Jonathan F. Marsden

Identifying brain regions for integrative sensorimotor processing with ankle movements

The objective of this study was to define cortical and subcortical structures activated during both active and passive movements of the ankle, which have a fundamental role in the physiology of locomotion, to improve our understanding of brain sensorimotor integration. Sixteen healthy subjects, all right-foot dominant, performed a dorsi-plantar flexion task of the foot using a custom-made wooden manipulandum, which enabled measurements of the movement amplitude. All subjects underwent a training session, which included surface electromyography, and were able to relax completely during passive movements. Patterns of activation during active and passive movements and differences between functional MRI (fMRI) responses for the two types of movement were assessed. Regions of common activation during the active and passive movements were identified by conjunction analysis. We found that passive movements activated cortical regions that were usually similar in location to those activated by active movements, although the extent of the activations was more limited with passive movements. Active movements of both feet generated greater activation than passive movements in some regions (such as the ipsilateral primary motor cortex) identified in previous studies as being important for motor planning. Common activations during active and passive movements were found not only in the contralateral primary motor and sensory cortices, but also in the premotor cortical regions (such as the bilateral rolandic operculum and contralateral supplementary motor area), and in the subcortical regions (such as the ipsilateral cerebellum and contralateral putamen), suggesting that these regions participate in sensorimotor integration for ankle movements. In future, similar fMRI studies using passive movements have potential to elucidate abnormalities of sensorimotor integration in central nervous system diseases that affect motor function.

Theta Burst Stimulation in the Rehabilitation of the Upper Limb: A Semirandomized, Placebo-Controlled Trial in Chronic Stroke Patients

Background. Noninvasive cortical stimulation could represent an add-on treatment to enhance motor recovery after stroke. However, its clinical value, including anticipated size and duration of the treatment effects, remains largely unknown. Objective. The authors designed a small semi-randomized clinical trial to explore whether long-lasting clinically important gains can be achieved by adding theta burst stimulation (TBS), a form of repetitive transcranial magnetic stimulation (TMS), to a rehabilitation program for the hand. Methods. A total of 41 chronic stroke patients received excitatory TBS to the ipsilesional hemisphere or inhibitory TBS to the contralesional hemisphere in 2 centers; each active group was compared with a group receiving sham TBS. TBS was followed by physical therapy for 10 working days. Patients and therapists were blinded to the type of TBS. Primary outcome measures (9-hole Peg Test [9HPT], Jebsen Taylor Test [JTT], and grip and pinch-grip dynamometry) were assessed 4, 30, and 90 days post treatment. The clinically important difference was defined as 10% of the maximum score. Results. There were no differences between the active treatment and sham groups in any of the outcome measures. All patients achieved small sustainable improvements—9HPT, 5% of maximum (confidence interval [CI] = 3%-7%); JTT, 5.7% (CI = 3%-8%); and grip strength, 6% (CI = 2%-10%)—all below the defined clinically important level. Conclusions. Cortical stimulation did not augment the gains from a late rehabilitation program. The effect size anticipated by the authors was overestimated. These results can improve the design of future work on therapeutic uses of TMS.

The vestibular control of balance after stroke

Objectives: To examine vestibular control of balance in those who recovered the ability to stand after middle cerebral artery (MCA) stroke. Methods: Sixteen patients with MCA stroke were compared with 10 age matched controls. Two additional patients were studied with isolated corticospinal tract lesions, one each at the level of the pons and medulla. Vestibular evoked postural responses were obtained using galvanic vestibular stimulation (GVS) while patients stood with their eyes closed and head facing forwards, equally loading both legs. The GVS response was characterised by measuring the amplitude of the stimulus evoked lateral forces acting through each leg and the lateral displacement of the axial skeleton. Results: Lateral displacement and net lateral force following GVS were significantly larger after stroke. Unlike controls, the lateral forces in the stroke group were asymmetrical, being enhanced on the side of the non-paretic limb and small on the side of the paretic limb. The degree of GVS evoked asymmetry correlated with corticospinal damage assessed using transcranial magnetic stimulation. A similar asymmetrical response was seen in the patient with the pontine lesion but not the patient with the medullary lesion. Conclusions: MCA stroke may disrupt corticobulbar projections to brainstem output pathways involved in vestibular control of balance. These projections are either collaterals of the corticospinal tract or lie close to that tract and terminate in the pons/upper medulla. This hypothesis accounts for the association between corticospinal tract damage and GVS response asymmetry, and the lack of GVS evoked asymmetry with corticospinal lesions below the rostral medulla.

Bipedal distribution of human vestibular-evoked postural responses during asymmetrical standing

Galvanic vestibular stimulation (GVS) evokes responses in muscles of both legs when bilateral stimuli are applied during normal stance. We have used this technique to assess whether asymmetrical standing alters the distribution of responses in the two legs. Subjects stood either asymmetrically with 75 % of their body weight on one leg or symmetrically with each leg taking 50 % of their body weight. The net response in each leg was taken from changes in ground reaction force measured from separate force plates under each foot. The net force profile consisted of a small initial force change that peaked at ∼200 ms followed by an oppositely directed larger component that peaked at ∼450 ms. We analysed the second force component since it was responsible for the kinematic response of lateral body sway and tilt towards the anode. In the horizontal plane, both legs produced lateral force responses that were in the same direction but larger in the leg ipsilateral to the cathodal ear. There were also vertical force responses that were of equal size in both legs but acted in opposite directions. When subjects stood asymmetrically the directions of the force responses remained the same but their magnitudes changed. The lateral force response became 2‐3 times larger for the more loaded leg and the vertical forces increased 1.5 times on average for both legs. Control experiments showed that these changes could not be explained by either the consistent (< 5 deg) head tilt towards the side of the loaded leg or the changes in background muscle activity associated with the asymmetrical posture. We conclude that the redistribution of force responses in the two legs arises from a load‐sensing mechanism. We suggest there is a central interaction between load‐related afferent input from the periphery and descending motor signals from balance centres.

Functional response to active and passive ankle movements with clinical correlations in patients with primary progressive multiple sclerosis

Patients with multiple sclerosis (MS) activate a more diffuse cortical network than do healthy subjects when they perform motor tasks. This brain functional reorganisation might contribute to the limiting of disability, but it is unclear whether there is a loss of regional activation in more advanced disease. The aim of this study was to assess whether functional reorganisation diminishes in more disabled patients with primary progressive (PP) MS. The differences in the fMRI response to active and passive movements of the dominant ankle of 13 patients and 16 controls were assessed. The relationships between functional activation and disability and brain lesion load and atrophy were investigated.Patients showed greater fMRI activation than controls with passive movements in the superior temporal gyrus, rolandic operculum, and putamen. The fMRI response to active and passive movements in the ipsilateral inferior frontal gyrus was lower in patients with greater disability and greater brain T2 lesion load, respectively. Furthermore, the fMRI activation with active movements in the contralateral cerebellum was lower in patients with worse mobility.The increased activity with passive movements in regions that participate in sensori–motor integration, such as the putamen, reflects true functional reorganisation, since passive movements induce brain activation through sensory afferents only. The inverse correlation between the fMRI response in regions that are associated with motor control, and clinical or MRI measures of disease progression, suggests that there is a loss of distributed activation in more disabled patients. This may inform future treatment strategies.

De-stabilizing and training effects of foot orthoses in multiple sclerosis

This study evaluates the effects of dynamic foot orthoses (DFO) on walking and balance performance in people with multiple sclerosis (MS). Sixteen ambulant subjects with MS and ten age-matched healthy control subjects were studied on initial receipt of foot orthoses and after four weeks of daily wear. Walking speed, MS Walking Scale-12 (MSWS-12) and standing balance were assessed with and without orthoses at both these times. During standing, stance width and vision were varied, and performance was quantified using the velocity of the centre of pressure (COP), body sway velocity and the mean COP position relative to the shoe. People with MS walked slower (p<0.001) and showed increased sway when standing (p<0.001). At the first assessment, the foot orthoses caused an increase in sway and a medial and posterior shift of the COP position. At repeat measurement, the DFOs continued to increase sway compared to a shoe only condition. However, MS subjects reported an improvement in the MSWS-12 (p<0.05) and, compared to the initial session, showed decreased sway when eyes were closed both with and without DFOs. Dynamic foot orthoses may increase sway and change COP position by altering foot alignment and/or plantar afferent stimulation. Improvement in body sway over time may be an overall training effect of the DFOs, as MS subjects adapt to the initial de-stabilization.

The management of spasticity in adults

#### Summary points Spasticity is a common disorder affecting people with long term neurological conditions such as stroke, multiple sclerosis, and traumatic brain and spinal cord injuries. A systematic review of 24 studies on the epidemiology of leg spasticity reported a prevalence of 28-38% in patients with stroke, 41-66% in patients with multiple sclerosis, and 13% in patients with traumatic brain injury.1 Spasticity varies from a subtle neurological sign to a gross increase in tone causing immobility of joints. The disorder is associated with several complications, including falls, pain, pressure ulcers, infections, and contractures,2 although it is not clear whether these complications are caused by spasticity or co-exist independently.1 Spasticity increases care needs and utilisation of healthcare resources,3 and carers of patients with spasticity are more likely to experience anxiety and depression.4 Some patients may make use of their spasticity to sit, stand, walk, or transfer. Management of spasticity requires a balanced approach, weighing the benefits of treatment against the usefulness of the spasticity. Current interventions to treat spasticity lack a robust evidence base, and guidelines often depend on expert recommendations. This review discusses the assessment and treatment of spasticity in adults. #### Sources and selection criteria We searched the databases PubMed, AMED, Embase, Medline, British Nursing Index, and CINAHL using the keywords “spasticity”, “contracture”, “upper motor neurone”, and “muscle tone” from 2004 to 2014. We based this review …

Hip flexor fatigue limits walking in Charcot–Marie–Tooth disease

Charcot–Marie–Tooth (CMT) disease results in distal lower limb weakness that affects walking. In this study we assess the role of the hip flexors in compensating for distal weakness while walking and the effects of prolonged walking on these putative compensatory strategies. Eighteen subjects with CMT disease were compared with 14 matched controls while they walked on a treadmill to a predetermined point of perceived effort. A significant reduction was observed in peak hip flexor velocity during walking and hip flexor maximal voluntary contraction. In a second session following selective fatigue of the hip flexors, hip flexor velocity decreased immediately on walking, and walking duration was greatly reduced. This study suggests that hip flexors compensate for distal weakness and that fatigue in the hip flexors can limit walking duration. Treatments directed toward improving proximal muscle strength may therefore help to delay onset of hip flexor fatigue and thus prolong walking duration. Muscle Nerve, 2009

Randomised Feasibility Study of Physiotherapy for Patients with Functional Motor Symptoms

Objective To determine the feasibility of conducting a randomised controlled trial of a specialist physiotherapy intervention for functional motor symptoms (FMS). Methods A randomised feasibility study was conducted recruiting patients with a clinically established diagnosis of FMS from a tertiary neurology clinic in London, UK. Participants were randomised to the intervention or a treatment as usual control. Measures of feasibility and clinical outcome were collected and assessed at 6 months. Results 60 individuals were recruited over a 9-month period. Three withdrew, leaving 29 intervention and 28 controls participants in the final analysis. 32% of patients with FMS met the inclusion criteria, of which 90% enrolled. Acceptability of the intervention was high and there were no adverse events. At 6 months, 72% of the intervention group rated their symptoms as improved, compared to 18% in the control group. There was a moderate to large treatment effect across a range of outcomes, including three of eight Short Form 36 (SF36) domains (d=0.46–0.79). The SF36 Physical function was found to be a suitable primary outcome measure for a future trial; adjusted mean difference 19.8 (95% CI 10.2 to 29.5). The additional quality adjusted life years (QALY) with intervention was 0.08 (95% CI 0.03 to 0.13), the mean incremental cost per QALY gained was £12 087. Conclusions This feasibility study demonstrated high rates of recruitment, retention and acceptability. Clinical effect size was moderate to large with high probability of being cost-effective. A randomised controlled trial is needed. Trial registration number NCT02275000; Results.

Standardizing the intensity of upper limb treatment in rehabilitation medicine

Objective: To describe a treatment protocol for the upper limb that standardizes intensity of therapy input regardless of the severity of presentation. Design: The protocol is described (Part 1) and feasibility and effect explored (Part 2). Subjects: Participants (n = 11) had a single ischaemic stroke in the middle cerebral artery territory more than one year previously, and had residual weakness of the hand with some extension present at the wrist and the ability to grasp. Interventions: Following two baseline assessments, participants attended therapy for 1 hour a day for 10 consecutive working days. Treatment consisted of a combination of strength and functional task training. Outcomes were measured immediately after training, at one month and three months. Outcome measures: Intensity was measured with Borg Rating of Perceived Exertion. Secondary outcome measures included Action Research Arm Test (ARAT), nine-hole peg test, and Goal Attainment Scale. Results: Borg scores indicated that the level of intensity was appropriate and similar across all participants despite individual differences in the severity of their initial presentation (median (interquartile range) = 14 (13—15)). The mean ARAT score significantly increased by 6.8 points (χ2(3) = 15.618, P<0.001), and was maintained at three-month follow-up (z = - 2.384, P = 0.016). The nine-hole peg test also showed a main effect of time and 88% of goals set were achieved. Conclusions: The physiotherapy protocol standardized intensity of treatment by grading exercise and task-related practice according to the person’s residual ability, rather than simply standardizing treatment times. It was feasible and well tolerated in this group.