Restorative Neurology and Neuroscience - Volume 40, issue 2

Authors: El nahas, Nevine | Roushdy, Tamer M. | Shokri, Hossam M. | Moustafa, Ramez R. | Elsayed, Ahmed M. | Amin, Randa M. | Ashour, Aya A. | Abd Eldayem, Eman H. | Elhawary, Ghada A. | Elbokl, Ahmed M.

Article Type: Research Article

Abstract: Highlights • In healthy adults, the lateralized readiness potential (LRP) is localized to the hemisphere contralateral to a moving limb. • In stroke, the LRP can lateralize contra-, or ipsilateral to the paretic limb depending on the stage of recovery. • Identification of hemisphere of recovery can guide further measures for enhancing brain plasticity. Background: Event related cortical potentials related to motor action are referred to as movement related cortical potentials. The late component of which is the readiness potential (RP) and its polarity is more negative in the hemisphere responsible for planning of motor action. This lateralized nature of RP …during unilateral hand movement is studied as lateralized readiness potential (LRP) by calculating the contralateral-minus-ipsilateral difference wave for each hand. Objective: The aim was to identify the hemisphere contributing to motor recovery in acute and chronic stroke patients through recording LRPs. Methods: Twenty-nine cases with cerebrovascular stroke (15 acute and 14 chronic) were included in the study. EEG was recorded in response to self-cued button presses by the paretic side to obtain the averaged LRP amplitude. The hemisphere with greater negativity was considered the side of recovery. Functional recovery was assessed by Fugl Meyer test. Results: In acute cases, recovery was more related to LRP activity in the contralesional hemisphere (73%), whereas lateralization was equal in chronic cases; 50% in either group. LRP amplitude was higher in the contralesional hemisphere (p  = 0.02). Functional recovery assessed by the Fugl Meyer test (FM) was similar whether recovery was ipsi- or contralesional. Conclusions: Early after stroke, motor recovery is more likely to involve compensatory activity in the contralesional hemisphere, while in the chronic phase, the ipsilesional hemisphere may recover its function and become more active. Further research is needed to verify if the technique mentioned in our study could be used to guide customized NIBS protocols tailoring the optimal site and parameters for each patient. Show more

Keywords: Lateralized readiness potentials, stroke, functional recovery, movement related cortical potentials, brain plasticity

DOI: 10.3233/RNN-211222

Citation: Restorative Neurology and Neuroscience, vol. 40, no. 2, pp. 63-71, 2022

Authors: Cabral, Danylo F. | Fried, Peter | Koch, Sebastian | Rice, Jordyn | Rundek, Tatjana | Pascual-Leone, Alvaro | Sacco, Ralph | Wright, Clinton B. | Gomes-Osman, Joyce

Article Type: Research Article

Abstract: Background: The sequelae of stoke, including the loss and recovery of function, are strongly linked to the mechanisms of neuroplasticity. Rehabilitation and non-invasive brain stimulation (NIBS) paradigms have shown promise in modulating corticomotor neuroplasticity to promote functional recovery in individuals post-stroke. However, an important limitation to these approaches is that while stroke recovery depends on the mechanisms of neuroplasticity, those mechanisms may themselves be altered by a stroke. Objective: Compare Transcranial Magnetic Stimulation (TMS)-based assessments of efficacy of mechanism of neuroplasticity between individuals post-stroke and age-matched controls. Methods: Thirty-two participants (16 post-stroke, 16 control) underwent an …assessment of mechanisms of neuroplasticity, measured by the change in amplitude of motor evoked potentials elicited by single-pulse TMS 10–20 minutes following intermittent theta-burst stimulation (iTBS), and dual-task effect (DTE) reflecting cognitive-motor interference (CMI). In stroke participants, we further collected: time since stroke, stroke type, location, and Stroke Impact Scale 16 (SIS-16). Results: Although there was no between-group difference in the efficacy of TMS-iTBS neuroplasticity mechanism (p  = 0.61, η 2  = 0.01), the stroke group did not exhibit the expected facilitation to TMS-iTBS (p  = 0.60, η 2  = 0.04) that was shown in the control group (p  = 0.016, η 2  = 0.18). Sub-cohort analysis showed a trend toward a difference between those in the late-stage post-stroke and the control group (p  = 0.07, η 2  = 0.12). Within the post-stroke group, we found significant relationships between TMS-iTBS neuroplasticity and time since stroke onset, physical function (SIS-16), and CMI (all rs > |0.53| and p -values < 0.05). Conclusions: In this proof-of-principle study, our findings suggested altered mechanisms of neuroplasticity in post-stroke patients which were dependent on time since stroke and related to motor function. TMS-iTBS neuroplasticity assessment and its relationship with clinical functional measures suggest that TMS may be a useful tool to study post-stroke recovery. Due to insufficient statistical power and high variability of the data, generalization of the findings will require replication of the results in a larger, better-characterized cohort. Show more

Keywords: Mechanism of neuroplasticity, transcranial magnetic stimulation, iTBS, functional capacity, motor function, stroke

DOI: 10.3233/RNN-211227

Citation: Restorative Neurology and Neuroscience, vol. 40, no. 2, pp. 73-84, 2022

Authors: Baroni, Andrea | Magro, Giacomo | Martinuzzi, Carlotta | Brondi, Laura | Masiero, Stefano | Milani, Giada | Zani, Giulia | Bergonzoni, Antonella | Basaglia, Nino | Straudi, Sofia

Article Type: Research Article

Abstract: Background: Balance and mobility impairments are frequent in people with multiple sclerosis, partly due to cerebellar dysfunctions. Task-oriented behavioural approaches were previously shown to promote physical function. The possibility exists that cerebellar transcranial direct current stimulation (ctDCS) applied during training, known to increase the excitability of the brain, can boost rehabilitation effects through modulation of cerebellum-brain inhibition. Objective: To test the efficacy of cerebellar ctDCS stimulation combined with motor training on mobility and balance in people with multiple sclerosis. Methods: 16 subjects were randomly assigned to receive real- or sham-ctDCS and task-oriented training daily over two …weeks in a double-blind, randomised clinical pilot trial. Functional mobility, balance, walking performance and quality of life were tested before and after treatment and at two-week follow-up. Effects of cerebellar stimulation on psychological and executive functions were also recorded. Results: Walking performance, balance and quality of life improved for both groups at post-treatment assessment which was maintained at 2-weeks follow up. A two-way ANOVA revealed a significant time effect for balance and walking performance. A significant interaction effect of time–treatment (F  = 3.12, df = 2,26; p  = 0.03) was found for motor aspects of quality of life assessment in patients who received real-ctDCS. Conclusions: Task-oriented training improves balance and mobility in people with multiple sclerosis, but ctDCS does not boost motor training effects. Show more

Keywords: Multiple sclerosis, mobility, balance, tDCS, task-oriented, cerebellum

DOI: 10.3233/RNN-211245

Citation: Restorative Neurology and Neuroscience, vol. 40, no. 2, pp. 85-95, 2022

Authors: Ranganathan, Rajiv | Doherty, Carson | Gussert, Michael | Kaplinski, Eva | Koje, Mary | Krishnan, Chandramouli

Article Type: Research Article

Abstract: Background: Despite tremendous advances in the treatment and management of stroke, restoring motor and functional outcomes after stroke continues to be a major clinical challenge. Given the wide range of approaches used in motor rehabilitation, several commentaries have highlighted the lack of a clear scientific basis for different interventions as one critical factor that has led to suboptimal study outcomes. Objective: To understand the content of current therapeutic interventions in terms of their active ingredients. Methods: We conducted an analysis of randomized controlled trials in stroke rehabilitation over a 2-year period from 2019-2020. Results: …There were three primary findings: (i) consistent with prior reports, most studies did not provide an explicit rationale for why the treatment would be expected to work, (ii) most therapeutic interventions mentioned multiple active ingredients and there was not a close correspondence between the active ingredients mentioned versus the active ingredients measured in the study, and (iii) multimodal approaches that involved more than one therapeutic approach tended to be combined in an ad-hoc fashion, indicating the lack of a targeted approach. Conclusion: These results highlight the need for strengthening cross-disciplinary connections between basic science and clinical studies, and the need for structured development and testing of therapeutic approaches to find more effective treatment interventions. Show more

Keywords: Rationale, ingredients, sample size, power, specificity, impairment

DOI: 10.3233/RNN-211243

Citation: Restorative Neurology and Neuroscience, vol. 40, no. 2, pp. 97-107, 2022

Authors: Fiselier, Anna | Mychasiuk, Richelle | Muhammad, Arif | Hossain, Shakhawat | Ghose, Abhijit | Kirkby, Charles | Ghasroddashti, Esmaeel | Kovalchuk, Olga | Kolb, Bryan

Article Type: Research Article

Abstract: Purpose: In recent years, much effort has been focused on developing new strategies for the prevention and mitigation of adverse radiation effects on healthy tissues and organs, including the brain. The brain is very sensitive to radiation effects, albeit as it is highly plastic. Hence, deleterious radiation effects may be potentially reversible. Because radiation exposure affects dendritic space, reduces the brain’s ability to produce new neurons, and alters behavior, mitigation efforts should focus on restoring these parameters. To that effect, environmental enrichment through complex housing (CH) and exercise may provide a plausible avenue for exploration of protection from brain …irradiation. CH is a much broader concept than exercise alone, and constitutes exposure of animals to positive physical and social stimulation that is superior to their routine housing and care conditions. We hypothesized that CHs may lessen harmful neuroanatomical and behavioural effects of low dose radiation exposure. Methods: We analyzed and compared cerebral morphology in animals exposed to low dose head, bystander (liver), and scatter irradiation on rats housed in either the environmental enrichment condos or standard housing. Results: Enriched condo conditions ameliorated radiation-induced neuroanatomical changes. Moreover, irradiated animals that were kept in enriched CH condos displayed fewer radiation-induced behavioural deficits than those housed in standard conditions. Conclusions: Animal model-based environmental enrichment strategies, such as CH, are excellent surrogate models for occupational and exercise therapy in humans, and consequently have significant translational possibility. Our study may thus serve as a roadmap for the development of new, easy, safe and cost-effective methods to prevent and mitigate low-dose radiation effects on the brain. Show more

Keywords: Dendritic morphology, radiation-induced brain changes, behavior

DOI: 10.3233/RNN-211216

Citation: Restorative Neurology and Neuroscience, vol. 40, no. 2, pp. 109-124, 2022