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Sensory feedback through spinal interneurons contributes to plantar flexor muscle activity during walking, but it is unknown whether this is also the case during nonlocomotor movements. Here, we explored the effect of temporary reduction of sensory feedback to ankle plantar flexors during voluntary contraction in sitting subjects. Thirteen healthy adults (mean age 32 yr) were seated with the right leg attached to a foot plate which could be moved in dorsi- or plantarflexion direction by a computer-controlled motor. EMG was recorded from the tibialis anterior (TA) and soleus (Sol) muscles. During static plantar flexion, while the plantar flexors were slowly stretched, a sudden plantar flexion caused a decline in Sol EMG at the same latency as the stretch reflex. This decline in EMG activity was still observed when transmission from dorsiflexors was blocked. It disappeared when transmission from ankle plantar flexors was also blocked. The same quick plantarflexion failed to produce a decline in EMG activity at the latency of the stretch reflex in the absence of slow stretch of the plantar flexors. Instead, a decline in EMG activity was observed 15-20 ms later. This decline disappeared following block of transmission from antagonists, suggesting that reciprocal inhibition was involved. These findings show that unload of ankle plantar flexors does not cause a similar drop in Sol EMG during voluntary contraction as during walking. This implies that sensory feedback through spinal interneurons only contributes little to the neural drive to plantar flexor muscles during human voluntary contraction in sitting subjects.NEW & NOTEWORTHY Sensory feedback through spinal reflex pathways makes only a minor contribution to neural drive to muscles during voluntary ankle plantar flexion. This differs distinctly from observations during walking and suggests that the neural drive to ankle plantar flexors during voluntary contraction do not rely on sensory feedback through simil

Problemstilling: Formålet med dette studie er at se på, om TENS kan bruges som behandling til at reducere centrale neuropatiske smerter ved patienter med skader i centralnervesystemet (CNS) herunder rygmarvskadede, stroke og multipel sclerose. Metode: PubMed, Embase og Google Scholar søgedatabaserne blev brugt til systematisk søgning i litteraturstudiet. Effektstudier fra 1989 til 2018 med TENS, som behandlingsmetode blev inkluderet. Resultater: 8 effektstudier med TENS blev inkluderet, herunder 5 studier med rygmarvsskadede patienter, 1 studie med multipel sclerose (MS) patienter, 1 studie med stroke patienter og 1 studie med alle 3 diagnosegrupper. Effekten af TENS var signifikant i alle studierne, men effekten på VAS- skalaen (Visuel Analog Skala) varierede fra største reduktion på 3,65 til mindste reduktion på 0,51 point på skalaen. Det ser ud til effekten af TENS er størst på rygmarvsskadede patienter. Konklusion: TENS ser ud til at være effektiv i forhold til at reducere centrale neuropatiske smerter hos patienter med skader i CNS. Evidensen er dog relativ svag. Fremtidige studier skal være veldesignet med større populationer for at kunne fremvise større effekt af behandlingen. Desuden mangler der flere studier, der specifikt ser på effekten af TENS ved MS-patienter og stroke patienter. Nøgleord: Central neuropatisk smerte (CNP), Central poststroke smerte (CPSP), Transkutan Elektrisk Nervestimulering (TENS), Rygmarvskadede, Multipel Sclerose (MS), Stroke patienter., Problem: The purpose of this study is to investigate if transcutaneous electrical nerve stimulation (TENS) can be used as a treatment to reduce central neuropathic pain in patients with injuries to the central nervous system (CNS), including people suffering from spinal cord injuries, stroke or multiple sclerosis. Method: The databases PubMed, Embase and Google Scholar were used in a systematic literature review, and effect studies from 1989 to 2018 in which TENS was used as the method of treatment included. Results: 8 effect studies using TENS were used, including 5 studies of patients with spinal cord injuries, 1 of multiple sclerosis (MS) patients, 1 of stroke patients, and 1 featuring all 3 groups. The impact of TENS was significant in all the studies, but the effect on the Visual Analog Scale (VAS) varied from a highest reduction of 3.65 points on the scale to a lowest reduction of 0.51. This indicates that the effect of TENS is greatest in patients with spinal cord injuries. Conclusion: TENS seems to be efficient when it comes to reducing central neuropathic pain in patients with CNS injuries. The evidence, however, is fairly weak. Future studies must be well designed and comprise bigger populations in order to demonstrate a greater effect of the treatment. Additionally, more studies need to focus specifically on the effect of TENS in MS and stroke patients. Key words: Central neuropathic pain (CNP), central post-stroke pain (CPSP), Transcutaneous Electric Nerve Stimulation (TENS), Spinal cord injuries, Multiple Sclerosis (MS), Stroke patients.

BACKGROUND: Cerebral palsy (CP) is a neurodevelopmental disturbance characterized by impaired control of movement. Function often decreases and 15% of adults are classified as severely affected (Gross Motor Function Classification Scale III-V). Little is known about interventions that aim to improve functional abilities in this population.OBJECTIVE: To evaluate a 12-week intervention based on motor learning principles on functional ability in adults with severe CP.METHODS: 16 adults (36±10 years, GMFCS III-V) were enrolled and divided into an intervention group (Active group) and a standard care group (Control group). Primary outcome measure was Gross Motor Function Measure (GMFM-88). Secondary measures were neurological status. The Active group were measured at baseline, after the intervention and at one-month follow-up. The Control group were measured at baseline and after one month.RESULTS: Analysis showed statistically significant improvement in GMFM-88 for the Active group from baseline to post assessment compared with the Control group (group difference: 5 points, SE 14.5, p = 0.008, CI: 1.2 to 8.7). Improvements were maintained at follow-up. Results from the neurological screening showed no clear tendencies.CONCLUSIONS: The study provides support that activities based on motor learning principles may improve gross motor function in adults with severe CP.

Hyperexcitable stretch reflexes are often not present despite of other signs of spasticity in people with brain lesion. Here we looked for evidence that increased resistance to length change of the plantar flexor muscle-fascicles may contribute to a reduction in the stretch reflex response in adults with cerebral palsy (CP). A total of 17 neurologically intact (NI) adults (mean age 36.1; 12 female) and 13 ambulant adults with CP (7 unilateral; mean age 33.1; 5 female) participated in the study. Subjects were seated in a chair with the examined foot attached to a foot plate, which could be moved by a computer-controlled electromotor. An ultrasound probe was placed over the medial aspect of the leg to measure the length of medial gastrocnemius muscle fascicles. Slow (7 deg/s) and fast (200 deg/s) stretches with amplitude 6 deg of the plantar flexors were applied over an ankle range of 70 deg at 10 deg intervals between 60 and 130 deg plantarflexion. It was checked by EMG electrodes that the slow stretches were sufficiently slow not to elicit any activity and that the fast stretches were sufficiently quick to elicit a maximal stretch reflex in both groups. The torque elicited by the stretches was measured together with changes in the length of medial gastrocnemius muscle fascicles. Muscle fascicles increased significantly in length with increasing dorsiflexion position in both populations (p <0.001), but the fascicles were shorter in the CP population at all positions. Slow stretches elicited significantly larger torque and significantly smaller length change of muscle fascicles as the ankle joint position was moved more towards dorsiflexion in CP than in NI (p <0.001). Fast stretches elicited larger torque responses at ankle joint positions of 80-100 deg in the NI than in the CP group (p <0.01). A significant negative correlation was observed between the torque response and muscle fascicle length change to slow stretch in CP (p <0.05), but not in NI. Th

The present study used coherence and directionality analyses to explore whether the motor cortex contributes to plantar flexor muscle activity during the stance phase and push-off phase during gait. Subjects walked on a treadmill, while EEG over the leg motorcortex area and EMG from the medial gastrocnemius and soleus muscles was recorded. Corticomuscular and intermuscular coherence were calculated from pair-wise recordings. Significant EEG-EMG and EMG-EMG coherence in the beta and gamma frequency bands was found throughout the stance phase with the largest coherence towards push-off. Analysis of directionality revealed that EEG activity preceded EMG activity throughout the stance phase until the time of push-off. These findings suggest that the motor cortex contributes to ankle plantar flexor muscle activity and forward propulsion during gait.

Exaggerated sensory activity has been assumed to contribute to functional impairment following lesion of the central motor pathway. However, recent studies have suggested that sensory contribution to muscle activity during gait is reduced in stroke patients and children with cerebral palsy (CP). We investigated whether this also occurs in CP adults and whether daily treadmill training is accompanied by alterations in sensory contribution to muscle activity. Seventeen adults with CP and 12 uninjured individuals participated. The participants walked on a treadmill while a robotized ankle-foot orthosis applied unload perturbations at the ankle, thereby removing sensory feedback naturally activated during push-off. Reduction of electromyographic (EMG) activity in the soleus muscle caused by unloads was compared and related to kinematics and ankle joint stiffness measurements. Similar measures were obtained after 6 wk of gait training. We found that sensory contribution to soleus EMG activation was reduced in CP adults compared with uninjured adults. The lowest contribution of sensory feedback was found in participants with lowest maximal gait speed. This was related to increased ankle plantar flexor stiffness. Six weeks of gait training did not alter the contribution of sensory feedback. We conclude that exaggerated sensory activity is unlikely to contribute to impaired gait in CP adults, because sensory contribution to muscle activity during gait was reduced compared with in uninjured individuals. Increased passive stiffness around the ankle joint is likely to diminish sensory feedback during gait so that a larger part of plantar flexor muscle activity must be generated by descending motor commands. NEW & NOTEWORTHY Findings suggest that adults with cerebral palsy have less contribution of sensory feedback to ongoing soleus muscle activation during push-off than uninjured individuals. Increased passive stiffness around the ankle joint is likely to diminishn sens

PURPOSE: We investigated if 30 min of daily treadmill training with an incline for 6 weeks would reduce ankle joint stiffness and improve active range of movement in adults with cerebral palsy (CP).METHODS: The study was designed as a randomized controlled clinical trial including 32 adults with CP (GMFCS 1-3) aged 38.1 SD 12 years. The training group (n = 16) performed uphill treadmill training at home daily for 30 min for 6 weeks in addition to their usual activities. Passive and reflex mediated stiffness and range of motion (ROM) of the ankle joint, kinematic and functional measures of gait were obtained before and after the intervention/control period. Intervention subjects trained 31.4 SD 10.1 days for 29.0 SD 2.3 min (total) 15.2 h.RESULTS: Passive ankle joint stiffness was reduced (F = 5.1; p = 0.031), maximal gait speed increased (F = 42.8, p < 0.001), amplitude of toe lift prior to heel strike increased (F = 5.3, p < 0.03) and ankle angle at heel strike was decreased (F = 12.5; p < 0.001) significant in the training group as compared to controls.CONCLUSION: Daily treadmill training with an incline for 6 weeks reduces ankle joint stiffness and increases active ROM during gait in adults with CP. Intensive gait training may thus be beneficial in preventing and reducing contractures and help to maintain functional gait ability in adults with CP. Implications for rehabilitation Uphill gait training is an effective way to reduce ankle joint stiffness in adult with contractures. 6 weeks of daily uphill gait training improves functional gait parameters such as gait speed and dorsal flexion during gait in adults with cerebral palsy.