A chronic, progressive, hereditary disease of the nervous system resulting in progressive involuntary choreiform movement and dementia.
- Affects 1 in 10,000 individuals at midlife, equally between men, women, and races.
- All individuals have the gene for Huntington, but the disease requires inheritance of the expansion of the gene. Huntington is transmitted through an autosomal dominant gene, having a 50% risk of inheriting the disorder from a parent.
- The genetic mutation in Huntington disease (HTT) has been identified and mapped. Genetic testing for its presence is possible, but it cannot predict the time of onset. Patients may also refrain from testing to avoid employment and healthcare discrimination due to their disease. Genetic counseling is crucial. Long-term psychological, emotional, financial, and legal support may be required.
- Onset is often between 35 and 45 years of age, though 10% of cases are in children.
- Despite ravenous appetites, patients often become emancipated and exhausted.
- Cases often result in death within 10 to 20 years from heart failure, pneumonia, infection, falls, or choking.
Pathophysiology
The reason why abnormal proteins only damages the brain cells is unexplained. One possible theory is that glutamine, a building block for protein, abnormally collects in cell nuclei, causing cell death.
- Death of cells in the striatum (caudate and putamen) of the basal ganglia, which plays a vital part in the control of motor movements.
- Death of the cells in the cortex, the region associated with thinking, memory, proprioception, judgment, and behavior
- Death of the cells in the cerebellum, the region associated with coordinating voluntary muscle activity.
- A decrease in GABA and Acetylcholine (both excitatory neurotransmitters) leads to brisk, jerky, purposeless movements, particularly in the hands, face, tongue, and legs.
Clinical Manifestations
HD has triad signs:
- Motor Dysfunction: Chorea/Choreiform movements, rapid, jerky, involuntary, and purposeless movements
- As the disease progresses, the writhing, twisting movements may involve the entire body; all body musculature is involved. They have no purpose nor rhythm. Facial movements produce tics and grimaces.
- Speech becomes slurred, hesitant, often explosive, and eventually unintelligible.
- Chewing and swallowing is difficult. Choking and aspiration are constant risks.
- Disorganized gait eventually makes ambulation impossible, making a wheelchair necessary. Even sitting may become impossible, and the patient becomes impaired in bed.
- Urinary and bowel control are lost.
- Cognitive Impairment: attention problems, emotion recognition are early forms of cognitive impairment. As the disease progresses, marked dementia becomes present.
- Behavioral Features: apathy and blunted affect; the patient may become nervous, irritable, or impatient.
- They are particularly subject to uncontrollable fits of anger, profound and often suicidal depression, apathy, anxiety, psychosis, or euphoria in the early stages of disease.
- Hallucinations, delusions, and paranoid thinking may precede the appearance of disjointed movements.
- Changes in emotional and cognitive symptoms become less acute in later stages of disease.
The disease progresses through three general stages: (1) onset of neurologic or psychological signs and symptoms, (2) increasing dependence on others, and (3) loss of independent functions. Death follows from complications such as choking, falls, infection, pneumonia, or heart failure generally 10 to 20 years after the onset of the disease.
Diagnostic Examination
- Diagnosis is based on characteristic symptoms (motor dysfunction, cognitive impairment, and behavioral features), positive family history, and presence of genetic marker CAG repeating on the Huntington (HTT) gene.
- CT or MRI imaging shows bilateral striatal atrophy of the basal ganglia before motor symptoms appear.
Medical Management
There is no treatment that stops or reverses the underlying process. The focus of treatment is on optimizing quality of life with available medication and supportive treatment. Motor signs must be assessed and evaluated on an on-going basis so that optimal therapeutic drug levels can be reached.
- The only approved medication for chorea is tetrabenazine. Phenothiazine and Reserpine blocks and depletes dopamine respectively.
- Benzodiazepines and neuroleptic drugs have also been reported to control chorea.
- Akathisia (motor restlessness) in the patient who is overmedicated is dangerous because it may be mistaken for the expected restless fidgeting of the illness and consequently may be overlooked.
- In some types of the disease, hypokinetic motor impairment may resemble PD.
- In patients who present with rigidity, some temporary benefit may be obtained from antiparkinsonian medications.
- Psychiatric symptoms can be controlled with SSRIs and TCAs.
- Suicide is a risk, especially in the early stages of the disease.
- Antipsychotic medications often work for psychotic symptoms.
- Anxiety and stress may be reduced by psychotherapy.
Nursing Process
Assessment
- Frequently assess and evaluate the patient’s motor signs.
- Interact with the patient in a creative manner.
- Learn how this particular patient expresses needs and wants.
Diagnosis, Intervention
- Risk for injury from falls and possible skin breakdown (pressure injury abrasions), resulting from constant movement
- Pad the bed and bony prominences (heel, elbow, knee). Use soft sheets and bedding. Have the patient wear pads e.g. football padding. If necessary, secure the patient in bed or chair with padded protective devices.
- Provide skin care, use emollient cleansing agents and skin lotion as needed.
- Impaired nutritional intake due to inadequate ingestion and dehydration resulting from swallowing or chewing disorders and danger of choking or aspirating food
- Relaxation techniques and medication may be used. Provide the patient with assistive devices (warming tray, etc) and adequate time to eat. Food should be easy to chew and bite-sized. Blenderized meals are used if the patient cannot chew. If swallowing is difficult, the nurse should be familiar with the abdominal thrust technique for choking and aspiration.
- Impaired verbal communication from excessive grimacing and unintelligible speech
- Maintain communication with the patient even if they are unable to communicate. Establish alternate methods of communication and determine the individual’s expressions and their meanings. Consult with a speech therapist if beneficial.
- Acute confusion and impaired socialisation
- Reorient the patient after awakening. Orienting devices in speech and the environment is also useful (calendars, clock, wall posters).
- Maintain the patient’s medical identification bracelet.
- Keep the patient in the social mainstream.