Spasticity or reversible muscle hypertonia?

PTEN deletion in spinal pathways via retrograde transduction with AAV-RG enhances forelimb motor recovery after cervical spinal cord injury; Sex differences and late-onset pathophysiologies

Spinal cord injuries (SCI) cause permanent functional impairments due to interruption of motor and sensory pathways. Regeneration of axons does not occur due to lack of intrinsic growth capacity of adult neurons and extrinsic inhibitory factors, especially at the injury site. However, some regeneration can be achieved via deletion of the phosphatase and tensin homolog (PTEN) in cells of origin of spinal pathways. Here, we deployed an AAV variant that is retrogradely transported (AAV-rg) to deliver gene modifying cargos to the cells of origin of multiple pathways interrupted by SCI, testing whether this promoted recovery of motor function. PTENf/f;RosatdTomato mice and control RosatdTomato mice received injections of different doses (number of genome copies, GCs) of AAV-rg/Cre into the cervical spinal cord at the time of a C5 dorsal hemisection injury. Forelimb grip strength was tested over time using a grip strength meter. PTENf/f;RosatdTomato mice with AAV-rg/Cre (PTEN-deleted) exhibited substantial improvements in forelimb gripping ability in comparison to controls. Of note, there were major sex differences in the extent of recovery, with male mice exhibiting greater recovery than females. However, at around 5-7 weeks post-injury/injection, many mice with SCI and AAV-rg-mediated PTEN deletion began to exhibit pathophysiologies involving excessive scratching of the ears and back of the neck and rigid forward extension of the hindlimbs. These pathophysiologies increased in incidence and severity over time. Our results reveal that although intra-spinal injections of AAV-rg/Cre in PTENf/f;RosatdTomato mice can enhance forelimb motor recovery after SCI, late-developing functional abnormalities occur with the experimental conditions used here. Mechanisms underlying late-developing pathophysiologies remain to be defined.

PTEN deletion in spinal pathways via retrograde transduction with AAV-rg enhances forelimb motor recovery after cervical spinal cord injury; sex differences and late-onset pathophysiologies

Spinal cord injuries (SCI) cause permanent functional impairments due to interruption of motor and sensory pathways. Regeneration of axons does not occur due to lack of intrinsic growth capacity of adult neurons and extrinsic inhibitory factors, especially at the injury site. However, some regeneration can be achieved via deletion of the phosphatase and tensin homolog (PTEN) in cells of origin of spinal pathways. Here, we deployed an AAV variant that is retrogradely transported (AAV-rg) to deliver gene modifying cargos to the cells of origin of multiple pathways interrupted by SCI, testing whether this promoted recovery of motor function. PTEN f/f ;Rosa tdTomato mice and control Rosa tdTomato mice received injections of different doses (number of genome copies, GCs) of AAV-rg/Cre into the cervical spinal cord at the time of a C5 dorsal hemisection injury. Forelimb grip strength was tested over time using a grip strength meter. PTEN f/f ;Rosa tdTomato mice with AAV-rg/Cre (PTEN-deleted) exhibited substantial improvements in forelimb gripping ability in comparison to controls. Of note, there were major sex differences in the extent of recovery, with male mice exhibiting greater recovery than females. However, at around 5-7 weeks post-injury/injection, many mice with SCI and AAV-rg-mediated PTEN deletion began to exhibit pathophysiologies involving excessive scratching of the ears and back of the neck and rigid forward extension of the hindlimbs. These pathophysiologies increased in incidence and severity over time. Our results reveal that although intra-spinal injections of AAV-rg/Cre in PTEN f/f ;Rosa tdTomato mice can enhance forelimb motor recovery after SCI, late-developing functional abnormalities occur with the experimental conditions used here. Mechanisms underlying late-developing pathophysiologies remain to be defined.

Spastic dystonia in stroke subjects: prevalence and features of the neglected phenomenon of the upper motor neuron syndrome

OBJECTIVE

Spastic dystonia is one of the positive phenomena of the upper motor neuron syndrome (UMNS). It is characterised by the inability to relax a muscle leading to a spontaneous, although stretch-sensitive, tonic contraction. Although spastic dystonia is a recognized cause of muscle hypertonia, its prevalence among hypertonic muscles of stroke subjects has never been investigated. Differently from spasticity, which is an exaggerated stretch reflex, spastic dystonia is viewed as an efferent phenomenon, due to an abnormal central drive to motoneurons.

METHODS

In 23 hemiparetic stroke subjects showing increased muscle tone of wrist flexors, surface EMG was used to investigate the presence of spontaneous, stretch-sensitive EMG activity in flexor carpi radialis.

RESULTS

Spontaneous, stretch-sensitive EMG activity was found in 17 subjects. In the remaining 6 subjects, no spontaneous EMG activity was found.

CONCLUSIONS

The majority of stroke subjects is affected by spastic dystonia in their hypertonic wrist flexor muscles. Only a minority of subjects is affected by spasticity.

SIGNIFICANCE

To stop spastic dystonia from being the neglected aspect of UMNS, it is essential to link its definition to increased muscle tone, as occurred for spasticity. Recognizing the real phenomena underling muscle hypertonia could improve its management.

Ixcellence Network®: an international educational network to improve current practice in the management of cervical dystonia or spastic paresis by botulinum toxin injection

Botulinum toxin is a well-established treatment for a number of conditions involving muscle hyperactivity, such as focal dystonia and spastic paresis. However, current injection practice is not standardized and there is a clear need for structured training. An international group of experts in the management of patients with cervical dystonia (CD) and spastic paresis created a steering committee (SC). For each therapeutic area, the SC developed a core slide set on best practice, based on the literature. International sites of expertise were identified for training and courses were designed to include lectures and casebased learning. Where possible, courses received accreditation from the European Union of Medical Specialists (UEMS). Each course was peer reviewed by the SC, the UEMS accreditation board and the attendees themselves (through evaluation questionnaires). Attendees' feedback was shared with the SC and the trainers to tailor future training sessions. From the program launch in 2012 to December 2014, 328 physicians from 34 countries were trained in a total of 58 courses; 67% of the courses focused on spastic paresis and 33% on CD. Of the 225 (69%) physicians who completed feedback forms, 95% rated their course as 'above average/excellent' in meeting the preset learning objectives. Most (90%) physicians declared that attending a course would lead them to change their practice. The development of the 'Ixcellence Network' for continuous medical education in the fields of spastic paresis and CD has provided a novel and interactive way of training physicians with previous experience in botulinum toxin injection.

Non-pharmacological interventions for spasticity in adults: An overview of systematic reviews

OBJECTIVES

Spasticity causes significant long-term disability-burden, requiring comprehensive management. This review evaluates evidence from published systematic reviews of clinical trials for effectiveness of non-pharmacological interventions for improved spasticity outcomes.

METHODS

Data sources: a literature search was conducted using medical and health science electronic (MEDLINE, EMBASE, CINAHL, PubMed, and the Cochrane Library) databases for published systematic reviews up to 15th June 2017.

DATA EXTRACTION AND SYNTHESIS

two reviewers applied inclusion criteria to select potential systematic reviews, independently extracted data for methodological quality using Assessment of Multiple Systematic Reviews (AMSTAR). Quality of evidence was critically appraised with Grades of Recommendation, Assessment, Development and Evaluation (GRADE).

RESULTS

Overall 18 systematic reviews were evaluated for evidence for a range of non-pharmacological interventions currently used in managing spasticity in various neurological conditions. There is "moderate" evidence for electro-neuromuscular stimulation and acupuncture as an adjunct therapy to conventional routine care (pharmacological and rehabilitation) in persons following stroke. "Low" quality evidence for rehabilitation programs targeting spasticity (such as induced movement therapy, stretching, dynamic elbow-splinting, occupational therapy) in stroke and other neurological conditions; extracorporeal shock-wave therapy in brain injury; transcranial direct current stimulation in stroke; transcranial magnetic stimulation and transcutaneous electrical nerve stimulation for other neurological conditions; physical activity programs and repetitive magnetic stimulation in persons with MS, vibration therapy for SCI and stretching for other neurological condition. For other interventions, evidence was inconclusive.

CONCLUSIONS

Despite the available range of non-pharmacological interventions for spasticity, there is lack of high-quality evidence for many modalities. Further research is needed to judge the effect with appropriate study designs, timing and intensity of modalities, and associate costs of these interventions.

Spasticity and spastic dystonia: the two faces of velocity-dependent hypertonia

BACKGROUND

Spasticity and spastic dystonia are two separate phenomena of the upper motor neuron syndrome. Spasticity is clinically defined by velocity-dependent hypertonia and tendon jerk hyperreflexia due to the hyper-excitability of the stretch reflex. Spastic dystonia is the inability to relax a muscle leading to a spontaneous tonic contraction. Both spasticity and spastic dystonia are present in patients who are at rest; however, only patients with spasticity are actually able to kept their muscles relaxed prior to muscle stretch. The idea that has inspired the present work is that also in patients with spastic dystonia the stretch reflex is likely to be hyper-excitable. Therefore, velocity-dependent hypertonia could be mediated not only by spasticity, but also by spastic dystonia.

METHODS

Tonic stretch reflexes in the rectus femoris muscle were evoked in 30 patients with multiple sclerosis showing velocity-dependent hypertonia of leg extensors and the habituation of the reflex was studied. Moreover, the capability of relax the muscle prior to muscle stretch (spastic dystonia) was also investigated.

RESULTS

A tonic stretch reflex was evoked in all the enrolled patients. 73% of the patients were able to relax their rectus femoris muscle prior to stretch (spasticity). In the overwhelming majority of these patients, the tonic stretch reflex decreased during repeated stretches. In the remaining 27% of the subjects, the muscle was tonically activated prior to muscle stretch (spastic dystonia). In the patients in whom spastic dystonia progressively increased over the subsequent stretches (50% of the subjects with spastic dystonia), the habituation of the reflex was replaced by a progressive reflex facilitation.

DISCUSSION

This study shows for the first time that velocity-dependent hypertonia can be caused by two distinct phenomena: spasticity and spastic dystonia. The habituation of the tonic stretch reflex, which is a typical feature of spasticity, is replaced by a reflex facilitation in the half of the subject with spastic dystonia. These preliminary findings suggest that differentiating the two types of velocity-dependent muscle hypertonia (spasticity and spastic dystonia) could be clinically relevant.

Description of common musculoskeletal findings in Williams Syndrome and implications for therapies

Williams syndrome (WS), also referred to as Williams-Beuren syndrome (WBS), is a relatively rare genetic disorder affecting ∼1/10,000 persons. Since the disorder is caused by a micro-deletion of ∼1.5 Mb, it is not surprising that the manifestations of WS are extremely broad, involving most body systems. In this paper, we primarily focus on the musculoskeletal aspects of WS as these findings have not been the subject of a comprehensive review. We review the MSK features commonly seen in individuals with WS, along with related sensory and neurological issues interacting with and compounding underlying MSK abnormalities. We end by providing perspective, particularly from the vantage point of a physical therapist, on therapeutic interventions to address the most common MSK and related features seen in WS. Clin. Anat. 29:578-589, 2016. © 2016 Wiley Periodicals, Inc.

Botulinum Neurotoxin Type A in Neurology: Update

This paper reviews the current and most neurological (central nervous system, CNS) uses of the botulinum neurotoxin type A. The effect of these toxins at neuromuscular junction lends themselves to neurological diseases of muscle overactivity, particularly abnormalities of muscle control. There are seven serotypes of the toxin, each with a specific activity at the molecular level. Currently, serotypes A (in two preparations) and B are available for clinical purpose, and they have proved to be safe and effective for the treatment of dystonia, spasticity, headache, and other CNS disorders in which muscle hyperactivity gives rise to symptoms. Although initially thought to inhibit acetylcholine release only at the neuromuscular junction, botulinum toxins are now recognized to inhibit acetylcholine release at autonomic cholinergic nerve terminals, as well as peripheral release of neuro-transmitters involved in pain regulation. Its effects are transient and nondestructive, and largely limited to the area in which it is administered. These effects are also graded according to the dose, allowing individualized treatment of patients and disorders. It may also prove to be useful in the control of autonomic dysfunction and sialorrhea. In over 20 years of use in humans, botulinum toxin has accumulated a considerable safety record, and in many cases represents relief for thousands of patients unaided by other therapy.

Multidisciplinary rehabilitation following botulinum toxin and other focal intramuscular treatment for post-stroke spasticity

BACKGROUND

Spasticity may affect stroke survivors by contributing to activity limitations, caregiver burden, pain and reduced quality of life (QoL). Spasticity management guidelines recommend multidisciplinary (MD) rehabilitation programmes following botulinum toxin (BoNT) treatment for post-stroke spasticity. However, the evidence base for the effectiveness of MD rehabilitation is unclear.

OBJECTIVES

To assess the effectiveness of MD rehabilitation, following BoNT and other focal intramuscular treatments such as phenol, in improving activity limitations and other outcomes in adults and children with post-stroke spasticity. To explore what settings, types and intensities of rehabilitation programmes are effective.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register (February 2012), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 12), MEDLINE (1948 to December 2011), EMBASE (1980 to January 2012), CINAHL (1982 to January 2012), AMED (1985 to January 2012), LILACS (1982 to September 2012), PEDro, REHABDATA and OpenGrey (September 2012). In an effort to identify further published, unpublished and ongoing trials we searched trials registries and reference lists, handsearched journals and contacted authors.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that compared MD rehabilitation (delivered by two or more disciplines in conjunction with medical input) following BoNT and other focal intramuscular treatments for post-stroke spasticity with placebo, routinely available local services, or lower levels of intervention; or studies that compared MD rehabilitation in different settings, of different types, or at different levels of intensity. We excluded RCTs that assessed the effectiveness of unidisciplinary therapy (for example physiotherapy only) or a single modality (for example stretching, casting, electrical stimulation or splinting only). The primary outcomes were validated measures of activity level (active and passive function) according to the World Health Organization's International Classification of Functioning, Disability and Health. Secondary outcomes included measures of symptoms, impairments, participation, QoL, impact on caregivers and adverse events.

DATA COLLECTION AND ANALYSIS

We independently selected the trials, extracted data, and assessed methodological quality using the Grades of Recommendation, Assessment, Development and Evaluation (GRADE). Due to the limited number of included studies, with clinical, methodological and statistical heterogeneity, quantitative meta-analysis was not possible. Therefore, GRADE provided qualitative synthesis of 'best evidence'.

MAIN RESULTS

We included three RCTs involving 91 participants. All three studies scored 'low quality' on the methodological quality assessment, implying high risk of bias. All studies investigated various types and intensities of outpatient rehabilitation programmes following BoNT for upper limb spasticity in adults with chronic stroke. Rehabilitation programmes included: modified constraint-induced movement therapy (mCIMT) compared with a neurodevelopmental therapy programme; task practice therapy with cyclic functional electrical stimulation (FES) compared with task practice therapy only; and occupational, manual therapy with dynamic elbow extension splinting compared with occupational therapy only. There was 'low quality' evidence for mCIMT improving upper limb motor function and spasticity in chronic stroke survivors with residual voluntary upper limb activity, up to six months, and 'very low quality' evidence for dynamic elbow splinting and occupational therapy reducing elbow range of movement at 14 weeks. Task practice therapy with cyclic FES did not improve upper limb function more than task practice therapy alone, only at 12 weeks. No studies addressed interventions in children and those with lower limb spasticity, or after other focal intramuscular treatments for spasticity.

AUTHORS' CONCLUSIONS

At best there was 'low level' evidence for the effectiveness of outpatient MD rehabilitation in improving active function and impairments following BoNT for upper limb spasticity in adults with chronic stroke. No trials explored the effect of MD rehabilitation on 'passive function' (caring for the affected limb), caregiver burden, or the individual's priority goals for treatment. The optimal types (modalities, therapy approaches, settings) and intensities of therapy for improving activity (active and passive function) in adults and children with post-stroke spasticity, in the short and longer term, are unclear. Further research is required to build evidence in this area.

The gap between clinical gaze and systematic assessment of movement disorders after stroke

Background

Movement disorders after stroke are still captured by clinical gaze and translated to ordinal scores of low resolution. There is a clear need for objective quantification, with outcome measures related to pathophysiological background. Neural and non-neural contributors to joint behavior should be separated using different measurement conditions (tasks) and standardized input signals (force, position and velocity).

Methods

We reviewed recent literature for the application of biomechanical and/or elektromyographical (EMG) outcome measures under various measurement conditions in clinical research.

Results

Since 2005, 36 articles described the use of biomechanical and/or EMG outcome measures to quantify post-stroke movement disorder. Nineteen of the articles strived to separate neural and non-neural components. Only 6 of the articles measured biomechanical and EMG outcome measures simultaneously, while applying active and passive tasks and multiple velocities.

Conclusion

The distinction between neural and non-neural components to separately assess paresis, stiffness and muscle overactivity is not commonplace yet, while a large gap is to be bridged to attain reproducible and comparable results. Pathophysiologically clear concepts, substantiated with a comprehensive and concise measuring protocol will help professionals to identify and treat limiting factors in movement capabilities of post-stroke patients.