This article examines artificial intelligence (AI) applications in spasticity assessment, analyzing technological innovations from 2020 to 2024 literature. Key findings demonstrate potential. Sensor-based systems achieve 91% to 94% accuracy in automated clinical assessment; computer vision enables precise markerless motion analysis, and natural language processing facilitates automated goal extraction. Digital twin technologies offer personalized treatment simulation capabilities. However, implementation challenges persist, including validation requirements, workflow integration demands, and ethical considerations. The authors conclude that AI represents a transformative paradigm shift toward data-driven, multidomain, objective, reliable, and patient-centered spasticity evaluation methodologies, although large-scale validation studies and seamless clinical integration remain development priorities.
Key points
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Traditional assessment limitations: Current clinical spasticity evaluation methods (Modified Ashworth Scale, Tardieu Scale) demonstrate poor inter-rater reliability and weak correlation with functional outcomes, failing to distinguish neural from non-neural components.
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Machine learning integration: Artificial intelligence-enhanced sensor systems achieve 91% to 94% accuracy in automated clinical assessments, providing objective and reproducible measurements through wireless sensors, electromyography, and sophisticated algorithms.
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Advanced technology applications: Computer vision enables markerless motion analysis, while natural language processing facilitates the automated extraction of goals and the formatting of SMART criteria for patient-centered care delivery, including data from wearable sensors related to real-world activities.
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Digital twin innovation: Virtual patient representations integrate multiple data sources to enable the simulation of treatment and the prediction of outcomes, thereby optimizing therapeutic approaches before clinical implementation.
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Implementation challenges: Despite technological promise, significant barriers include validation requirements, workflow integration complexities, data privacy concerns, and the need for comprehensive training while maintaining human clinical oversight.
Abbreviations
| AI | artificial intelligence |
| EMG | electromyographic |
| GAS | goal attainment scaling |
| NLP | natural language processing |
| RF | random forest |
| ROM | range of motion |
| SMART | specific, measurable, achievable, relevant, time-bound |
| SVM | support vector machine |
Introduction
Artificial intelligence (AI) is quickly modifying the health care landscape, transforming diagnostic approaches, treatment planning methodologies, and comprehensive patient monitoring systems across various medical specialties, with radiology, cardiology, and pathology at the top. In physical medicine and rehabilitation, AI has the potential to address persistent challenges in objective assessment protocols and data-driven personalized care delivery frameworks, representing a paradigm shift toward precision rehabilitation medicine. Among the various fields of rehabilitation medicine, spasticity has long faced the challenge of providing objective assessment measures and capturing the complexity of patients’ dysfunction across multiple domains related to central nervous system lesions and spastic muscle overactivity.
Spasticity, characterized by Dressler and colleagues as involuntary muscle hyperactivity occurring in the presence of central paresis, affects millions of individuals worldwide across diverse neurologic conditions, including stroke, spinal cord injury, multiple sclerosis, and cerebral palsy. The clinical management of spasticity has traditionally relied heavily upon subjective assessment scales, particularly the Modified Ashworth Scale and Tardieu Scale. These demonstrate significant limitations, including poor inter-rater reliability, limited construct validity, and weak correlation with functional multidomain outcomes that matter most to patients and their families. , More critically, these conventional clinical measures of muscle response to stretch, although valuable for initial assessment, often fail to capture the complex functional implications of spasticity in real-world environments where patients actually live and interact. This fundamental disconnect between clinical measurement and functional reality represents one of the most significant challenges in contemporary spasticity management.
The complexity of patients with spasticity, a multifaceted phenomenon, extends far beyond simple muscle tone assessment, requiring extensive evaluation approaches that catch the diverse components of the condition. Modern understanding recognizes spasticity as an integral component of a broader upper motor neuron syndrome encompassing positive symptoms such as spasticity, clonus, and hyper-reflexia, alongside negative symptoms including weakness, loss of dexterity, and fatigue. , To these known features, one can also add components of the patient’s personal experience with this condition, as disfigurement, reduction in self-esteem, and pain. This requires comprehensive assessment methods capable of detecting the analytical features of spasticity syndrome and their significant impact on functional performance and quality of life.
The gap between laboratory-based measurements and real-world functional performance has become increasingly apparent as clinicians recognize that traditional spasticity metrics provide limited insight into how patients actually function in their home and community environments. Patients may demonstrate relatively mild spasticity on clinical examination yet experience significant functional limitations during activities of daily living, or conversely, may show severe clinical signs while maintaining surprising functional capabilities through compensatory strategies. This disconnect highlights the critical need for assessment approaches that can bridge the gap between clinical measures and meaningful functional outcomes.
Recent technological advances have created unprecedented opportunities to revolutionize spasticity assessment through sophisticated artificial intelligence (AI)-enhanced methodologies that address fundamental limitations of conventional traditional approaches. The possibility to converge data from wearable sensor technologies, advanced computer vision systems, clinical history evaluation through natural language processing, and, in the near future also digital twin technologies, could offer new possibilities for continuous monitoring, for a better objective quantification, real-word activities data for treatment prediction, and seamless integration of multidomain data sources. , These capabilities address fundamental limitations of current assessment approaches while opening innovative avenues for precision medicine implementation in comprehensive and patient-centered spasticity management.
One of the points of this article is to understand if and how AI-driven assessment platforms could bridge the critical gap between laboratory-based measurements and real-world functional performance, providing clinically meaningful interpretations of traditional spasticity metrics within the context of each patient’s specific functional challenges and life priorities. This data-driven approach aims to facilitate the establishment of personalized, evidence-based treatment goals that directly address each patient’s specific functional limitations and life priorities, moving beyond generic clinical targets to focus on outcomes that truly matter to patients and their families.
Traditional spasticity assessment: limitations and clinical challenges
Clinical Scales and Their Methodological Limitations
Despite significant limitations in objectivity, reliability, and correlation with functional outcomes that patients consider most important, the Modified Ashworth Scale remains the most widely used clinical measure of spasticity. The scale grades resistance to passive movement using a 6-point ordinal scale, based entirely on the clinician’s subjective perception during manual stretching procedures, which introduces substantial variability and potential bias. Inter-rater reliability has been consistently questioned across multiple studies, with research demonstrating only moderate agreement even among highly experienced clinicians with extensive spasticity management expertise.
The construct validity of the Modified Ashworth Scale has been fundamentally challenged based on its inability to distinguish between neural components, such as spasticity, and non-neural components, including muscle stiffness and contracture formation. The scale measures resistance to passive movement, which is influenced by multiple factors beyond spasticity, including mechanical properties of muscles and soft tissues, contracture development, and voluntary muscle activation patterns. This fundamental limitation significantly restricts the Modified Ashworth Scale’s ability to specifically measure the neurophysiological phenomenon of spasticity as distinct from other contributors to movement resistance.
The Tardieu Scale attempts to address some limitations by incorporating assessments at different stretch velocities, thereby better capturing the velocity-dependent nature of spasticity, a key pathophysiological characteristic. However, standardizing stretch velocities remains challenging in diverse clinical settings, and the time required for proper administration significantly limits their practical application in busy clinical environments.
Functional Assessment Challenges and Clinical Implementation
The recognition that impairment-based measures demonstrate poor correlation with functional outcomes has led to an increased emphasis on functional assessment and goal-based approaches, prioritizing patient-centered outcomes. Trying to address this problem, goal attainment scaling (GAS) has emerged as a valuable methodology for setting individualized treatment goals structured according to SMART (specific, measurable, achievable, relevant, time-bound) criteria, representing a shift toward patient-centered care delivery. GAS has become a new standard in clinical evaluation of patients with spasticity, and is now also used in research studies. However, GAS is time consuming and needs thorough clinical expertise to implement because of its steep learning curve. Moreover, it could suffer from subjectivity, potentially introducing biases that may influence treatment outcomes and evaluation processes. Some authors have proposed that Web-based tools could help clinicians overcome these limitations by improving their ability to select adequate and reliable goals, reducing the time required, and implementing GAS in a clinical setting.
The multidimensional nature of spasticity, encompassing neural and non-neural components, static and dynamic elements, and impairment alongside functional aspects, creates complex assessment challenges that prove difficult to address comprehensively with traditional methodologies. This complexity is further compounded by the variability of spasticity across different contexts, activities, and environmental factors, requiring sophisticated assessment approaches to capture this multifaceted presentation.
Discussion
Artificial Intelligence Technologies in Comprehensive Spasticity Assessment
Machine learning approaches for advanced sensor-based assessment
Machine learning algorithms can analyze complex sensor data to provide objective measures of spasticity, addressing the fundamental limitations of traditional assessment methods. Recent research by Yee and colleagues has led to a comprehensive sensor-based system that integrates wireless wearable sensors, including sophisticated goniometers, myometers, and surface electromyography sensors, to create a holistic assessment framework. Their innovative approach extracted 18 distinct features from comprehensive sensor data and used a combined logical support vector machine (SVM)-random forest (RF) approach that achieved an impressive 91% accuracy in predicting Modified Ashworth Scale scores, substantially outperforming individual classifiers and demonstrating the power of ensemble learning approaches.
Artificial neural networks have shown particular promise in learning complex patterns from biomechanical data, with the ability to capture subtle relationships that may not be apparent through traditional analytical approaches. Park and colleagues demonstrated that neural networks could be trained to mimic spasticity assessment performed by human clinicians, achieving satisfactory agreement with multiple expert raters while providing consistent, reproducible evaluations that eliminate inter-rater variability concerns.
With sophisticated algorithms trained to detect abnormal muscular activity patterns that characterize spasticity, AI technologies could analyze electromyographic signals during gait or upper extremity movements, whether passive or active. Implementing such tools is technically feasible, considering that semi-automated electrocardiogram analysis has been successfully used for several years, while recent studies in electroencephalogram analysis have shown that AI-based evaluation equals or exceeds human expert evaluation capabilities. Because most currently available data focus on gait and lower extremity movement patterns, applications in gait analysis appear most feasible for immediate implementation, offering the potential for semi-automated gait analysis while enabling longitudinal tracking of patient modifications over time.
Machine learning applications in gait analysis include sophisticated joint moment prediction from kinematic data, representing a significant advancement in biomechanical assessment capabilities. Using video-based, markerless assessment associated with AI-based moment prediction, clinicians could obtain comprehensive gait analysis using portable devices, resulting in substantial time savings and significant cost reductions compared with traditional laboratory-based approaches. However, several technical challenges currently prevent commercial implementation, particularly difficulties in accurately predicting hip moments from video-based kinematic data, although ongoing research continues to address these limitations.
Patient movements could be evaluated, rated automatically, and compared with a dataset from healthy subjects. Again, there are currently more data for gait than upper limb movements. One domain in which AI-based assessment is relatively advanced is passive and active range of motion (ROM) measurement. With automated AI-based optical systems, measuring hand movements (discriminating each finger and metacarpophalangeal joints and interphalangeal joints) in less than a second is possible. As for tremor analysis, deep learning systems could assist in evaluating patterned movements to classify and/or identify modifications in spasticity.
Applying machine learning to electromyographic signal analysis has yielded promising results in distinguishing between voluntary and involuntary muscle contractions. Lonini and colleagues developed a sophisticated system using skin-mounted, flexible wireless sensors to collect electromyographic and motion data from individuals with stroke, computing 15 distinct features from electromyographic data and using linear discriminant analysis to distinguish between voluntary muscle contractions and spastic contractions with remarkable accuracy, achieving an area under the curve of 0.94. In another recent paper, Merlo and colleagues demonstrated in 10 individuals with central nervous system lesions and complete paralysis of the upper extremity that an automated algorithm had the potential to detect involuntary muscle activity in the elbow flexors, combining accelerometer and electromyographic (EMG) signals in all patients.
Computer vision and advanced markerless motion analysis
Computer vision technologies have fundamentally changed movement analysis by enabling comprehensive, markerless motion capture and the automated assessment of movement patterns, without the constraints of traditional marker-based systems. A systematic review by Lam and colleagues examined 65 studies on markerless motion capture technology for clinical measurement in rehabilitation settings, identifying Microsoft Kinect as the most frequently used system. However, recent trends demonstrate increasing adoption of smartphone-based motion analysis systems because of their enhanced accessibility and portability.
Computer vision applications in spasticity assessment focus on the automated analysis of movement patterns during passive and active movements, using sophisticated algorithms that can detect subtle changes in movement quality, timing, and coordination that may not be apparent to human observers. Current algorithms can analyze video data, extracting precise kinematic parameters, including joint angles, velocities, and accelerations, and provide objective measures of movement characteristics associated with spasticity, while eliminating subjective interpretation variability. Recent advancements in deep learning have significantly improved the capabilities of automated video recording for movement analysis. Neural networks can now precisely identify specific movement patterns associated with spasticity. These systems can process video data in real time, providing clinicians and patients with immediate feedback.
Automated detection of muscular modifications using advanced ultrasound technologies
Muscle modifications in patients with spasticity are primarily characterized by fibrofatty infiltration of muscles alongside fascial thickening and progressive muscle atrophy, representing essential markers of disease progression and treatment response. These modifications can be clinically observed using ultrasound imaging, with evaluation currently performed through qualitative assessment of muscle echo intensity using the modified Heckmatt scale. AI technologies, combined with the appropriate ultrasound settings, can facilitate the automated assessment of muscle characteristics and the identification of regions of interest within muscle tissue.
Recent research has demonstrated that AI-powered software can successfully automate muscle thickness and echo intensity measurements in healthy subjects and patients hospitalized in intensive care units, taking 99.8% less time than human experts while maintaining similar consistency and accuracy levels. Relatively spared structures within muscle tissue, such as hypoechoic pouches, could theoretically be automatically identified and highlighted in AI-enhanced ultrasound systems, potentially assisting clinicians in identifying optimal targets for botulinum toxin injection procedures.
Natural language processing for clinical documentation and comprehensive outcome assessment
Natural language processing (NLP) represents an emerging and particularly promising application of AI in spasticity assessment, with specific relevance to goal setting, clinical documentation, and comprehensive outcome evaluation. These sophisticated technologies can analyze unstructured clinical text to extract meaningful information, standardize terminology across different providers and settings, and provide valuable assistance in clinical decision-making processes.
The application of NLP to goal setting addresses one of the most challenging aspects of patient-centered care delivery. NLP systems can analyze patient interviews and read comprehensive clinical notes and historical documentation to automatically extract patient (or caregiver) priorities and translate them into structured treatment goals aligned with established frameworks. These systems may assist in formatting goals according to SMART criteria, transforming patient expressions into objectives that facilitate effective treatment planning and outcome measurement.
This represents one of the most clinically relevant AI-based tools for spasticity assessment in the immediate future, particularly as clinical practice shifts from impairment-based evaluation relying primarily on tone scales such as the Modified Ashworth Scale and Tardieu Scale toward goal-based approaches that guide comprehensive spasticity treatment. Patient experience, individual needs, and personal preferences are critical determinants in choosing treatment (indication and modalities) and outcome selection, representing a fundamental shift toward patient-centered care delivery.
With NLP technologies, it is possible to automate the analysis of clinical notes; patient and caregiver experiences can be captured through audio recordings during clinical visits, and multidimensional data from electronic medical records can be transcribed and analyzed. These systems can extract priorities and assist clinicians in translating them into relevant treatment goals while ensuring consistency and comprehensiveness. This capability has been evaluated and tested in health care situations sharing similar backgrounds to rehabilitation medicine, including trained NLP systems capable of detecting goals of care relevant to end-of-life decisions in palliative care medicine through analysis of electronic medical records and clinical notes.
Another NLP system was able to accurately extract headache frequency from clinical notes, showing that even nonstructured written notes could be examined, decoded, and evaluated automatically.
NLP could also help format goals in SMART criteria, translating a nonstructured goal into a structured and measurable one (eg, “I want to reduce pain in my shoulder” into “The goal is to reduce pain at the shoulder at rest of at least 40% at 4 weeks after botulinum toxin injection”).
NLP could also review electronic patients’ documentation, identify response patterns to previous treatments, and suggest goal modifications.
Another aspect that could be improved in spasticity assessment using NLP is consistency in documentation. Because of time constraints and variability among more and less experienced clinicians, NLP could ensure proper terminology use and standardize patient descriptions.
The clinician could dictate or type notes during their assessment, and the NLP system directly processes this input. The system could identify key clinical findings and the patient’s expectations and goals directly during the clinical examination and history. The system could also suggest appropriate outcome measures for a specific goal (eg, a 6-minute walking test if the goal is to improve walking endurance).
NLP could also facilitate goal formatting according to SMART criteria, transforming nonstructured goals into structured and measurable objectives while reviewing electronic patient documentation to identify response patterns to previous treatments and suggest appropriate goal modifications. Another significant aspect that could be improved through NLP implementation is consistency in clinical documentation, addressing time constraints and variability among clinicians with different experience levels.
Wearable technology and comprehensive continuous monitoring
For over a decade, wearable sensor technologies have offered the potential for continuous monitoring of patients in real-world environments. Wearables could provide clinicians with unique insights into the variability and progression of spasticity symptoms across different contexts and periods, revealing modifications in a patient’s activities. Modern wearable sensors can simultaneously capture multiple physiologic and biomechanical parameters relevant to comprehensive spasticity assessment, including detailed movement patterns, muscle activation characteristics, and tremor characteristics with high temporal resolution. ,
Recent advances in flexible, skin-mounted sensors have effectively overcome many practical limitations of traditional wearable devices by conforming to body contours and offering comfortable, long-term monitoring without disrupting daily activities. More advanced AI algorithms for wearable sensors will likely be able to identify specific patterns linked to spastic muscle contractions, distinguishing them from voluntary movements in real time.
The continuous monitoring capabilities enable detection of patterns and trends that would not be apparent from intermittent clinical assessments, including circadian variations in spasticity severity, individual responses to medication timing, and the impact of specific activities on symptom expression. This comprehensive information proves invaluable for optimizing treatment timing and dosing while facilitating personalized care approaches that account for individual variation in symptom presentation.
Digital twin technology and personalized medicine applications
One of the biggest challenges in complex evaluations is combining vast amounts of data from different sources into a coherent picture. AI can provide the capability to integrate diverse data points of comprehensive assessment, combining traditional clinical scales, sophisticated biomechanical measurements, patient-reported outcomes, and continuous data from wearable devices. This integration can provide a more holistic view of individual patients than any single assessment method while leveraging the capability to handle large datasets to reveal trends and associations that remain invisible through traditional single-evaluation approaches.
Digital twin technology is the most advanced use of AI in personalized medicine, creating detailed virtual models of individual patients for treatment simulation, outcome prediction, and personalized care planning. Recent research by Mikołajewska and colleagues emphasized the potential of AI-based digital patient twins in rehabilitation, allowing customized treatment plans by simulating various rehabilitation scenarios with predictive modeling capabilities.
Digital twins in spasticity management can simulate the effects of other treatment methods before clinical use, potentially enhancing treatment choices while reducing trial-and-error approaches. Their predictive abilities go beyond immediate treatment results to advanced long-term outcome modeling, analyzing patterns from similar patients while including individual traits to forecast the chances of reaching specific functional goals with different treatment options.
Clinical implementation and workflow integration considerations: comprehensive decision support
AI-powered decision support systems provide clinicians with evidence-based recommendations for treatment selection, optimal dosing, and timing of interventions based on a comprehensive analysis of patient-specific data combined with large databases of treatment outcomes. These sophisticated systems analyze individual patient characteristics in conjunction with extensive outcome databases to generate personalized recommendations for comprehensive spasticity management, accounting for individual variation and treatment response patterns.
User interface design and comprehensive training requirements
The success of AI implementation depends heavily on intuitive user interface design that integrates seamlessly with existing clinical workflows while minimizing disruption to established practices. Effective artificial intelligence systems should present information in formats familiar to clinicians while providing real-time feedback during clinical assessments that enhances rather than replaces clinical decision-making capabilities.
The integration of AI recommendations with clinical judgment represents a critical consideration. AI medical systems are designed to support rather than replace clinical decision making while providing evidence-based guidance that enhances clinical expertise. Comprehensive training programs are essential for successful implementation, addressing both the technical aspects of system operation and the clinical interpretation of AI-generated results, while ensuring appropriate integration with existing clinical knowledge and experience.
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