Characterization of Involuntary Contractions after Spinal Cord Injury Reveals Associations between Physiological and Self-Reported Measures of Spasticity

A scoping review on muscle cramps and spasms in upper motor neuron disorder-two sides of the same coin?

Background

Muscle cramps are typically regarded as benign muscle overactivity in healthy individuals, whereas spasms are linked to spasticity resulting from central motor lesions. However, their striking similarities made us hypothesize that cramping is an under-recognized and potentially misidentified aspect of spasticity.

Methods

A systematic search on spasms and cramps in patients with Upper Motor Neuron Disorder (spinal cord injury, cerebral palsy, traumatic brain injury, and stroke) was carried out in Embase/Medline, aiming to describe the definitions, characteristics, and measures of spasms and cramps that are used in the scientific literature.

Results

The search identified 4,202 studies, of which 253 were reviewed: 217 studies documented only muscle spasms, 7 studies reported only cramps, and 29 encompassed both. Most studies (n = 216) lacked explicit definitions for either term. One-half omitted any description and when present, the clinical resemblance was significant. Various methods quantified cramp/spasm frequency, with self-reports being the most common approach.

Conclusion

Muscle cramps and spasms probably represent related symptoms with a shared pathophysiological component. When considering future treatment strategies, it is important to recognize that part of the patient's spasms may be attributed to cramps.

Accuracy and Reliability of Single-Camera Measurements of Ankle Clonus and Quadriceps Hyperreflexia

Objective

To evaluate the accuracy and reliability of a simple, single-camera smartphone-based method, named the Reflex Tracker (RT) system, for measuring reflex threshold angles related to ankle clonus and quadriceps hyperreflexia.

Design

A prospective comparison study using a high-fidelity reference standard was constructed employing a 2 × 2 × 2 factorial design, with factors of rater (tester) type (student and experienced physical therapist), joint (ankle and knee), and repetition (2 per condition).

Setting

This multicenter study was conducted at 4 outpatient rehabilitation clinics.

Participants

A convenience sample of 14 individuals with a neurologic condition presented with 20 lower limbs that exhibited ankle clonus and/or quadriceps hyperreflexia and were included in the study. Also participating in the study were 8 student and 8 experienced physical therapist raters (testers) (N=16).

Interventions

Not applicable.

Main Outcome Measures

The plantar flexor reflex threshold angle (PFRTA) related to ankle clonus and the quadriceps reflex threshold angle (QRTA) related to quadriceps hyperreflexia were quantified.

Results

PFRTA and QRTA results were compared between the smartphone RT method and synchronous 3-dimensional inertial measurement unit (IMU) sensor motion capture. Mean difference (bias) was minimal between RT and IMU measurements for PFRTA (bias≤0.2°) and QRTA (bias≤1.2°). Intrarater reliability for PFRTA ranged from 0.85-0.90 using RT and from 0.85-0.87 using IMU; QRTA ranged from 0.97-0.98 using RT and from 0.96-0.99 using IMU. Intersensor reliability for PFRTA and QRTA was 0.97 and 0.99, respectively. Minimum detectable change for PFRTA ranged from 7.1°- 8.7° and for QRTA ranged from 6.1°-8.3°.

Conclusions

RT performed comparable to IMU for accurate and reliable measurement of PFRTA and QRTA to quantify ankle clonus and quadriceps hyperreflexia in clinical settings.

Properties of the surface electromyogram following traumatic spinal cord injury: a scoping review

Traumatic spinal cord injury (SCI) disrupts spinal and supraspinal pathways, and this process is reflected in changes in surface electromyography (sEMG). sEMG is an informative complement to current clinical testing and can capture the residual motor command in great detail-including in muscles below the level of injury with seemingly absent motor activities. In this comprehensive review, we sought to describe how the sEMG properties are changed after SCI. We conducted a systematic literature search followed by a narrative review focusing on sEMG analysis techniques and signal properties post-SCI. We found that early reports were mostly focused on the qualitative analysis of sEMG patterns and evolved to semi-quantitative scores and a more detailed amplitude-based quantification. Nonetheless, recent studies are still constrained to an amplitude-based analysis of the sEMG, and there are opportunities to more broadly characterize the time- and frequency-domain properties of the signal as well as to take fuller advantage of high-density EMG techniques. We recommend the incorporation of a broader range of signal properties into the neurophysiological assessment post-SCI and the development of a greater understanding of the relation between these sEMG properties and underlying physiology. Enhanced sEMG analysis could contribute to a more complete description of the effects of SCI on upper and lower motor neuron function and their interactions, and also assist in understanding the mechanisms of change following neuromodulation or exercise therapy.

The influence of physiologic and atmospheric variables on spasticity after spinal cord injury

BACKGROUND

A number of physiological and atmospheric variables are believed to increase spasticity in persons with spinal cord injury (SCI) based on self-reported measures, however, there is limited objective evidence about the influence of these variables on spasticity.

OBJECTIVE

We investigated the relationship between physiological/ atmospheric variables and level of spasticity in individuals with SCI.

METHODS

In 53 participants with motor-incomplete SCI, we assessed the influence of age, time since injury, sex, injury severity, neurological level of injury, ability to walk, antispasmodic medication use, temperature, humidity, and barometric pressure on quadriceps spasticity. Spasticity was assessed using the pendulum test first swing excursion (FSE). To categorize participants based on spasticity severity, we performed cluster analysis. We used multivariate stepwise regression to determine variables associated with spasticity severity level.

RESULTS

Three spasticity groups were identified based on spasticity severity level: low, moderate, and high. The regression analysis revealed that only walking ability and temperature were significantly related to spasticity severity.

CONCLUSIONS

These outcomes validate the self-reported perception of people with SCI that low temperatures worsen spasticity. The findings refine prior evidence that people with motor-incomplete SCI have higher levels of spasticity, showing that those with sufficient motor function to walk have the highest levels of spasticity.

Characterizing the Experience of Spasticity after Spinal Cord Injury: A National Survey Project of the Spinal Cord Injury Model Systems Centers

OBJECTIVE

To characterize the qualities that individuals with spinal cord injury (SCI) associate with their experience of spasticity and to describe the relationship between spasticity and perceived quality of life and the perceived value of spasticity management approaches.

DESIGN

Online cross-sectional survey.

SETTING

Multicenter collaboration among 6 Spinal Cord Injury Model Systems hospitals in the United States.

PARTICIPANTS

Individuals with SCI (N=1076).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Qualities of Spasticity Questionnaire, modified Spinal Cord Injury-Spasticity Evaluation Tool (mSCI-SET), and the modified Patient-Reported Impact of Spasticity Measure (mPRISM).

RESULTS

Respondents indicated that spasms most often occurred in response to movement-related triggering events. However, spontaneous spasms (ie, no triggering event) were also reported to be among the most common types. Frequency of spasms appears to decline with age. The highest frequency of spasms was reported by 56% of respondents aged <25 years and by only 28% of those >55 years. Stiffness associated with spasticity was reported to be more common than spasms (legs, 65% vs 54%; trunk, 33% vs 18%; arms, 26% vs 15%). Respondents reported negative effects of spasticity more commonly than positive effects. Based on their association with negative scores on the mSCI-SET and the mPRISM, the 5 most problematic experiences reported were stiffness all day, interference with sleep, painful spasms, perceived link between spasticity and pain, and intensification of pain before a spasm. Respondents indicated spasticity was improved more by stretching (48%) and exercise (45%) than by antispasmodics (38%).

CONCLUSIONS

The experience of spasticity after SCI is complex and multidimensional, with consequences that affect mobility, sleep, comfort, and quality of life. Stiffness, rather than spasms, appears to be the most problematic characteristic of spasticity. Physical therapeutic interventions to treat spasticity warrant in-depth investigation.

Epidural stimulation for cardiovascular function increases lower limb lean mass in individuals with chronic motor complete spinal cord injury

NEW FINDINGS

What is the central question of this study? Spinal cord injury results in paralysis and deleterious neuromuscular and autonomic adaptations. Lumbosacral epidural stimulation can modulate motor and/or autonomic functions. Does long-term epidural stimulation for normalizing cardiovascular function affect leg muscle properties? What is the main finding and its importance? Leg lean mass increased after long-term epidural stimulation for cardiovascular function, which was applied in the sitting position and did not activate the leg muscles. Leg muscle strength and fatigue resistance, assessed in a subgroup of individuals, also increased. These adaptations might support interventions for motor recovery and warrant further mechanistic investigation.

ABSTRACT

Chronic motor complete spinal cord injury (SCI) results in paralysis and deleterious neuromuscular and autonomic adaptations. Paralysed muscles demonstrate atrophy, loss of force and increased fatigability. Also, SCI-induced autonomic impairment results in persistently low resting blood pressure and heart rate, among other features. We previously reported that spinal cord epidural stimulation (scES) optimized for cardiovascular (CV) function (CV-scES), which is applied in sitting position and does not activate the leg muscles, can maintain systolic blood pressure within a normotensive range during quiet sitting and during orthostatic stress. In the present study, dual-energy X-ray absorptiometry collected from six individuals with chronic clinically motor complete SCI demonstrated that 88 ± 11 sessions of CV-scES (7 days week^-1 ; 2 h day^-1 in four individuals and 5 h day^-1 in two individuals) over a period of ∼6 months significantly increased lower limb lean mass (by 0.67 ± 0.39 kg or 9.4 ± 8.1%; P < 0.001). Additionally, muscle strength and fatigability data elicited by neuromuscular electrical stimulation in three of these individuals demonstrated a general increase (57 ± 117%) in maximal torque output (between 2 and 44 N m in 14 of the 17 muscle groups tested overall) and torque-time integral during intermittent, fatiguing contractions (63 ± 71%; between 7 and 230% in 16 of the 17 muscle groups tested overall). In contrast, whole-body mass and composition did not change significantly. In conclusion, long-term use of CV-scES can have a significant impact on lower limb muscle properties after chronic motor complete SCI.

Vibration attenuates spasm-like activity in humans with spinal cord injury

KEY POINTS

Cutaneous reflexes were tested to examine the neuronal mechanisms contributing to muscle spasms in humans with chronic spinal cord injury (SCI). Specifically, we tested the effect of Achilles and tibialis anterior tendon vibration on the early and late components of the cutaneous reflex and reciprocal Ia inhibition in the soleus and tibialis anterior muscles in humans with chronic SCI. We found that tendon vibration reduced the amplitude of later but not earlier cutaneous reflex in the antagonist but not in the agonist muscle relative to the location of the vibration. In addition, reciprocal Ia inhibition between antagonist ankle muscles increased with tendon vibration and participants with a larger suppression of the later component of the cutaneous reflex had stronger reciprocal Ia inhibition from the antagonistic muscle. Our study is the first to provide evidence that tendon vibration attenuates late cutaneous spasm-like reflex activity, likely via reciprocal inhibitory mechanisms, and may represent a method, when properly targeted, for controlling spasms in humans with SCI.

ABSTRACT

The neuronal mechanisms contributing to the generation of involuntary muscle contractions (spasms) in humans with spinal cord injury (SCI) remain poorly understood. To address this question, we examined the effect of Achilles and tibialis anterior tendon vibration at 20, 40, 80 and 120 Hz on the amplitude of the long-polysynaptic (LPR, from reflex onset to 500 ms) and long-lasting (LLR, from 500 ms to reflex offset) cutaneous reflex evoked by medial plantar nerve stimulation in the soleus and tibialis anterior, and reciprocal Ia inhibition between these muscles, in 25 individuals with chronic SCI. We found that Achilles tendon vibration at 40 and 80 Hz, but not other frequencies, reduced the amplitude of the LLR in the tibialis anterior, but not the soleus muscle, without affecting the amplitude of the LPR. Vibratory effects were stronger at 80 than 40 Hz. Similar results were found in the soleus muscle when the tibialis anterior tendon was vibrated. Notably, tendon vibration at 80 Hz increased reciprocal Ia inhibition between antagonistic ankle muscles and vibratory-induced increases in reciprocal Ia inhibition were correlated with decreases in the LLR, suggesting that participants with a larger suppression of later cutaneous reflex activity had stronger reciprocal Ia inhibition from the antagonistic muscle. Our study is the first to provide evidence that tendon vibration suppresses late spasm-like activity in antagonist but not agonist muscles, likely via reciprocal inhibitory mechanisms, in humans with chronic SCI. We argue that targeted vibration of antagonistic tendons might help to control spasms after SCI.

Spinal Cord Injury: Lessons about Neuroplasticity from Paired Associative Stimulation

Paired associative stimulation (PAS) is a noninvasive neuromodulation method with rare cases of adverse effects for the patients with neurological injuries such as spinal cord injury (SCI). PAS is based on the principles of associative long-term potentiation and depression where the activation of presynaptic and postsynaptic neurons correlated in time is artificially induced. Statistically significant improvement in motor functions after applying PAS has been reported by several research groups. With further standardization of the technique, PAS could be an effective treatment for functional rehabilitation of SCI patients. In this review, we have summarized the methods and findings of PAS on SCI rehabilitation to facilitate the readers to understand the potentials and limitations of PAS for its future clinical use.

Adjusting Assistance Commensurates with Patient Effort During Robot-Assisted Upper Limb Training for a Patient with Spasticity After Cervical Spinal Cord Injury: A Case Report

Limited evidence is available on optimal patient effort and degree of assistance to achieve preferable changes during robot-assisted training (RAT) for spinal cord injury (SCI) patients with spasticity. To investigate the relationship between patient effort and robotic assistance, we performed training using an electromyography-based robotic assistance device (HAL-SJ) in an SCI patient at multiple settings adjusted to patient effort. In this exploratory study, we report immediate change in muscle contraction patterns, patient effort, and spasticity in a 64-year-old man, diagnosed with cervical SCI and with American Spinal Injury Association Impairment Scale C level and C4 neurological level, who underwent RAT using HAL-SJ from post-injury day 403. Three patient effort conditions (comfortable, somewhat hard, and no-effort) by adjusting HAL-SJ’s assists were set for each training session. Degree of effort during flexion and extension exercise was assessed by visual analog scale, muscle contraction pattern by electromyography, modified Ashworth scale, and maximum elbow extension and flexion torques, immediately before and after each training session, without HAL-SJ. The amount of effort during training with the HAL-SJ at each session was evaluated. The degree of effort during training can be set to three effort conditions as we intended by adjusting HAL-SJ. In sessions other than the no-effort setting, spasticity improved, and the level of effort was reduced immediately after training. Spasticity did not decrease in the training session using HAL-SJ with the no-effort setting, but co-contraction further increased during extension after training. Extension torque was unchanged in all sessions, and flexion torque decreased in all sessions. When performing upper-limb training with HAL-SJ in this SCI patient, the level of assistance with some effort may reduce spasticity and too strong assistance may increase co-contraction. Sometimes, a patient’s effort may be seemingly unmeasurable; hence, the degree of patient effort should be further measured.

Impact of spasticity on transfers and activities of daily living in individuals with spinal cord injury

CONTEXT/OBJECTIVE

For persons with spinal cord injury, spasticity commonly interferes with activities of daily living such as transfers. Electromyography can be used to objectively measure muscle spasms during transfers, but how electromyographic measures relate to the impact spasticity has on life, or to clinically-rated spasticity, is unclear. We aimed to characterize relationships among spasm duration and magnitude, impact of spasticity on daily life, and a clinical measure of extensor spasticity, as well as to determine reliability of the electromyographic measures.

DESIGN

Participants (N=19) underwent electromyographic measurements of involuntary muscle activity (spasm duration and magnitude) evoked in quadriceps muscles during transfers on two days. Impact of spasticity on daily life was measured with the Spinal Cord Injury Spasticity Evaluation Tool. Clinically-rated spasticity severity was measured with the Spinal Cord Assessment Tool for Spastic reflexes.

RESULTS

No significant associations were found between impact of spasticity and spasm duration, spasm magnitude, or clinical extensor spasticity score. Absolute and normalized spasm duration were positively associated with clinical extensor spasticity score (rho=0.510-0.667, P < 0.05). Spasm measures during transfers had good to excellent day-to-day reliability (rho=0.656-0.846, P < 0.05).

CONCLUSIONS

Electromyographic and clinical measures of involuntary activity in the lower extremity do not significantly relate to perceived impact of spasticity on daily life. However, quadriceps spasm duration during transfers is related to clinically-rated extensor spasticity. Electromyography is a reliable method of quantifying quadriceps spasms during transfers. Future investigations should identify factors that influence the impact of spasticity on life, which may help direct treatment strategies to reduce problematic impact.

Assessment of quality of life in relation to spasticity severity and socio-demographic and clinical factors among patients with spinal cord injury

Objective: To assess the impact of spasticity severity as well as socio-demographic and clinical factors on quality of life (QOL) and to identify factors predicting poor QOL among patients with spinal cord injury (SCI)Design: Descriptive cross-sectional study.Setting: Tertiary care clinic in Istanbul, Turkey.Participants: A total of 110 patients with SCI (mean (SD) age: 43.8 (14.7) years, 58.2% were males) were enrolled.Assessments: The American Spinal Injury Association (ASIA) Impairment Scale (AIS), Modified Ashworth Scale (MAS) and Turkish version of the World Health Organization Quality of life questionnaire (WHOQOL-BREF) were utilized to determine the SCI category, severity of spasticity and QOL scores, respectively.Outcome measures: The WHOQOL-BREF scores were evaluated with respect to the severity of spasticity, aetiology and duration of SCI, AIS category and method of bladder management.Results: The mean (SD) physical health (41.9 (15.3) vs. 46.5 (10.9), P = 0.029), social relationships (45.6 (20.2) vs. 53.8 (17.3), P = 0.025) and total WHOQOL-BREF scores were significantly lower in patients with more severe spasticity. Multivariate linear regression analysis revealed that severity of spasticity was a significant predictor of decreased WHOQOL-BREF total scores, physical domain scores and social relations domain scores by 11.381 (P = 0.007), 11.518 (P = 0.005) and 17. 965 (P = 0.004), respectively.Conclusion: In conclusion, addressing QOL in relation to severity of spasticity for the first time among Turkish SCI patients, our findings revealed a negative impact of the spasticity severity on the WHOQOL-BREF scores, particularly for physical health and social relationship domains.

Temporal Indices of Ankle Clonus and Relationship to Electrophysiologic and Clinical Measures in Persons With Spinal Cord Injury

BACKGROUND AND PURPOSE

Clonus arising from plantar flexor hyperreflexia is a phenomenon that is commonly observed in persons with spastic hypertonia. We assessed the temporal components of a biomechanical measure to quantify ankle clonus, and validated these in persons with spasticity due to spinal cord injury.

METHODS

In 40 individuals with chronic (>1 year) spinal cord injury, we elicited ankle clonus using a standardized mechanical perturbation (drop test). We examined reliability and construct validity of 2 components of the drop test: clonus duration (timed with a stopwatch) and number of oscillations in the first 10-second interval (measured via optical motion capture). We compared these measures to the Spinal Cord Assessment Tool for Spastic reflexes (SCATS) clonus score and H-reflex/M-wave (H/M) ratio, a clinical and electrophysiologic measure, respectively.

RESULTS

Intra- and interrater reliability of clonus duration measurement was good [intraclass correlation coefficient, ICC (2, 1) = 1.00]; test-retest reliability was good both at 1 hour [ICC (2, 2) = 0.99] and at 1 week [ICC (2, 2) = 0.99]. Clonus duration was moderately correlated with SCATS clonus score (r = 0.58). Number of oscillations had good within-session test-retest reliability [ICC (2, 1) > 0.90] and strong correlations with SCATS clonus score (r = 0.86) and soleus H/M ratio (r = 0.77).

DISCUSSION AND CONCLUSIONS

Clonus duration and number of oscillations as measured with a standardized test are reliable and valid measures of plantar flexor hyperreflexia that are accessible for clinical use. Tools for objective measurement of ankle clonus are valuable for assessing effectiveness of interventions directed at normalizing reflex activity associated with spasticity.Video Abstract available for more insights from the authors (see Supplemental Digital Content 1, http://links.lww.com/JNPT/A179).

Body System Effects of a Multi-Modal Training Program Targeting Chronic, Motor Complete Thoracic Spinal Cord Injury

The safety and efficacy of pharmacological and cellular transplantation strategies are currently being evaluated in people with spinal cord injury (SCI). In studies of people with chronic SCIs, it is thought that functional recovery will be best achieved when drug or cell therapies are combined with rehabilitation protocols. However, any functional recovery attributed to the therapy may be confounded by the conditioned state of the body and by training-induced effects on neuroplasticity. For this reason, we sought to investigate the effects of a multi-modal training program on several body systems. The training program included body-weight-supported treadmill training for locomotion, circuit resistance training for upper body conditioning, functional electrical stimulation for activation of sublesional muscles, and wheelchair skills training for overall mobility. Eight participants with chronic, thoracic-level, motor-complete SCI completed the 12-week training program. After 12 weeks, upper extremity muscular strength improved significantly for all participants, and some participants experienced improvements in function, which may be explained by increased strength. Neurological function did not change. Changes in pain and spasticity were highly variable between participants. This is the first demonstration of the effect of this combination of four training modalities. However, balancing participant and study-site burden with capturing meaningful outcome measures is also an important consideration.

Increases in human motoneuron excitability after cervical spinal cord injury depend on the level of injury

After human spinal cord injury (SCI), motoneuron recruitment and firing rate during voluntary and involuntary contractions may be altered by changes in motoneuron excitability. Our aim was to compare F waves in single thenar motor units paralyzed by cervical SCI to those in uninjured controls because at the single-unit level F waves primarily reflect the intrinsic properties of the motoneuron and its initial segment. With intraneural motor axon stimulation, F waves were evident in all 4 participants with C₄-level SCI, absent in 8 with C₅ or C₆ injury, and present in 6 of 12 Uninjured participants (P < 0.001). The percentage of units that generated F waves differed across groups (C₄: 30%, C₅ or C₆: 0%, Uninjured: 16%; P < 0.001). Mean (±SD) proximal axon conduction velocity was slower after C₄ SCI [64 ± 4 m/s (n = 6 units), Uninjured: 73 ± 8 m/s (n = 7 units); P = 0.037]. Mean distal axon conduction velocity differed by group [C₄: 40 ± 8 m/s (n = 20 units), C₅ or C₆: 49 ± 9 m/s (n = 28), Uninjured: 60 ± 7 m/s (n = 45); P < 0.001]. Motor unit properties (EMG amplitude, twitch force) only differed after SCI (P ≤ 0.004), not by injury level. Motor units with F waves had distal conduction velocities, M-wave amplitudes, and twitch forces that spanned the respective group range, indicating that units with heterogeneous properties produced F waves. Recording unitary F waves has shown that thenar motoneurons closer to the SCI (C₅ or C₆) have reduced excitability whereas those further away (C₄) have increased excitability, which may exacerbate muscle spasms. This difference in motoneuron excitability may be related to the extent of membrane depolarization following SCI.

NEW & NOTEWORTHY

Unitary F waves were common in paralyzed thenar muscles of people who had a chronic spinal cord injury (SCI) at the C₄ level compared with uninjured people, but F waves did not occur in people that had SCI at the C₅ or C₆ level. These results highlight that intrinsic motoneuron excitability depends, in part, on how close the motoneurons are to the site of the spinal injury, which could alter the generation and strength of voluntary and involuntary muscle contractions.