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Please note: This is a basic revision aid, not a comprehensive and reliable statement of medical fact. These notes should not be used to guide treatment. For reliable information and advice, consult a qualified practitioner.
(Last updated: 19 March 2001)
1:20000 worldwide, all ethnic groups. Some reports say 1:10000.
Usually 30-55 years old, but can be earlier or later.
Autosomal dominant genetic disorder (i.e. if one parent has HD, there is a 50% chance of each child developing HD). See our separate guide to genetic conditions for a fuller explanation of genetic transmission. The gene for HD is on chromosome 4 and is involved in producing a protein called Huntingtin, but there is little more useful information on how this leads to damage to the central nervous system.
Caudate nucleus atrophy with generalised cerebral atrophy and atrophy of the corpus striatum. The particular mechanisms are unknown.
Progressive dementia with increasingly prominent choreiform movements and likely personality and behavioural changes.
Unremitting progression, gradual and insidious. The disease usually runs its course within 15-20 years, though life expectancy can be shorter if onset is before 50 years, or longer if onset is after 50 years. If a person has a positive predictive test for the HD gene, there is no way to reliably predict when symptoms will appear.
Symptomatic treatments only, at this stage. Tetrabenazine or haloperidol may alleviate movement difficulties (though haloperidol can cause confusion, anxiety, headaches, dystonic reactions, etc. and tetrabenazine has been noted to sometimes cause depressive side-effects). Family members can be tested for the gene, as can foetuses, but thorough counselling is vital due to the severe implications of a positive test. They will have to decide whether they want to know or not, and this can be an incredibly difficult choice. Further ethical complications emerge if a grandchild of a person with HD wants to be tested thought their parent has chosen not to, as a positive test for the grandchild is also a positive test for their parent.
Mobility is likely to be one of the first problems requiring intervention, as stumbling and falls may be an issue. Loss of roles and adjustment to the implications of the condition will be a challenge in the early course of the disease. There may be problems with depression, and guilt if the disease has been passed on to a child. Attention will also need to be paid to issues around dementia and cognitive loss, with psychiatric symptoms as another likely problem. Pressure care considerations will emerge later in the course of the disease, due to decreased mobility and, commonly, significant weight loss. The entire family should be taken into consideration, given the genetic nature of the disease and the likely issues of carer strain and carer stress. Consideration will need to be given to the likelihood of injury to self or others due to uncontrolled movements. Moving and handling intervention will be complicated by choreiform movements. Eating and drinking may become difficult, and closed cups with drinking spouts may help. Diet needs considerable attention, given the tendency toward weight loss, and likely difficulties with swallowing later on, meaning there is a significant role in the multi disciplinary team for a speech and language therapist (SLT) and dietician.
Seating may be a problem, as choreiform movements can make it difficult for the person to remain safely seated. It may be necessary to use a seat with a backward tilt, so that gravity assists in maintaining sitting posture. Side supports may also be needed, as may head support, and seating should provide good support to the spine whilst minimising pressure risk. See the Huntington's Disease Association factsheet (in PDF format) on Seating, Equipment and Adaptations for more on this. The Association also has useful downloadable factsheets (all in PDF format) on predictive testing and many other issues for people with HD.
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