Treatment of spasticity with tizanidine in multiple sclerosis

Repurposable Drugs That Interact with Steroid Responsive Gene Targets for Inner Ear Disease

Corticosteroids, oral or transtympanic, remain the mainstay for inner ear diseases characterized by hearing fluctuation or sudden changes in hearing, including sudden sensorineural hearing loss (SSNHL), Meniere's disease (MD), and autoimmune inner ear disease (AIED). Despite their use across these diseases, the rate of complete recovery remains low, and results across the literature demonstrates significant heterogeneity with respect to the effect of corticosteroids, suggesting a need to identify more efficacious treatment options. Previously, our group has cross-referenced steroid-responsive genes in the cochlea with published single-cell and single-nucleus transcriptome datasets to demonstrate that steroid-responsive differentially regulated genes are expressed in spiral ganglion neurons (SGN) and stria vascularis (SV) cell types. These differentially regulated genes represent potential druggable gene targets. We utilized multiple gene target databases (DrugBank, Pharos, and LINCS) to identify orally administered, FDA approved medications that potentially target these genes. We identified 42 candidate drugs that have been shown to interact with these genes, with an emphasis on safety profile, and tolerability. This study utilizes multiple databases to identify drugs that can target a number of druggable genes in otologic disorders that are commonly treated with steroids, providing a basis for establishing novel repurposing treatment trials.

Contribution of sensory feedback to plantar flexor muscle activation during push-off in adults with cerebral palsy

Exaggerated sensory activity has been assumed to contribute to functional impairment following lesion of the central motor pathway. However, recent studies have suggested that sensory contribution to muscle activity during gait is reduced in stroke patients and children with cerebral palsy (CP). We investigated whether this also occurs in CP adults and whether daily treadmill training is accompanied by alterations in sensory contribution to muscle activity. Seventeen adults with CP and 12 uninjured individuals participated. The participants walked on a treadmill while a robotized ankle-foot orthosis applied unload perturbations at the ankle, thereby removing sensory feedback naturally activated during push-off. Reduction of electromyographic (EMG) activity in the soleus muscle caused by unloads was compared and related to kinematics and ankle joint stiffness measurements. Similar measures were obtained after 6 wk of gait training. We found that sensory contribution to soleus EMG activation was reduced in CP adults compared with uninjured adults. The lowest contribution of sensory feedback was found in participants with lowest maximal gait speed. This was related to increased ankle plantar flexor stiffness. Six weeks of gait training did not alter the contribution of sensory feedback. We conclude that exaggerated sensory activity is unlikely to contribute to impaired gait in CP adults, because sensory contribution to muscle activity during gait was reduced compared with in uninjured individuals. Increased passive stiffness around the ankle joint is likely to diminish sensory feedback during gait so that a larger part of plantar flexor muscle activity must be generated by descending motor commands.NEW & NOTEWORTHY Findings suggest that adults with cerebral palsy have less contribution of sensory feedback to ongoing soleus muscle activation during push-off than uninjured individuals. Increased passive stiffness around the ankle joint is likely to diminish sensory feedback during gait, and/or sensory feedback is less integrated with central motor commands in the activation of spinal motor neurons. Consequently, muscle activation must to a larger extent rely on descending drive, which is already decreased because of the cerebral lesion.

Pharmacological management of spasticity in multiple sclerosis: Systematic review and consensus paper

Background and objectives:

Treatment of spasticity poses a major challenge given the complex clinical presentation and variable efficacy and safety profiles of available drugs. We present a systematic review of the pharmacological treatment of spasticity in multiple sclerosis (MS) patients.

Methods:

Controlled trials and observational studies were identified. Scientific evidence was evaluated according to pre-specified levels of certainty.

Results:

The evidence supports the use of baclofen, tizanidine and gabapentin as first-line options. Diazepam or dantrolene could be considered if no clinical improvement is seen with the previous drugs. Nabiximols has a positive effect when used as add-on therapy in patients with poor response and/or tolerance to first-line oral treatments. Despite limited evidence, intrathecal baclofen and intrathecal phenol show a positive effect in severe spasticity and suboptimal response to oral drugs.

Conclusion:

The available studies on spasticity treatment offer some insight to guide clinical practice but are of variable methodological quality. Large, well-designed trials are needed to confirm the effectiveness of antispasticity agents and to produce evidence-based treatment algorithms.

A Comparison of Methods to Assess the Excitability of Lower Motoneurones

The purpose of this investigation was to compare three methods of assessing the excitability of lower motoneurones—TA-reflex, H-reflex and F-wave—in 120 patients with spastic hemiparesis following a stroke. The H-reflex was recorded from the soleus muscle after submaximal electrostimulation of the tibial nerve. The T-Achilles (TA) reflex was recorded from the soleus muscle after percussion of the Achilles tendon. The F-wave was recorded in the distal limb muscles after supramaximal electrostimulation of the median, ulnar, fibular and tibial nerves. The patient’s healthy side was used as a control. The TA-reflex, H-reflex and F-wave showed increased amplitudes on the spastic side. All amplitude ratios: TA/M, H/M, Fmax/M and Fmean/M were increased. The H-reflex thresholds were decreased. The F-wave duration, persistence and number of phases were also increased on the spastic side. Despite clinically decreased muscle tone, there were no changes in TA or H-reflex parameters after treatment. On the other hand, F-wave parameters tended to normalize after treatment in all groups. In conclusion, the F-wave is a more sensitive method than the TA and H-reflexes in assessing the excitability of the lower motoneurone.

Burden of disease in multiple sclerosis patients with spasticity in Germany: mobility improvement study (Move I)

OBJECTIVES

To describe the current management patterns of multiple sclerosis (MS) patients with spasticity in Germany and the impact of MS spasticity on quality of life (QoL) and associated costs.

METHODS

Non-interventional, multicentre, cross-sectional and retrospective burden-of-disease study including 414 MS patients with spasticity (age from 25 to 80 years) from 42 clinical practices across Germany. All patients were diagnosed with MS-related spasticity based on neurological examination at least 12 months before inclusion in the study. Three different forms were completed on different aspects of the disease: the patient questionnaire, the chart documentation form and the physician questionnaire.

RESULTS

Mild, moderate and severe spasticity were found in 27.3, 44.0 and 28.7 % of patients, respectively. Associated symptoms and QoL scores were worse in patients with higher degrees of spasticity. In particular, higher mean scores for sleep impairment (mild vs. severe, 2.1 vs. 4.3), mean spasm count (3/day vs. 10.1/day), mean WEIMuS fatigue score (15.8 vs. 19.8), increased walking time (9.6 vs. 20.2 s) and lower mean QoL scores (MSQoL-54 physical subscale, 54.9 vs. 39.5; EQ-5D, 0.60 vs. 0.30) were reported in patients with severe spasticity in comparison to patients with mild spasticity. Patient management mainly comprised physiotherapy (mild vs. severe, 65.5 vs. 85.7 %) and medication (84.2 vs. 64.8 %) with baclofen. The average cost for patients with mild spasticity was €2,268/year, increasing to €8,688/patient/year for patients with severe spasticity. The health insurance costs showed the same trend.

CONCLUSIONS

MS patients with spasticity suffer a significant burden because of resulting disabilities and reduced QoL, especially in cases of severe spasticity. Moreover, spasticity causes high costs that increase with increasing severity.

Spasticity

Antispastic medications that are directed to reduce clinical signs of spasticity, such as exaggerated reflexes and muscle tone, do not improve the movement disorder. Medication can even increase weakness which might interfere with functional movements, such as walking. In this chapter we address how spasticity affects mobility and how this should be taken into account in the treatment of spasticity. In clinical practice, signs of exaggerated tendon tap reflexes associated with muscle hypertonia are the consequence of spinal cord injury (SCI). They are generally thought to be responsible for spastic movement disorders. Most antispastic treatments are, therefore, directed at the reduction of reflex activity. In recent years, a discrepancy between spasticity as measured in the clinic and functional spastic movement disorder was noticed, which is primarily due to the different roles of reflexes in passive and active states, respectively. We now know that central motor lesions are associated with loss of supraspinal drive and defective use of afferent input with impaired behavior of short-latency and long-latency reflexes. These changes lead to paresis and maladaptation of the movement pattern. Secondary changes in mechanical muscle fiber, collagen tissue, and tendon properties (e.g., loss of sarcomeres, subclinical contractures) result in spastic muscle tone, which in part compensates for paresis and allows functional movements on a simpler level of organization. Antispastic drugs should primarily be applied in complete SCI. In mobile patients they can accentuate paresis and therefore should be applied with caution.

[Pharmacological treatment of spasticity in multiple sclerosis]

The medicinal treatment of spasticity includes use of oral treatments (baclofène and tizanidine), botulinum toxin, intrathecal baclofène and local application of alcohol or phenol. However, spasticity may not be uncomfortable and may even be useful. Therefore, all spastic diseases do not systematically require treatment. First-line treatments (oral treatments and botulinum toxin) can be considered depending on the local or diffuse nature of the spasticity and depending on the etiology.

Potent suppression of stretch reflex activity after systemic or spinal delivery of tizanidine in rats with spinal ischemia-induced chronic spastic paraplegia

BACKGROUND

Spasticity and rigidity are serious complications associated with spinal traumatic or ischemic injury. Clinical studies show that tizanidine (Tiz) is an effective antispasticity agent; however, the mechanism of this effect is still not clear. Tiz binds not only to α2-adrenoreceptors (AR) but also to imidazoline (I) receptors. Both receptor systems (AR+I) are present in the spinal cord interneurons and α-motoneurons. The aim of the present study was to evaluate the therapeutic potency of systematically or spinally (intrathecally [IT]) delivered Tiz on stretch reflex activity (SRA) in animals with ischemic spasticity, and to delineate supraspinal or spinal sites of Tiz action.

EXPERIMENTAL PROCEDURES

Animals were exposed to 10 min of spinal ischemia to induce an increase in SRA. Increase in SRA was identified by simultaneous increase in recorded electromyography (EMG) activity and ankle resistance measured during computer-controlled ankle dorsiflexion (40°/3 s) in fully awake animals. Animals with increased SRA were divided into several experimental subgroups and treated as follows: (i) Tiz administered systemically at the dose of 1 mg kg(-1), or IT at 10 μg or 50 μg delivered as a single dose; (ii) treatment with systemic Tiz was followed by the systemic injection of vehicle, or by nonselective AR antagonist without affinity for I receptors; yohimbine (Yoh), α2A AR antagonist; BRL44408 (BRL), α2B AR antagonist; ARC239 (ARC), nonselective AR and I(1) receptor antagonist; efaroxan (Efa), or nonselective AR and I(2) receptor antagonist; idazoxan (Ida); (iii) treatment with IT Tiz was followed by the IT injection of selective α2A AR antagonist; atipamezole (Ati). In a separate group of spastic animals the effect of systemic Tiz treatment (1 mg/kg) or isoflurane anesthesia on H-reflex activity was also studied.

RESULTS

Systemic and/or IT treatment with Tiz significantly suppressed SRA. This Tiz-mediated anti-SRA effect was reversed by BRL (5 mg kg(-1)), Efa (1 mg kg(-1)), and Ida (1 mg kg(-1)). No reversal was seen after Yoh (3 mg kg(-1)) or ARC (5 mg kg(-1)) treatment. Anti-SRA induced by IT Tiz (50 μg) was reversed by IT injection of Ati (50 μg). Significant suppression of H-reflex was measured after systemic Tiz treatment (1 mg/kg) or isoflurane (2%) anesthesia, respectively. Immunofluorescence staining of spinal cord sections taken from animals with spasticity showed upregulation of α2A receptor in activated astrocytes.

CONCLUSIONS

These data suggest that α2A AR and I receptors, but not α2B AR, primarily mediate the Tiz-induced antispasticity effect. This effect involves spinal and potentially supraspinal sites and likely targets α2A receptor present on spinal neurons, primary afferents, and activated astrocytes. Further studies using highly selective antagonists are needed to elucidate the involvement of specific subtypes of the AR and I receptors in the antispasticity effect seen after Tiz treatment.

Symptomatic therapy in multiple sclerosis: a review for a multimodal approach in clinical practice

As more investigations into factors affecting the quality of life of patients with multiple sclerosis (MS) are undertaken, it is becoming increasingly apparent that certain comorbidities and associated symptoms commonly found in these patients differ in incidence, pathophysiology and other factors compared with the general population. Many of these MS-related symptoms are frequently ignored in assessments of disease status and are often not considered to be associated with the disease. Research into how such comorbidities and symptoms can be diagnosed and treated within the MS population is lacking. This information gap adds further complexity to disease management and represents an unmet need in MS, particularly as early recognition and treatment of these conditions can improve patient outcomes. In this manuscript, we sought to review the literature on the comorbidities and symptoms of MS and to summarize the evidence for treatments that have been or may be used to alleviate them.

Relative bioavailability of tizanidine hydrochloride capsule formulation compared with capsule contents administered in applesauce: a single-dose, open-label, randomized, two-way, crossover study in fasted healthy adult subjects

BACKGROUND

The alpha2-adrenergic agonist tizanidine has been reported to have a narrow therapeutic index. A multiparticulate capsule formulation of tizanidine has been developed in an attempt to improve patient tolerability.

OBJECTIVE

This study assessed bioequivalence between a single, intact, 6-mg capsule of tizanidine and the capsule contents sprinkled in applesauce in fasted healthy subjects.

METHODS

Healthy male and female subjects aged 18 to 45 years completed 2 treatment periods: one with a tizanidine 6-mg capsule administered intact and the other with capsule contents sprinkled in applesauce. The 2 treatment periods had a 6-day washout period between administrations. Plasma tizanidine concentrations were determined for blood samples collected over 24 hours after administration. All treatment-emergent adverse events were recorded and graded by intensity and relationship to the study drug (not, improbable, possible, probable, definite) by the attending physician based on his or her clinical impression.

RESULTS

A total of 19 men and 9 women (mean age, 26 years) completed the trial. Geometric mean natural logarithm-transformed AUC values (AUC(0-infinity) [AUC to infinity] and AUC(0-t) [AUC to the last measurable time point]) and C(max) ratios were significantly (P <or= 0.035) increased to 1.14 (90% CI, 105.47%-127.01%), 1.16 (90% CI, 106.80%-130.53%), and 1.17 (90% CI, 103.95%-133.66%), respectively, when the contents were sprinkled, with 90% CIs laying outside the 0.80 to 1.25 ratio established by regulatory authorities for bioequivalence. A total of 31 adverse events were reported by 17 of the 28 subjects (61%), including 15 subjects (54%) with the intact capsule reporting 18 events and 11 subjects (39%) with the sprinkled contents reporting 13 events. No serious adverse events or deaths were reported, and no subjects were discontinued due to adverse events.

CONCLUSIONS

The contents of the tizanidine capsule sprinkled in applesauce were not bioequivalent to the intact 6-mg capsule in these fasted healthy volunteers. Therefore, if switching from the intact capsule to the capsule contents mixed in applesauce, monitoring for adverse events is recommended; in this situation, dose adjustment could be necessary.

Spastic movement disorder: impaired reflex function and altered muscle mechanics

In clinical practice, signs of exaggerated tendon tap reflexes associated with muscle hypertonia are generally thought to be responsible for spastic movement disorders. Most antispastic treatments are, therefore, directed at the reduction of reflex activity. In recent years, however, researchers have noticed a discrepancy between spasticity as measured in the clinic and functional spastic movement disorders, which is primarily due to the different roles of reflexes in passive and active states, respectively. We now know that central motor lesions are associated with loss of supraspinal drive and defective use of afferent input with impaired behaviour of short-latency and long-latency reflexes. These changes lead to paresis and maladaptation of the movement pattern. Secondary changes in mechanical muscle fibre, collagen tissue, and tendon properties (eg, loss of sarcomeres, subclinical contractures) result in spastic muscle tone, which in part compensates for paresis and allows functional movements on a simpler level of organisation. Antispastic drugs can accentuate paresis and therefore should be applied with caution in mobile patients.

Effects of food on the single-dose pharmacokinetics/pharmacodynamics of tizanidine capsules and tablets in healthy volunteers

BACKGROUND

A multiparticulate capsule formulation of the alpha2-adrenergic agonist tizanidine has been developed to decrease C(max), AUC, and associated somnolence, while maintaining efficacy.

OBJECTIVE

The purpose of this study was to compare the pharmacokinetics and impact of somnolence on cognitive function after single doses of the tablet and capsule formulations of tizanidine under fed and fasted conditions in healthy volunteers.

METHODS

This Phase I, single-dose, randomized, open-label, 4-way crossover study was conducted at MDS Pharma Services, Belfast, United Kingdom. Healthy male and female adult subjects received tizanidine (8 mg) as tablets and capsules under fasting and nonfasting conditions. Blood samples were collected to determine plasma tizanidine pharmacokinetic profiles, and computerized cognitive function tests were performed that yielded a validated composite score, Power of Attention, an index of sedation.

RESULTS

Ninety-six patients were enrolled in the study (54 men, 42 women; mean [SD] age, 27 [8] years [range, 18-52 years]; mean [SD] body weight, 71.7 [12.4] kg [range, 46-102 kg]). Tizanidine tablets and capsules were found to be bioequivalent after fasting. In the fed state, mean C(max) and AUC(0-t) were substantially decreased, by 33.8% and 15.4%, comparing the capsules and tablets, respectively. The median T(max) increased significantly from 1.41 to 3.0 hours (P < 0.001). Administration of the capsules with food resulted in <20% difference in mean C(max) and AUC(0-t) compared with the fasting state, whereas mean C(max) and AUC(0-t) were 22.6% and 45.2% higher when the tablet formulation was administered with food. The onset of impairment in Power of Attention was significantly delayed from 0.75 to 1.5 hours postdose when capsules were administered with food compared with the other conditions (P < 0.001). The most commonly reported adverse events were asthenia, somnolence, and orthostatic hypotension. A significantly lower adverse event rate was observed in the combined capsules group compared with the tablets, suggesting that differences in tolerability may exist.

CONCLUSIONS

The results of this study in healthy volunteers suggest that the capsule and tablet formulations of tizanidine were bioequivalent only in the fasted state. The capsule formulation exhibited a food effect that reduced C(max) and AUC(0-t), and significantly increased T(max), which was associated with a delay in cognitive impairment. The large interpatient variability in plasma profiles most likely dampened the ability to fully elucidate the differences between the 2 formulations.

Multiple Sclerosis and Spasticity

Spasticity is a common impairment in MS. It can result in significant medical complications and is associated with increased disability. Treatment strategies include skilled rehabilitation strategies, neuromuscular blocks, oral agents, intrathecal management, and surgery. Rehabilitation strategies are central, whereas other strategies are added based on the level of impairment and functional loss. Treatment strategies for spasticity management are far from optimal and are complicated in MS as a result of lesions in the brain and the spinal cord. Pharmaceutical management in MS is complicated by the numerous secondary impairments in MS and its associated polypharmacy.Head-to-head studies of the various agents are rare. The studies that exist are small and do not point to any one strategy over another. Although management is difficult, it is essential for the health, functional status, and well-being of the individual who has MS. Providers must use well-developed clinical skills to arrive at optimal individualized treatment programs and monitor them frequently. For spasticity that is unresponsive, referral to a MS Center with a spasticity program is ideal.

Hepatic injury, liver monitoring and the beta-interferons for multiple sclerosis

This review explores the salient issues surrounding liver injury and liver monitoring associated with beta-interferon (IFNB) treatment for multiple sclerosis (MS). Post-marketing studies have found a higher proportion of IFNB-treated MS patients with elevated aminotransferases than reported in the pivotal clinical trials. Although the risk of severe liver injury appears small, the true incidence is unknown. Post-marketing studies have shown that the greatest period of risk for the development of liver test abnormalities appears to be in the first year of IFNB treatment. The risk also increases with the more frequently administered, higher-dosage IFNBs. Males are more likely than females to develop elevated aminotransferases (> upper normal limit), although females appear at a greater risk of severe liver injury. Of the commonly used biochemical liver tests, alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (AP) and bilirubin appear the most useful for routine monitoring of IFNB treatment. Whilst many other factors can affect liver test results, including obesity, alcohol, concomitant medications, co-morbidities and theoretically even MS itself, regular liver testing both prior and during IFNB therapy might help minimise Type A or dose/frequency dependent aminotransferase elevations. However, testing will probably not prevent the Type B idiosyncratic reactions which can result in severe hepatic injury; hence patients need to be aware, and to report hepatic side effects promptly.

Comparative efficacy and safety of skeletal muscle relaxants for spasticity and musculoskeletal conditions: a systematic review

Skeletal muscle relaxants are a heterogeneous group of medications used to treat two different types of underlying conditions: spasticity from upper motor neuron syndromes and muscular pain or spasms from peripheral musculoskeletal conditions. Although widely used for these indications, there appear to be gaps in our understanding of the comparative efficacy and safety of different skeletal muscle relaxants. This systematic review summarizes and assesses the evidence for the comparative efficacy and safety of skeletal muscle relaxants for spasticity and musculoskeletal conditions. Randomized trials (for comparative efficacy and adverse events) and observational studies (for adverse events only) that included oral medications classified as skeletal muscle relaxants by the FDA were sought using electronic databases, reference lists, and pharmaceutical company submissions. Searches were performed through January 2003. The validity of each included study was assessed using a data abstraction form and predefined criteria. An overall grade was allocated for the body of evidence for each key question. A total of 101 randomized trials were included in this review. No randomized trial was rated good quality, and there was little evidence of rigorous adverse event assessment in included trials or observational studies. There is fair evidence that baclofen, tizanidine, and dantrolene are effective compared to placebo in patients with spasticity (primarily multiple sclerosis). There is fair evidence that baclofen and tizanidine are roughly equivalent for efficacy in patients with spasticity, but insufficient evidence to determine the efficacy of dantrolene compared to baclofen or tizanidine. There is fair evidence that although the overall rate of adverse effects between tizanidine and baclofen is similar, tizanidine is associated with more dry mouth and baclofen with more weakness. There is fair evidence that cyclobenzaprine, carisoprodol, orphenadrine, and tizanidine are effective compared to placebo in patients with musculoskeletal conditions (primarily acute back or neck pain). Cyclobenzaprine has been evaluated in the most clinical trials and has consistently been found to be effective. There is very limited or inconsistent data regarding the effectiveness of metaxalone, methocarbamol, chlorzoxazone, baclofen, or dantrolene compared to placebo in patients with musculoskeletal conditions. There is insufficient evidence to determine the relative efficacy or safety of cyclobenzaprine, carisoprodol, orphenadrine, tizanidine, metaxalone, methocarbamol, and chlorzoxazone. Dantrolene, and to a lesser degree chlorzoxazone, have been associated with rare serious hepatotoxicity.

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.

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.

Anti-spasticity agents for multiple sclerosis

BACKGROUND

Spasticity is a common problem in MS patients causing pain, spasms, loss of function and difficulties in nursing care. A variety of oral and parenteral medications are available.

OBJECTIVES

To assess the absolute and comparative efficacy and tolerability of anti-spasticity agents in multiple sclerosis (MS) patients.

SEARCH STRATEGY

Randomised controlled trials (RCTs) of anti-spasticity agents were identified using MEDLINE, EMBASE, bibliographies of relevant articles, personal communication, manual searches of relevant journals and information from drug companies.

SELECTION CRITERIA

Double-blind, randomised controlled trials (either placebo-controlled or comparative studies) of at least seven days duration.

DATA COLLECTION AND ANALYSIS

Two independent reviewers extracted data and the findings of the trials were summarised. Missing data were collected by correspondence with principal investigators. A meta-analysis was not performed due to the inadequacy of outcome measures and methodological problems with the studies reviewed.

MAIN RESULTS

Twenty-three placebo-controlled studies (using baclofen, dantrolene, tizanidine, botulinum toxin, vigabatrin, prazepam and threonine) and thirteen comparative studies met the selection criteria. Only thirteen of these studies used the Ashworth scale, of which only three of the six placebo-controlled trials and none of the seven comparative studies showed a statistically significant difference between test drugs. Spasms, other symptoms and overall impressions were only assessed using unvalidated scores and results of functional assessments were inconclusive.

REVIEWER'S CONCLUSIONS

The absolute and comparative efficacy and tolerability of anti-spasticity agents in multiple sclerosis is poorly documented and no recommendations can be made to guide prescribing. The rationale for treating features of the upper motor neurone syndrome must be better understood and sensitive, validated spasticity measures need to be developed.

Spasticity and 'spastic' gait in children with cerebral palsy

The current notion of spasticity as a velocity-dependent increase of muscle response to imposed stretch was mainly derived from studies performed under stationary experimental conditions. To address the issue of a spastic muscle behaviour under dynamic conditions, we conceived a novel approach, aimed at quantitatively assessing motor output over the lengthening periods which take place during unperturbed functional movements. Application to the analysis of overground walking in children with spastic cerebral palsy (CP) revealed that, for representative lower limb muscles, the relationship between EMG levels and estimated muscle lengthening rate displays either increased gain or reduced velocity threshold. Parallel measurement of gait kinetics frequently showed congruent increase of the mechanical resistance to joint rotation. Abnormalities preferentially targeted the lengthening contractions occurring around the ground contact period of the stride. The pathophysiological profile of what is clinically defined as 'spastic' gait in CP children did not only consist of dynamic spasticity, as described above. Most often it resulted from the simultaneous contribution of other factors, including paresis, co-contraction, immature and non-neural components.

Management of impairment, disability, and handicap due to multiple sclerosis

In this article, we update management measures for patients with multiple sclerosis (MS) that can improve or prevent impairment, disability, and handicap and include those factors that a primary-care physician can implement or facilitate. The medical literature since 1989 was reviewed. Although new drug trials hold promise to decrease impairment from MS, well-coordinated interdisciplinary care to minimize disability and handicap most profoundly affect the quality of life for patients with MS. MS is usually not severely disabling, and appropriately timed intervention can prevent secondary impairment and reduce disability and handicap. Pharmacologic, physical, and psychosocial issues--ranging from spasticity, pain, weakness, and tremor to neurogenic bowel management and sexuality--are addressed. General wellness measures remain important. The influence of the Americans With Disabilities Act is discussed, and specific adaptive equipment and social resources are outlined. The ultimate goals of management of patients with MS are functional independence and efficient use of medical and community resources: a focus on "ability" rather than "disability." Although impairment can limit function, wellness and adjustment have no boundaries.

Tizanidine. A review of its pharmacology, clinical efficacy and tolerability in the management of spasticity associated with cerebral and spinal disorders

The central alpha 2 adrenoceptor agonist tizanidine is a myotonolytic agent used in the treatment of spasticity in patients with cerebral or spinal injury. Wide interpatient variability in the effective plasma concentrations of tizanidine means that the optimal dosage must be titrated over 2 to 4 weeks for each patient (dosages of 2 to 36 mg/day have been used in clinical trials). Maximum effects occur within 2 hours of administration. Antispastic efficacy has been demonstrated for tizanidine in placebo-controlled trials, with reduction in mean muscle tone scores of 21 to 37% versus 4 to 9% for patients receiving placebo. Improvement in muscle tone occurred in 60 to 82% of tizanidine recipients, compared with 60 to 65% of baclofen and 60 to 83% of diazepam recipients. Spasm frequency and clonus are also reduced by tizanidine. The most common adverse effects associated with tizanidine are dry mouth and somnolence/drowsiness. Muscle strength, as assessed by objective means, appears not to be adversely affected by tizanidine and subjective muscle weakness is reported less often by tizanidine recipients than by those receiving baclofen or diazepam. Global tolerability was assessed as good to excellent in 44 to 100% of patients receiving tizanidine, compared with 38 to 90% of baclofen and 20 to 54% of diazepam recipients. In conclusion, tizanidine is an antispastic agent with similar efficacy to that of baclofen and a more favourable tolerability profile. While drowsiness is a frequently reported adverse effect with both agents, subjective muscle weakness appears to be less of a problem with tizanidine than with baclofen. Tizanidine, therefore, appears to be an attractive therapeutic alternative for patients with spasticity associated with cerebral or spinal damage.

Multiple sclerosis therapy. A practical guide

A growing amount of evidence suggests that a disturbance of immunological function is of importance in the pathogenesis of multiple sclerosis. This is reflected in the drugs used to slow progression and to treat relapses. Immunosuppressive drugs such as azathioprine, cyclophosphamide and cyclosporin might have some potential to slow down progression of multiple sclerosis, but their use is limited by potentially serious adverse effects. Recently, it was shown that interferon-beta-1b can diminish the exacerbation rate in multiple sclerosis without leading to unacceptable adverse effects. Nevertheless, symptomatic treatment remains of crucial importance in the management of multiple sclerosis patients. Spasticity, depression, fatigue and urinary, paroxysmal and sensory symptoms can all be alleviated to some extent with pharmacological interventions, although rehabilitation procedures and psychosocial consultations are no less important. Further therapeutic approaches to multiple sclerosis will be directed at either the specificity of the immune response or the grade of activation of the immune response. Magnetic resonance imaging techniques will play an important role in the evaluation of efficacy of new therapeutic agents.

Correlations between dose, plasma concentrations, and antispastic action of tizanidine (Sirdalud)

In a double blind, placebo controlled, cross over study the correlations between single doses (2, 4, and 8 mg), plasma concentrations, and antispastic action of tizanidine were investigated in 16 patients with extensor spasticity of the legs due to multiple sclerosis. An electrogoniometer was used to assess muscle tone at knee extensors, applying Wartenberg's pendulum test. Blood samples, a clinical assessment of muscle tone by the Ashworth scale, and muscle strength by the British Medical Research Council scale were obtained concomitantly. Confirmatory analysis using the change in the relaxation index (R2 value) 1.5 hours after each treatment, showed a statistically significant (p = 0.0123) linear dose-response relation between single doses and antispastic action of tizanidine. Further statistical analysis showed a strong within patient linear correlation between plasma concentrations and antispastic action at 4 and 8 mg doses (p = 0.014 and 0.004 respectively), but only weak between patient correlations. The analysis of the dose-plasma concentration relation showed results consistent with linear pharmacokinetics. The comparison of changes in the R2 ratio with concomitant Ashworth scores showed a significant correlation between the two. It is concluded that there are linear correlations between single doses, plasma concentrations, and antispastic action of tizanidine. Because of the strong within patient but weak between patient correlation between plasma concentrations and antispastic action of tizanidine the effective doses should be determined individually.

Mechanisms of tizanidine action on spasticity

This investigation estimated the mechanisms of tizanidine action on spasticity using a battery of neurophysiological methods. Thirty patients with old post-stroke spastic hemiparesis took part in the investigation. They were treated with tizanidine-mean daily dose 15.8 +/- 5.6 mg for a mean of 23.3 +/- 4.8 days. A questionnaire for assessment of subjective improvement after treatment used a 5-point scale. For standardization of the neurological examination 5-point scales were used to assess muscle tone, muscle force and tendon reflexes. A battery of neurophysiological methods was used to analyze different mechanisms of spasticity: for alpha motoneuron excitability--the F wave parameters; for presynaptic inhibition--the ratio of H reflex amplitudes before and after vibration of the achilles tendon (Hvibr/Hmax); for common interneuron activity--the flexor reflex parameters. Our results revealed that tizanidine reduces spastically increased muscle tone, but has no influence on muscle force, tendon reflexes, Babinski sign and ankle clonus. Tizanidine is supposed to act by increasing the presynaptic inhibition and decreasing of alpha motoneuron excitability. When spasticity has decreased presynaptic inhibition and increased motoneuron excitability, it is better to treat with tizanidine.

Reflex activity and muscle tone during elbow movements in patients with spastic paresis

Reflex behavior and tension development in upper limb muscles were analyzed and comparisons made between the unaffected and spastic sides of patients with spastic hemiparesis. During sinusoidal (0.3-Hz) isometric or isotonic elbow tracking, with a control either of joint position or of torque, randomly timed displacements were induced (at one of three velocities) stretching either the activated flexor or the extensor muscles. On the spastic side, exaggerated short-latency reflexes were apparent, but in contrast, the amplitude of long-latency electromyography (EMG) responses was reduced. The latter responses were differentially modulated on the unaffected side, predominantly by the acceleration signal during control of position and more by the velocity signal during control of torque, while the mode of muscle contraction (isometric or isotonic) had little influence on this behavior. This difference in reflex modulation was lost on the spastic side. The functional consequence of this reduced EMG modulation could be difficulty in performing finely controlled arm movements. The ratio of torque to EMG activity during displacements was higher for both background and reflex-induced EMG on the spastic limb than on the unaffected side. This effect was more pronounced for the flexor than for the extensor muscles. Consequently, the development of spastic muscle hypertonia cannot be attributed to an increase in EMG activity. It is suggested that secondary to a supraspinal lesion, mechanical muscle properties change in such a way that the activated spastic muscle develops more tension when it is stretched.

Rehabilitation in multiple sclerosis

Despite the lack of a definitive remedy for central nervous system demyelination in multiple sclerosis, certain manifestations of the disease are treatable. Recognition and identification of specific impairments, disabilities, and handicaps faced by the patient afford the physician the best opportunity to provide effective intervention. Impairments are ameliorated with difficulty; however, when comprehensive methods of rehabilitation are applied to the associated disabilities and handicaps, meaningful improvements can be achieved. The goal of rehabilitation in multiple sclerosis is to maximize the patient's physical, emotional, social, and vocational independence. Through the multidisciplinary efforts of numerous health-care workers in close cooperation with the patient and the family, this goal can be attained.