Browsing by Subject "Spasticity"

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Accuracy and reliability of single camera measurements of ankle clonus and quadriceps hyperreflexia
(2020-08-13) Macon, Keith Browning; Sulzer, James S.
In people with stroke, spinal cord injury, multiple sclerosis, and other upper motorneuron lesions, ankle clonus and quadriceps spasms may limit self-care and mobility tasks. The ankle clonus drop test, which measures the plantar flexor reflex threshold angle (PFRTA), and the pendulum test, which measures the quadriceps reflex threshold angle (QRTA), provide valid and reproducible measurements of ankle clonus and quadriceps hyperreflexia. However, measuring the PFRTA and QRTA requires high fidelity motion capture systems that are limited to laboratory settings by cost and complexity. The aim of this study was to evaluate a simple, single-camera based method of measuring ankle clonus and quadriceps spasticity in clinical settings. With synchronous 3-D inertial motion capture to provide a high fidelity reference, we used a smartphone camera and green stickers to measure the PFRTA and QRTA of 14 individuals with ankle clonus or quadriceps hyperreflexia in one or both legs. This resulted in test sessions on 22 impaired legs with four repetitions of each test on each leg conducted by a student physical therapist and an experienced physical therapist. We hypothesized that the smartphone camera measurements would provide clinically useful outcome measures for assessing ankle clonus and quadriceps spasticity. To assess accuracy of the camera-measurements, we computed the bias and limits of agreement between the camera and the inertial motion capture measurements. For reliability, we computed intra-rater and inter-sensor reliability coefficients in addition to the minimum detectable change. The smartphone PFRTA biases were smaller than 0.2° and the QRTA biases smaller than 1.2°. The limits of agreement for the PFRTA were ±4.66°/ ±7.49° (student/expert), and for the QRTA were ±4.40°/±4.67°. Reliability was similar between the camera and inertial measurements of tests by both rater types: intra-rater reliability ranged from 0.85-0.90 for the PFRTA and ranged from 0.96-0.98 for the QRTA. The inter-sensor reliability when measuring the PFRTA and QRTA was 0.97 and 0.99. The minimum detectable change for the PFRTA ranged from 7.10°-8.70°, while for the QRTA ranged from 7.65°-8.27°. Based on prior research, the limits of agreement and minimum detectable change were sufficiently low for purposes of interindividual, repeatable measurement. These data show that student and experienced physical therapists using ubiquitous existing hardware such as a smartphone can produce accurate, reliable assessments of ankle clonus and quadriceps hyperreflexia in a clinical environment.
Association between reduced limb perfusion and muscle spasticity in persons with spinal cord injury
(2010-12) Parmar, Yesha Jayantilal; Griffin, Lisa; Tanaka, Hirofumi
Individuals with spinal cord injury (SCI) demonstrate reduced limb blood flow and muscle spasticity. It is plausible that the accumulation of metabolites, resulting from reduced perfusion, could exacerbate spasticity via activation of fusimotor neurons by Group III and IV afferents. PURPOSE: To determine the association between peripheral blood flow and muscle spasticity in persons with SCI. METHODS: A total of 16 individuals with SCI were classified into high (N=6), low (N=5), and no (N=5) spasticity groups according to their spasticity levels indicated by the modified Ashworth scale scores. Blood flow was measured in femoral and brachial arteries using duplex Doppler ultrasound and was normalized to limb lean mass obtained with dual energy X-ray absorptiometry. RESULTS: There were no significant group differences in age (30.5±4.15, 38.48±4.61, 32.6±4.89 years), time post SCI (8.5±4.2, 12.6±4.74, 6.8±1.66 years), American SCI Association motor scores (39.2±7.78, 59±12.34, 53.4±1.08), or sensory scores (96±22.1, 144.4±13.97, 130±13.8). Femoral artery blood flow, adjusted for limb lean mass, was significantly different (p=0.002) across the three leg spasticity groups (high 76.03±6.44, low 95.12±15.49, no 142.53±10.86 ml/min/kg).Total leg muscle spasticity scores were significantly and negatively correlated with femoral artery blood flow (r=-0.60, p=0.014). There was no significant difference in brachial artery blood flow between the three groups, indicating that the reduction in blood flow was confined to injured limbs and not due to systemic cardiovascular disorder. CONCLUSION: Among SCI patients, whole-leg blood flow is progressively lower in individuals with greater spasticity scores. These results suggest that a reduction in lower limb perfusion, among other factors, plays a significant role in the pathogenesis leading to muscle spasticity after SCI.
Operant conditioning of monosynaptic spinal reflexes and its computational modeling and simulation
(2023-04-18) Kim, Kyoungsoon; Sulzer, James S.; Deshpande, Ashish; Djurdjanovic, Dragan; Manella, Kathleen
Spasticity, or more specifically hyperreflexia, is a common impairment following neurological injury such as stroke. Current clinical interventions aimed at reducing rectus femoris (RF) hyperreflexia have shown modest effect but entails side effects and limited clinical evidence. My previous research has shown that RF hyperreflexia is associated with reduced knee flexion in people post-stroke with Stiff-Knee gait (SKG). I posit that reducing RF hyperreflexia should improve walking following SKG after stroke. I developed a non-pharmacological procedure using operant H-reflex conditioning of the RF, which allows the patient to self-modulate one’s spinal reflex activity, elicited via electrical stimulation on peripheral nerve. With current evidence that operant H-reflex conditioning enhances gait function in individuals with SCI, I conducted a proof-of-concept study to examine the feasibility of this procedure on the RF for healthy and post-stroke individuals. Operant conditioning of neural activation has a high incidence of non-responders, and delineating the explicit response to feedback can help determine why some individuals may not respond to neurofeedback training. I developed a simulated operant H-reflex conditioning neurofeedback environment that separated the ability to self-regulate the neurofeedback signal from its perception by using an explicit, unskilled visuomotor task. Main outcomes indicated that biological variability modulates performance and operant strategy depending on the feedback type. While previous results provided a holistic view of the effect of feedback parameters on overall performance and operant strategy, the next approach focused on determining whether such decisions could be predicted based on feedback on a trial-by-trial basis. I observed that the feedback sensitivity was modulated by biological variability and reward threshold. I used computational models to investigate the best estimate of learning resulting in feedback-weighted averages of previous decisions. This thesis introduces a novel simulated operant H-reflex conditioning environment that serves as a simple and robust model to quickly examine learning mechanisms, optimize learning, and potentially identify non-responders.