Huntington’s disease

Management of dysphagia in Huntington's disease: a descriptive review

Huntington's disease (HD) is a rare neurodegenerative disorder of the central nervous system characterized by involuntary choreatic movements, cognitive, behavioral, and psychiatric disturbances. Most HD suffer from dysphagia and aspiration pneumonia is the leading cause of death. However, little is known about dysphagia management in HD. A revision of the literature was conducted to depict the state of the art on the assessment and treatment of dysphagia in HD. Literature search of the last 10 years was performed using PubMed and EMBASE. Twenty-four studies were included: 16 cross-sectional studies, 2 case reports, 2 case series, 2 open-label trials, 1 pre-post study, and 1 randomized controlled trial. Based on the studies retrieved, dysphagia should be assessed from the early stage of the disease, especially when specific clinical markers occur. Timing for dysphagia re-assessment should be based on the recommendation of the swallowing experts on the individual case. Instrumental assessment of swallowing by videofluoroscopy or videoendoscopy is feasible and recommended to diagnose dysphagia in patients with HD. Clinical assessment tools and patient-reported outcome measures may be used to complete the swallowing examination, but not to replace instrumental assessment. The impact of pharmacological and rehabilitative treatments on dysphagia in HD has been little studied in literature. While the effect of tetrabenazine on swallowing is still controversial, compensatory strategies seem to be applicable and efficacious. To date, there are no well-proven rehabilitative strategies to improve swallowing function in patients with HD. The topic of dysphagia in HD remains poorly studied compared with its clinical relevance.

A Systematic Review of Rehabilitation for Corticobulbar Symptoms in Adults with Huntington's Disease

Background:

Corticobulbar symptoms have been reported in all stages of Huntington’s disease (HD); aspiration pneumonia associated with swallowing impairment has been identified as the most common cause of death. Whilst recent research has described positive effects of corticobulbar rehabilitation in other neurodegenerative conditions, it is unclear if this is similarly effective in HD. Preliminary evidence in corticospinal rehabilitation has revealed physical therapy and exercise could be beneficial for individuals with HD.

Objective:

This systematic review will explore the literature relative to rehabilitation of corticobulbar symptoms in adults with HD.

Methods:

Two investigators independently searched relevant electronic databases for literature related to corticobulbar rehabilitation in HD, published in English until October 2019. Included studies were critically appraised using the Oxford Centre for Evidence-based Medicine Levels of Evidence, Cochrane Risk of Bias Tool and Scottish Intercollegiate Guidelines Network checklists. Study outcomes included measurements of function, quality of life or neuromuscular physiology.

Results:

Seventy-seven publications were screened with eight studies meeting the inclusion criteria – two randomised control trials and six intervention studies. Validated and objective outcome measures of corticobulbar symptoms were infrequently used. There was a high risk of bias identified in 7/8 studies. The data suggested positive clinical outcomes, no adverse effects and no deterioration observed across longitudinal studies.

Conclusions:

This systematic review documented a lack of high-quality evidence to support the use of rehabilitation to treat corticobulbar symptoms in HD. However, the suggestion of potential positive effects based on available, albeit limited, studies provides justification for further research in this area.

Canadian Association of Neurosciences Review: The Role of Dopamine Receptor Function in Neurodegenerative Diseases

Dopamine (DA) receptors, which are heavily expressed in the caudate/putamen of the brain, represent the molecular target of several drugs used in the treatment of various neurological disorders, such as Parkinson's disease. Although most of the drugs are very effective in alleviating the symptoms associated with these conditions, their long-term utilization could lead to the development of severe side-effects. In addition to uncovering novel mediators of physiological DA receptor functions, recent research advances are suggesting a role of these receptors in toxic effects on neurons. For instance, accumulating evidence indicates that DA receptors, particularly D1 receptors, are central in the neuronal toxicity induced by elevated synaptic levels of DA. In this review, we will discuss recent findings on DA receptors as regulators of long term neuronal dysfunction and neurodegenerative processes.

Physical therapy for a child with sudden-onset choreoathetosis: a case report

PURPOSE

This case report describes the physical therapy examination, intervention, and outcomes for a 5-year-old girl who developed choreoathetosis following mitral valve repair.

CASE DESCRIPTION

This child was admitted to an inpatient short-term rehabilitation program with marked choreoathetosis and dependence for all functional mobility. She received physical therapy twice a day for 5 weeks. Physical therapy intervention included therapeutic exercise emphasizing stabilization and closed chain exercises, aquatic therapy, and functional training to improve gross motor skills and mobility. Tests and measures included the Selective Control Assessment of the Lower Extremity, 66-item Gross Motor Function Measure, and Pediatric Evaluation of Disability Inventory.

OUTCOMES

At discharge, this child demonstrated improvements in her Selective Control Assessment of the Lower Extremity, Gross Motor Function Measure, and Pediatric Evaluation of Disability Inventory scores. She was independent in all functional mobility tasks.

SUMMARY

This case study describes physical therapy tests and measures, intervention, and positive outcomes for a child with sudden-onset choreoathetosis.

Development of guidelines for occupational therapy in Huntington’s disease

SUMMARY This paper introduces the ‘Guidelines for Occupational Therapists working with people with Huntington’s disease’ which is currently being developed by the European Huntington’s Disease Network (EHDN) Standards of Care Occupational Therapists working group. This article aims to describe the everyday functional problems experienced by people with Huntington’s disease, the role of the occupational therapist, the systematic literature review which preceded the formulation of the guidelines and use excerpts from the guideline to illustrate some of the issues raised.

Huntington's disease

Huntington's disease is an autosomal-dominant, progressive neurodegenerative disorder with a distinct phenotype, including chorea and dystonia, incoordination, cognitive decline, and behavioural difficulties. Typically, onset of symptoms is in middle-age after affected individuals have had children, but the disorder can manifest at any time between infancy and senescence. The mutant protein in Huntington's disease--huntingtin--results from an expanded CAG repeat leading to a polyglutamine strand of variable length at the N-terminus. Evidence suggests that this tail confers a toxic gain of function. The precise pathophysiological mechanisms of Huntington's disease are poorly understood, but research in transgenic animal models of the disorder is providing insight into causative factors and potential treatments.

Dopamine enhances motor and neuropathological consequences of polyglutamine expanded huntingtin

An expansion in the CAG repeat of the IT15 (huntingtin) gene underlies the development of Huntington's disease (HD), but the basis for the specific vulnerability of dopamine-receptive striatal neurons remains unclear. To examine the potential role of the dopamine system in the emergence of pathological conditions in HD, we generated a double mutant mouse strain with both enhanced dopamine transmission and endogenous expression of a mutant huntingtin gene. This strain was generated by crossing the dopamine transporter knock-out mouse, which exhibits a 5-fold elevation in extracellular dopamine levels in the striatum and locomotor hyperactivity, to a knock-in mouse model of HD containing 92 CAG repeats. These double mutant mice exhibited an increased stereotypic activity at 6 months of age, followed by a progressive decline of their locomotor hyperactivity. Expression of the mutated huntingtin did not alter dopamine or its metabolite levels in normal or dopamine transporter knock-out mice. However, the mutant huntingtin protein aggregated much earlier and to a greater extent in the striatum and other dopaminergic brain regions in the hyperdopaminergic mouse model of HD. Furthermore, the formation of neuropil aggregates in the striatum and other regions of hyperdopaminergic HD mice was observed at 4 months of age, well before similar events occurred in normal HD mice (12 months). These findings indicate that dopamine contributes to the deleterious effects of mutated huntingtin on striatal function, and this is accompanied by enhanced formation of huntingtin aggregates.