Treatment of Generalized Dystonia

Pharmacological and neurosurgical interventions for managing dystonia in cerebral palsy: a systematic review

AIM

To systematically review evidence for pharmacological/neurosurgical interventions for managing dystonia in individuals with cerebral palsy (CP) to inform a care pathway.

METHOD

Searches included studies with a minimum of five participants with dystonia in CP receiving oral baclofen, benzodiazepines (clonazepam, diazepam, lorazepam), clonidine, gabapentin, levodopa, trihexyphenidyl, botulinum toxin, intrathecal baclofen (ITB), or deep brain stimulation (DBS). Evidence was classified according to American Academy of Neurology guidelines.

RESULTS

Twenty-eight articles underwent data extraction: one levodopa, five trihexyphenidyl, three botulinum toxin, six ITB, and 13 DBS studies. No articles for oral baclofen, benzodiazepines, clonidine, or gabapentin met the inclusion criteria. Evidence for reducing dystonia was level C (possibly effective) for ITB and DBS; level C (possibly ineffective) for trihexyphenidyl; and level U (inadequate data) for botulinum toxin.

INTERPRETATION

For dystonia reduction, ITB and DBS are possibly effective, whereas trihexyphenidyl was possibly ineffective. There is insufficient evidence to support oral medications or botulinum toxin to reduce dystonia. There is insufficient evidence for pharmacological and neurosurgical interventions to improve motor function, decrease pain, and ease caregiving. The majority of the pharmacological and neurosurgical management of dystonia in CP is based on clinical expert opinion.

WHAT THIS PAPER ADDS

Intrathecal baclofen and deep brain stimulation are possibly effective in reducing dystonia. Current evidence does not support effectiveness of oral medications or botulinum toxin to reduce dystonia. Evidence is inadequate for pharmacological/neurosurgical interventions impact on improving motor function, pain/comfort, and easing caregiving. The majority of the care pathway rests on expert opinion.

Complex care of individuals with multiple sulfatase deficiency: Clinical cases and consensus statement

Multiple sulfatase deficiency (MSD) is an ultra-rare neurodegenerative disorder that results in defective sulfatase post-translational modification. Sulfatases in the body are activated by a unique protein, formylglycine-generating enzyme (FGE) that is encoded by SUMF1. When FGE is absent or insufficient, all 17 known human sulfatases are affected, including the enzymes associated with metachromatic leukodystrophy (MLD), several mucopolysaccharidoses (MPS II, IIIA, IIID, IVA, VI), chondrodysplasia punctata, and X-linked ichthyosis. As such, individuals demonstrate a complex and severe clinical phenotype that has not been fully characterized to date. In this report, we describe two individuals with distinct clinical presentations of MSD. Also, we detail a comprehensive systems-based approach to the management of individuals with MSD, from the initial diagnostic evaluation to unique multisystem issues and potential management options. As there have been no natural history studies to date, the recommendations within this report are based on published studies and consensus opinion and underscore the need for future research on evidence-based outcomes to improve management of children with MSD.

Revised consensus statement on the preventive and symptomatic care of patients with leukodystrophies

Leukodystrophies are a broad class of genetic disorders that result in disruption or destruction of central myelination. Although the mechanisms underlying these disorders are heterogeneous, there are many common symptoms that affect patients irrespective of the genetic diagnosis. The comfort and quality of life of these children is a primary goal that can complement efforts directed at curative therapies. Contained within this report is a systems-based approach to management of complications that result from leukodystrophies. We discuss the initial evaluation, identification of common medical issues, and management options to establish a comprehensive, standardized care approach. We will also address clinical topics relevant to select leukodystrophies, such as gallbladder pathology and adrenal insufficiency. The recommendations within this review rely on existing studies and consensus opinions and underscore the need for future research on evidence-based outcomes to better treat the manifestations of this unique set of genetic disorders.

Hypertonia

Hypertonia is the abnormal increase in muscle tone as a result of upper motor neuron lesions. There are three following clinical types: spasticity, dystonia, and rigidity. Management of hypertonia is individualized and should be directed by the patient and/or family׳s goals of care as well as the underlying cause of the hypertonia. Treatment options include stretching, strengthening, positioning, oral medications, botulinum toxin injections, phenol injections, as well as surgical procedures. Without effective management, hypertonia can result in muscle imbalance, abnormal movement patterns, pain, joint contracture, joint deformity, and ultimately negatively impact a patient׳s function. This discussion serves as an overview of hypertonia, focusing on spasticity and dystonia, in the pediatric population by examining the causes and epidemiology, elucidating its symptoms, discussing available treatment and management options, and clarifying why this all matters.

l-Dopa in dystonia

“Every child exhibiting dystonia merits anl-dopa trial, lest the potentially treatable condition of dopa-responsive dystonia (DRD) is missed” has been a commonly cited and highly conserved adage in movement disorders literature stemming from the 1980s. We here provide a historical perspective on this statement, discuss the current diagnostic and therapeutic applications ofl-dopa in everyday neurologic practice, contrast these with its approved indications, and finish with our view on both a diagnostic and therapeutic trial in children and adults with dystonia. In light of the relatively low prevalence of DRDs, the large interindividual variation in the requiredl-dopa dose, the uncertainty about an adequate trial duration, the substantial advances in knowledge on etiology and pathophysiology of these disorders, and the availability of various state-of-the-art diagnostic tests, we think that a diagnosticl-dopa trial as a first step in the approach of early-onset dystonia (≤25 years) is outdated. Rather, in high-resource countries, we suggest to usel-dopa after biochemical corroboration of a defect in dopamine biosynthesis, in genetically confirmed DRD, or if nigrostriatal degeneration has been demonstrated by nuclear imaging in adult patients presenting with lower limb dystonia. Furthermore, our literature study on the effect of a therapeutic trial to gain symptomatic relief revealed thatl-dopa has occasionally proven beneficial in several established “non-DRDs” and may therefore be considered in selected cases of dystonia due to other causes. In summary, we argue against the application ofl-dopa in every patient with early-onset dystonia and support a more rational therapeutic use.

Lesch-Nyhan Syndrome: Models, Theories, and Therapies

Lesch-Nyhan syndrome (LNS) is a rare X-linked disorder caused by mutations in HPRT1, an important enzyme in the purine salvage pathway. Symptoms of LNS include dystonia, gout, intellectual disability, and self-mutilation. Despite having been characterized over 50 years ago, it remains unclear precisely how deficits in hypoxanthine and guanine recycling can lead to such a profound neurological phenotype. Several studies have proposed different hypotheses regarding the etiology of this disease, and several treatments have been tried in patients, though none have led to a satisfactory explanation of the disease. New technologies such as next-generation sequencing, optogenetics, genome editing, and induced pluripotent stem cells provide a unique opportunity to map the precise sequential pathways leading from genotype to phenotype.

Intraoperative MRI for neurosurgical and general surgical interventions

PURPOSE OF REVIEW

The use of intraoperative magnetic resonance imaging (IMRI) during surgeries and procedures has expanded in the last decade. Not only is it becoming more commonly used for a variety of adult and pediatric neurosurgical procedures, but also its use has expanded to other types of surgeries. Along with using IMRI for removing tumors of the spinal cord, surgeons are now using it for other types of surgical operations of the kidney and liver. The increased utilization during the intraoperative period warrants the anesthesia provider to assure that patients and staff are unharmed because of increased risk of the powerful magnet.

RECENT FINDINGS

Recent literature is reviewed regarding the expansive use of IMRI in the operating and procedure room. Safety issues and anesthetic implications are also addressed.

SUMMARY

IMRI is becoming increasingly more popular, especially with neurosurgeons, but its use is also expanding to other types of surgeries. Because of the increased use, the anesthesia provider must be aware of the dangers that it imposes to those involved and take necessary safety precautions. This will help assure that no one is harmed during the operation or procedure.

Bilateral globus pallidus interna deep-brain stimulation in a patient with myoclonus-dystonia: a case report

OBJECTIVE

Myoclonus-dystonia is a movement disorder characterized by childhood onset of myoclonus and dystonia. We report a case of the epsilon-sarcoglycan mutation-negative myoclonus-dystonia patient who underwent bilateral globus pallidus interna deep-brain stimulation with subsequent improvement of both myoclonus and dystonia.

CASE REPORT

A 37-year-old woman with myoclonic jerks and dystonia affecting predominantly the lower limbs was treated with chronic bilateral globus pallidus interna deep-brain stimulation.

RESULTS

The movement subscore of the Burke-Fahns-Marsden Dystonia Rating Scale was 38 before surgery and improved to 7 after 3 years. The disability subscore of the Burke-Fahns-Marsden Dystonia Rating Scale improved from 7 to 2. The Unified Myoclonus Rating Scale also decreased significantly from 93 to 39. No hardware- or stimulation-related complications occurred during follow-up.

CONCLUSION

This report suggests that patients with myoclonus-dystonia may significantly benefit from bilateral globus pallidus interna deep-brain stimulation. Larger studies of this patient population are needed to confirm the optimal target.

Lessons Learned from Open-label Deep Brain Stimulation for Tourette Syndrome: Eight Cases over 7 Years

Background

Deep brain stimulation (DBS) remains an experimental but promising treatment for patients with severe refractory Gilles de la Tourette syndrome (TS). Controversial issues include the selection of patients (age and clinical presentation), the choice of brain targets to obtain optimal patient-specific outcomes, and the risk of surgery- and stimulation-related serious adverse events.

Methods

This report describes our open-label experience with eight patients with severe refractory malignant TS treated with DBS. The electrodes were placed in the midline thalamic nuclei or globus pallidus, pars internus, or both. Tics were clinically assessed in all patients pre- and postoperatively using the Modified Rush Video Protocol and the Yale Global Tic Severity Scale (YGTSS).

Results

Although three patients had marked postoperative improvement in their tics (>50% improvement on the YGTSS), the majority did not reach this level of clinical improvement. Two patients had to have their DBS leads removed (one because of postoperative infection and another because of lack of benefit).

Discussion

Our clinical experience supports the urgent need for more data and refinements in interventions and outcome measurements for severe, malignant, and medication-refractory TS. Because TS is not an etiologically homogenous clinical entity, the inclusion criteria for DBS patients and the choice of brain targets will require more refinement.

TC-8831, a nicotinic acetylcholine receptor agonist, reduces L-DOPA-induced dyskinesia in the MPTP macaque

Long-term L-DOPA treatment for Parkinson's disease (PD) is limited by motor complications, particularly L-DOPA-induced dyskinesia (LID). A therapy with the ability to ameliorate LID without reducing anti-parkinsonian benefit would be of great value. We assessed the ability of TC-8831, an agonist at nicotinic acetylcholine receptors (nAChR) containing α6β2/α4β2 subunit combinations, to provide such benefits in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine- (MPTP) lesioned macaques with established LID. Animals were treated orally for consecutive 14-day periods with twice-daily vehicle (weeks 1-2) or TC-8831 (0.03, 0.1 or 0.3 mg/kg, weeks 3-8). L-DOPA was also administered, once-daily, (weeks 1-12, median-dose 30 mg/kg, p.o.). For the following two-weeks (weeks 9-10), TC-8831 was washed out, while once-daily L-DOPA treatment was maintained. The effects of once-daily amantadine (3 mg/kg, p.o.) were then assessed over weeks 11-12. LID, parkinsonism, duration and quality of ON-time were assessed weekly by a neurologist blinded to treatment. TC-8831 reduced the duration of 'bad' ON-time (ON-time with disabling dyskinesia) by up to 62% and decreased LID severity (median score 18 cf. 34 (vehicle), 0.1 mg/kg, 1-3 h period). TC-8831 also significantly reduced choreiform and dystonic dyskinesia (median scores 6 and 31 cf. 19 and 31 respectively (vehicle), both 0.03 mg/kg, 1-3 h). At no time did TC-8831 treatment result in a reduction in anti-parkinsonian benefit of L-DOPA. By comparison, amantadine also significantly reduced dyskinesia and decreased 'bad' ON-time (up to 61%) but at the expense of total ON-time (reduced by up to 23%). TC-8831 displayed robust anti-dyskinetic actions and improved the quality of ON-time evoked by L-DOPA without any reduction in anti-parkinsonian benefit.

Surgical treatment for secondary dystonia

Surgical therapy for the secondary dystonias is generally perceived to be less effective than for primary disease. However, a number of case reports and small open series have recently appeared describing quite favorable outcomes following surgery for some nonprimary dystonias. We discuss surgical treatment options for this group of diverse conditions, including tardive dystonia, dystonic cerebral palsy, and certain heredodegenerative diseases in which deep brain stimulation and ablative lesions of the posteroventral pallidum have been shown to be effective. Other types of secondary dystonia respond less well to pallidal surgery, particularly when anatomical lesions of the basal ganglia are prominent on preoperative imaging. For these conditions, central baclofen delivery and botulinum toxin denervation may be considered. With optimal medical and surgical care, some patients with secondary dystonia have achieved reductions in disability and pain that approach those documented for primary dystonia.

Early gene mapping after deep brain stimulation in a rat model of tardive dyskinesia: comparison with transient local inactivation

Deep brain stimulation (DBS) has been extensively used in Parkinson's disease and is also currently being investigated in tardive dyskinesia (TD), a movement disorder induced by chronic treatment with antipsychotic drugs such as haloperidol (HAL). In rodents, vacuous chewing movements (VCMs) following chronic HAL administration are suggested to model orofacial dyskinesias in TD. We show that 60 min of DBS (100 μA, 90 μs, 130 Hz) applied to the entopeduncular (EPN) or subthalamic (STN) nuclei significantly decreases HAL-induced VCMs. Using zif268 as a neural activity marker, we found that in HAL-treated animals EPN stimulation increased zif268 mRNA levels in the globus pallidus (+65%) and substantia nigra compacta (+62%) and reticulata (+76%), while decreasing levels in the motor cortex and throughout the thalamus. In contrast, after STN DBS zif268 levels in HAL-treated animals decreased in all basal ganglia structures, thalamus and motor cortex (range: 29% in the ventrolateral caudate-putamen to 100% in the EPN). Local tissue inactivation by muscimol injections into the STN or EPN also reduced VCMs, but to a lesser degree than DBS. When applied to the EPN muscimol decreased zif268 levels in substantia nigra (-29%), whereas STN infusions did not result in significant zif268 changes in any brain area. These results confirm the effectiveness of DBS in reducing VCMs and suggest that tissue inactivation does not fully account for DBS effects in this preparation. The divergent effects of STN vs. EPN manipulations on HAL-induced zif268 changes suggest that similar behavioral outcomes of DBS in these two areas may involve different neuroanatomical mechanisms.