The physiology of stroke neurorehabilitation

The Journal of Physiology, Journal Year: 2025, Volume and Issue: 603(3), P. 611 - 615

Published: Jan. 21, 2025

The Cochrane network, in its definition of rehabilitation, refers to "interventions targeting a person's" capacity (by addressing body structures, functions, and activities/participation) … with the goal "optimizing" "functioning" "persons health conditions currently experiencing disability or likely experience …" (Negrini et al., 2022). In respect significance accorded 'capacity' 'functioning', rehabilitation lies squarely within purview physiology, emphasis on integration molecular, cellular, systems whole-body function. Neurorehabilitation (a.k.a. neurological rehabilitation) deals more specifically (e.g. National Institute for Health & Care Excellence, 2021) impairments that arise from injury brain, spine peripheral nerves, caused by disease, trauma, tumours, infections, metabolic insults disorders blood supply – such as stroke. terms ramifications, stroke ranks second highest cause death (Roth 2018), follows only neonatal ischaemic heart disease an agent long-term (Kyu 2018). Most notably, has impact severity, greater than any other chronic Adamson 2004). It is estimated approximately 15 million strokes occur worldwide every year (World Organization, 2024). Of those who survive, half will be left demands neurorehabilitation. With lethality falling, incidence rising especially low-income middle-income countries (Prust 2024), there renewed imperative direct research towards life after stroke, particularly since targets neurorehabilitation feature prominently among priorities identified survivors their carers (Pollock 2012). seems self-evident physiological knowledge should inform neurorehabilitation, when aspiration increase efficacy efficiency delivery. this context, might extend mechanisms mediate adaptation to, recovery from, brain damage. may also encompass means through which technique exerts effect. Writing collection, Carson Hayward (2025) point out these strands are integrated less frequently one suppose. addition, unlike many areas clinical science, relevant physiology sought (if at all) following concoction novel therapy, rather precursor. Perhaps due lack appreciation existing corpus directly This special issue Journal Physiology been devised aim highlighting recent empirical contributions corpus, along key theoretical concepts information can parsed. Many features responses observed tissue (and beyond) haemorrhagic have deeply characterised cellular levels, primarily using animal models. Especially salient context relationships exist between specific sequelae acute effects functions human nervous system. describing pathophysiology post-stroke dysphagia (PSD), Sasegbon al. emphasise understand PSD, it first necessary comprehend neurophysiology swallowing humans. complex involve dynamic interplay control centres defined level brainstem, well higher cerebellum cerebral cortices. Damage element distributed network result discoordination oropharyngeal oesophageal muscles otherwise engaged precise sequence safely convey ingested material oral cavity stomach. Yet, highlight, our interactions give rise requisite muscle synergies remains incomplete. Consequentially, not yet possible determine whether subcortical lesions arises damage centres, alterations connectivity cortical centres. gap understanding reflects general tension long-standing view functional deficits grey matter 'hub regions' (i.e. loci), increasingly influential conception 'circuitopathy' (Cassidy 2022), whereby magnitude white determines severity capacity. regard, Urbin draws attention observation macro-level typically lower threshold infarction matter. highlight findings integrity structural (brain) connectome preeminent factor determining extent motor function occurs weeks Structural disconnection seen exert causal influence (on capacity) disruption circuits tracts afford. support position, they review observations 'cross-road' regions comprising several expressed span multiple domains memory spatial memory, attention, motor, language). upper limb, long recognised (constituting 'projectome') efferent commands spinal neurons profound degree movement preserved Much contemporary discourse has, however, exclusive focus fibres corticospinal tract. exhaustive review, rich detailed analysis neuroanatomy, reminds us neural impulses goal-directed conveyed single Rather, keeping notion 'volitional set' Gottlieb, 1996), corticospinal-mediated changes excitability motoneurons shaped descending segmental pathways. Neuroanatomy further dictates rarely affects tract, heterogeneity distribution sustained across accounting least some variation impairment loss exhibited individuals (Urbin, 2025). nature imposes especial challenges forecast outcomes individual patients. Undertaken subacute stage, presence absence motor-evoked potentials (MEPs) contralateral delivery transcranial magnetic stimulation (TMS) scalp locations overlying primary cortex, offers promise biomarker limb Due various pathways (other tract) post-synaptic state motoneurons, MEPs cannot simply interpreted indicative tract integrity. does not, diminish potential utility MEPS, provide broadly encompassing measure corticomotor access final common pathway preserved. issue, Shanks Byblow argue binary MEP outcome (present absent) hitherto used biomarker, fail fully exploit prognostic power potentials. because criterion applied present arbitrary amplitude value 50 µV). As out, sub-threshold contain appraisal impairment, recovery. extension refinement approach, advocate use TMS-evoked obtained simultaneously wide range intensities. Three classes response designated: (1) meet conventional deemed 'present'; (2) below ordinarily (in scheme) marked 'absent'; (3) instances which, given muscle, intensity fails elicit MEP. resulting 'threshold matrix', subject compositional data analysis, represented ternary plot. Beyond providing granular status, phase during attenuated absent, hypothesise sub-regions plot differentiate phenotypes. A challenge determination optimal basis upon phenotypes recovery) defined. wide-ranging fatigue, Kuppuswamy argues presently unknown derived class variable perceptual/behavioural/neuronal), composite types. Although evidently broad significance, question relation fatigue. Divination answer is, hampered multidimensional fatigue symptomology, transcends paradigms assessment. Arguing that, fundamentally, 'fatigue' perceptual experience, makes case systematisation phenotyping precursor, firstly, enhanced pathophysiology, secondly, development effective treatments. While necessarily, multiplicity engenders manifestation models ground process beginning emerge. Analysing merits models, 'sensory attenuation model' dysfunction, provides promising account diverse phenomenology particular mediating altered attentional processes. model complementary conceptions apathy (described Hayward, 2025) diffuse cerebrovascular pathology impairs large-scale networks underpin control, reinforcement learning reward-based decision-making. theme emerge again, concept 'neuroplasticity' underpins much conducted domain fired popular imagination, works Brain That Changes Itself (Doidge, 2007). supposition instilled most vivid portrayals neuroplasticity, 'endless adaptability' (Sacks, An allied conjecture 'reorganisation' idea take new (for critical discussion see Makin Krakauer, 2023). inspirational studies notwithstanding, considerations evidence indicate, instead, neuroplastic adaptations already 'representational computational capacity' compromised. 'structural blueprint' system strong constraints realisable (Makin notes even cases severe paresis tends preservation brainstem origin course carry neuron pools. Rehabilitating therefore involves certain reintegration supraspinal circuits, vascular insult restricted former. Focussing neuraxis transmission tracts, study transneuronal degeneration regeneration) cord 'poor cousin' concerns itself infarcts circuits. 'Downstream' 'upstream' can, levels These include segregation into origins frontal parietal areas, funiculi terminations lumbar cervical segments, pools ventral horn Importantly, remain viable responsive excitation regardless identity fibre considerable period cells deprived usual trophic inputs. remarks, 'restoring about forming extensively circuitry altering substrate remains'. comprehensive focussing experience-driven competition reorganisation Jones emphasises under consideration, fundamental assumption regenerative reactions activity-dependent. practice tenet equivalent status behavioural interventions activity patterns manner promotes reactions. resides principles guide design interventions. Drawing work undertaken rodent seeks delineate permit identified, generalise populations. consistent experimentally induced cortex rodents de novo skill performed non-paretic forelimb interfere rehabilitative training engender improvements paretic paw. implication new-experience dependent performance paw disruptive (Jones, At glance, appear run counter impaired (discussed Kitchen 2025 (through 'cross education' effect) bring limb. detrimental consequences arising counteracted bimanual training, interleaving limbs. To echo raised (2025), determined whether, patients, schedule alternating engagement delineating molecular processes remodelling overstated, (which occupies bulk (Ebbesen Brecht, 2017)) very rare humans (van Assche 2021). interest additional yield convergent role both hemispheres promoting presumption endogenous CNS augmented neurons. employed engendering non-invasively (see 2025), current (tDCS) variants repetitive TMS (rTMS). balance available Ahmed 2023) protocols designed ipsilesional hemisphere efficacy, whereas intention decreasing contralesional limited meta-analysis (Ahmed indicated positive transcutaneous vagus nerve (VNS) exceeded physical alone outranked all forms non-invasive stimulation, measures activities daily living. contribution Schambra Hays survey foundational VNS therapy. They optimally mechanistic acts network. underlined probably different ascribed tDCS rTMS. large 'paired therapy' lends weight assertion. Applied non-invasively, administered ('open loop') (usually limb). paired VNS, bursts electrical delivered via implanted electrodes, intervals relative movements made 'closed loop' arrangement. Detailed profiling form supports triggers widespread release neuromodulatory neurotransmitters (including noradrenaline, serotonin acetylcholine), alters synapses generation movement) activated recently. Timing critical. Delivered 2 s event, experimental indices gains. If, hand, delay 10 s, no (Schambra Hays, There observation. When preclinical employed, traces synaptic differ depending spared injury. instrumental drive practical delivering electrode specificity suggests accommodate life-threatening event requiring urgent medical assistance care hospital, public education campaigns rightly urge vigilance manifestations. example, Service UK includes cardinal sign: 'weakness numbness down 1 side your body'. Medical textbooks too Torbey Selim, 2013), put unilateral expression symptoms. vein also, scientific literature replete articles draw contrast 'impaired limb' 'non-impaired limb'. tendency thus conceive body. Surveying garnered over decades, sometimes subtle, but definitively systematic, arm follow hemispheric specialisation selective demonstrated arms contingent injured. Expressed language dominance hypothesis (Sainburg, 2002, 2005), right-handed individuals) contains 'tuned' facilitate dynamics. Whereas right adapted regulation impedance. corollary while differentiation revealed clearly (the characteristics of) arm, local each play ipsilateral (Kitchen Consistent model, show early reaching misspecification initial direction), often achieving accurate position contrast, suffered commonly exhibit abnormalities decelerative accentuated errors positioning What more, appears closely related New strategies paresis) advanced remediate hemisphere-specific reader note convergence outworking approaches driven cross-education. Remaining way generated tests therapeutic phenomenon cross-education (Calvert Carson, 2022; lateralisation became functionally adaptive, i.e. phylogenetic sense, presumably evolved neuroanatomical structures capable supporting two hemispheres. Integration counterpart (hemispheric) specialisation. Accordingly, appraised callosum largest connecting hemispheres, significant bearing scope subsequent 2020). important future disconnectome modelling delineated scan referred either atlas structural/functional database healthy brains (dis)connectivity (Carson survivor, programme tailored 'recovery connectome' (Latifi Carmichael. papers collected illustrate concerning level, antecedent efficacious Such interruptions brain. lingua franca demanded match 2024) constituted processes, Please note: publisher responsible content functionality supplied authors. Any queries missing content) directed corresponding author article. No competing interests declared. Sole author. funding.

Language: Английский

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The relationship between the functional status of upper extremity motor neurons and motor function and prognosis in stroke patients

Frontiers in Neurology, Journal Year: 2024, Volume and Issue: 15

Published: Sept. 20, 2024

Introduction This study investigates the correlation between neuroelectrop-hysiological assessments such as motor unit number estimation (MUNE) and F-waves with upper extremity function one-year prognosis in stroke patients. Methods Neuroelectrophysiological of abductor pollicis brevis muscle, including MUNE F-waves, were conducted. Upper was evaluated using Fugl-Meyer Assessment Extremity (FMA-UE) Modified Ashworth Scale (MAS). Pearson multiple linear regression analyses performed to explore relationship variables F-waves. ROC curve analysis assessed predictive ability for function, binary logistic examined factors related improvement 1 year post-discharge. Results A total 130 patients ultimately included. Significant differences occupancy rate non-repeater (non-ORF) found hemiplegic unaffected sides ( p < 0.001), a significant difference F-wave mean latency 0.05). showed positive FMA-UE at admission side’s non-ORF 0.001). Multiple indicated that β = 0.88, 0.001) 0.275, 0.005) influenced FMA-UE. demonstrated higher (AUC 0.696, than 0.622, 0.018). Binary associated Conclusion are correlated patients, reflecting their status. These indicators have good value certain extent.

Language: Английский

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Preserved force control by the digits via minimal sparing of cortico‐spinal connectivity after stroke

Experimental Physiology, Journal Year: 2024, Volume and Issue: unknown

Published: Dec. 14, 2024

Abstract The ability to regulate finger forces is critical for manipulating objects during everyday tasks but impaired after damage white matter tracts that transmit motor commands into the spinal cord. This study examines cortico‐spinal connectivity required force control by digits neurological injury. We report on a unique case of stroke survivor who retained at level comparable neurologically intact adults despite extensive loss volume and severely compromised transmission from cortical areas onto final common pathway. Using combination imaging methods noninvasive stimulation techniques, we illustrate structure function slow‐conducting, pathway minimally spared underlies this survivor's transition stabilize paretic hand precision grip. interpret findings in context physiological mechanisms underlying distal limb current thinking neural adaptation brain injury due stroke.

Language: Английский

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Microstructure of the residual corticofugal projection from primary motor cortex in chronic stroke

Brain Communications, Journal Year: 2024, Volume and Issue: 7(1)

Published: Dec. 24, 2024

Movement dysfunction after stroke is largely due to the inability of cortical motor neurons activate spinal via transmission descending commands along corticofugal projection from primary cortex. Pathophysiological processes that ensue following injury have mostly resolved and white matter volume within remodelled tract has stabilized by chronic stage many months years symptom onset. Where cranial course residual microstructure explains potential muscles weakened at this still not well understood. Here, diffusion spectrum imaging was used reconstruct quantify its in survivors (n = 25) with longstanding hand impairment (7.7 ± 6.5 years). Portions overlapping abnormalities on structural images were defined as 'Overlap' compartment, portions above below compartment 'Rostral' 'Caudal' compartments, respectively. Maximal precision grip force size motor-evoked potentials elicited transcranial magnetic stimulation activation paretic muscles. Coherence fibre anisotropy directional diffusivities between tracts either cerebral hemisphere reduced relative neurologically-intact controls, most abnormal asymmetries observed compartment. While differences diffusivity intact detected prominently overall magnitude unrestricted closely linked muscle activation. The ability access neuron pools long onset therefore associated microstructural integrity subject secondary degeneration. These findings expand knowledge adaptation response neurological may inform applications seek reverse brain pathology when movement tends persist.

Language: Английский

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