Mechanisms of baclofen action on spasticity

Potentially Life-Threatening Interaction between Opioids and Intrathecal Baclofen in Individuals with a Childhood-Onset Neurological Disorder: A Case Series and Review of the Literature

BACKGROUND

Spasticity and dystonia are movement impairments that can occur in childhood-onset neurological disorders. Severely affected individuals can be treated with intrathecal baclofen (ITB). Concomitant use of ITB and opioids has been associated with central nervous system (CNS) depression. This study aims to describe the clinical management of this interaction, based on a case series and review of literature.

METHODS

Four individuals with childhood-onset CNS disorders (age 8-24) and CNS-depressant overdose symptoms after the concomitant use of ITB and opioids are described. The Drug Interaction Probability Scale (DIPS) was calculated to assess the cause-relationship (doubtful <2, possible 2-4, probable 5-8, and highly probable >8) of the potential drug-drug interaction. A literature review of similar previously reported cases and the possible pharmacological mechanisms of opioid-baclofen interaction is provided.

RESULTS

After ITB and opioid co-administration, three out of four patients had decreased consciousness, and three developed respiratory depression. DIPS scores indicated a possible cause-relationship in one patient (DIPS: 4) and a probable cause-relationship in the others (DIPS: 6, 6, and 8). Discontinuation or adjusting ITB or opioid dosages resulted in clinical recovery. All patients recovered completely. In the literature, two articles describing nine unique cases were found.

CONCLUSION

Although the opioid-ITB interaction is incompletely understood, concomitant use may enhance the risk of symptoms of CNS-depressant overdose, which are potentially life-threatening. If concomitant use is desirable, we strongly recommend to closely monitor these patients to detect interaction symptoms early. Awareness and monitoring of the potential opioid-ITB interaction is essential to reduce the risk of severe complications.

Nanosuspension-based microneedle skin patch of baclofen for sustained management of multiple sclerosis-related spasticity

Baclofen (BAC) is the first-line recommendation to treat spasticity in people with multiple sclerosis whose treatment goals include improving mobility or easing pain. The short half-life of BAC calls for multiple daily dosing which may be eliminated by the development of a transdermal system. This study aimed to assess the effect of transdermal microneedle patches on improving the skin permeation of BAC. Nanosuspension-loaded microneedle patch containing BAC was fabricated and characterized. In vitro permeation of BAC across intact and microneedle-treated dermatomed porcine ear skin was evaluated. In vitro passive permeation of BAC solution after 72 h was observed to be 92.56 ± 11.24 µg/cm2. A near 9-fold enhancement was observed when employing the strategy of microneedle-mediated delivery of the solution. To increase drug loading, two strategies, nanosizing and microneedle-mediated delivery, were combined and permeation of BAC after 72 h resulted to be 1951.95 ± 82.01 µg/cm2 (p < 0.05). Microneedle-mediated transdermal delivery of BAC holds potential for sustained management of multiple sclerosis-related spasticity. Nanosizing of BAC particles facilitated higher drug loading in MN patches and an eventual increase in cumulative drug permeation from the patches.

Hemodialysis as emergency treatment of a severe baclofen intoxication in a 3 kg dog

OBJECTIVE

To describe the clinical efficacy and drug removal kinetics of hemodialysis (HD) as emergency treatment in a small size dog with severe baclofen intoxication.

CASE DESCRIPTION

A 2-year-old dog was presented in stupor to the emergency service a few hours after ingestion of up to 25 mg of baclofen. Medical stabilisation was attempted but was unsuccessful in improving the neurological condition and the patient rapidly progressed to coma. A 4-h session of HD was performed in emergency with near complete resolution of neurological signs and only mild disorientation by the end of the treatment. No adverse side effects occurred during HD. Baclofen concentration was measured serially during the session. Drug extraction ratio, clearance and mass removal by the dialyser were calculated. Dialytic elimination rate constant (K_d ) was seven times higher than the intrinsic elimination rate constant (K_intr ) and the half-life (t½) during HD was nearly nine times shorter than the endogenous one.

NEW OR UNIQUE INFORMATION PROVIDED

This is the first case report providing pharmacokinetic data associated with HD treatment of severe baclofen intoxication in a dog.

Spastic muscle stiffness evaluated using ultrasound elastography and evoked electromyogram in patients following severe traumatic brain injury: an observational study

OBJECTIVE

To determine the relationship between muscle stiffness assessed using ultrasound shear wave elastography, spinal motor neuron excitability assessed using the F wave, and clinical findings of spasticity in patients with spastic muscle overactivity following severe traumatic brain injury.

METHODS

This study enrolled 17 inpatients with severe traumatic brain injury and 20 healthy volunteers. Biceps brachii muscle stiffness was then evaluated using ultrasound shear wave speed. Spinal motor neuron excitability was evaluated using the F/M ratio recorded from abductor pollicis brevis muscle. Clinical parameters, such as the modified Ashworth scale and modified Tardieu scale, were assessed in the patient with traumatic brain injury.

RESULTS

The patients with traumatic brain injury group had a significantly higher shear wave speed and F/M ratio compared with the healthy group. A higher shear wave speed was correlated with higher clinical spastic severity in patients with traumatic brain injury. The F/M ratio was not significantly correlated with clinical spastic severity.

CONCLUSION

Ultrasound shear wave elastography might be helpful for assessing muscle stiffness in patients with spastic muscle overactivity following severe traumatic brain injury. Further studies comprising larger cohorts are warranted.

Baclofen in gamma-hydroxybutyrate withdrawal: patterns of use and online availability

Purpose

Gamma-hydroxybutyrate (GHB) withdrawal is a life-threatening condition that does not always respond to standard treatment with benzodiazepines. Baclofen has potential utility as a pharmacological adjunct and anecdotal reports suggest that it is being used by drug users to self-manage GHB withdrawal symptoms. Here, we investigate current patterns of use and the online availably of baclofen.

Methods

Data triangulation techniques were applied to published scientific literature and publicly accessible Internet resources (grey literature) to assess the use of baclofen in GHB withdrawal. An Internet snapshot survey was performed to identify the availability of baclofen for online purchase and the compliance of retailers with the UK regulations. Data were collected according to pre-defined criteria.

Results

A total of 37 cases of baclofen use in GHB withdrawal were identified in the scientific literature, as well as 51 relevant discussion threads across eight Internet forums in the grey literature. Baclofen was available to purchase from 38 online pharmacies, of which only one conformed to the UK regulations.

Conclusions

There is limited published evidence on the use of baclofen in GHB withdrawal, but both scientific and grey literature suggests clinical utility. Online pharmacies are readily offering prescription-only-medication without prescription and due to inadequate regulation, pose a danger to the public.

Electronic supplementary material

The online version of this article (10.1007/s00228-017-2387-z) contains supplementary material, which is available to authorized users.

Deep brain stimulation for stroke: Current uses and future directions

BACKGROUND

Survivors of stroke often experience significant disability and impaired quality of life related to ongoing maladaptive responses and persistent neurologic deficits. Novel therapeutic options are urgently needed to augment current approaches. One way to promote recovery and ameliorate symptoms may be to electrically stimulate the surviving brain. Various forms of brain stimulation have been investigated for use in stroke, including deep brain stimulation (DBS).

OBJECTIVE/METHODS

We conducted a comprehensive literature review in order to 1) review the use of DBS to treat post-stroke maladaptive responses including pain, dystonia, dyskinesias, and tremor and 2) assess the use and potential utility of DBS for enhancing plasticity and recovery from post-stroke neurologic deficits.

RESULTS/CONCLUSIONS

A large variety of brain structures have been targeted in post-stroke patients, including motor thalamus, sensory thalamus, basal ganglia nuclei, internal capsule, and periventricular/periaqueductal grey. Overall, the reviewed clinical literature suggests a role for DBS in the management of several post-stroke maladaptive responses. More limited evidence was identified regarding DBS for post-stroke motor deficits, although existing work tentatively suggests DBS-particularly DBS targeting the posterior limb of the internal capsule-may improve paresis in certain circumstances. Substantial future work is required both to establish optimal targets and parameters for treatment of maladapative responses and to further investigate the effectiveness of DBS for post-stroke paresis.

The comparative effects of aminoglycoside antibiotics and muscle relaxants on electrical field stimulation response in rat bladder smooth muscle

It has been reported that several aminoglycoside antibiotics have a potential of prolonging the action of non-depolarizing muscle relaxants by drug interactions acting pre-synaptically to inhibit acetylcholine release, but antibiotics itself also have a strong effect on relaxing the smooth muscle. In this study, four antibiotics of aminoglycosides such as gentamicin, streptomycin, kanamycin and neomycin were compared with skeletal muscle relaxants baclofen, tubocurarine, pancuronium and succinylcholine, and a smooth muscle relaxant, papaverine. The muscle strips isolated from the rat bladder were stimulated with pulse trains of 40 V in amplitude and 10 s in duration, with pulse duration of 1 ms at the frequency of 1-8 Hz, at 1, 2, 4, 6, 8 Hz respectively. To test the effect of four antibiotics on bladder smooth muscle relaxation, each of them was treated cumulatively from 1 μM to 0.1 mM with an interval of 5 min. Among the four antibiotics, gentamicin and neomycin inhibited the EFS response. The skeletal muscle relaxants (baclofen, tubocurarine, pancuronium and succinylcholine) and inhibitory neurotransmitters (GABA and glycine) did not show any significant effect. However, papaverine, had a significant effect in the relaxation of the smooth muscle. It was suggested that the aminoglycoside antibiotics have inhibitory effect on the bladder smooth muscle.

The Inhibitory Mechanism of Gentamicin on Electrical Field Stimulation Response in Rat Bladder Smooth Muscle

To see the inhibitory mechanism of gentamicin in response to electrical field stimulation (EFS) using the rat bladder smooth muscle, atropine or guanethidine was treated but had no effect. Methylsergide, a non-selective 5-HT1, 5-HT2 receptor antagonist was also treated but had on effect. Kinase inhibitors, such as chelerythrine (PKC inhibitor), ML-9 (MLCK inhibitor), or Y27632 (rho kinase inhibitor) were pretreated before gentamicin treatment, but did not have effect. For U73122, a phospholipase C (PLC) inhibitor however, the inhibitory effect to gentamicin was significantly attenuated in all frequencies given by the EFS. Therefore gentamicin induced inhibitory effect on EFS response in rat bladder smooth muscle was not mediated by the activation of adrenergic, cholinergic, or serotonergic receptor. The inhibition of gentamicin might be mediated through the PLC dependent pathway, but not through the PKC, MLCK or rho kinase dependent pathway.

Immediate therapeutic effect of interferential current therapy on spasticity, balance, and gait function in chronic stroke patients: a randomized control trial

OBJECTIVE

To determine whether a single trial of interferential current therapy (ICT) can immediately alleviate spasticity and improve balance and gait performance in patients with chronic stroke.

DESIGN

Randomized, placebo-controlled clinical trial.

SETTING

Inpatient rehabilitation in a local center.

SUBJECTS

A total of 42 adult patients with chronic stroke with plantar flexor spasticity of the lower limb.

INTERVENTION

The ICT group received a single 60-minute ICT stimulation of the gastrocnemius in conjunction with air-pump massage. In the placebo-ICT group, electrodes were placed and air-pump massage performed without electrical stimulation.

MAIN MEASURES

After a single ICT application, spasticity was measured immediately using the Modified Ashworth Scale (MAS), and balance and functional gait performance were assessed using the following clinical tools: Functional Reach Test (FRT), Berg Balance Scale (BBS), Timed Up and Go Test (TUG), and 10-m Walk Test (10MWT).

RESULTS

Gastrocnemius spasticity significantly decreased in the ICT group than in the placebo-ICT group (MAS: ICT vs placebo-ICT: 1.55±0.76 vs 0.40±0.50). The ICT group showed significantly greater improvement in balance and gait abilities than the placebo-ICT group (FRT: 2.62±1.21 vs 0.61±1.34, BBS: 1.75±1.52 vs 0.40±0.88, TUG: 6.07±6.11 vs 1.68±2.39, 10MWT: 7.02±7.02 vs 1.96±3.13). Spasticity correlated significantly with balance and gait abilities (P < 0.05).

CONCLUSION

A single trial of ICT is a useful intervention for immediately improving spasticity, balance, and gait abilities in chronic stroke patients, but not for long-term effects. Further study on the effects of repeated ICT is needed.

Symptomatic treatment and management of multiple sclerosis

The range of symptoms which occur in multiple sclerosis (MS) can have disabling functional consequences for patients and lead to significant reductions in their quality of life. MS symptoms can also interact with each other, making their management challenging. Clinical trials aimed at identifying symptomatic therapies have generally been poorly designed and have tended to be underpowered. Therefore, the evidence base for the management of MS symptoms with pharmacologic therapies is not strong and tends to rely upon open-label studies, case reports, and clinical trials with small numbers of patients and poorly validated clinical outcome measures. Recently, there has been a growing interest in the management of MS symptoms with pharmacologic treatments, and better-designed, randomized, double-blind, controlled trials have been reported. This chapter will describe the evidence base predominantly behind the various pharmacologic approaches to the management of MS symptoms, which in most, if not all, cases, requires multidisciplinary input. Drugs routinely recommended for individual symptoms and new therapies, which are currently in the development pipeline, will be reviewed. More interventional therapies related to symptoms that are refractory to pharmacotherapy will also be discussed, where relevant.

A single trial of transcutaneous electrical nerve stimulation (TENS) improves spasticity and balance in patients with chronic stroke

Spasticity management is pivotal for achieving functional recovery of stroke patients. The purpose of this study was to investigate the effects of a single trial of transcutaneous electrical nerve stimulation (TENS) on spasticity and balance in chronic stroke patients. Forty-two chronic stroke patients were randomly allocated into the TENS (n = 22) or the placebo-TENS (n = 20) group. TENS stimulation was applied to the gastrocnemius for 60 min at 100 Hz, 200 µs with 2 to 3 times the sensory threshold (the minimal threshold in detecting electrical stimulation for subjects) after received physical therapy for 30 min. In the placebo-TENS group, electrodes were placed but no electrical stimulation was administered. For measuring spasticity, the resistance encountered during passive muscle stretching of ankle joint was assessed using the Modified Ashworth Scale, and the Hand held dynamometer was used to assess the resistive force caused by spasticity. Balance ability was measured using a force platform that measures postural sway generated by postural imbalance. The TENS group showed a significantly greater reduction in spasticity of the gastrocnemius, compared to the placebo-TENS group (p < 0.05). TENS resulted in greater balance ability improvements, especially during the eyes closed condition (p < 0.05). However, these effects returned to baseline values within one day. This study shows that TENS provides an immediately effective means of reducing spasticity and of improving balance in chronic stroke patients. The present data may be useful to establish the standard parameters for TENS application in the clinical setting of stroke.

Treatment for spasticity in amyotrophic lateral sclerosis/motor neuron disease

BACKGROUND

Spasticity commonly affects patients with motor neuron disease. It is likely to contribute to worsening muscle dysfunction, increased difficulty with activities of daily living and deteriorating quality of life. This is an update of a review first published in 2003 and previously updated in 2005 and 2008.

OBJECTIVES

The objective of this review is to systematically review treatments for spasticity in amyotrophic lateral sclerosis, also known as motor neuron disease.

SEARCH METHODS

We searched the Cochrane Neuromuscular Disease Group Specialized Register (4 July 2011), CENTRAL (2011, Issue 2), MEDLINE (January 1966 to July 2011), EMBASE (January 1980 to July 2011 ), CINAHL Plus (January 1937 to July 2011), AMED (January 1985 to July 2011) and LILACS (January 1982 to July 2011 ). We reviewed the bibliographies of the randomized controlled trials identified, and contacted authors and experts in the field.

SELECTION CRITERIA

We included quasi-randomized or randomized controlled trials of participants with probable or definite amyotrophic lateral sclerosis according to the El Escorial diagnostic criteria (or a revised version) or the Airlie House revision. We would have included trials of physical therapy, modalities, prescription medications, non-prescription medications, chemical neurolysis, surgical interventions, and alternative therapies. Our primary outcome measure was reduction in spasticity at three months or greater as measured by the Ashworth (or modified Ashworth) spasticity scale. Our secondary outcome measures were: validated measures based on history, physical examination, physiological measures, measures of function, measures of quality of life, all adverse events, and measures of cost.

DATA COLLECTION AND ANALYSIS

Two authors independently screened the abstracts of potential trials retrieved from the searches. Two authors extracted the data. We also contacted the author of the paper and obtained information not available in the published article. All three authors assessed the methodological quality of all included trials independently.

MAIN RESULTS

We identified only one randomized controlled trial that met our inclusion criteria and no further trials were identified in subsequent updates. The included study was a trial of moderate intensity, endurance type exercise versus 'usual activities' in 25 patients with amyotrophic lateral sclerosis. The risk of bias was high and no adverse events were reported. At three months patients performing the 15 minute twice daily exercises had significantly less spasticity overall (mean reduction of -0.43, 95% confidence interval (CI) -1.03 to +0.17 in the treatment group versus an increase of +0.25, 95% CI -0.46 to +0.96 in control) but the mean change between groups was not significant (-0.68, 95% CI -1.62 to +0.26), as measured by the Ashworth scale (possible scores 0 to 5, where higher is worse).

AUTHORS' CONCLUSIONS

The single trial performed was too small to determine whether individualized moderate intensity endurance type exercises for the trunk and limbs are beneficial or harmful. No other medical, surgical or alternative treatment and therapy has been evaluated in a randomized fashion in this patient population. More research is needed.

The occurrence of the Babinski sign in complete spinal cord injury

The purpose of the present study was to explore factors that influence the occurrence of the Babinski sign (BS) in complete spinal cord injury patients. At Balgrist University Hospital, Zurich, Switzerland, thirty-five subjects suffering from a complete traumatic spinal cord injury (ASIA A) were examined for the occurrence of the BS, tendon reflex excitability and spastic muscle tone (Modified Ashworth Scale). Five subjects were acute/subacute (1-6 months after spinal cord injury (SCI)), 30 were chronic (SCI > 1 year). In one subject, the measures were examined before and after injection of intrathecal Baclofen. Subjects with a negative BS were investigated electrophysiologically for possible peripheral nerve damage. In 17 subjects (49%), the BS was present, while it was absent in 18 subjects (51%). The occurrence of the BS did not depend on the level of lesion. Most patients with a positive BS also presented a high spastic muscle tone, while those with a negative BS showed low level or absent spastic muscle tone. In 11 SCI subjects, absence of the BS was associated with peripheral nerve damage. In one patient, the BS along with spastic signs disappeared after intrathecal injection of Baclofen. In complete SCI subjects, the occurrence of the BS is connected with spastic muscle tone. The absence of the BS is frequently due to associated peripheral nerve damage.

Oral baclofen increases maximal voluntary neuromuscular activation of ankle plantar flexors in children with spasticity due to cerebral palsy

Although spasticity is a common symptom in children with cerebral palsy, weakness may be a much greater contributor to disability. We explore whether a treatment that reduces spasticity may also have potential benefit for improving strength. Ten children with cerebral palsy and spasticity in the ankle plantar flexor muscles were treated with oral baclofen for 4 weeks. We tested voluntary ability to activate ankle plantar flexor muscles using the ratio of the surface electromyographic signal during isometric maximal voluntary contraction to the M-wave during supramaximal electrical stimulation of the tibial nerve and tested muscle strength using maximal isometric plantar flexion torque. Mean maximal voluntary neuromuscular activation increased from 1.13 +/- 1.02 to 1.60 +/- 1.30 ( P < .05) after treatment, corresponding to an increase in 9 of 10 subjects. Mean maximal plantar flexion torque did not change. We conjecture that antispasticity agents could facilitate strength training by increasing the ability to voluntarily activate muscle.

Measurement of plantarflexor spasticity in traumatic brain injury: correlational study of resistance torque compared with the modified Ashworth scale

OBJECTIVES

To examine the usefulness of a biomechanical measure, resistance torque (RT), in quantifying spasticity by comparing its use with a clinical scale, the modified Ashworth scale (MAS), and quantitative electrophysiological measures.

DESIGN

This is a correlational study of spasticity measurements in 34 adults with traumatic brain injury and plantarflexor spasticity. Plantarflexor spasticity was measured in the seated position before and after cryotherapy using the MAS and also by strapping each subject's foot and ankle to an apparatus that provided a ramp and hold stretch. The quantitative measures were (1) reflex threshold angle (RTA) calculated through electromyographic signals and joint angle traces, (2) Hdorsiflexion (Hdf)/Hcontrol (Hctrl) amplitude ratio obtained through reciprocal inhibition of the soleus H-reflex, (3) Hvibration (Hvib)/Hctrl ratio obtained through vibratory inhibition of the soleus H-reflex, and (4) RT calculated as the time integral of the torque graph between the starting and ending pulses of the stretch.

RESULTS

Correlation coefficients between RT and MAS scores in both pre-ice (0.41) and post-ice trials (0.42) were fair (P = 0.001). The correlation coefficients between RT scores and RTA scores in both the pre-ice (0.66) and post-ice trials (0.75) were moderate (P <or= 0.001).

CONCLUSION

RT is a measure of the cumulative torque during an imposed stretch. The MAS is a subjective measure of the cumulative resistance perceived by the clinician during an imposed stretch. RT seems to be a fair quantitative correlate of the MAS in assessing spasticity.

Treatment for spasticity in amyotrophic lateral sclerosis/motor neuron disease

BACKGROUND

Spasticity commonly affects patients with motor neuron disease. It is likely to contribute to worsening muscle dysfunction, increased difficulty with activities of daily living and deteriorating quality of life.

OBJECTIVES

The objective of this review is to systematically review treatments for spasticity in amyotrophic lateral sclerosis, also known as motor neuron disease.

SEARCH STRATEGY

We searched the Cochrane Neuromuscular Disease Group trials register (January 2003 and January 2005), MEDLINE (January 1966 to February 2005), EMBASE (January 1980 to February 2005), CINAHL (January 1982 to February 2005), AMED (January 1985 to February 2005) and LILACS (January 1982 to January 2003). We reviewed the bibliographies of the randomized controlled trials identified, and contacted authors and experts in the field.

SELECTION CRITERIA

We included quasi-randomized or randomized controlled trials of participants with probable or definite amyotrophic lateral sclerosis according to the El Escorial diagnostic criteria (or a revised version) or the Airlie House revision. We would have included trials of physical therapy, modalities, prescription medications, non-prescription medications, chemical neurolysis, surgical interventions, and alternative therapies. Our primary outcome measure was reduction in spasticity at three months or greater as measured by the Ashworth (or modified Ashworth) spasticity scale. Our secondary outcome measures were: validated measures based on history, physical examination, physiological measures, measures of function, measures of quality of life, serious adverse events, and measures of cost.

DATA COLLECTION AND ANALYSIS

We identified only one randomized controlled trial that met our inclusion criteria. Two authors extracted the data. We also contacted the author of the paper and obtained information not available in the published article.

MAIN RESULTS

The included study was a trial of moderate intensity, endurance type exercise versus 'usual activities' in 25 patients with amyotrophic lateral sclerosis. At three months patients performing the 15 minute twice daily exercises had significantly less spasticity overall (mean reduction of -0.43, 95% CI -1.03 to +0.17 in the treatment group versus an increase of +0.25, 95% CI -0.46 to +0.96 in control) but the mean change between groups was not significant (-0.68, 95% CI -1.62 to +0.26), as measured by the Ashworth scale.

AUTHORS' CONCLUSIONS

The single trial performed was too small to determine whether individualised moderate intensity endurance type exercises for the trunk and limbs are beneficial or harmful. No other medical, surgical or alternative treatment and therapy has been evaluated in a randomized fashion in this patient population. More research is needed.

The lower limb flexion reflex in humans

The flexion or flexor reflex (FR) recorded in the lower limbs in humans (LLFR) is a widely investigated neurophysiological tool. It is a polysynaptic and multisegmental spinal response that produces a withdrawal of the stimulated limb and resembles (having several features in common) the hind-paw FR in animals. The FR, in both animals and humans, is mediated by a complex circuitry modulated at spinal and supraspinal level. At rest, the LLFR (usually obtained by stimulating the sural/tibial nerve and by recording from the biceps femoris/tibial anterior muscle) appears as a double burst composed of an early, inconstantly present component, called the RII reflex, and a late, larger and stable component, called the RIII reflex. Numerous studies have shown that the afferents mediating the RII reflex are conveyed by large-diameter, low-threshold, non-nociceptive A-beta fibers, and those mediating the RIII reflex by small-diameter, high-threshold nociceptive A-delta fibers. However, several afferents, including nociceptive and non-nociceptive fibers from skin and muscles, have been found to contribute to LLFR activation. Since the threshold of the RIII reflex has been shown to correspond to the pain threshold and the size of the reflex to be related to the level of pain perception, it has been suggested that the RIII reflex might constitute a useful tool to investigate pain processing at spinal and supraspinal level, pharmacological modulation and pathological pain conditions. As stated in EFNS guidelines, the RIII reflex is the most widely used of all the nociceptive reflexes, and appears to be the most reliable in the assessment of treatment efficacy. However, the RIII reflex use in the clinical evaluation of neuropathic pain is still limited. In addition to its nocifensive function, the LLFR seems to be linked to posture and locomotion. This may be explained by the fact that its neuronal circuitry, made up of a complex pool of interneurons, is interposed in motor control and, during movements, receives both peripheral afferents (flexion reflex afferents, FRAs) and descending commands, forming a multisensorial feedback mechanism and projecting the output to motoneurons. LLFR excitability, mediated by this complex circuitry, is finely modulated in a state- and phase-dependent manner, rather as we observe in the FR in animal models. Several studies have demonstrated that LLFR excitability may be influenced by numerous physiological conditions (menstrual cycle, stress, attention, sleep and so on) and pathological states (spinal lesions, spasticity, Wallenberg's syndrome, fibromyalgia, headaches and so on). Finally, the LLFR is modulated by several drugs and neurotransmitters. In summary, study of the LLFR in humans has proved to be an interesting functional window onto the spinal and supraspinal mechanisms of pain processing and onto the spinal neural control mechanisms operating during posture and locomotion.

Comparison of Clinical and Neurophysiologic Responses to Intrathecal Baclofen Bolus Administration in Moderate-to-Severe Spasticity After Acquired Brain Injury

OBJECTIVES

To compare clinical and neurophysiologic responses to intrathecal baclofen (ITB) bolus injection in subjects with spasticity after acquired brain injury.

DESIGN

Prospective case series.

SETTING

Tertiary care rehabilitation center.

PARTICIPANTS

Thirty consecutive ITB pump candidates with dysfunctional spasticity caused by traumatic brain injury, hypoxic encephalopathy, or stroke.

INTERVENTION

A single 50-microg ITB bolus.

MAIN OUTCOME MEASURES

Lower-extremity Ashworth Scale score at 2, 4, and 6 hours after ITB bolus; soleus Hoffmann reflex (H-reflex)/M-wave amplitude (H/M) ratio and abductor hallucis F-wave persistence and F/M ratio at 5 hours. Nonparametric repeated-measures analysis of variance and paired t test were used for statistical analyses.

RESULTS

The Ashworth score on the more involved side significantly decreased from 2.4+/-0.7 at baseline to 1.5+/-0.6 and 1.4+/-0.6 at 4- and 6-hour evaluations, respectively (P<.001). H/M ratio significantly decreased bilaterally (more involved side, 62%+/-28% to 14%+/-19%; less involved side, 59%+/-26% to 11%+/-20%; P<.001). F-wave persistence significantly decreased on the more involved side (86%+/-17% to 75%+/-13%, P<.05) with no change in F/M ratio. There was no significant correlation among these outcome measures before or after the ITB bolus injection.

CONCLUSIONS

H/M ratio is more sensitive than the Ashworth score or F-wave persistence in detecting a physiologic response to ITB bolus. H-reflex is useful for verification of ITB bolus administration, as an adjunct to clinical evaluation, particularly among patients with moderate spasticity at rest or with small changes in Ashworth score. However, potential application of the marked sensitivity of the H-reflex to other clinically challenging situations, such as early detection of possible ITB system malfunction, awaits further investigation.

Transcutaneous electrical nerve stimulation versus baclofen in spasticity: clinical and electrophysiologic comparison

OBJECTIVES

Clinical and electrophysiologic comparison of the efficacy of transcutaneous electrical nerve stimulation (TENS) and oral baclofen in the treatment of spasticity.

DESIGN

Patients with spinal cord injury and spasticity were included in the study. Ten patients were assigned to oral baclofen and 11 to TENS groups. For the comparison of H-reflex variables, 20 healthy individuals were allocated to a control group. TENS was applied to the tibial nerve for 15 days at a frequency of 100 Hz. Clinical (spasm frequency scale, painful spasm scale, lower limb Ashworth score, clonus score, deep tendon reflex score, plantar stimulation response score) and electrophysiologic evaluations (H-reflex response at the highest amplitude, latency of maximum H-reflex, and ratio of H-reflex response at the highest amplitude to M response at maximum amplitude) of the lower limb and functional evaluations (functional disability score and FIM) were carried out in baclofen and TENS groups before and after treatment. Posttreatment evaluation was made 24 hrs after the 15th session in the TENS group. In addition, clinical spasticity scores and electrophysiologic variables were measured 15 mins after the first application and 15 mins after the 15th session.

RESULTS

Significant improvement was detected in lower limb Ashworth score, spasm frequency scale, deep tendon reflex score, functional disability score, and FIM in the baclofen (P = 0.011, P = 0.014, P = 0.025, P = 0.004, and P = 0.005, respectively) and TENS (P = 0.020, P = 0.014, P = 0.025, P = 0.003, and P = 0.003, respectively) group after treatment. Decrease in H-reflex maximum amplitude was significant in the TENS group (P = 0.026). Most marked improvement was observed in the third evaluation, 15 mins after the 15th session, particularly in lower limb Ashworth score (P = 0.006) and H-reflex maximum amplitude (P = 0.006) in the TENS group. The percentage change in clinical, electrophysiologic, and functional variables caused by baclofen was not different from that caused by repeated applications of TENS in the short- and long-term evaluations (P > 0.05).

CONCLUSION

TENS may be recommended as a supplement to medical treatment in the management of spasticity.

Baclofen-loaded microspheres: preparation and efficacy testing in a new rabbit model

Intrathecal baclofen is the reference treatment for severe spasticity. This drug has to be injected chronically in the intrathecal space by implanted pumps which are very expensive, uncomfortable and sometimes lead to side effects. Previous work has been performed by our group to assess the feasibility of encapsulating baclofen into poly(lactide-co-glycolide) (PLGA) microspheres and injecting these preparations in the intrathecal space of rabbits. The aims of the present study were to improve the encapsulation process for industrial application (scale-up), and to set up an animal model to assess the duration of effect of the new formulations. Modifications included the replacement of methylene chloride by a less toxic solvent, ethyl acetate, and the use of high molecular weight polymers to extend the release rate of the drug. The temperature and organic solvent extraction rate were fully controlled during the whole manufacturing process. All these modifications resulted in high quality microsphere batches with a CV inferior to 5% for encapsulation efficiency and drug loading. Encapsulation efficiency and release patterns were dependent on the drug payload and the polymer used. A formulation displaying a sustained release of baclofen over 174 days and a moderate burst effect of 16% in the first day in vitro was evaluated in a new reliable model of baclofen activity based on electrophysiological measurement of H-reflex in the rabbit. The activity of a very low dose of baclofen microspheres in vivo was sustained over 35 days. Furthermore, the preparation was well tolerated. These newly developed preparations are a very promising approach for enhancing the efficacy and comfort of patients undergoing spasticity treatment.

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.

Neurophysiologic evaluation of spastic hypertonia: implications for management of the patient with the intrathecal baclofen pump

A number of techniques attempt to objectively quantify various clinical characteristics associated with spastic hypertonia and related motor disorders. These range in cost, complexity, physiologic basis of measured response, and invasiveness. With a greater range of treatment options for spasticity and an increase in the number of centers participating in studies of interventions for spasticity, published reports reflect increasing use of objective quantification techniques. We review studies that highlight the potential utility of neurophysiologic techniques, including the H-reflex, F-wave, and flexion withdrawal reflex, in the objective evaluation of response to intrathecal baclofen administration. The accumulated knowledge suggests that neurophysiologic evaluation is useful for assessing spinal cord responsiveness, and we recommend it as an adjunct to clinical evaluation when judging the overall effectiveness of intrathecal baclofen administration.

Treatment for spasticity in amyotrophic lateral sclerosis/motor neuron disease

BACKGROUND

Spasticity commonly affects patients with motor neuron disease and it is likely to contribute to worsening muscle dysfunction, increased difficulty with activities of daily living and deteriorating quality of life.

OBJECTIVES

The objective of this review is to systematically review all types of treatments for spasticity in amyotrophic lateral sclerosis, also known as motor neuron disease.

SEARCH STRATEGY

We searched the Cochrane Neuromuscular Disease Group specialised trials register (searched January 2003), MEDLINE (January 1966 to January 2003), EMBASE (January 1980 to January 2003), CINAHL (January 1982 to January 2003), AMED (January 1985 to January 2003) and LILACS (January 1982 to January 2003) for randomized controlled trials. We reviewed the bibliographies of the randomized trials identified, and contacted trial authors and known experts in the field.

SELECTION CRITERIA

We included quasi-randomized or randomized controlled trials of participants with probable or definite amyotrophic lateral sclerosis according to the El Escorial diagnostic criteria (or a revised version) or the Airlie House revision. We would have included trials of physical therapy, modalities, prescription medications, non-prescription medications, chemical neurolysis, surgical interventions, alternative therapies. Our primary outcome measure was reduction in spasticity at three months or greater as measured by Ashworth (or modified Ashworth) spasticity scale. Our secondary outcome measures were: validated measures based on history, physical examination, physiological measures, measures of function, measures of quality of life, serious adverse events, and measures of cost.

DATA COLLECTION AND ANALYSIS

We identified only one randomized controlled trial that met the inclusion criteria for this review. Two authors extracted the data. We also contacted the author of the paper and obtained further information not available in the published article.

MAIN RESULTS

The included study was a trial of moderate intensity, endurance type exercise versus 'usual activities' in 25 patients with amyotrophic lateral sclerosis. At three months patients performing the 15 minute twice daily exercises had significantly less spasticity (mean reduction of 0.43 Ashworth grades versus an increase of 0.25 in controls), as measured by the Ashworth scale.

REVIEWER'S CONCLUSIONS

Individualized, moderate intensity, endurance type exercises for the trunk and limbs may help to reduce spasticity in motor neuron disease. No other medical, surgical or alternative treatment and therapy has been evaluated in a randomized fashion in this patient population.

Outcome Assessment for Spasticity Management in the Patient With Traumatic Brain Injury

The objective of this article was to (1) review the engineering and medical literature to structure the available information concerning the assessment of spasticity in the neurological population; (2) to discuss the strengths and weaknesses of the different methods currently in use in spasticity assessment; and (3) make recommendations for future efforts in spasticity outcome assessment. Spasticity textbooks, Web sites, and OVID, IEEE, and Medline searches from 1966 through 2003 of spasticity, quantitative measure, or outcome assessment in the rehabilitation population were used as data sources. Over 500 articles were reviewed. Articles that discussed outcome measures used to assess interventions and evaluation of spasticity were included. Authors reviewed the articles looking at inclusion criteria, data collection, methodology, assessment methods, and conclusions for validity and relevance to this article. Issues such as clinical relevance, real-world function and lack of objectivity, and time consumed during performance are important issues for spasticity assessment. Some measures such as the Ashworth Scale remain in common use secondary to ease of use despite their obvious functional limitations. More functional outcome goals are plagued by being more time consuming and a general inability to demonstrate changes after an intervention. This may be secondary to the other factors that combine with spasticity to cause dysfunction at that level. Quantitative metrics can provide more objective measurements but their clinical relevance is sometimes problematic. The assessment of spasticity outcome is still somewhat problematic. Further work is necessary to develop measures that have real-world functional significance to both the individuals being treated and the clinicians. A lack of objectivity is still a problem. In the future it is important for clinicians and the engineers to work together in the development of better outcome measures.

Influence of long-term spaceflight on neuromechanical properties of muscles in humans

Reflex and elastic properties of the triceps surae (TS) were measured on 12 male cosmonauts 28-40 days before a 3- to 6-mo spaceflight, 2 or 3 days after return (R+2/+3) and a few days later (R+5/+6). H reflexes to electrical stimulations and T reflexes to tendon taps gave the reflex excitability at rest. Under voluntary contractions, reflex excitability was assessed by the stretch reflex, elicited by sinusoidal length perturbations. Stiffness measurements concerned the musculoarticular system in passive conditions and the musculotendinous complex in active conditions. Results indicated 1) no changes (P > 0.05) in H reflexes, whatever the day of test, and 2) increase in T reflexes (P < 0.05) by 57%, despite a decrease (P < 0.05) in musculoarticular stiffness (11%) on R+2/+3. T reflexes decreased (P < 0.05) between R+2/+3 and R+5/+6 (-21%); 3) increase in stretch reflexes (P < 0.05) on R+2/+3 by 31%, whereas it decreased (P < 0.05) between R+2/+3 and R+5/+6 (-29%). Musculotendinous stiffness was increased (P < 0.05) whatever the day of test (25%). Links between changes in reflex and stiffness were also studied by considering individual data. At R+2/+3, correlated changes between T reflexes and musculoarticular stiffness suggested that, besides central adaptive phenomena, musculoarticular structures took part in the reflex adaptation. This mechanical contribution was confirmed when data collected at R+2/+3 and R+5/+6 were used because correlations between changes in stretch reflexes and musculotendinous stiffness were improved. In conclusion, the present study shows that peripheral influences take part in reflex changes in gravitational unloaded muscles, but can only be revealed when central influences are reduced.

Intrathecal baclofen for spasticity caused by thrombotic stroke

This study was undertaken to determine the efficacy of intrathecal baclofen therapy in patients who suffer spasticity after a stroke. This case involves a 64-yr-old woman whose thrombotic strokes resulted in severe left-upper and lower-limb spasticity. The patient achieved substantial functional gains as well as improved ease of care, quality of life, and cessation of narcotic use.

Sensitivity of qualitative and quantitative spasticity measures to clinical treatment with cryotherapy

This study examined the extent to which a battery of tests could detect a reduction of plantarflexor spasticity resulting from cryotherapy. The tests included a traditional qualitative spasticity scale, three potential quantitative spasticity measures and a measure of voluntary ankle muscle function. Twenty-six adult traumatic-brain-injured subjects were examined; these included 22 males and 4 females. The mean age was 28.15 years (range: 18-57, SD 10.78). The five tests were performed in random sequence on both ankles of each subject, before and after a 20 minute cold pack application to the calf. Tests were: modified Ashworth scale (MAS) scoring; H-reflex testing with and without dorsiflexor contraction (Hdf/Hctrl ratio); H-reflex testing with and without Achilles tendon vibration (Hvib/Hctrl ratio); reflex threshold angle (RTA) and timed toe tapping (TIT). Cryotherapy resulted in lowered MAS scores consistent with a reduction in spasticity. Doubly multivariate repeated measures ANOVA revealed a significant difference (F = 24.16, P < 0.001) in test scores between the pre- and post-cryotherapy test batteries. Significant pre- and post-cryotherapy differences (P < or = 0.03) for all dependent measures contributed to the main effect for cryotherapy. However, among the potential quantitative measures of spasticity only the RTA test demonstrated appropriate sensitivity to the reduction in spasticity. In spite of spasticity reduction, TIT performance was impaired following muscle cooling. Failure of the H-reflex ratios to show a reduction consistent with reduced spasticity was attributed to competing alpha and gamma motoneuron effects resulting from peripheral cooling.

The effect of baclofen on the transmission in spinal pathways in spastic multiple sclerosis patients

OBJECTIVES

To measure the effect of baclofen on the transmission in different spinal pathways to soleus motoneurones in spastic multiple sclerosis patients.

METHODS

Baclofen was administered orally in 14 and intrathecally in 8 patients. H(max)/M(max), presynaptic inhibition by biceps femoris tendon tap of femoral nerve stimulation, depression of the soleus H-reflex following previous activation of the Ia afferents from the soleus muscle (i.e. postactivation depression), disynaptic reciprocal Ia inhibition of the soleus H-reflex and the number of backpropagating action potentials in primary afferents, which may be a sign of presynaptic inhibition, were examined.

RESULTS

Baclofen depressed the soleus H(max)/M(max) ratio significantly following oral and intrathecal baclofen. None of the two tests of presynaptic inhibition, or the postactivation depression or the disynaptic reciprocal Ia inhibition of the soleus H-reflex were affected by baclofen administration. Also the action potentials of the primary afferents were unchanged during baclofen administration.

CONCLUSIONS

The antispastic effect of baclofen is not caused by an effect on the transmitter release from Ia afferents or on disynaptic reciprocal Ia inhibition. One possible explanation of the depression of the H-reflex by baclofen is suggested to be a direct depression of motoneuronal excitability.

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.

Responses of thenar muscles to transcranial magnetic stimulation of the motor cortex in patients with incomplete spinal cord injury

OBJECTIVE

To investigate changes in electromyographic (EMG) responses to transcranial magnetic stimulation (TMS) of the motor cortex after incomplete spinal cord injury in humans.

METHODS

A group of 10 patients with incomplete spinal cord injury (motor level C3-C8) was compared with a group of 10 healthy control subjects. Surface EMG recordings were made from the thenar muscles. TMS was applied with a 9 cm circular stimulating coil centred over the vertex. The EMG responses to up to 50 magnetic stimuli were rectified and averaged.

RESULTS

Thresholds for compound motor evoked potentials (cMEPs) and suppression of voluntary contraction (SVC) elicited by TMS were higher (p < 0.05) in the patient group. Latency of cMEPs was longer (p < 0.05) in the patient group in both relaxed (controls 21.3 (SEM 0.5) ms; patients 27.7 (SEM 1.3) ms) and voluntarily contracted (controls 19.8 (SEM 0.5) ms; patients 27.6 (SEM 1.3) ms) muscles. The latency of SVC was longer (p < 0.05) in the patients (51.8 (SEM 1.8) ms) than in the controls (33.4 (SEM 1.9) ms). The latency difference (SVC-cMEP) was longer in the patients (25.3 (SEM 2.4) ms) than in the controls (13.4 (SEM 1.6) ms).

CONCLUSION

The longer latency difference between cMEPs and SVC in the patients may reflect a weak or absent early component of cortical inhibition. Such a change may contribute to the restoration of useful motor function after incomplete spinal cord injury.

Clinical value of F-wave recordings in traumatic cervical spinal cord injury

F-waves and motor/sensory nerve conduction (NCS) of the median and ulnar nerves were examined in 66 patients with traumatic motoneurone lesion due to acute and chronic cervical spinal cord injury (SCI). The examinations were performed in parallel in chronic tetraplegics once and in acute tetraplegic patients monthly for the first 3 months, after 6 months and 1 year post-trauma. A pathological reduction of the compound muscle action potential (CMAP) (in 10% even a complete loss of the CMAP) was present in about 50% of the patients. The mean CMAP values of tetraplegic patients with either acute or chronic SCI were significantly (P < 0.001) reduced compared to normal subjects. Because sensory nerve conduction in these patients was normal, the reduction of CMAP should be due to damage of intramedullar motoneurones or anterior nerve roots. While in all chronic SCI patients with preserved CMAP F-waves could be elicited, 50% of the acute SCI patients showed a complete loss of F-waves of both nerves during the initial examination due to spinal shock. After 6 months all acute SCI patients with preserved motor potentials regained F-waves. Therefore, the excitability of F-waves is influenced by spinal shock in acute SCI. The mean F-wave latencies (Fmin-response, Fmin-M response) revealed no significant difference between healthy subjects and SCI patients. However, the frequency of F-wave production was related to the severity of the motoneurone lesion. Furthermore, while the F-wave latencies and CMAP values did not change significantly with time after acute SCI, the frequency of F-wave production increased, but remained reduced compared to normal subjects.

Correlation of quantitative measures with the modified Ashworth scale in the assessment of plantar flexor spasticity in patients with traumatic brain injury

This study of plantar flexor spasticity describes relationships among a traditional qualitative spasticity scale, three potential quantitative spasticity measures and a measure of voluntary ankle muscle function. Thirty-four volunteer adult patients with traumatic brain injuries participated. There were 28 males and 6 females; the mean age was 30.3 years. A battery of five randomly sequenced tests was performed for each subject on one ankle. Tests were: modified Ashworth scale (MAS) scoring; H-reflex testing with and without Achilles tendon vibration; H-reflex testing with and without dorsiflexor contraction; reflex threshold angle and timed toe tapping (TTT). Twenty-six subjects returned to have the second ankle tested, resulting in 60 ankles for the analyses. Spearman's coefficients for correlation of quantitative spasticity measures with MAS scores ranged from 0.39 to 0.49 with associated probabilities < or = 0.002. Pearson coefficients for correlation of quantitative spasticity measures with TTT scores were lower but also significant (P < or = 0.07). Multiple correlation for the set of quantitative measures yielded R = 0.614 (P < 0.001) with MAS scores and R = 0.365 (P = 0.045) with TTT scores. These findings reveal statistically significant relationships of low to moderate strength among potential quantitative spasticity measures, a traditional qualitative spasticity scale and a simple measure of voluntary ankle muscle function. Understanding these relationships is an essential part of the ongoing search for quantitative spasticity measures.

GABAB receptors

GABAB receptors are a distinct subclass of receptors for the major inhibitory transmitter 4-aminobutanoic acid (GABA) that mediate depression of synaptic transmission and contribute to the inhibition controlling neuronal excitability. The development of specific agonists and antagonists for these receptors has led to a better understanding of their physiology and pharmacology, highlighting their diverse coupling to different intracellular effectors through Gi/G(o) proteins. This review emphasises our current knowledge of the neurophysiology and neurochemistry of GABAB receptors, including their heterogeneity, as well as the therapeutic potential of drugs acting at these sites.

Involvement of the nucleus accumbens in the myorelaxant effect of baclofen in rats

The study was designed to search for brain structures responsible for the myorelaxant action of baclofen. Rats were chronically implanted with cannulae in the medial nucleus accumbens (NAS). The muscle tone was increased by reserpine (10 mg/kg i.p.) and measured as a resistance of the hind foot, developed in response to successive passive bendings and straightenings in the ankle joint. (+/-)Baclofen (1 or 2.5 mg/0.5 microliter), injected bilaterally into the NAS 1.5 h after pretreatment with reserpine, decreased the muscle tone of flexors and extensors enhanced by that compound. It is suggested that GABAB receptors of the NAS are involved in the myorelaxant action of baclofen.