Understanding Huntington's Disease

• Huntington's Disease is also known as Huntington Chorea
• CNS TX 400 FT 500 PT

What is it?

• Huntington's Disease is an inherited, neurodegenerative disease.
• It is characterized by choreiform movements and progressive dementia.
• Choreiform movements are brief, purposeless and random.
• The disease is progressive, usually leading to death in 15-20 years after onset of neurologic or psychological impairment.
• In adults, HD causes involuntary movements, but rigidity can also be a feature.
• Males and females are diagnosed in equal numbers.
• Symptoms usually appear between ages 35-55 years.
• Juvenile HD can appear in those 20 years and under, accounting for 10% of cases.
• Late Onset HD can appear in those 60 years and older, accounting for 10% of cases as well.
• The prevalence of HD in North America ranges from 4 to 8 cases per 100,000 persons.

Etiology

• The etiology of Huntington's Disease is a mutation in the gene for the huntingtin protein.
• This gene is present on chromosome 4.
• The defect causes the cytosine, adenine, and guanine (CAG) sequence to replicate excessively.
• Each child of a parent with HD has a 50/50 chance of inheriting the HD gene.
• A child who doesn't inherit the gene will not develop the disease or pass it on.

Pathophysiology

• Huntington's disease is inherited as an autosomal dominant disorder.
• Pathologic findings reveal tissue changes in the brain.
• The ventricles enlarge due to atrophy of the adjacent basal ganglia, affecting the caudate nucleus and putamen.
• This is due to extensive loss of small and medium-sized neurons.
• The volume of the brain can decrease by 20%.
• The normal balance of excitation and inhibition responses in the basal ganglia and thalamus is disrupted.
• With the loss of neurons neurotransmitters are affected.

Signs & Symptoms

• Physical symptoms include weight loss, involuntary movements (chorea), diminished coordination, difficulty walking, talking, and swallowing.
• Cognitive symptoms include difficulty with focus, planning, recall of information, making decisions, and impaired insight.
• Emotional symptoms include depression, apathy, irritability, anxiety, and obsessive behavior.
• There's impairment in voluntary movements vs involuntary movements - greater impact on ability to work, ADLs, communicate, and independence.
• The etiology of depression is due to injury to the brain and subsequent changes in brain function vs reaction to dx.

Signs & Symptoms - Early Stage

• In the early stage, those affected can still function well at work and home.
• Early symptoms can include difficulties with organizing routine and coping with new situations.
• Other early symptoms include decreased ability to recall, make decisions, and give attention to detail.
• Early symptoms include mood changes and irritability.
• Other early symptoms can include minor involuntary movements, fidgeting, twitching, and excessive restlessness.
• Early changes in handwriting.
• Difficulties with daily tasks like driving can present.

Signs & Symptoms - Intermediate Stage

• Increased difficulties with working and managing household, but still able to deal with ADLs Symptoms progress from early stage and can include the following:
• More obvious involuntary movements (chorea)
• Increased difficulties with walking, coordination, balance
• Challenges with speaking (slurred)
• Problem solving becomes more difficult, thinking process
• Difficulties with swallowing
• Weight loss - d/t energy expenditure from choreoathetoid movements

Signs & Symptoms - Advanced Stages

• At this point manage ADLs can't be managed and usually require professional care.
• Symptoms include decrease in involuntary movements & increase in rigidity.
• There can be increased difficulties swallowing.
• The ability to communicate diminishes.
• Understanding what others are saying may still be possible.
• Significant weight loss occurs.
• Dementia appears.
• Bradykinesia emerges.
• Dystonia (involuntary mm contractions) appears.

Signs & Symptoms - JHD & LOHD

• Juvenile HD follows a more rapid course, chorea is less prominent & may be absent altogether.
• In Juvenile HD initial symptoms can include slow stiff movements (rigidity), sometimes tremors.
• Initial symptoms can include seizures, falls, or clumsiness.
• Initial symptoms can include contracted and rigid muscles that affect gait (especially in young children).
• Additional initial symptoms include difficulties learning in school and attention deficits.
• There is increase in responsive behaviours.
• In Late Onset HD - diagnosis past 60, sometimes is misdiagnosed.
• This is due to doctors believing patients is too old to develop HD (typical onset is 35-55).

Diagnosis

• There is no diagnostic testing.
• Diagnosis based on clinical symptoms, family history, and genetic testing.
• Other tests to assess that contribute to diagnosis include neurological examination that test motor, sensory, psychiatric symptoms.
• Another test contributing to diagnosis is neuropsychological testing to check memory, reasoning, mental agility, language skills, spatial reasoning.
• Further tests include psychiatric evaluation by psychiatrist looking at emotional state, patterns of behaviours, quality of judgement, coping skills, signs of disorder thinking, evidence of substance abuse.
• Other tests include MRI, CT, genetic counseling & testing, and predictive genetic tests.

Treatment

• There is no cure - so treatment is symptom management.
• Can use medications to help control chorea.
• Meds for psychiatric disorders include antidepressants, antipsychotics, and mood-stabilizing drugs.
• Psychotherapy includes psychiatrist, psychologist or clinical social worker.
• Other treatments include speech therapy, physical therapy, and occupational therapy.

Massage & Clinical Manifestations

• Those affected present with classic choreiform movements such as piano-playing motions in fingers, and facial grimaces.
• Trunk involvement and dancing gait are characteristics.
• The patient may appear off balance but the ability to balance is well preserved.
• Patients who develop HD by aged 35 years often become bedridden within 15-20 years.
• Patients may be argumentative, impulsive or erratic.
• Sleep disorders can emerge.
• Urinary incontinence can occur.
• Muscle strength is usually normal.
• Tendon reflexes are usually normal.