Spasticity in spinal cord injured persons: quantitative effects of baclofen and placebo treatments

Single-Case Design, Analysis, and Quality Assessment for Intervention Research

BACKGROUND AND PURPOSE

The purpose of this article is to describe single-case studies and contrast them with case studies and randomized clinical trials. We highlight current research designs, analysis techniques, and quality appraisal tools relevant for single-case rehabilitation research.

SUMMARY OF KEY POINTS

Single-case studies can provide a viable alternative to large group studies such as randomized clinical trials. Single-case studies involve repeated measures and manipulation of an independent variable. They can be designed to have strong internal validity for assessing causal relationships between interventions and outcomes, as well as external validity for generalizability of results, particularly when the study designs incorporate replication, randomization, and multiple participants. Single-case studies should not be confused with case studies/series (ie, case reports), which are reports of clinical management of a patient or a small series of patients.

RECOMMENDATIONS FOR CLINICAL PRACTICE

When rigorously designed, single-case studies can be particularly useful experimental designs in a variety of situations, such as when research resources are limited, studied conditions have low incidences, or when examining effects of novel or expensive interventions. Readers will be directed to examples from the published literature in which these techniques have been discussed, evaluated for quality, and implemented.

Effect of oral baclofen on spasticity poststroke: responders versus non-responders

Objective To assess quantitatively the efficacy of oral baclofen for spasticity poststroke. Methods The participants were 29 persons poststroke with increased resistance to passive ankle dorsiflexion and ankle clonus on clinical assessment. Baclofen was administered at 20 mg/day for 1 week. The ankle joint was passively dorsiflexed at either 5°/s (slow stretch) or 90°/s (fast stretch) by a custom-built device. The ankle joint angle and resistive torque were measured during the ramp-and-hold stretch, with gastrocnemius electromyogram. The main outcome measures were the numbers of ankle clonus during hold, and the torques at 10° of ankle dorsiflexion in slow stretch (T-slow) and fast stretch (T-fast). Moreover, the velocity-dependent torque (ΔT = T-fast - T-slow) was compared between before and after oral baclofen. Results The numbers of ankle clonus, T-slow, T-fast, and ΔT for all participants did not exhibit significant differences between before and after baclofen administration. However, reduction in the number of ankle clonus of five or more was accompanied with a reduction in ΔT (4.0 ± 1.8 Nm) in three participants (the responders). Conclusion Although the responder rate was low, some participants responded to oral baclofen. Thus, a short-term trial of oral baclofen, and quantitative and electrophysiological assessments of muscle tone and ankle clonus are recommended.

Spasticity following spinal cord injury

BACKGROUND

Up to 70% of patients with spinal cord injuries develop spasticity. The main aim of the paper is to provide an overview of spasticity management, primarily in patients with spinal cord injuries.

METHOD

The article is based on literature searches in PubMed using the keyphrases «spasticity» and «spasticity AND spinal cord injury», and own clinical experience and research.

RESULTS

Spasticity may be general, regional or localised. Factors such as an over-filled bladder, obstipation, acute infections, syringomyelia or bone fractures may substantially influence the degree of spasticity and must be determined. An assessment of the clinical and functional consequences for the patient is decisive before management. Active exercise, physiotherapy and peroral drugs are the simplest and cheapest options. Baclofen is the only centrally acting spasmolytic registered in Norway and is the first choice for peroral treatment. Benzodiazepines can also be used. The effect of the tablets is generally limited and there are often pronounced side effects. Local spasticity can be treated with botulinum toxin injections. The effect is time-limited and the treatment must be repeated. International guidelines recommend a combination of botulinum toxin injections and physiotherapy. In cases of regional spasticity, particularly in the lower limbs, intrathecal baclofen administered via a programmable pump may provide a continuous spasm-reducing effect. Orthopaedic surgery or neurosurgery may be an option for selected patients with intractable spasticity.

INTERPRETATION

Spasticity following a spinal cord injury must be assessed regularly. The treatment strategy depends on the degree of functional failure caused by the spasticity and its location.

A randomized, double-blind, placebo-controlled study of the efficacy and safety of tolperisone in spasticity following cerebral stroke

To study the efficacy and safety of tolperisone - a centrally acting muscle relaxant with membrane stabilizing activity - in the treatment of stroke-related spasticity. This was a randomized, double-blind, placebo-controlled, multicenter study with parallel groups. Treatment lasted 12 weeks and was started with a titration period of variable length (dose range 300-900 mg tolperisone daily). The degree of spasticity determined on the Ashworth Scale in the most severely affected joint area was defined as primary target parameter. Hundred and twenty patients (43 females, 77 males) in a mean age of 63.3 +/- 10.6 years were recruited and received treatment. In the majority of patients both limbs of each side (right: n = 59; left: n = 56) were affected by the spasticity which on average had been present for 3.3 +/- 4.4 years. A 62% of the patients were treated with a daily dose >/=600 mg tolperisone. Tolperisone reduced the mean Ashworth Score by a mean of 1.03 +/- 0.71 compared with a mean reduction of 0.47 +/- 0.54 in the placebo group (P < 0.0001). A 78.3% of the patients on tolperisone versus 45% of the placebo patients experienced a reduction by at least 1 point on the Ashworth Scale (P < 0.0001). Functional and overall assessments of efficacy confirmed superior efficacy of tolperisone. Adverse events occurred less often on active treatment (n = 19) than on placebo (n = 26) and were mostly of mild-to-moderate intensity. No withdrawals caused by adverse events were reported in the tolperisone group. The findings of the present study demonstrate the efficacy and excellent tolerance of tolperisone in the treatment of spastic hypertonia following cerebral stroke. Study data further suggest that an individual dose titration which may exceed the recommended maximum dose of 450 mg daily results in optimized therapeutic benefit.

A benefit-risk assessment of baclofen in severe spinal spasticity

Baclofen is used for treatment of the spasticity of spinal origin that is a common sequela of spinal cord injury and multiple sclerosis; spasticity occurs in about 50% of patients affected by these disorders. In open-label studies of oral baclofen, the drug improved spasticity in 70-87% of patients; additionally, improvement in spasms was reported in 75-96% of patients. In double-blind, crossover, placebo-controlled trials, baclofen was reported to be effective, producing statistically significant improvements in spasticity. Tizanidine is the antispasticity drug that has been most widely compared with oral baclofen; studies have generally found the two drugs to have equivalent efficacy. However, tizanidine has better tolerability, in particular weakness was reported to be occur less frequently with tizanidine than with baclofen. The main adverse effects of oral baclofen include: sedation or somnolence, excessive weakness, vertigo and psychological disturbances. The incidence of adverse effects is reported to range from 10% to 75%. The majority of adverse effects are not severe; most are dose related, transient and/or reversible. The main risks of oral baclofen administration are related to withdrawal: seizures, psychic symptoms and hyperthermia can occur. These symptoms improve after the reintroduction of baclofen, usually without sequelae. When not related to withdrawal; these symptoms mainly present in patients with brain damage and in the elderly. The limited data on baclofen toxicity in patients with renal disease suggest that administration of the drug in these persons may carry an unnecessarily high risk. Intrathecal baclofen is indicated for use in patients with spasticity of spinal origin unresponsive to treatment with maximum doses of oral baclofen, tizanidine and/or dantrolene. The benefits of continuous intrathecal baclofen infusion have been demonstrated: >80% and >65% of patients have improvement in tone and spasms, respectively. The main risks of intrathecal baclofen infusion are symptoms related to overdose or withdrawal; the latter is more important because of the associated severe effects on clinical status and the possibility of death, but it is responsive to rapid treatment. Overdose primarily arises from drug test doses or human error during refill and programming of the pump, and withdrawal most commonly occurs as a result of a problem with the delivery system. Since the adverse consequences do not exceed the benefits of oral and intrathecal baclofen for patients with spinal spasticity, the benefit/risk assessment is favourable.

Pain and spasticity after spinal cord injury: mechanisms and treatment

STUDY DESIGN

A comprehensive survey of literature on the proposed mechanisms and treatment of pain and spasticity after spinal cord injury (SCI) was completed.

OBJECTIVES

To define the current understanding of these entities and to review various treatment options.

SUMMARY OF BACKGROUND DATA

The neurophysiologic basis of spasticity after SCI is well established. The mechanism of neuropathic pain after SCI remains conjectural, although considerable new data, much of it from animal models, now add to our understanding of this condition.

METHODS

A comprehensive search and review of the published literature was undertaken.

RESULTS

Treatment options for spasticity are effective and include oral medication (baclofen, tizanidine), intrathecal baclofen, and rarely, surgical rhizotomy or myelotomy. Selected patients with post-SCI pain can respond to surgical myelotomy (DREZ lesions) or intrathecal agents (e.g., morphine + clonidine), but the majority continue to suffer.

CONCLUSIONS

Medical and surgical treatments for spasticity are established and highly successful. Management of post-SCI pain remains a clinical challenge, as there is no uniformly successful medical or surgical treatment.

Evidence-based practice: methods to evaluate individual patient improvement

The expectations and demands associated with evidence-based practice in medical rehabilitation require the use of research procedures that are practice based and practitioner oriented. Traditional research methods, including randomized clinical trials, are powerful techniques for determining the efficacy of rehabilitation interventions; however, randomized clinical trials have some practical and ethical limitations when applied to many research questions important to the field of medical rehabilitation, and alternative methods are needed to fully examine the effectiveness of treatment techniques for individual patients and to document clinical accountability. This paper examines the use of single-system designs and N of 1 research strategies. The advantages and limitations of single-system methods are described, and examples relevant to the documentation of clinical outcomes in medical rehabilitation are presented.

Drugs used to treat spasticity

Spasticity is a common and disabling symptom for many patients with upper motor neuron dysfunction. It results from interruption of inhibitory descending spinal motor pathways, and although the pathophysiology of spasticity is poorly understood, the final common pathway is overactivity of the alpha motor neuron. Therapy for spasticity is symptomatic with the aim of increasing functional capacity and relieving discomfort. Any approach to treatment should be multidisciplinary, including physical therapy, and possibly surgery, as well as pharmacotherapy. It is important that treatment be tailored to the individual patient, and that both patient and care giver have realistic expectations. Pharmacotherapy is generally initiated at low dosages and then gradually increased in an attempt to avoid adverse effects. Optimal therapy is the lowest effective dosage. Baclofen, diazepam, tizanidine and dantrolene are currently approved for use in patients with spasticity. In addition, clonidine (usually as combination therapy), gabapentin and botulinum toxin have shown efficacy, however, more studies are required to confirm their place in therapy. Intrathecal baclofen, via a surgically implanted pump and reservoir, may provide relief in patients with refractory severe spasticity.

Quantitative assessment of intrathecally administered baclofen in spasticity

OBJECTIVE

To quantitatively assess the antispastic effect of intrathecally administered baclofen on muscle stiffness in spastic patients.

DESIGN

Case-control study.

SETTING

Clinical laboratory in a university hospital of a city of more than 1,000,000 inhabitants.

PARTICIPANTS

Eighteen healthy adult volunteers (9 men, 9 women) were recruited for establishing the normal values. Eleven spastic patients (8 men, 3 women) comprised the study group.

MAIN OUTCOME MEASURES

The resistance to passive sinusoidal displacement of 5 degrees imposed to the ankle joint was measured at frequencies from 3 to 12 Hz. Torque and displacement signals were subjected to a Fourier analysis to isolate the elastic and viscous components of the total muscle stiffness.

RESULTS

In comparison with the period before intrathecal injection, and with the control group, it was shown that at 4 hours after injection, stretch reflex activity was abolished and elastic and viscous muscle stiffness approached control values. The abnormal residual stiffness concerned only the elastic component due to chronic transformations of the spastic muscle and/or due to changes in joints and periarticular connective tissue. This antispastic effect was completely reversed 36 hours after injection.

CONCLUSION

The present study shows that the antispastic effect of intrathecally administered baclofen in spastic patients can be quantitatively assessed by a sensitive method allowing measurement of elastic and viscous components of muscle stiffness.

Pharmacological interventions for spasticity following spinal cord injury

BACKGROUND

Spasticity is a major health problem for patients with a spinal cord injury (SCI) that limits patients' mobility and affects independence in activities of daily living and work. Spasticity may also cause pain, loss of range of motion, contractures, sleep disorders and impair ambulation in patients with an incomplete lesion. The effectiveness of available drugs is still uncertain and they may cause adverse effects. Assessing what works in this area is complicated by the lack of valid and reliable measurement tools. The aim of this systematic review is to critically appraise and summarise existing information of the effectiveness of available treatments and to identify areas where further research is needed.

OBJECTIVES

To assess the effectiveness and safety of Baclofen, Dantrolene, Tizanidine and any other drugs for the treatment of long term spasticity in SCI patients as well as the effectiveness and safety of different routes of administration of Baclofen.

SEARCH STRATEGY

We searched the Injuries Group specialised register, the Cochrane Controlled Trials Register, MEDLINE, EMBASE and CINHALH up to 1998. Drug companies and experts active in the area were also contacted.

SELECTION CRITERIA

All parallel and crossover RCTs including spinal cord injury patients complaining of "severe spasticity". Studies where less than 50% of patients had a spinal cord injury were excluded.

DATA COLLECTION AND ANALYSIS

Methodological quality of studies (allocation concealment, blinding, patients characteristics, inclusion and exclusion criteria; interventions; outcomes; lost to follow up) was independently assessed by two investigators. The heterogeneity among studies did not allow quantitative combination of results.

MAIN RESULTS

Nine out of 53 studies met the inclusion criteria. Study design was: 8 cross over, 1 parallel-group trial. Two studies (14 SCI patients), showed a significant effect of intrathecal baclofen in reducing spasticity (Ashworth Score and ADL performances), compared to placebo, without any side effect. The study comparing tizanidine to placebo (118 SCI patients) showed a significant effect of tizanidine in improving Ashworth Score but not in ADL performances. Tizanidine group reported significant rates of adverse effects (drowsiness, xerostomia). For the other drugs (Gabapentine, Clonidine, Diazepam, Amytal and oral Baclofen ) the results do not provide evidence for a clinical significant effectiveness.

REVIEWER'S CONCLUSIONS

There is insufficient evidence to assist clinicians in a rational approach to antispastic treatment for SCI. Further research is urgently needed to improve the scientific basis of patient care.

Case studies, single-subject research, and N of 1 randomized trials: comparisons and contrasts

Case studies, single-subject research designs, and N of 1 randomized clinical trials are methods of scientific inquiry applied to an individual or small group of individuals. A case study is a form of descriptive research that seeks to identify explanatory patterns for phenomena and generates hypotheses for future research. Single-subject research designs provide a quasi-experimental approach to investigating causal relationships between independent and dependent variables. They are characterized by repeated measures of an observable and clinically relevant target behavior throughout at least one pretreatment (baseline) and intervention phase. The N of 1 clinical trial is similar to the single-subject research design through its use of repeated measures over time but also borrows principles from the conduct of large, randomized controlled trials. Typically, the N of 1 trial compares a therapeutic procedure with placebo or compares two treatments by administering the two conditions in a predetermined random order. Neither the subject nor the clinician is aware of the treatment condition in any given period of time. All three approaches are relatively easy to integrate into clinical practice and are useful for documenting individualized outcomes and providing evidence in support of rehabilitation interventions.

Single-subject research in rehabilitation: a review of studies using AB, withdrawal, multiple baseline, and alternating treatments designs

OBJECTIVE

To review the "methodologic rules" for using single-subject research designs (SSRDs) and to review the use of SSRDs in rehabilitation research of the past decade.

DATA SOURCES

CINAHL and MEDLINE searches using "single subject" and "single system" as key words for the period 1985-1995 yielded 61 articles related to rehabilitation.

STUDY SELECTION

Studies were selected for review if they described one of four commonly used SSRDs, specifically AB, withdrawal, multiple baseline, or alternating treatments.

DATA EXTRACTION

Studies cited were identified by consensus and either exemplify adherence to the experimental rules of SSRDs or illustrate errors that result in threats to the validity of stated findings.

DATA SYNTHESIS

All four types of SSRDs have been reported in rehabilitation studies, sometimes incorrectly.

CONCLUSIONS

SSRDs, with their client-centered focus, are ideally suited for researching human behavior in the rehabilitation practice environment. Although numerous sources clearly identify the methodologic requirements for single-subject experiments, several studies violate the basic rules, threatening the validity of the results of these studies. Other properly applied SSRDs illustrate the strengths of this approach, which can produce empirical support for rehabilitation interventions.

The stretch reflex response in the normal and spastic ankle: effect of ankle position

OBJECTIVE

The influence of stretch of the gastrocnemiussoleus muscle on the stretch reflex activity was studied, by varying the ankle angle in steps from 10 degrees of plantarflexion (PF) to 5 degrees of dorsiflexion (DF).

DESIGN

Nonrandomized control trial.

SETTING

Department of Rehabilitation Medicine of a university medical center.

PATIENTS

Sixteen subjects with and 16 subjects without spasticity.

MAIN OUTCOME MEASURES

The passive elastic stiffness and active reflex response, expressed by the total and elastic path lengths, were determined at each ankle angle as a sinusoidal displacement of 5 degrees was applied to the joint at frequencies from 3 to 12 Hz.

RESULTS

The elastic stiffness showed no difference between the spastic and normal subjects for all ankle angles (p > .05). The elastic stiffness increased linearly similarly in both groups when the ankle was dorsiflexed. The reflex response was significantly greater in the spastic group for all positions (p < or = .01). The total and elastic path lengths showed a linear increase in both groups when the ankle angle was varied from PF to DF. The spastic group, however, had a significantly faster increase (p < or = .005). Between-group comparison showed a significant quadratic trend in the elastic path length for the spastic group (p < or = .05), with a maximum at 2.5 degrees of DF.

CONCLUSIONS

This study showed that the stretch reflex activity varies with the ankle position. This must be considered when performing spasticity tests subsequent to an intervention that has changed the available range of motion and when comparing subjects measured at different ankle positions.

A comparison of clonidine, cyproheptadine and baclofen in spastic spinal cord injured patients

In twenty-five SCI subjects, antispasticity effects of three putative antispasticity agents [clonidine (an alpha-2 noradrenergic agonist), cyproheptadine (a 5-HT2 antagonist) and baclofen (a GABA-B agonist)] were tested in terms of changes in leg tone as graded by the Ashworth scale (AS), in terms of the vibratory inhibition of the H-reflex (VII) and in terms of the ability of the knee to swing passively in the pendulum test as quantified by video motion analysis. When compared to the no drug period, all three drug treatments showed an antispasticity effect on the AS, the VII and the amplitude of the first swing and the relaxation index of the pendulum test, p. < 0001. Surprisingly, cyproheptadine and baclofen produced a greater reduction in the VII than clonidine, p. < 01. The amplitude of the first swing in the pendulum test correlated well with the AS, r = .88, and the antispasticity effects of the drugs produced improvements in both measures, a reduced AS and increased amplitude of knee swing in the pendulum test. Therefore, video motion analysis of the pendulum test is as valid a measure of spasticity as the Ashworth scale and is not limited by subjectivity of the examiner.