Running head: HUNTINGTON’S DISEASE

Huntington’s Disease
Bradley Amos
St. Ambrose University
March 21, 2011

Huntington’s Disease Huntington’s disease is a devastating and progressive neurological disorder that results primarily from degeneration of nerve cells deep in the center of the brain that waste away (PubMed Health, 2011). According to National Institute of Neurological Disorder and Stroke (2010) more than 15,000 Americans suffer from this debilitating disease. Nearly all people who develop Huntington’s disease will die within 10 to 30 years from onset. This disease does not show bias to any sex, ethnicity or race. The pathophysiology of Huntington’s disease is inherited as an autosomal dominant trait with high penetrance (Jarvis, 2008, p.360). The symptoms of Huntington’s disease are abnormal uncontrollable movements and personality changes (Jarvis, 2008, p.360). As the disease progresses so does the severity of the symptoms. It is a genetic disease that is passed on from generation to generation. A person can be genetically tested to determine if you have the gene for this disease. To date there is not a cure for this rare debilitating disease (Medline Plus, 2009).
Definition of Disorder
Huntington’s disease was named after an American doctor George Huntington in 1872. Before it was named by Doctor Huntington it was called “chorea” which means choreography in Greek. It was named so because people affected by this disease would twist, turn and jerk in uncontrollable movements that others perceived as dancing moves (National Institute of Neurological Disorder and Stroke, 2010). There are two forms of Huntington’s disease. Adult-onset, which is the most common, usually develops when the person is in their mid 30s or 40s. Early-onset is rarer and develops in childhood or adolescents (Medline Plus, 2009). This devastating disease comes on gradually then increases over the years which can be separated into three stages. The first early symptoms are subtle and light uncontrollable muscular movements. This includes the lack of concentration and some short-term memory loss, which results in depression and changes of mood. During the next stage the patient needs some assistance with the activities of daily living because of the uncontrollable movements have disrupted walking, talking and eating. In the final stage the patient now needs full-time care because they are unable to speak or walk. Since the body has had many years of prolong uncontrollable movement it starts to become stiff and rigid (Mayo Clinic, 2009). Nevertheless, even as the disease advances, individuals with the disorder still are able to recognize their families, are aware of their condition, and have the ability to understand what is happening to them. People affected with Huntington’s disease usually die of infection, malnutrition, or heart failure (Mayo Clinic, 2009). Causes and Etiological Factors Huntington’s disease is a genetic autosomal dominant disease. If an individual’s parent has the disease they have a fifty percent chance of inheriting Huntington’s. Since most people don’t develop any signs or symptoms until their middle aged they don’t realize that they have already passed on the trait. If a person inherits the defective gene it will eventually become active and brain cells in the body's central nervous system will begin to die. This is when a human begins to develop the indications of Huntington’s disease. If someone does inherit the gene they will not pass it on to the next generation (Mayo clinic, 2009). Huntington’s disease is caused by a mutation in the gene located on chromosome 4. This defect is caused by an abnormal expansion of a part of DNA called a CAG repeat that occurs many more times than usual. It is normally supposed to repeat 10 to 35 times, but in a person with Huntington’s it repeats more than 36 to 120 times (Medline Plus, 2009). The large size of this section makes the DNA more unstable, which in turn creates an abnormal shape.
Pathophysiology of Disorder

HD is connected with progressive degeneration of neurons in certain areas of the brain, including the basal ganglia and the existence of astrocytes that build up due to obliteration of close by neurons (gliosis). The basal ganglia consist of particular nerve cell groups within the brain that manage motor behavior. Main substructures of the basal ganglia include the caudate nuclei and the globus pallidus. This deterioration of the basal ganglia, mainly the caudate nucleus, is the major pathologic characteristic of Huntington disease (American Society of Neural Therapy and Repair, 2008). Protein accumulates in the brain cells and masses of glutamine stick to each other on the irregular molecules. As a result of this there is a biochemical alteration to the gamma-amino butyric acid (GABA) pathway, a neurotransmitter, which alters the integration of motor and mental function (Jarvis, 2008, p.360).

Degeneration of pathways causes GABA depletion which causes degeneration within the temporal and frontal lobes of the cerebral cortex. Frontal cerebral weakening takes place late in the illness. One theory proposes that selective loss of specialized cells results in reduced inhibition of the thalamus. Therefore the thalamus intensifies its production to certain areas of the brain's cerebral cortex (National Institute of Neurological Disorder and Stroke, 2010). This may develop gradually and contain hypotonia and involuntary, fragmentary movements, such as chorea (Jarvis, 2008, p.360).
Clinical Manifestations The clinical manifestations of Huntington disease comprise a movement disorder, a cognitive disorder, and a behavioral disorder. Patients may have characteristics of one or all of the disorders in varying amounts (eMedicine, 2010). Chorea, the most frequent type of irregular movement disturbing these individuals, initiates in the face and arms, eventually affecting the entire body (Jarvis, 2008, p.360). Dysarthria and dysphagia are common. Abnormal eye movements may be seen early in the disease as well (eMedicine, 2010). Cognitive shortages include loss of memory and reduced ability to plan, organize, and sequence. Thoughts and judgment are slow. Agitation and irritability are frequent. The classic manifestations of Huntington disease are abnormal movement and progressive dysfunction of intellectual and thought processes (dementia) (Jarvis, 2008, p.360). Dementia and the psychiatric features of HD are perhaps the first and most vital gauges of functional impairment. The behavioral disorder of Huntington’s disease is embodied most commonly by emotional illnesses. Depression is more widespread, with some patients experiencing periodic spells of bipolar disorder. As a result of depression many patients with Huntington’s disease and even persons at risk for Huntington’s disease may have an amplified rate of suicide. Patients with HD also can develop psychosis, obsessive-compulsive symptoms, sexual and sleep disorders and changes in personality (eMedicine, 2010). Any one of these features may mark the onset of the disease (Jarvis, 2008, p.360). Treatment and Evaluation The diagnosis of Huntington disease is based primarily on the family history and the clinical appearance of the disorder itself. There is no cure for Huntington's disease at this time and no known treatment is successful in halting the degeneration or development of symptoms. Drug therapies are being still being explored to stop this process and Recombinant genetic techniques may someday prevent or control the disorder. As of now the treatment for Huntington's disease focuses on controlling symptoms and improving daily functioning (Jarvis, 2008, p.360). There are several tests that may be used to evaluate Huntington's disease. Although prognostic genetic tests may specify whether individuals hold the infectious gene, these tests are not capable of confirming the onset of the disorder itself. Therefore, the diagnosis of Huntington’s disease is also based on a total physical and neurologic evaluation including; discovery of distinguishing symptoms and findings such as chorea, depression, or dementia, as well as a careful patient and family history (National Institute of Neurological Disorder and Stroke, 2010). Specialized brain imaging studies may also offer confirmation that supports an analysis of Huntington’s disease. Genetic testing is the main indicator and can be tested by a CT scan of the brain, MRI scan of the brain, or a PET scanning of the brain. These scans can detect changes in brain metabolism and activity (PubMed Health, 2011).In some patients with advanced cases of the disease, computerized tomography (CT) scanning revealed characteristic mutual neurodegeneration of the caudate nuclei and the putamen as well as connected neuronal failure within the temporal and frontal lobes of the cerebral cortex. Additionally, CT scanning might also identify featured enlargement of cavities of the brain. According to some experts, magnetic resonance imaging (MRI) may be more responsive, which would help detect putamen atrophy before evident neurodegeneration within the caudate nuclei occurred. Furthermore, positron emission tomography (PET) scanning may show reduced glucose and oxygen metabolism inside the caudate nuclei. (National Institute of Neurological Disorder and Stroke, 2010). Medications differ depending on the symptoms. Dopamine blockers may assist to decrease irregular behaviors and movements. Drugs such as haloperidol, tetrabenazine, and amantadine are used to attempt to manage extra movements (Medline Plus, 2009). Depression or psychosis is treated with drug therapy. Phenothiazines, which are antidopaminergic, may relieve some symptoms of chorea (Jarvis, 2008, p.360). Other treatments may include medications to control muscle spasms, antipsychotic medications, speech therapy, and occupational therapy (PubMed Health, 2011).There has also been suggestions that co-enzyme Q10 may also help slow down the disease. As the disease develops overtime, patients will eventually need some kind of support and supervision that may be up to 24 hours (Medline Plus, 2009). Nursing Implications: Holistic approach Although there is no cure for Huntington’s disease the early onset can be managed with proper care. Conclusion In conclusion, as stated above, this disease is incurable to date. Drugs that are used to treat Huntington's disease help manage the signs and symptoms but do not slow the disease process itself and can't prevent the physical and mental decline associated with the condition. (American Society of Neural Therapy and Repair, 2008). Huntington's disease is a progressive, degenerative disease that causes nerve cells in your brain to die and causes people to experience uncontrolled movements, emotional disturbances and mental deterioration. This disease is inherited and develops around your middle ages but can also develop in children, although rarely (Mayo clinic, 2009). Since people with this disease usually die within 15 to 20 years genetic counseling is highly recommended if you have a family history of Huntington's disease or for couples with a family history of the disease who are considering having children (Medline Plus, 2009).

References
American Society for Neural Therapy and Repair. (2008). Pathophysiology of Huntington’s disease: from huntingtin functions to potential treatments. Retrieved from http://www.asntr.org/news/pathophysiology-of-huntingtons-disease-from
EMedicine. (2010). Huntington’s Disease. Retrieved from http://emedicine.medscape.com/article/1150165-overview
Huether, S. E., & McCance, K.L. (2008). Understanding pathophysiology (4th ed.). St. Louis, MO: Mosby Elsevier.
Mayo Clinic. (2010). Huntington’s disease. Retrieved from http://www.mayoclinic.com/health/huntingtons-disease/DS00401
National Institute of Nuerological Disorders and Stroke. (2010). Huntington’s disease: Hope through research. Retrieved from http://www.ninds.nih.gov/disorders/huntington/detail_huntington.htm#160493137
Medline Plus. (2009). Huntington’s disease. Retrieved from http://www.nlm.nih.gov/medlineplus/ency/article/000770.htm
PubMed Health. (2011). Huntington’s Disease: Huntington’s Chorea. Retrieved from http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001775/