Huntington’s disease is a chronic, hereditary disease of the nervous system that results in progressive involuntary choreiform or dancelike movement and dementia. It affects men and women of all races. Because it is transmitted as an autosomal dominant genetic disorder, each child of a parent with Huntington’s disease (HD) has a 50% risk of inheriting the illness. Huntington’s disease affects all races and ethnic group. Both sexes are affected too. It was estimated by the experts that in every 10,000 persons in the United States 30,000 have Huntington’s disease.
The basic pathology involves premature death of cells in the striatum (Caudate and putamen) of the basal ganglia, the region deep within the brain in the control of movement. There is also loss of cells in the cortex, the region of the brain associated with thinking, memory, perception and judgment and in the cerebellum, the area that coordinates voluntary muscle activity. Researchers now believe that a building block from a protein, called glutamine, abnormally collects in the cell nucleus, causing cell death (Barinaga, 1996). Why the protein destroys only certain brain cells is unknown.
The cells destruction results in the lack of the neurotransmitters, gamma-aminobutyric acid and ecetycholine, which inhibit nerve action. Onset usually occurs between the ages of 35 and 45 years; about 10% of patients are children. The disease progresses slowly. Despite a ravenous appetite, patients usually become emaciated and exhausted. Patients succumb in 10 to 15 years to heart failure, pneumonia or infection or file as a result of fall or choking. The most prominent clinical features of the disease are abnormal involuntary movements (chorea), intellectual decline and often emotional disturbance.
As the disease progress, a constant writhing, twisting, uncontrollable movement may involve the entire body. These motions are devoid of purpose or rhythm, although patients may try to turn them into purposeful movement. All of the body musculature is involved. Facial movements produce tics and grimaces. Speech is affected, becoming slurred, hesitant, often explosive, and eventually unintelligible. Chewing and swallowing are difficult, and there is a constant danger of choking and aspiration. Choreiform movements persist but diminish during sleep.
As with speech, the gait becomes disorganized to the point that ambulation eventually is impossible. Although independent should be encouraged for as long as possible, a wheelchair usually becomes necessary at some point. Eventually, the patient is confined to bed when the chorea interferes with walking, sitting and all other activities. Cognitive function is usually affected, with dementia usually occurring. Initially, the patient generally is aware that the disease is responsible for the myriad dysfunctions that are occurring.
The mental and emotional changes that are occurring with HD may be more devastating to the patient and family than the abnormal movements. Patients may be nervous, irritable or impatient. In the early stages of the illness, patients are particularly subject to uncontrollable fits of anger; profound, often suicidal depression; apathy or euphoria. Judgment and memory are impaired and dementia eventually ensures. Hallucination, delusions and paranoid thinking may precede the appearance of disjointed movements. Emotional symptoms often become less acute as the disease progresses.
The diagnosis of HD is made on clinical presentation of characteristic symptoms, establish of positive family history, and exclusion of others causes. Although there is no specific diagnostic test, imaging studies, such as CT and MRI, may show atrophy of the striatum once HD is well established. A generic marker for HD has been identified through the use of recombinant deoxyribonucleic acid (DNA) technology. As a result, researchers can now identify pre-symptomatic individuals who will develop this disease.
Although this pre-symptomatic for HD can remove the uncertainty, it offers no hope of cue or even specific determination of its onset. Researchers continue to study the generic causes that lead to the death of brain cells. Although no treatment halts or reverse the underlying process, several methods of management have fairly good palliative results. The phenothiazine, butyrophenones and thioxanthones, which predominantly block dopamine receptors, improve the chorea in many patients. Chorea also lessened by reserpine and tetrabenazine (reduces dopaminergic transmission).
The patient’s motor signs must be assessed and evaluated on an ongoing basis so that optimal therapeutic drug level may be reached. Recently, a study was conducted in order to treat speech and language problem in relation to Huntington’s disease. On a hypothesis that linguistic faculties includes both lexical storage in the temporal cortex and combinatorial rules in the striatal circuits, several researchers presented that patients with striatal damaged has an impairment in conjugation while they retain their lexical knowledge of irregular verbs.
Evidenced showed that mental dictionary is part of declarative memory, and that grammatical rules are processed by the procedural system. However there is a problem because such impairment was only documented with explicit conjugation tasks in the production domain. A question was raised whether it generalizes other language modalities such as perception and whether it refers to implied language processing or rather to intentional rule operations through executive functions.
In order to resolve the issues, the study was conducted and investigated in an early stage of Huntington’s disease by assessing the perceptive processing of conjugated verb forms in a model of striatal dysfunction. Evaluation was done in both the rule application and lexical processes in an explicit and implicit task. Striatal atrophy was evaluated using magnetic resonance imaging while the HD patient was assessed in executive functions. Results showed that HD patients were selectively impaired for rule application while lexical capacity spared.
It was argued by the researchers that the striatum has a core function in linguistic rule application that generalizes perceptive aspect of morphological operations pertaining to implicit language processes. In conclusion the needs of the patients with Huntington’s disease and the family for education depend on the nature and severity of physical, cognitive, and psychological changes experienced by the patient. Patients and their family members are taught about medications that are prescribed.
Teaching plans includes strategies to manage symptoms such as chorea, and swallowing problems. Consultation with a speech therapist is also indicated to assist in identifying alternative communication strategies if the patient’s speech is affected.
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