to the hemicord caudal to the lesion, we concluded that there was no substantial reconstruction of this projection over a recovery period of more than 2 years.

Manual dexterity and corticospinal connectivity following unilateral section of the cervical spinal cord in the macaque monkey

The macaque recovers quite rapidly from the immediate severe flaccid hemiparesis that results from unilateral section of the cervical spinal cord (between C3 and C6) and starts to use the impaired hand to pick up objects within about 30 days following the surgery. Within another 60 days, the monkey is quite dexterous; nonetheless, there is a persisting deficit. We used video recording to study the long-term recovery of manual dexterity following unilateral section of the cervical cord in newborn and juvenile monkeys. A reach-and-retrieve manual task was examined. By using a preset oppositional force, opposition of the pads of the index finger and thumb in the vertical plane was needed to retrieve the desired target object. The corticospinal connectivity of each monkey was also examined by using retrograde or anterograde tracers at the end of the experimental period (Galea and Darian-Smith [1997] J. Comp. Neurol., this issue) and was correlated with the manual performance. Manually retrieving an object depends on the coordination of several control processes acting in parallel, including 1) visually guided components, such as directing the arm toward the object, aligning the digits with the target object by pronating the forearm, and preshaping the index/thumb separation to match with the size and shape of the target, and 2) manipulative components that depend on tactual input and that also include independent movements of the digits and the application of the appropriate oppositional forces. The impairment of manual dexterity that persisted after a cervical section, although it was small, involved these processes and was evident in 1) the less direct trajectory used in reaching, 2) the loss of preshaping of the separated index finger and thumb prior to grasping the target object, and 3) a weakening of the oppositional forces that could be developed between the pads of the index finger and thumb. Although, in the accompanying paper, we did not preclude some regeneration of severed corticospinal connections, we did show that, if any such reconstruction occurred, then it was limited. The remarkable but incomplete recovery of dexterity over a period of 6-12 months, therefore, must be achieved by 1) optimizing the transmission of information from the cortex to the spinal cord by the substantially reduced populations of corticospinal neurons and corticobulbospinal projections and/or 2) the effective use of spinal circuitry in regulating the more stereotyped elements of the manual task.

Manual dexterity: how does the cerebral cortex contribute?

1. Manual dexterity, of great evolutionary significance to the primates, ranges in complexity from the precise opposition of finger and thumb to Brendal playing Mozart. All dexterity depends on a sustained and rapid transfer of sensorimotor information between the cerebral cortex and the cervical spinal cord. 2. Multiple separate corticospinal neuron populations originate from cortical areas four, the supplementary motor area, anterior cingulate, postarcuate, parietal and insular cortex. Each corticospinal neuron population projects in parallel to all spinal segments, and has a distinctive pattern of terminations. 3. Each corticospinal neuron population has a unique thalamic input which can relay particular sensorimotor information from the sense organs, cerebellum and basal ganglia. The overall structural framework of these sensorimotor pathways, with many parallel corticospinal channels, with interconnections in the cerebral cortex and spinal cord to enable crosstalk between the channels, is that needed for parallel distributed processing, which would enable the very rapid transfer of information between the cerebral cortex and spinal cord needed for any sophisticated use of the hand. 4. Hemisection of the cervical spinal cord in the macaque results in an immediate hemiplegia, with subsequent remarkable although incomplete recovery of hand and finger movements. The only direct corticospinal input to the hemicord caudal to the hemisection, even after 3 years, is the approximately 10% of fibres which cross the midline caudal to the lesion: the fibres 'spared' by the hemisection. A matching 'sparing' of somatosensory input from the paresed limb also occurs. No regeneration of the interrupted pathways has been visualized using modern tracer techniques. 5. Cervical hemisection permanently reduces the number of parallel channels which transmit information between cortex and spinal cord, but does not reduce their cortical origins nor the neuron populations targeted in the spinal cord. We infer that the content of the information that can be transmitted between the cortex and spinal cord is not greatly changed, but the rate of transmission of this information is sharply reduced, and is the 'bottleneck' that limits the complete recovery of dexterity following hemisection. The remarkable recovery that does occur presumably reflects more economic transmission of information by the few spared channels. We guess that this involves substantial synaptic reorganization not visualized by the procedures we have used.

Postnatal maturation of the direct corticospinal projections in the macaque monkey

Postnatal changes in the topography of the multiple corticospinal projections in the macaque monkey were followed using retrogradely transported fluorescent tracers, and related to the monkey's acquisition of manual dexterity; both behavioral and anatomical maturation were completed by about 8 postnatal months. Cortical origins of the corticospinal projections were examined by constructing planar projection maps of the distributions of labeled corticospinal neuron somas; these somas were found only in lamina V. At birth elaborate somatotopically organized corticospinal projections from primary motor cortex (area 4), the mesial supplementary motor area and cingulate areas 23 and 24, area 12, dorsolateral area 6a beta, the dorsolateral and ventral area 6a alpha (area F4), parietal areas 2/5, 7b and the peri-insular cortex (including area SII), were clearly defined, with axons extending to all spinal cord segments. While this pattern of regional projections broadly resembled that of the mature macaque, there were, however, substantial maturational changes during the 8 months after birth. These included (1) a halving of the area of cerebral cortex from which the contralateral corticospinal projection originated and (2) a threefold reduction in the number of labeled corticospinal neurons projecting to all segments of the cord. Collateral elimination rather than neuronal cell death was the likely mechanism for this reduction in the population and areal extent of corticospinal neurons in the maturing macaque. The surviving corticospinal axon terminals also developed substantially during the postnatal period. At birth some terminals had invaded the intermediate zone in each spinal segment, but few had penetrated the dorsal and ventral horns. By 6 postnatal months, however, many corticospinal neurons were retrogradely labeled following the injection of fluorescent labels into each of these spinal zones in cervical and lumbar spinal segments. These data demonstrate a considerable postnatal reduction in corticospinal neurons projecting to the contralateral spinal cord, and imply that many of the axons that are eliminated never synapse on spinal neurons. It is suggested that during the middle fetal period the axons of many of the cortical neurons in lamina V that in the mature monkey will terminate on particular neuron populations in the thalamus, brainstem, or spinal cord, traverse a common pathway down through the internal capsule into the spinal cord, passing close to these successive targets, and possibly forming collaterals at these levels. In the postnatal period each such neuron establishes a stable, effective synaptic input to only one or a few of these subcortical target populations, and the remaining collateral branches regress. The postnatal maturation of corticospinal neurons, examined in this study, is compatible with such a model.

Multiple corticospinal neuron populations in the macaque monkey are specified by their unique cortical origins, spinal terminations, and connections

In primates, multiple corticospinal projections from the sensorimotor cortex operate in concert to regulate voluntary action. We examined the soma distributions of all those corticospinal neuron populations projecting to different zones in the cervical and more caudal spinal segments in the macaque that are labeled with retrogradely transported fluorescent tracers; 2-4 differentiable dyes were injected into different sites in the cervical spinal cord of each of 11 monkeys. Lamina V of the cerebral cortex, in which all corticospinal neuron somas were located, was unfolded with computer assistance to form a flat surface, and local soma densities were displayed on this plane as contour and 3-D maps. At least nine discrete, somatotopically organized corticospinal projections were identified. Three separate corticospinal projections originated in frontal cortex. The first projected mostly from area 4 (approximately 35% of the total contralateral neuron population), but also from the adjacent dorsolateral area 6a alpha (approximately 6% of total). The second large corticospinal projection (approximately 15% of total) originated in the supplementary motor area and a third small projection (approximately 2.6% of total) projected from the "postarcuate" cortex. Two separate corticospinal neuron populations were identified in areas 24 (approximately 6% of total) and 23 (approximately 4% of total) of the cingulate cortex. Thus, nearly 70% of the contralateral corticospinal projection originated in frontal and cingulate cortex. At the boundary between the primary motor and somatosensory cortex there was a sharp change in the pattern of projections. Only approximately 2.2% of the contralateral corticospinal projection originated in area 3a, rising to approximately 9% in areas 3b/1, and approximately 13% in areas 2/5. The projections from SII and insula totaled 3.4%. Ipsilateral and contralateral corticospinal projection patterns were similar, but the ipsilateral projection was only approximately 8.1% of that from the contralateral cortex. Each corticospinal neuron population had terminals in the intermediate zone of all spinal segments; additionally, there were ventral horn projections from the primary motor and cingulate cortex, and dorsal horn projections from the somatosensory cortex. Recognizing a number of separate populations of corticospinal neurons in the frontal, parietal, and insular cortex, each with unique thalamic and cortical inputs, and each of which has continuous access to all spinal motoneuron populations, underlines the importance of cortical and spinal connections linking them and coordinating their action. No coherent model of the cortical control of limb movements that incorporates this functional anatomy yet exists.