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Interventions Based on Various Forms of Afferent Stimulation

There are a variety of approaches that have been investigated which employ afferent (i.e., sensory) stimulation for the reduction of spasticity in people with SCI. As noted previously, electrical stimulation, TENS, is one of the preferred methods for providing afferent stimulation. This technique differs from the approaches noted in the previous sections that involve stimulation to the motor system, whether via muscles or motor nerves. TENS may involve the stimulation of large, low threshold afferent nerves (Goulet et al. 1996) or dermatomal stimulation which is directed towards cutaneous skin receptors supplying the skin in the dermatome of the muscle of interest (Bajd et al. 1985; van der Salm et al. 2006). These methods are aimed at altering motor-neuron excitability through sensory reflex arcs, thereby reducing spasticity. An alternate approach employing electrical stimulation involves rectal probe stimulation, developed originally to enable ejaculation in males and heretofore a technique employed only within fertility clinics (Halstead & Seager 1991).

In addition, a variety of methods of mechanical or thermal stimuli to various afferent systems have also been studied. These include therapeutic massage over the spastic muscle (Goldberg et al. 1994), penile vibration (Laessoe et al. 2004; Alaca et al. 2005), the application of cold (i.e., cryotherapy) to reduce local muscle spasticity (Price et al. 1993), also irradiation of the skin overlying sensory nerves with a helium-neon laser purported to induce photochemical reactions which may trigger neural activity (Walker 1985). It should be noted that the article examining cryotherapy (i.e., Price et al. 1993) did not meet the review criteria of having 50% of subjects with SCI. The article was included in the review as individual results were presented for all subjects with SCI (N=7), enabling independent discernment of the effects on SCI (thereby meeting review criteria for studies having SCI N³3).

Table 4 Studies of Various Forms of Afferent Stimulation for Reducing Spasticity

Author Year

Country
Research Design

Score
Total Sample Size

MethodsOutcome
Taping
Tamburella et al. 2014

Italy

RCT Crossover

PEDro=7

N=11

Population: Mean age: 52.0 yr; Gender: males=6, females=5; Injury etiology: traumatic=4, non-traumatic=7; Level of injury: cervical=5, thoracic=6; Level of severity: AIS D=11.

Intervention: Individuals were randomly allocated to receive either KinesioTape (KT) or conventional silk tape (ST) for 48 hr. After a 7 days washout period, the individuals were crossed over and received another 48 hr of intervention. Tape was applied to the soleus and gastrocnemius muscles with the knee extended and ankle at 90o passive dorsiflexion. Assessments were conducted at baseline and at post- intervention.

Outcome Measures: Modified Ashworth Scale (MAS), Penn modified Spasm Frequency Scale (PSFS), Spinal Cord Assessment Tool for Spastic Reflexes subscale for clonus assessment (SCATS), Global Pain Scale (GPS), Berg Balance Scale (BBS), Walking Index for Spinal Cord Injury (WISCI), 10-meter Walk Test (10WT), 6-minute Walking Test (6MWT), Timed Up and Go test (TUG), Range of motion (ROM), Centre of pressure (COP) parameters,

Kinematic gait parameters.

1.     Patients who received KT demonstrated significant improvements from baseline to post- intervention in active ROM, passive ROM, extended knee SCATS, MAS, PSFS, BBS and 6MWT (all p<0.001), flexed knee SCATS (p<0.005), and GPS (p<0.05) compared to the ST condition. No significant differences were reported on the WISCI, 10MWT and TUG.

2.     COP parameters revealed significant improvements for the KT condition in regard to path length, mean duration and anteroposterior velocity with eyes open (all p<0.05) and path length, mean duration, laterolateral velocity and anteroposterior velocity with eyes closed (all p<0.05) from baseline to post- intervention compared to the ST condition.

3.     Patients who received KT also reported significant improvements in all kinematic gait parameters compared to the ST condition including stride length, stance phase (both p<0.001), speed, cadence and double-time support phase (all p<0.05) from baseline to post- intervention.

Effect Sizes: Forest plot of standardized mean differences (SMD±95%C.I.) as calculated from pre- and post-intervention data.

TENS
Oo, 2014

Myanmar

RCT

PEDro=9

N=16

Population: TENS group (n=8): Mean age: 33.4 yr; Gender: males=8, females=0; Level of injury: AIS A=3, AIS B=3, AIS C=1, AIS D=1; Mean time since injury: 3.3 mo. Control group (n=8): Mean age: 40.5 yr; Gender: males=7, females=1; Level of injury: AIS A=3, AIS B=2, AIS C=1, AIS D=2; Mean time since injury: 3.1 mo.

Intervetion: Study the immediate and short-term efficacy of adding transcutaneous electrical nerve stimulation (TENS) to standardized physical therapy on subacute spasticity.

Outcome Measures: Composite spasticity score (sub-scores: ankle jerk, muscle tone, ankle clonus scores), Serial evaluations.

1.     After first session: statistical significance for reduction in clinical spasticity for TENS group (mean difference=1.75; 99%CI, 0.47-3.03; p=0.002) but not significant in control group (mean difference=0.63; 99%CI, -0.51-1.76; p=0.095).

2.     After first session: significant between group difference in composite spasticity score (mean difference 1.63; 99% CI, 0.14-3.11; p=0.006).

3.     After first session: within-group and between-group differences in sub-scores revealed no significant improvement.

4.     After final session: significant improvement for composite spasticity score in TENS group (2.75; 99% CI, 1.31-4.19; p<0.001) but not significant in control group (1.13; 99% CI, -0.55-2.80; p=0.051).

5.     After final session: significant between group difference in composite spasticity score (2.13; 99% CI, 0.59-3.66; p=0.001).

6.     After final session: sub-score analysis showed significant decreases for muscle tone score in TENS group (1.75; 99% CI, 0.16-3.34; p=0.006) and ankle clonus score (0.75; 99% CI, 0.18-1.32; p=0.003), no sub-scores in control group significantly reduced.

7.     After final session: between-group differences, muscle tone score significant after 15 TENS sessions (1.50; 99% CI, 0.15-2.85; p=0.005).

Effect Sizes: Forest plot of standardized mean differences (SMD±95%C.I.) as calculated from pre- and post-intervention data.

Chung & Cheng 2010

Hong Kong

RCT

PEDro=10

N=18

Population: Age range: 24-82 yr; Injury etiology: traumatic, non-traumatic SCI; Level of injury: C3-T12; Level of severity: AIS A-D; Time since injury range: 4-364 wk.

Intervention: 60 min of active TENS (0.25 ms, 100 Hz, 15 mA) or 60 min of placebo non-electrically stimulated TENS over the common peroneal nerve.

Outcome Measures: Composite Spasticity Score (CSS), Achilles tendon jerks.

1.      Significant reductions were shown in the CSS by 29.5% (p=0.017), resistance to full-range passive ankle dorsiflexion by 31.0% (p=0.024) and ankle clonus by 29.6% (p=0.023) in the intervention group; these reductions were not observed in the placebo group.

2.      Between-group differences on both CSS and resistance to full-range passive ankle dorsiflexion were significant (p=0.027 and p=0.024, respectively).

Effect Sizes: Forest plot of standardized mean differences (SMD±95%C.I.) as calculated from pre- and post-intervention data.

Aydin et al. 2005

Turkey

RCT

PEDro=6

N=41

Population: SCI (n=21): Injury etiology: trauma; Level of severity: complete, incomplete; Chronicity: chronic. Health controls (n=20).

Intervention: Either oral baclofen (titrated up to 80 mg/day) for 8 wk or TENS for 15 min/day for 15 days.

Outcome Measures: SFS, Painful Spasm Scale (PSS), Ashworth Scale (AS), Various clinical (clonus, deep tendon reflexes, Response to plantar stimulation) or electrophysiologic measures (H-reflex latency and amplitude, H/M ratio) of spasticity as well as measures of function (FIM and FDS. Measures were taken pre-and post-first intervention (15min after) and 15 min and 24 hr after the last TENS session.

1.      For both intervention groups a significant improvement was noted immediately post intervention in the lower limb AS (p<0.011 baclofen group and p=0.020 TENS group), SFS (p<0.014 for both groups), deep tendon reflex score (p=0.025 for both groups) as well as in measures of disability (FIM-baclofen group p=0.005, TENS group p=0.003; FDS–baclofen group p=0.004, TENS group p=0.003.

2.      In comparison with baseline, TENS showed a trend for a reduced AS immediately after the first intervention (p=0.059), a significant reduction immediately after the last intervention (p=0.006) and a significant but lesser reduction 24 hr after the last intervention (p=0.020). Similar findings were obtained for Deep Tendon Reflex scores. Plantar Stimulus Response scores were only significantly reduced immediately following the last intervention session (p=0.034) whereas clonus scores were only significantly reduced immediately following the first intervention (p=0.046).

3.      There was a significant reduction in H-reflex maximal amplitude (p=0.032) 24 hr after the final session. This reduction was even more apparent when tested only 15 min after the last intervention (p=0.026). There were only small (statistically non-significant) changes in other electrophysiologic variables with either baclofen or TENS.

Effect Sizes: Forest plot of standardized mean differences (SMD±95%C.I.) as calculated from pre- and post-intervention data.

Goulet et al. 1996

Canada

Pre-Post

N=14

Population: Age range: 21-54 yr; Gender: males=13, females=1; Level of injury: C4-T12; Level of severity: AIS: A-D; Time since injury range: 2-194 mo.

Intervention: TENS stimulation (i.e., low threshold afferent nerve stimulation) over the common peroneal nerve for 30 min.

Outcome Measures: Modified Ashworth Scale (MAS), Clonus score, Achilles tendon reflex score (ATR), H-reflex amplitude, and H-reflex/M response ratio collected just prior to and after TENS. H-reflex and M responses were also collected during TENS.

1.     Significant decreases were seen in clinical measures of spasticity as seen by reductions in MAS (p=0.04), ATR (p=0.01), and global spasticity scores (p=0.01). A trend was seen with reduced clonus scores (p=0.11).

2.     No significant effects of TENS were seen with electrophysiological measures of spasticity as indicated by H-reflex amplitudes (p=0.89) and H/M ratio (p=0.50).

Bajd et al. 1985

Yugoslavia

Pre-Post

N=6

Population: Age range: 11-52 yr; Level of injury: C5-T9; Level of severity: complete=4, incomplete=2; Time since injury range: 5-48 mo.

Intervention: TENS stimulation over L3, 4 dermatomes. Stimulation amplitude of up to 50 mA was used and applied continuously for 20 min.

Outcome Measures: Pendulum test (relaxation index) performed just prior to and just after stimulation as well as 2 hr post-stimulation.

1.     Group statistical analysis was not conducted.

2.     In 3 individuals, spasticity decreased markedly as indicated by increased relaxation index values immediately after the stimulation and returned to pre-stimulation values at 2 hr. The remaining 3 individuals showed no change.

Penile Vibratory Stimulation
Laessoe et al. 2004

Denmark

RCT

PEDro=6

N=9

Population: Age range: 27-67 yr; Gender: males=9, females=0; Level of injury: C2-T8; Level of severity: AIS: A–D; Time since injury range: 4 mo-50 yr.

Intervention: Penile Vibratory stimulation for 5 min or to ejaculation.

Outcome Measures: Modified Ashworth Scale (MAS), Penn Spasm Frequency Scale (PSFS), 24 hr EMG recordings of quadriceps and tibialis anterior activity. All collected pre-stimulation and 24 hr post-stimulation. MAS was also collected immediately after stimulation.

 

1.     There was a significant decrease in spasticity after penile stimulation as indicated by decreases MAS (p<0.01). This was not sustained at 24 hr.

2.     There was a slight reduction in the PSFS 24 hr after penile stimulation but this was not significant.

3.     There was a significant reduction in EMG activity in the initial 3 hr after vibration, as compared to before vibration (p<0.05). This was not seen in the no-vibration condition.

4.     The largest reduction in EMG activity occurred in the 1st hr after vibration, after which the events gradually decreased until no significant effect was observed following the 3 hr after vibration.

Effect Sizes: Forest plot of standardized mean differences (SMD±95%C.I.) as calculated from pre- and post-intervention data.

Alaca et al. 2005

Turkey

Pre-Post

N=10

Population: Age range: 22-35 yr; Gender: males=10, females=0; Level of injury: C8-L1; Level of severity: AIS A; Time since injury range: 1.1-9 yr.

Intervention: Penile Vibratory stimulation for 6, 3 min periods (separated by 1 min) or to ejaculation.

Outcome Measures: Ashworth Scale (AS), Spasm Frequency Scale (SFS) and nominal scales of painful spasms, plantar stimulation response, deep tendon reflexes, clonus and effect on function. All collected pre-stimulation and 3, 6, 24 hr and 48 hr post-stimulation.

1.     There was a significant decrease in spasticity after penile stimulation as indicated by decreases in the AS (p<0.001). This was significantly lower than baseline at hr 3 (p=0.001) and 6 (p=0.03) with a trend lower at 24 hr (p=0.08).

2.     There were slight (non-significant) reductions in the SFS and clonus scores at hr 3.

3.     There were no changes in painful spasms, plantar stimulation responses, deep tendon reflexes and effect on function scale scores with penile vibration.

Helium-Neon Laser Irradiation
Walker 1985

USA

RCT

PEDro=4

N=41

Population: Level of injury: T12-L2; Time since injury: >2 yr.

Intervention: Helium-neon laser irradiation to peripheral nerve sites (radial, median, saphenous nerves) for 20 or 40 sec to each site versus a variety of control conditions including sham irradiation (same probe but not emitting laser), irradiation to skin not innervated by peripheral nerves and electrical stimulation for 45 min or 1 hr over innervated and non-innervated areas. (n=5-7 in various experimental groups).

Outcome Measures: Clonus count after brisk dorsiflexion of the foot by a blinded registered PT before intervention and at 30 min intervals up to 2 hr after irradiation.

1.     No statistical comparisons reported.

2.     40 sec of laser irradiation and 1 hr of electrical stimulation similarly produce complete suppression of clonus lasting 30 and 60 min after cessation of stimulation.

3.     20 sec of laser irradiation and 45 min of electrical stimulation similarly only produce partial suppression of clonus.

4.     Distal nerve irradiation or electrical stimulation still produced clonus suppression but not when stimulation was applied to skin not overlying a peripheral nerve.

 

Electrical Nerve Stimulation
Possover et al. 2010

Switzerland

Case Reports

N=3

Population: Gender: males=2, females=1; Level of injury: T5=1, T7/8=1, T10=1.

Intervention: Continuous 20 Hz electrical stimulation to the sciatic, pudendal nerves and to the sacral nerve roots S3 and S4.

Outcome Measures: Spasticity of lower extremities, motion of the legs.

1.      A frequency of 20 Hz permitted complete control of the spasticity of the lower extremities and of reflex incontinence.

2.      Electrical stimulation of the femoral nerves enabled the T5 paraplegic lower-limb cycling and the two other individuals standing and alternative locomotion.

van der Salm et al. 2006

Netherlands

Pre-Post

N=10

Population: Age range: 21-42 yr; Gender: males=8, females=2; Level of injury: C3-T11; Level of severity: AIS A=9, AIS C=1; Time since injury range: 28-275 mo.

Intervention: Electrical motor (agonist or antagonist) or afferent (S1 dermatomal) stimulation of the triceps surae or a placebo (application of electrodes but no current). 1–45 min session of each type of stimulation. Intensity at 3x motor threshold for motor stimulation and 80% of motor threshold for afferent stimulation.

Outcome Measures: Modified Ashworth Scale (MAS), clonus score, H reflex, and H/M ratios. Measurements were conducted just prior to, immediately after, 1 hr after and 2 hr after the intervention for each of the 4 conditions.

1.     No significant difference was seen with S1 dermatomal stimulation. Only the agonist muscle stimulation differed significantly (46% reduction) from the placebo as indicated by reduced MAS (p<0.001)

2.     No significant carry-over effect (over 2hr) although there was a trend of continued reductions for the MAS (p=0.113).

3.     No significant intervention effect was shown for the clonus score or the H/M ratio.

4.     The reflex-initiating angle showed a significant change for antagonist stimulation (n=8, p=0.015) but the carryover effect was not significant.

Halstead et al. 1993

USA

Pre-Post

N=9

Population: Age range: 21-41 yr; Gender: males=6, females=3; Level of injury: paraplegia=3, tetraplegia=6; Level of severity: Frankel grade: A=4, B=5; Time since injury range: 0.5-15 yr.

Intervention: At least 6 sessions of Rectal Probe Electrical Stimulation (RPES) 6 times spaced 1-4 wk apart. Each session consisted of 7 or 15 stimulations of ~1 sec duration and lasted 5-10 min. Three subjects underwent a placebo with probe insertion but no stimulation.

Outcome Measures: Ashworth scale (AS), Spasm Frequency Scale (SFS), Deep Tendon Reflexes, Ankle Clonus, Subject self-report (5-point scale) on interference of spasticity on selected self-care activities. All were collected just prior to stimulation, within 1 hr after and 2-4 hr after. Subject self-reports were collected every 2 hr up to 24 hr after stimulation. Pendulum tests were collected on 4 subjects and somatosensory evoked potentials (SSEPs) on 2 subjects’ pre-and post.

1.     Spasticity was reduced as indicated by reduced AS assessed within 1hr post-stimulation (p<0.01).

2.     Spasticity relief as indicated by self-report was for 7.8/9.5 hr (quad/para mean values).

3.     No significant correlation of RPES effect on spasticity was seen with age, duration of injury, level of injury or completeness.

4.     In general, spasticity was reduced as indicated by the pendulum test in the 4 subjects assessed.

5.     SSEPs were abolished in the 2 subjects tested following stimulation.

6.     Probe size, number of stimuli, voltage and current did not reveal any significant correlation with the amount of relief provided.

Vibration
Estes et al. 2018

USA

RCT Crossover

PEDro=4

NInitial=35

NFinal=29

 

Population: SCI (n=34): Mean age=46.29±12.48yr; Gender: males=28, females=6; Level of injury: C=29, T=5, C=9, D=25; Mean time since injury=6.80±7.87yr; AIS scale: C=9, D=25.

Intervention: This RCT crossover study consisted of four whole-body vibration (WBV) intervention sessions at varying frequencies and durations and a sham control session. All sessions were separated by a minimum of 1 wk. WBV consisted of participants standing on a vibrational platform with knees flexed approximately 30 degrees from full extension for 45-second bouts. Participants had 1-minute seated rest in-between bouts. Sessions consisted of one of the following; high frequency (50 Hz vibration) with short duration (four 45-second bouts) (HFSD), low frequency (30 Hz vibration) with short duration(LFSD), high frequency with long duration (eight 45-second bouts) (HFLD), low frequency with long duration (LFLD), or sham (electrical stimulation while standing with eight 45-second bouts). Spasticity was assessed using the outcome listed below. The outcome measure was assessed at baseline, immediately after the intervention, and 15 min and 45 min post-intervention.      

Outcome Measures: First swing excursion (FSE) angle from the pendulum test.

1.     There were no significant between-group differences in baseline FSE (p>0.05).

2.     There were no significant between-group differences when comparing the four WBV groups to the sham at all time points (p>0.05).

3.     There was a significant within-group increase in FSE for the sham group when comparing baseline to the immediate post-intervention follow-up (p=0.023). However, none of the WBV groups showed a significant within-group change at any of the follow-up time points (p>0.05).

4.     Participants were also stratified into low and high spasticity. There were no significant between-group differences when comparing the four WBV groups to the sham group at all time points (p>0.05).

5.     For the high spasticity group, there were significant within-group increases in FSE for the sham and HFSD groups immediately after the intervention (p=0.013; p=0.048, respectively). Moreover, there were significant within-group increases in HFSD and HFLD at 15 min post-intervention (p=0.027; p=0.014). There were no significant within-group differences at the 45 min assessment (p>0.05).

6.     For the low spasticity group, there were no significant within-group changes immediately post-intervention (p>0.05). in contrast, there was a significant within-group increase in FSE for HFSD and HFLD at the 15-min and 45-min assessments (p<0.05 for all).

In et al. 2018

Korea

RCT

PEDro=7

NInitial=32

NFinal=28

 

Population: Whole-body vibration (WBV, n=14): Mean age=46.1±9.8yr; Gender: males=9, females=5; Level of injury: C=14; Mean time since injury=13.7±3.2mo; AIS scale: NR.

Control (CG, n=14): Mean age=49.9±9.3yr; Gender: males=10, females=4; Level of injury: C=14; Mean time since injury=14.3±4.9mo; AIS scale: NR.

Intervention: Participants were randomly assigned to either whole-body vibration (WBV) or a control group. The WBV training consisted of participants holding a semi-squat position while standing on a moveable platform that oscillated with a frequency of 30 Hz and a vertical displacement of 2-4 mm. WBV training sessions lasted 16 min/session, 2x/d, 5x/wk for 8 wk. The control group followed the same protocol, however, this group only received ultra-low frequency vibration. Both groups also received conventional physical therapy consisting of range of motion exercises, mat exercises, and gait training 30 min/d during the same period of the respective intervention. Outcome measures were assessed at baseline and post intervention.    

Outcome Measures: ankle plantar-flexor spasticity assessed using manual muscle tester (MMT).

1.     There was a significant time X group interaction for both right and left ankles (p<0.001 for both).

2.     WBV was more effective at reducing spasticity in both ankles compared to the control group (p<0.001).

3.     Both groups showed significant within-group decreases in spasticity in both ankles (p<0.05).

Murillo et al. 2011

Spain

Pre-Post

N=28

Population: Intervention group (n=19): Mean age: 36.0 yr; Gender: males=16, females=3; Injury etiology: trauma=1, myelitis=2; Level of injury: cervical=1, thoracic=6; Level of severity: AIS A=9, AIS C=9, AIS D=1; Mean time since injury: 5.6 mo. Healthy Controls (n=9): Mean age: 33.8 yr.

Intervention: Vibration at a frequency of 50 Hz during 10 min over the rectus femoris (RF) muscle was delivered in all participants.

Outcome Measures: Modified Ashworth Scale (MAS), Range of Motion (ROM), Frequency of clonus, Duration of clonus, Soleus T wave amplitude, Hmax/Mmax ratio. Assessments were conducted at baseline and during vibration.

1.     Significant intervention improvements in individuals with SCI:

·     Decrease in MAS at knee joint (p<0.001)

·     Increase in ROM for knee extension (p=0.001)

·     Reduction in duration and frequency of clonus (both p≤0.006).

2.     Vibration induced a significant reduction in Hmax/Mmax ratio in the control group (p=0.005) and in the individuals with SCI (p=0.001). The change was not significantly different between the two groups.

3.     Vibration induced a significant inhibition of Twave amplitude in both individuals with SCI (p=0.002), and control subjects (p=0.007).

4.     The Hmax and the Mmax were significantly smaller in the complete SCI than in the incomplete SCI (p=0.03, p=0.04).

5.     The Hmax/Mmax ratio was significantly greater in the individuals with complete SCI than in the individuals with incomplete SCI (p=0.02).

Ness & Field-Fote 2009

USA

Observational

N=16

Population: Mean age: 46.9 yr; Gender: males=14, females=2; Injury etiology: SCI=14; Level of injury: C3-C6=10, T4-T8=6; Time since injury: >1yr.

Intervention: Whole-body vibration (4, 45 sec bouts of 50 Hz stimulation) 3 days/wk for 4 wk.

Outcome Measures: Gravity-provoked stretch (swing excursion).

1.     Whole body vibration was associated with significant increase in first swing excursion (reduction in quadriceps spasticity) from the initial to final session (p=0.005) and persisted for at least 8 days.

2.      There was no significant difference between the initial first swing excursion values of subjects who did and those who did not use antispastic agents (p=0.198).

Massage
Goldberg et al. 1994

Canada

Pre-Post

N=17

Population: Study 2 (n=10): Age range: 21-33 yr; Gender: males=9, females=1; Level of injury: C4-T10; Severity of injury: complete, incomplete; Time since injury range: 3-11 mo. Study 1 (n=7): Healthy controls.

Intervention: One-handed petrissage (massage) applied to the belly of the triceps surae muscle group for 3 min.

Outcome Measures: H-reflex peak amplitude, H-reflex latency (Study 2, SCI only), M-responses collected during massage plus 3 and 6 min prior and 3 and 6 min after massage (10 responses of each averaged).

1.      Significant decrease in H-reflex amplitude during massage as compared to before and after (p=0.008). The response 3min after massage is somewhat reduced but not to the same extent as during the massage.

2.      No difference between M-response amplitudes (p=0.13) or H-Reflex latencies (p=0.22) before, during or after massage.

3.      Study 1: Verified that H-reflex amplitude decre ases seen in controls in supine position were also able to be obtained in prone position which was preferred position for SCI subjects.

Cryotherapy
Price et al. 1993

USA

Pre-Post

N=25

Population: Injury etiology: stroke=9, head injury=9, SCI=7.

Intervention: Cryotherapy (water and ice placed on calf for 20 min).

Outcome Measures: Elastic and viscous components of ankle stiffness represented by mathematical modelling of torque versus position in response to 5° sinusoidal ankle displacements at frequencies from 3 to 12 Hz. This resulted in measures of total path length associated mainly with passive spasticity of the ankle and elastic path length associated with viscous stiffness. Data was collected prior to, during and 1hr after cryotherapy.

1.     Clinically significant reductions in spasticity as indicated by a reduction in total path length of 11 Nm/rad or greater were seen in 5 of 7 subjects with SCI during cryotherapy and 5 of 7 one hr after.

2.     Reduction in spasticity as indicated by total (p=0.009) and elastic (p=0.006) path length resulted from cryotherapy compared to the baseline measures.

3.     Significant differences between the baseline measure and 1hr after intervention were noted in spasticity as indicated by elastic path length (p=0.0198) but only a trend was noted for total path length (p=0.058).

Extracorporal Shock Wave Therapy
Altindag & Gursoy 2014

Turkey

Pre-Post

N=9

Population: Mean age: 25.6 yr; Gender: males=5, females=4; Injury etiology: hemiplegia =3, cerebral palsy=2, SCI=4.

Intervention: Individuals received physiotherapy and extracorporeal shock wave therapy (ESWT; sound waves). ESWT was applied every other day during the 1st wk of physio (3 total). Outcomes were measured 2 wk after ESWT

Outcome Measures: Modified Ashworth Scale (MAS).

1.      There was a significant decrease in muscle tone 2 wk after ESWT intervention compared with the baseline measurement (p=0.001).
Galvanic Vestibular Simulation
Cobeljic et al. 2018

Denmark

Pre-Post

N=7

 

Population: SCI (n=7): Mean age=NR; Gender: males=NR, females=NR; Level of injury: Mean time since injury=NR; AIS scale: A=7.

Intervention: Participants underwent Galvanic vestibular stimulation (GVS) was administered by placing an anode and cathode over the right and left mastoid process, respectively. Participants received 10 monophasic pulses ranging from 1 to 10 mA over 15 seconds. A sham stimulation was administered after the initial GVS. Outcome measures were assessed prior to stimulation, immediately after, and 5min and 30 min after stimulation. Spasticity was assessed with the outcome measures listed below.

Outcome Measures: Spasticity: Modified Ashworth Scale (MAS); Pendulum test (PT).

1.     mAS and PT were reduced in 2 out of 7 participants, however there were no statistically significant changes overall in both MAS and PT (p>0.05).

Table 5. Systematic Review of Various Forms of Afferent Stimulation for Reducing Spasticity

Author Year

Country
Research Design

Score
Total Sample Size

MethodsOutcome
Sadeghi & Sawatzky

2014

Canada

Review of published articles between 1887-2013

AMSTAR=8

N=10

Method: Comprehensive literature search of articles on the application of either whole-body vibration (WBV) or focal vibration (FV). Articles were restricted to three or more participants >17 yr of age, with chronic SCI, and who had spasticity for >4 mo after their injury.

Databases: MEDLINE, EMBASE, CINAHL, PsycINFO.

Level of evidence: Evidence was categorized according to the Centre for Evidence Based Medicine levels of evidence. Level 2B: 1 paper, Level 2C: 1 paper, Level 3B: 6 papers, Level 4: 2 papers.

Questions/measures/hypothesis:

1. Examine the effectiveness of WBV and FV on managing spasticity in individuals with SCI.

1.   There is limited support for using WBV and FV to manage spasticity with SCI.

2.   A short-term reduction in spasticity is seen after FV within 50-100 Hz and 2.5-3 mm amplitude.

3.   A 6 to 8 day decrease in spasticity was observed after 1 mo of WBV at 50 Hz and 2-4 mm amplitude.

 

Discussion

It should be noted that several of the modalities described in this section have not been employed in regular clinical practice and may be deemed as more investigational in nature. For example, helium-neon laser irradiation has only been employed in one investigation and has not been considered as a viable therapeutic approach. Similarly, penile and rectal stimulation, first noted as delivering potential side benefits within fertility clinic investigations, may not be acceptable forms of therapy to individuals from either a safety or a psychological perspective. Other therapies might simply be impractical to implement. For example, hippotherapy requires access to a suitable equine facility with appropriately trained individuals.

Taping

Tamburella et al. (2014) completed a crossover RCT (n=11) to study the effects of Kinesio Tape versus silk tape on spasticity. Study subjects were randomly allocated to receive either Kinesio Tape or conventional silk tape (ST) for 48 hours. After a 7-day washout period, the study subjects were crossed over and received 48 hours of the alternate treatment. Tape was applied to the soleus and gastrocnemius muscles with the knee extended and ankle at 90o passive dorsiflexion. Baseline and post-treatment spasticity assessments included MAS, PSFS, Spinal Cord Assessment Tool for Spastic Reflexes and the subscale for clonus assessment (SCATS). Study subjects who received Kinesio Tape demonstrated significant improvements from baseline to post-treatment in active and passive ROM, extended knee SCATS, MAS, PSFS (all p<0.001) and flexed knee SCATS (p<0.005), compared to the ST condition.

Transcutaneous Electrical Nerve Stimulation (TENS)

Oo et al. (2014) completed a prospective randomized controlled single-blinded clinical trial (n=16) of active 3-week course (five sessions/week) of TENS and standard physical therapy (n=8) vs standard therapy alone (n=8) to study the immediate and short-term efficacy of TENS in subacute spinal spasticity. Composite spasticity scores of ankle jerk, muscle tone, and ankle clonus scores were completed at baseline and immediately after the first and last interventions for both groups by a physiatrist familiar with the testing procedures. After the first session, statistical significance for reduction in the composite spasticity score was seen in the TENS group only (mean difference=1.75; 99%CI, 0.47-3.03; p=0.002) which was also apparent in a significant between group difference (mean difference 1.63; 99% CI, 0.14-3.11; p=0.006). After the final session, a significant improvement for the composite spasticity score was seen in the TENS group only (2.75; 99% CI, 1.31-4.19; p<0.001) along with a related significant between-group difference in the composite spasticity score (2.13; 99% CI, 0.59-3.66; p=0.001). The study demonstrated that the combination of TENS with standard physical therapy was beneficial in the synergistic reduction of clinical spasticity in both the immediate and short-term basis in the subacute phase of SCI rehabilitation.

Aydin et al. (2005) employed an RCT design to compare oral baclofen (N=10) to TENS (N=11) to the bilateral tibial nerves (i.e., innervating gastrocnemius muscle) in reducing lower limb spasticity. 15-minute sessions of TENS were applied to the tibial nerve over 15 days demonstrating significantly reduced spasticity as indicated by reductions in the following measures assessed immediately after the last treatment session: AS, PSFS, deep tendon reflex score, FIM and Functional Disability Scores and H-reflex amplitude. In addition, there were also some lasting effects over the next 24 hours as repeat testing the next day indicated continued spasticity reductions although to a lesser degree. It should also be noted that significant reductions were obtained on some measures (but not all) following a single session. However, the long-term effects were more profound after the 15 sessions than those obtained following a single session.

Other researchers have examined the effects of TENS following a single session (Bajd et al. 1985; Goulet et al. 1996; Chung & Cheng 2010; van der Salm et al. 2006). Goulet et al. (1996) employed a single 30-minute bout of TENS over the common peroneal nerve in an attempt to reduce plantar flexor spasticity in 14 individuals with SCI. This study showed significant decreases in scores for the MAS and the Achilles tendon reflex but no significant changes were seen for H-reflex amplitude. A trend for decreased clonus scores was observed but this was not statistically significant. Chung and Cheng (2010) also examined the effect of 60-minute TENS sessions over the common peroneal nerve. The authors reported a significant reduction on the Composite Spasticity score (p=0.017), and a reduction in resistance to full range passive ankle dorsiflexion (p=0.024), and ankle clonus (p=0.023). In these two studies, TENS appears to be effective in reducing spinal spasticity following a single session.

In contrast, van der Salm et al. (2006) and Bajd et al. (1985) each examined dermatomal TENS as opposed to direct nerve stimulation with conflicting results. Bajd et al. (1985), in a small pre-post trial (n=6) reported reduced spasticity in three subjects as indicated by increased relaxation indexes associated with the pendulum test. However, no mean data or group statistical analysis was provided. Van der Salm et al. (2006) conducted a more thorough analysis of the effect of a single 45-minute session of TENS to the L1 dermatome in 10 individuals with longstanding SCI (mostly AIS A) and obtained no short-term effects, although as noted in the previous section obtained benefits with motor stimulation. A critical element within these investigations of single-session effects is the precise time of assessment, relative to treatment, a detail not always precisely reported in the various studies, although van der Salm et al. (2006) assessed individuals as close as possible to treatment cessation.

Penile Vibratory Stimulation

Penile vibration has also been investigated as a method of providing sensory stimulation to reduce spasticity (Laessoe et al. 2004; Alaca et al. 2005). In particular, Laessoe et al. (2004) employed an unblinded, crossover RCT design (N=9) in which male participants either received penile vibration or no treatment followed by the opposite condition with a minimum washout period of 1 week. The MAS and PSFS were conducted in addition to an EMG assessment in which ongoing muscle activity was recorded over a 24-hour period. Penile vibration was shown to be effective in reducing spasticity as indicated by reductions in MAS scores (p<0.01) and a slight trend for reduced PSFS scores (p=0.26). These were not maintained over 24 hours. The EMG analysis showed that reduced muscle activity was most apparent in the first hour post-stimulation, and had returned to baseline by 3 hours suggesting the effect lasted no more than 3 hours. The authors attempted to include female subjects involving clitoral vibratory stimulation but were only able to recruit two subjects willing to submit to the procedure. Both women reported similar reductions in spasticity although evaluation of the effectiveness of the stimulation was more difficult (i.e., no confirmatory ejaculation). Results from Alaca et al. (2005) confirmed the overall study findings as penile vibratory stimulation in 10 males resulted in significant reductions in AS scores as assessed 3 hours after stimulation (p=0.001) and maintained at 6 hours (p=0.03) with a trend for reduced values still apparent at 24 hours (p=0.08). The longer carry over effect in this study may have been due to a prolonged stimulus period as Alaca et al. (2005) employed six, 3-minute periods of stimulation (separated by 1-minute) whereas Laessoe et al. (2004) used a single 5-minute period.

Helium-neon Laser Stimulation

Walker (1985) employed a helium-neon laser to irradiate the skin overlying sensory nerves and demonstrated a similar beneficial effect of suppressing clonus as seen with electrical stimulation of sensory nerves. This investigator employed an RCT design with a variety of small group control conditions (N=5 to N=7), but failed to report several important experimental details (i.e., method of concealment, method of analysis and statistical comparisons). This approach has not been investigated since this brief 1985 report.

Rectal Electrostimulation

Halstead et al. (1993) have evaluated another form of electrical stimulation, rectal electrostimulation, when they observed individuals undergoing this procedure, for the purpose of sperm retrieval, reporting improved spasticity. These investigators conducted a prospective pre-post trial examining the effects of a minimum of six sessions of rectal probe electrostimulation on various clinical measures of spasticity including the AS, PSFS, deep tendon reflexes and ankle clonus. Although they achieved good to excellent effects in more than half of the individuals examined including significant reductions in the AS (p<0.01) and with the effects outlasting the intervention by a mean of 8.2 hours according to individual self-report further therapeutic development of this approach has not continued.

Vibration

Murillo et al. (2011) conducted a pre-post study (n=28) to determine if a decrease in muscle spasticity could be demonstrated with muscle vibration in study subjects with SCI. Muscle vibration at a frequency of 50 Hz during 10 minutes over the rectus femoris muscle was applied. The study showed significant treatment improvements in SCI study subjects with a decrease in MAS at the knee joint (p<0.001), an increase in ROM for knee extension (p=0.001) and a reduction in duration and frequency of clonus (both p≤0.006). Muscle vibration induced a significant reduction in Hmax/Mmax ratio in the control group (p=0.005) and in the individuals with SCI (p=0.001). The change was not significantly different between the two groups. Muscle vibration also induced a significant inhibition of Twave amplitude in both individuals with SCI (p=0.002), and control subjects (p=0.007). The Hmax and the Mmax were significantly smaller in the complete SCI than in the incomplete SCI (p=0.03, p=0.04) populations, and the Hmax/Mmax ratio was significantly greater in the individuals with complete SCI than in the individuals with incomplete SCI (p=0.02). The study showed that prolonged vibration on proximal extremity muscles decreased limb spasticity in study subjects in both complete and incomplete SCI.

Ness and Field-Fote (2009) examined the effect of whole-body vibration at 50 Hz on individuals with SCI for 4 weeks. Sessions occurred three times per week with four bouts of vibration occurring each day for 45 seconds each. A significant reduction in quadriceps spasticity was reported, as determined by first swing excursion, and persisted for at least 8 days.

In a small group of individuals with chronic motor incomplete SCI (N=29; Estes et al 2018, level 2 RCT), whole body vibration, across single sessions of 4 different frequency/duration parameters (with 1 week washout between sessions), did not result in quadriceps spasticity reduction as measured with the pendulum test (at baseline and immediately/15min/45min post-intevention) when compared to the sham-control group, but stretch reflex excitability was significantly dampened after high frequency/long duration whole body vibration in those participants with more severe spasticity. The whole-body vibration intervention consisted of 4 or 8, 45s bouts of 30 or 50 Hz vibration while sham-control treatment consisted of 8, 45s bouts of electrical stimulation. All bouts were interspersed with 1 minute of rest. Spasticity reduction was in part attributed to repeated sitting and standing across treatment bouts as some effect was also seen in sham- treated participants.

The effect of whole-body vibration training on ankle spasticity reduction did appear to be significant based on the work of In et al (2018; N=28; level 1b evidence). This group of participants with incomplete cervical SCI were randomly assigned to whole body vibration or placebo training. Whole body vibration included 16 minutes of 30Hz vibration, twice daily for 5 days each week over 8 weeks. Placebo training followed the same parameters with ultra low frequency vibration. Spasticity (passive resistive force) of the ankle plantar-flexors was measured with a hand-held dynamometer. The control group also showed a significant reduction in spasticity which was attributed to the standard physical therapy (range of motion, mat exercise and gait training). The added effect above this control effect was seen in the active intervention group and attributed to whole body vibration.

Therapeutic Massage

Afferent stimulation may also be produced via mechanical means. Goldberg et al. (1994) have employed therapeutic massage over the triceps surae muscle and assessed H-reflex amplitude to demonstrate that µ-motor neuron excitability is reduced significantly during a short 3-minute period of massage and somewhat reduced 3 minutes after but not 6 minutes after. Reductions in µ-motor neuron excitability are indicative of decreased spasticity.

Cryotherapy

The short-term effect of cryotherapy was investigated by Price et al. (1993) who used a biomechanical approach similar to that described earlier (i.e., Seib et al.1994) to monitor ankle viscoelastic stiffness through measurements of resistance torque to repetitive sinusoidal ankle movements. Although the majority of subjects were individuals with stroke or head injury, five of seven people with SCI showed a significant reduction in spasticity both immediately following cryotherapy and also at 1 hour after the cold stimulus was removed.

Sadeghi and Sawatzky (2014) completed a systematic review on the application of either whole body vibration or focal vibration for reducing spasticity. Articles were restricted to those published between 1987 and 2013 and having three or more participants >17 years of age, with chronic SCI, and who had spasticity for >4 months after their injury. Evidence was categorized according to the Centre for Evidence Based Medicine levels of evidence. Level 2B: one paper, Level 2C: one paper, Level 3B: six papers, Level 4: two papers (n=10). The authors found that there is limited support for using whole body vibration and focal vibration to manage spasticity secondary to SCI. A short-term reduction in spasticity is seen after focal vibration (frequency of 50-100Hz and amplitude of 2.5-3mm) and a 6 to 8 day decrease in spasticity was observed after 1 month of whole-body vibration at 50 Hz and 2-4 mm amplitude. Studies done by Murillo et al. (2011) and Ness and Field-Fote (2009) were also included in this literature review which did demonstrate a decrease in spasticity after use of vibration.

Galvanic Vestibular Stimulation

Galvanic vestibular stimulation involves painlessly and electrically activating the nerve in the ear that maintains balance. Galvanic vestibular stimulation applied to a small group of participants (N=7, Cobelijic et al 2018, level 4 evidence) with complete SCI did not significantly reduce lower extremity spasticity as measured by the MAS and the pendulum test, when compared to participants given a sham galvanic vestibular stimulation. That 2 participants experienced some anti-spasticity effects suggests that galvanic vestibular stimulation may be able to influence residual vestibulospinal influences over spasticity but that a better clinical and neurophysiological understanding of responders vs nonresponders is needed to optimize galvanic vestibular stimulation stimulation parameters.

Conclusions

Taping

There is level 1b evidence (from one RCT; Tamburella et al. 2014) that kinesio tape has short-term effects of decreasing spasticity and improving balance and gait in individuals with chronic SCI.

TENS

There is level 1a evidence (from three RCTs; Oo 2014; Chung & Cheng 2010; Aydin et al. 2005) that an ongoing program of TENS acts to reduce spasticity as demonstrated by various clinical and electrophysiological measures.

There is level 1b evidence (from a single RCT; Aydin et al. 2005) that reductions in spasticity with ongoing programs of TENS may persist for up to 24 hours.

There is level 1a evidence (from two RCTs; Oo 2014; Aydin et al. 2005) that a single treatment of TENS acts to reduce spasticity but to a lesser degree than that seen with ongoing programs of TENS.

Penile Vibratory Stimulation

There is level 1b evidence (from one RCT and one pre-post study; Laessoe et al. 2004; Alace et al. 2005) a single RCT supported by a single pre-post study that a single bout of penile vibration acts to reduce spasticity lasting for at least 3 hours and possibly up to 6 hours.

Helium-Neon Irradiation

There is level 2 evidence (from one RCT; Walker 1985) that helium-neon irradiation of sensory nerves may suppress ankle clonus for up to 60 minutes following 40 seconds of stimulation.

Electrical Nerve Stimulation

There is level 4 evidence (from one pre-post study; Halstead et al. 1993) that several sessions of rectal probe stimulation reduces lower limb muscle spasticity for up to 8 hours.

There is level 4 evidence (from one pre-post study; Van der Salm et al. 2006) that electrical stimulation of the triceps surae does not significantly reduce spasticity.

Vibration

There is level 1b (In et al, 2018, N=28 RCT) evidence that reflects reduced plantar-flexor spasticity resulting after whole body vibration (16 minutes, twice daily, 5 times per week over 8 weeks).

There is level 2 (Estes et al 2018, N-29 RCT) evidence supporting that single whole-body vibration sessions (4 or 8, 45 second bouts of 30 or 50Hz vibration) does not result in reduced quadriceps spasticity.

There is level 4 evidence (from one pre-post study; Murillo et al. 2011) that vibration over the rectus femoris muscle results in reduced knee spasticity and increased knee range of motion.

There is level 5 evidence (from one observational study; Ness & Field-Fote 2009) that (whole body vibration; 4, 45 second bouts of 50Hz vibration, 3 times per week over 4 weeks) results in reduced quadriceps spasticity over the short term.

Massage

There is level 4 evidence (from one pre-post study; Goldberg et al. 1994) that short periods of massage (e.g., 3 minutes) of the triceps surae results in reduced H-reflexes with the effect lasting no longer than a few minutes.

Cryotherapy

There is level 4 evidence (from one pre-post study; Price et al. 1993) that cryotherapy may reduce muscle spasticity for up to 1 hour after removal of the cold stimulus.

Extracorporal Shock Wave Therapy

There is level 4 evidence (from one pre-post study; Altindag & Gursoy 2014) that three sessions of extracorporal shock wave therapy may reduce muscle tone over the short term.

Galvanic Vestibular Stimulation

There is level 4 evidence (from one pre-post study; Cobelijic et al 2018) that better clinical and neurophysiological understanding is needed for galvanic vestibular stimulation responders vs nonresponders to potentially optimize galvanic vestibular stimulation stimulation parameters for responders.

  • Ongoing TENS nerve stimulation programs result in short-term reductions in spasticity which may last for up to 24 hours.

    Use of TENS and standard physical therapy showed a reduction in clinical spasticity in the subacute phase of rehabilitation.

    Penile vibration and rectal probe stimulation may be effective at reducing lower limb muscle spasticity for several hours.

    Other forms of afferent stimulation including taping, massage, cryotherapy, helium-neon irradiation, whole-body vibration, and galvanic vestibular stimulation may result in immediate spasticity reduction but require more research to understand effects and intervention parameters.