Huntington’s disease (HD) is a progressive neurodegenerative disorder that is caused by extra repeats of the cytosine-adenine-guanine (CAG) trinucleotide in the huntingtin gene. This leads to neuron dysfunction and death, mainly in the basal ganglia and cerebral cortex. While HD typically becomes apparent in adulthood, juvenile onset is possible. HD affects 4.1 to 8.4 individuals per 100,000 in the US, and 2.7 per 100,000 worldwide.
Who is most at risk for HD?
Individuals most at risk for Huntington’s are those who have inherited the gene from one or both parents. If one parent has HD, there is a 50% chance of the child having the disease. The more repeats of the CAG amino acid group, the higher the risk of passing the disease on to a child. Further, the number of repeats may increase with each generation in a phenomenon called “anticipation.” With a higher number of repeats, onset is earlier and disease severity is greater.
- Normal = 27-35 repeats
- Adult onset = 50-50 repeats (usually)
- Juvenile onset = 60+ repeats (usually)
Other risks for early onset of the disease include alcohol, tobacco and drug use.
What are the complications of Huntington’s Disease?
As a progressive neurodegenerative disorder, individuals with late-stage HD usually are bedbound, nonverbal and require total care with ADLs. Complications include:
- Pneumonia as a result of immobility and aspiration (patients with advanced HD are likely to have dysphagia). Pneumonia is a common cause of death in patients with HD.
- Suicide and suicidal ideation – one study showed about 25% of patients with HD attempt suicide
Now it’s time to dive into Huntington’s disease using the Straight A Nursing LATTE method.
L: How does the patient with Huntington’s disease LOOK? What are their signs and symptoms?
The signs and symptoms of HD can vary from person to person and throughout stages of the disease. The general categories are cognitive impairment, psychiatric disorders, and progressive motor dysfunction.
Cognitive impairment – Deficits in this area include forgetfulness, inattention, slow psychomotor response, altered perception of time, executive dysfunction, impaired emotion recognition, trouble with multitasking, and dementia. Cognitive symptoms typically start first and are the earliest signs of HD. Since mild cognitive impairment is often easily explained away, early diagnosis can be missed and is more likely if the individual is unaware of their HD risk.
Psychiatric disorders – Depression is common in patients with HD. Initially, patients often present with difficulty with impulse control and irritability. Over time the patient can progress to OCD behavior, apathy, anxiety, aggression and even psychosis. As with cognitive dysfunction, the psychiatric signs and symptoms typically are evident years before motor symptoms set in.
Progressive motor dysfunction – Motor dysfunction plays a key role in placing the patient at risk for falls and progressive disability. Is often initially seen in the extremities and can involve chorea (“dance-like” involuntary movements which includes finger/wrist movements called “piano fingers”), a jerky gait, tics, ataxia, and poor coordination. Pyramidal symptoms are also present and the patient will have a positive Babinski sign.
Motor dysfunction also affects the muscles of speech and swallowing leading to dysarthria and dysphagia. Over time the individual’s motor dysfunction progresses to hypokinesia, rigidity and contractures.
To see an example of chorea, check out this YouTube video.
The clinical course of Huntington’s disease
The clinical course of Huntington’s disease can be divided into three segments: presymptomatic, prodromal and manifest.
- Presymptomatic: At this stage the patient has no symptoms and imaging may show some HD changes; treatment is not indicated at this stage.
- Prodromal: At this stage, the patient may have some small motor and cognitive symptom as well as psychiatric symptoms such as depression; imaging will show evidence of HD and treatment is possibly indicated at this time.
- Manifest: At this stage, the patient is exhibiting significant motor, cognitive and psychiatric s symptoms; treatment is indicated at this stage.
Stages of Huntington’s Disease
The stages of HD are early, middle and late. In early HD, patients are able to function independently but they may have some minor involuntary or uncoordinated movements, have some difficulty concentrating, be irritable, and suffer from depression.
In middle-stage HD, the individual will begin to lose independence and show more obvious chorea and have issues with balance and swallowing. They will also have trouble organizing and prioritizing information. At this stage, the patient will need assistance with ADLs.
In late-stage HD, the individual definitely requires assistance with all ADLs and is bedridden as well as nonverbal. The patient may exhibit significant chorea, but is more likely to experience rigidity, dystonia and bradykinesia at this time. The psychiatric manifestations are present but are often masked by the inability to communicate.
Note that in juvenile onset, the symptoms are similar as adults, but seizures can occur as well.
A: How do you ASSESS a patient with Huntington’s Disease?
Assessment of the patient with HD will vary based on the individual’s unique clinical course and progression of the disease. In general, assessments for a patient with HD will often be closely correlated with patient safety as these patients are at high risk for falls, aspiration, infection and suicidal ideation.
- Assess motor symptoms such as ROM, muscle strength, gait and for evidence of contractures.
- Make note of changes in mood such as anxiety, anger, and depression.
- As you interact with the patient, assess for cognitive dysfunction such as memory loss, inattention and executive dysfunction.
- Ask the patient if they are thinking of harming themselves (remember they are at high risk for suicidal ideation!)
- Assess the patient’s ability to swallow and consult a speech language pathologist as needed. A patient who has dysphagia may have slurred speech and will cough when sipping water.
- Examine the skin carefully as patients with decreased mobility are at high risk for skin breakdown.
- Weigh the patient and monitor for weight loss and decreased intake.
- Assess for signs of dehydration secondary to decreased intake.
- Assess for pain, using the appropriate pain scoring tool for the patient’s condition. For example, consider using the ANPS (Adult Nonverbal Pain Scale) for nonverbal adults. This pain scale looks at five elements and assigns each a number based on the severity of observable symptoms. These are face, activity (movement), guarding, physiology (vital signs), and respiratory.
Be sure to include family, friends and caregivers as they can provide key information on the patient’s condition.
T: What TESTS will be ordered?
If the patient has a family history and symptoms of HD, no testing may be necessary in order for the MD to arrive at a diagnosis of Huntington’s disease. When tests are ordered, they can include:
- Genetic testing to look at CAG repeats – this is the “Gold Standard” for diagnosis. If there are no CAG repeats, this could possibly mean there is another gene responsible for the patient’s signs and symptoms. Note that genetic testing can be conducted prenatally if one or both parents know they have HD.
- Imaging studies (CT/MRI) may be utilized to evaluate the extent of cerebral atrophy. A typical HD patient will have convex shaped ventricles.
- Other labs may be used to rule out other possible causes for the patient’s symptoms. For example, liver disease can cause ataxia and confusion, so the patient could have their LFTs evaluated.
T: What TREATMENTS are utilized in the care of a patient with HD?
It’s important to understand that since Huntington’s is not curable, care is focused on palliation (comfort), reducing symptoms, and preventing complications.
Pharmacology – Antidepressants and antipsychotics may be utilized to lessen the burden of psychiatric symptoms. Antipsychotics and antidyskinetics are used to manage the motor symptoms of Huntington’s. Two medications specifically utilized for chorea are tetrabenazine and deutetrabenazine. And, of course, pain medication may be needed which can include NSAIDs, Tylenol and possibly opioids in severe cases.
Diet – Research shows that a Mediterranean style diet may delay onset of the disease or reduce symptom burden. This diet consists of fish, plant based foods, olive oil with low consumption of things like red meat, dairy and poultry.
Physical and occupational therapy – Both modalities can be utilized to improve physical functional capacity and promote independence with ADLs for as long as possible. PT and OT are also used to aid caregivers in learning how to provide safe care at home.
Speech language therapy – A licensed SLP may be consulted to assess the patient for dysphagia and to help the patient with both dysphagia and dysarthria. If the patient has dysphagia, the SLP will prescribe a specific texture to the patient’s diet such as chopped or pureed.
Potential future treatments for Huntington’s disease involve target therapy to inhibit expression of the huntingtin protein. Research is ongoing in this area.
E: How do you EDUCATE the patient and family?
- Genetic counseling plays a key role in patient and family education and goes far beyond the blood test for genetic testing. Prior to undergoing genetic testing for HD, the individual may receive counseling to examine how a positive result could impact them and their family emotionally, functionally and financially. Less than 20% of individuals with a 50% risk of HD seek genetic counseling, which is unfortunate considering the long-term implications of the disease and the risk for passing it on to children.
- Provide supportive care to the patient and family. Ensure the patient and family understand the increased risk for suicide and the burdens that the disease places on caregivers. Teach caregivers to seek respite care whenever possible and help them understand resources that are available to assist with finances and care (the family will likely have a social worker or case manager who will take the lead on this).
- Teach caregivers all aspects of home care as they will be assisting with ADLs. The physical therapist can teach caregivers how to transfer patients safely and avoid injury.
- Teach caregivers and patients the importance of eating upright to prevent aspiration and that the diet texture may be adjusted as the disease progresses. In later stages of the disease, the patient may not be able to swallow safely so teach caregivers how to administer enteral feeding and care for feeding tubes.
- Teach caregivers to monitor skin for signs of breakdown and the importance of keeping skin clean and dry.
- Teach caregivers and the patient fall prevention strategies such as changing position slowly, removing rugs, keeping pathways to the bathroom well-lit at night, installing grab bars, etc…
- Encourage physical activity and adherence to physical and occupational therapy.
- Teach infection prevention practices such as how and when to perform hand hygiene.
You can review huntington’s disease again on the go in episode 276 of the Straight A Nursing podcast. Tune in wherever you get your podcast fix, or straight from the website here.
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