Huntington's Disease Flashcards
Which two diseases have a relationship with the Basal Ganglia?
PD and HD
What is Huntington’s Disease
A progressive, hereditary (autosomal dominant), neurodegenerative disorder characterized by movement abnormalities personality disturbances decline in cognitive abilities dementia
Huntington’s Chorea
Brief, purposeless, involuntary and random movement
What happens to dopamine and Ach with Huntington’s Disease
You have an increase in dopamine and a decrease in Ach
there is also a decrease in amount of some neurotransmitters
Why would HD bring a lot of ethical questions
It is hereditary, if you have the gene you will get it
Almost always a history of a parent with the disease, and a 50% risk in each child of an affected adult
What is the onset of HD (2 types)
Adult HD (Sx development between 40-50 yo)
better prognosis, 15-20 years
Juvenile HD (sx before 20 yo)
poorer prognosis, 8-10 years
Pathogenogenesis of HD
Predominant findings are Atrophy of Corpus Striatum of the BG -Caudate nucleus -Putamen -Globus Pallidus
Neuronal degeneration of the temporal & frontal lobes of the cortex
-Brain starts breaking down
What happens when the brain starts breaking down
People have a significant cognitive and functional decline
Diagnosis of HD
Based on symptoms
You would get genetic testing - if you have the gene you will definitely develop it
CT and MRI only show visible atrophy in the advanced stages
What are the clinical manifestations of HD
Early choreic movements may be manifested as restlessness, or may be integrated into normal purposeful movement strategies
Cognitive & emotional manifestation: forgetfulness & slight personality changes
What happens in the late stages of HD
In late stage, there is greater inhibition, rather than excitation, of the thalamocortical output, resulting in bradykinesia
All caudate nucleus neurons will have been affected by this time
HD patients and risk of falls
Falls risk not as severe as in PD or MS, as the patient may integrate choreiform movements into normal movement patterns
What part of the body has more choreic movement
Choreic movements occur more in the UEs & face than in the LEs
↑ during complex motor, intellectual, or emotional tasks
What will movement testing in a pt with HD reveal
Movement testing will reveal dysmetria and dysdiadochokinesia
- they test positive but it is not true dysmetria from the cerebellum, it is coming from the excessive movement
What will movement testing in a pt with Juvenile HD reveal
In Juvenile HD, the chorea is exhibited briefly if at all, with rigidity being the dominant sx instead
What else do you have to watch out for with Juvenile HD
Seizures are also another common sx in juvenile HD
How is the muscle strength and tone of someone with HD (early and late stages)
They may appear weak but it is do to poor control and excessive motion
Muscle strength testing may be normal in the early stages, but testing may be difficult due to motor disturbances
Hypotonia may be present initially, but rigidity may be noted accompanying the end stage bradykinesia
-definitely gets worse later one
How does movement transform in HD from the early to late stages
too much in the beginning to really stiff later on
HD and Vision
Eye movement abnormalities are common 20 motor disturbances affecting ocular & extraocular muscles
Saccadic intrusions – dysmetria of the eyes
Saccades: ability to focus eyes from one target to another
↑ latency & under/over-shooting of the target
↓ gaze fixation or stabilization
↓ smooth pursuit (tracking)
Saccadic intrusions are
Dysmetria of the eyes
Saccades: ability to focus eyes from one target to another
↑ latency & under/over-shooting of the target
Gait and HD and what is it called
Chorea comes from the Greek word for “dance”
Choreiform gait is typified by a wide base of support, with staggering movements
Oromotor Impairments and HD
Speech is dysarthric, with some aspects of aphasia
Dysphagia is common, making eating and proper nutritional intake difficult
But cachexia (muscle wasting) is often noted even in the presence of normal intake
Sleep Disturbances and HD, when does it happen and what happens
Often seen in later stages
Manifests as insomnia
Potential reversal of sleep patterns (likely related to dementia)
Why do sleep disturbances and hallucinations happen later on in HD
(what other disease might you see this and why)
because of the significant increase of dopamine
you would see this if you are over-medicated with PD
B/B and HD
Incontinence is common, due to Immobility Hyperreflexia Depression Dementia
Can lead to UTI or skin breakdown
Neuropsychologic and Psychiatric Disturbances with HD
Cognitive and intellectual changes Personality & behavioral changes Emotional/behavioral changes Ideomotor apraxia visuospatial deficits depression
What can be early signs of HD (often subtle)
Neuropsychologic and Psychiatric Disturbances
What would cause Cognitive and intellectual changes in HD
Lack of blood flow to the striatum
What are some personality & behavioral changes for pts with HD
apathy, blunted affect, irritability, depression, violence or aggression, impulsivity and lability, anxiety, egocentrism, compulsive behaviors leading to addictions (alcoholism, gambling, hypersexuality)
With HD Emotional/behavioral changes are often followed by
Intellectual changes
Inability to recall stored memory
↓ organizational skills
Impaired sequencing
Other symptoms caused by the Huntington gene expressed throughout the body, and can cause other abnormalities peripheral to the brain
Muscle atrophy Cardiac failure Impaired glucose tolerance Weight loss Osteoporosis Testicular atrophy
Medical management of HD
No cure; treatment is symptomatic
Tetrabenazine – 1st FDA approved drug came out in 2008 for the tx of choreic symptoms
Anticonvulsants or antipsychotics are given to block dopamine transmission
These drugs also may treat the behavioral deficits
Only used if the chorea has reached a point of severity that interferes with normal movement and function
What are the side effects of medication for HD
High incidence of medication side effects
Acute dystonias – involuntary sustained muscle contractions
Pseudo-Parkinsonism
Akasthisia (uncontrollable physical restlessness)
Tardive dyskinesia (uncontrollable, involuntary movement of the face, lips and tongue)
Procedural Memory and HD
Ideomotor, they have procedural memory but cognitive decline
What is Tardive dyskinesia
uncontrollable, involuntary movement of the face, lips and tongue
What is Pseudo-Parkinsonism
Akasthisia
Uncontrollable physical restlessness
What is Acute dystonias
Involuntary sustained muscle contractions
Prognosis of HD
The earlier the onset of sx, the more severe the form of the disease
Death usually occurs 15-20 years after onset
Long term survival is possible with management of secondary complications
For HD death usually occurs 15-20 years after onset, usually due to
Pneumonia (~33%) – due to dysphagia causing aspiration & inability to synchronize respiratory muscles
Cardiac disease (~25%)
Suicide – 27% attempt it, ~7.3% succeed
Physical injuries from falls
Death usually occurs 15-20 years after onset, usually due to
usually die from a secondary issue
Pneumonia (~33%) – due to dysphagia causing aspiration & inability to synchronize respiratory muscles
Cardiac disease (~25%)
Suicide – 27% attempt it, ~7.3% succeed
Physical injuries from falls
