Absolutely nothing here helps survivors recover! I'd have you all fired!
The independence of impairments in proprioception and visuomotor adaptation after stroke
Journal of NeuroEngineering and Rehabilitation volume 21, Article number: 81 (2024)
Abstract
Background
Proprioceptive impairments are common after stroke and are associated with worse motor recovery and poor rehabilitation outcomes. Motor learning may also be an important factor in motor recovery, and some evidence in healthy adults suggests that reduced proprioceptive function is associated with reductions in motor learning. It is unclear how impairments in proprioception and motor learning relate after stroke. Here we used robotics and a traditional clinical assessment to examine the link between impairments in proprioception after stroke and a type of motor learning known as visuomotor adaptation.
Methods
We recruited participants with first-time unilateral stroke and controls matched for overall age and sex. Proprioceptive impairments in the more affected arm were assessed using robotic arm position- (APM) and movement-matching (AMM) tasks. We also assessed proprioceptive impairments using a clinical scale (Thumb Localization Test; TLT). Visuomotor adaptation was assessed using a task that systematically rotated hand cursor feedback during reaching movements (VMR). We quantified how much participants adapted to the disturbance and how many trials they took to adapt to the same levels as controls. Spearman’s rho was used to examine the relationship between proprioception, assessed using robotics and the TLT, and visuomotor adaptation. Data from healthy adults were used to identify participants with stroke who were impaired in proprioception and visuomotor adaptation. The independence of impairments in proprioception and adaptation were examined using Fisher’s exact tests.
Results
Impairments in proprioception (58.3%) and adaptation (52.1%) were common in participants with stroke (n = 48; 2.10% acute, 70.8% subacute, 27.1% chronic stroke). Performance on the APM task, AMM task, and TLT scores correlated weakly with measures of visuomotor adaptation. Fisher’s exact tests demonstrated that impairments in proprioception, assessed using robotics and the TLT, were independent from impairments in visuomotor adaptation in our sample.
Conclusion
Our
results suggest impairments in proprioception may be independent from
impairments in visuomotor adaptation after stroke. Further studies are
needed to understand factors that influence the relationship between
motor learning, proprioception and other rehabilitation outcomes
throughout stroke recovery.(What a pile of shit, suggesting further studies instead of during the correct research in the first place!)
Background
Stroke is a neurological disease that can result in a myriad of impairments. Although motor impairments are most common (80% of cases) [1], the majority of individuals with stroke (50–65%) also experience proprioceptive impairments affecting the sense of body position (position sense) and/or motion (kinesthetic sense) [2,3,4]. Despite growing recognition that proprioceptive impairments are associated with poorer motor recovery and rehabilitation outcomes [1, 5, 6], therapy tends to focus on improving the performance of movements that are important for daily living (e.g., feeding or grooming). It is unclear how proprioceptive impairments interact with the capacity to improve arm movements with practice after stroke.
Motor learning is a broad term that encompasses a variety of neural and behavioural processes that support long-term motor skill learning and short-term changes in behaviour that result from motor adaptation [7]. Skill learning involves processes that support the acquisition of new motor skills and sequences of movements. These movements are acquired over prolonged periods of practice and require retention to maintain skilled performance. Motor adaptation describes processes that are engaged by feedback mechanisms that eliminate errors and help to maintain the performance of skilled actions in different environments, tasks, and contexts [8,9,10,11,12,13,14,15]. Some evidence indicates these adaptive mechanisms may also be supported by neuroanatomical changes that help to retain and quickly engage memories of different environments, tasks, and contexts [16].
Rehabilitation interventions are generally based on the premise that motor learning is possible after stroke. Indeed, it is widely accepted that a variety of motor learning processes could be important for motor recovery [17, 18], and many forms of therapy attempt to leverage motor learning principles to promote neuroplasticity and facilitate the recovery of motor function in clinical settings [19]. The approach may be too simplistic. Growing evidence indicates that a wide range of motor learning impairments can occur after stroke, impacting the ability to learn sequences of arm and finger movements [20], perform tracking tasks [21, 22], and adapt reaching movements to counter visual [23,24,25,26,27] and force disturbances that disrupt movement accuracy [28,29,30].
Our understanding of how proprioceptive impairments interact with the ability to adapt and improve the performance of arm movements after stroke is limited. Much of our understanding comes from studies in healthy adults that have yielded mixed results. One study in healthy older adults reported that greater variability in position matching was associated with slower adaptation to a visuomotor rotation [31]. In contrast, others have reported that greater variability in position matching was associated with greater implicit adaptation in younger adults [32]. Finally, other work did not observe significant relationships between position or kinesthetic sense and visuomotor adaptation in healthy young or older adults [33]. These results have spurred an ongoing debate over the importance of proprioceptive function in motor adaptation.
Stroke may be a useful model for understanding how motor adaptation changes when proprioception is impaired. One study in chronic stroke demonstrated that reduced position sense was associated with reduced capacity to adapt and counter forces that disturb the arm during reaching movements [29]. It is unclear if a similar relationship exists between position sense and the capacity to adapt to visual disturbances since the processes that support adaptation to visual and force disturbances may rely on distinct behavioural mechanisms [13, 34] and neural structures [35, 36]. The relationship between kinesthetic sense and motor adaptation is also a relatively unexplored but important question since kinesthesia may rely on distinct neuroanatomical pathways from position sense [4, 37,38,39]. Characterizing the relationship between proprioceptive impairments and motor adaptation may be an important step in understanding factors that interact with the ability to adapt and improve the performance of upper limb movements after stroke.
Here we used a robotic device to examine the relationship between proprioception, assessed using bilateral position- and movement-matching tasks, and a specific type of motor learning known as visuomotor adaptation. Visuomotor adaptation describes the process of modifying movements in response to errors caused by a visual disturbance that systematically disrupts the relationship between the participant’s arm movements and visual feedback displayed in their workspace. This type of adaptation is thought to resemble challenges that individuals with stroke encounter on a daily basis while brushing their teeth in a mirror or using a computer mouse to guide a digital cursor on a screen [26]. Our objective was to examine the relationship between proprioception, assessed using robotic tasks and a traditional clinical scale (TLT—Thumb Localization Test), and measures of visuomotor adaptation after stroke.
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