Huntington's Disease Flashcards
What is the etiology of Huntington’s disease?
-usually diagnosed in middle-aged adults
-juvenile or late-onset is possible
-usually people of western European decent
-genetic disorder
What are the genetic causes?
-gene nutation on chromosome 4 that causes the DNA sequence on cytosine, adenine, and guanine (CAG) to repeat more than in normal DNA
-mutated protein in huntingtin
*mutations lead to a build of taxic fragments that lead to neuron death
*also damages the temporal and frontal loves of the cortex
How does huntington’s disease effect the basal ganglia?
-initially, in the disease, there is a disinhibition of the indirect D2 pathway
*the result is that the thalamus is excited leading to the excess movement (chorea)
-late stages of the disease there is damage to the direct D1 pathway
*the thalamus is inhibited thus leading to a loss of movement or hypokinesia
What are the signs and symptoms?
-personality changes, mood swings, depression
-forgetfulness and impaired judgement and memory
-unsteady gait and involuntary movements (chorea)
-slurred speech, difficulty swallowing, and significant weight loss
What are the types?
-sporadic
-genetic
-juvenile onset
-late onset
What is sporadic HD?
changed by a spontaneous mutation of the huntingtin protein
What is genetic HD?
inherited mutation of the huntingtin gene
What is juvenile onset HD?
-symptom onset before age 20
-has more rapid progression (usually 10 year life expectancy)
- more likely when the father has the HD gene
What is late onset HD?
symptom onset after age 59
Which type of HD is not inherited?
sporadic
Which type of HD is inherited?
genetic
What type of HD is the most common?
genetic
What are the symptoms of juvenile onset HD?
-stiffness in legs (rigidity > chorea)
-clumsiness in arms and legs
-seizures
-other typical symptoms of HD
What does the neurologic exam and medical history consist of when diagnosing HD?
-performed by a neurologist
-history goes extensively into family history
-the physical exam looks at reflexes, balance, tone, movement, gait, and mental status
What imaging is used to diagnose HD?
-with disease progression, you would see shrinking in the brain with enlargement of ventricles
-this would show up on CT of the head and MRI
*early HD would have normal imaging
What is the best diagnostic method for diagnosing HD?
genetic testing
What would be a positive genetic test for HD?
36+ repeats of CAG on the huntingtin gene
What would be a negative genetic test for HD?
26 or less repeats of CAG on the huntingtin gene
What is the prognosis?
-fatal
*usually due to secondary complications like heart failure and pneumonia
How long is the disease progression for HD?
10-25 years
What is the medical treatment/management?
-no cure
-management of symptoms
How would symptoms be managed?
-behavioral/psychological
*medication and a neurologist, neuropsychologist, or psychologist
-weight loss
*would need an SLP and nutritionist
-movement/balance/gait dysfunction
*we would treat this
-cognitive changes
*OT or SLP would treat this
What are the characteristics of early stage HD?
-largely functional
-difficulty with coordination
-mild chorea
-difficulty with a higher level of problem-solving
-mild depression, irritability, and disinhibition
What are the characteristics of middle stage HD?
-no longer able to go to work, drive, manage money, and do household chores
-need assistance with eating, dressing, and personal hygiene
-weight loss
-falls
-swallowing difficulty
-difficulty sequencing
-difficulty problem solving
-cannot prioritize tasks
-more chorea in this phase
-impulsivity
-suicidal behaviors
-paranoia/hallucinations
What are the characteristics of late stage HD?
-require assistance with all ADLs
-usually non-verbal and bedridden
-either severe chorea or it has been replaced with more parkinsonian symptoms of severe rigidity and bradykinesia
-delirium
-global dementia
What is the physical therapy exam/eval for HD?
-unified huntington’s disease rating scale (UHDRS)
-thorough neuro exam
*tone
*coordination
*strength
*balance
*cognition
*reflexes
*eye movement/function
* salient functional tasks
*fall risk
*ROM
*cranial nerves
*gait
What interventions can be used for HD?
-based on deficits
-think of future needs
-caregiver education and training
