Huntington's Disease Flashcards
1
Q
Describe Huntington’s disease
A
- Progressive hereditary disease characterized by abnormalities in movement, personality disturbances, & dementia
- AKA Huntington’s chorea: choreas is the most common movement dysfunction (purposeless, involuntary movements)
2
Q
Incidence of Huntington’s disease
A
- 25,000 in US
- 4-8/100,000
- Can start anytime after infancy but usually in middle age
- 25% have late onset (start after 50yrs)
3
Q
Etiology of Huntington’s disease
A
- Genetic disorder autosomal dominant disease with IT15 or HD marker on chromosome 4, almost always Hx of affected parent, all people who have this gene will develop the disease
4
Q
Describe prognosis of Huntington’s disease
A
- Rate of disease progression and duration varies
- Time from the 1st symptoms to death is often about 10-30yrs
5
Q
Pathogenesis of Huntington’s disease
A
- Consistent pattern o Brian tissue changes: enlargement of ventricles due to atrophy of adjacent basal ganglia (caudate and putamen)
- Extensive loss of small & medium sized neurons
- Atrophy of cortex & frontal white matter happen at same rate
6
Q
Damage of neurons in early stages
A
- Striatal neurons that connect substantial nigra are depleted leading to depletion of GABA/acetylcholine which leaves relatively higher concentrations of excitatory NTs like dopamine
- Imbalance increases excitatory responses to thalamus -> excitation of thalamocortical pathways -> may explain excessive abnormal movements of chorea
7
Q
Damage of neurons in later stages
A
- Dopamine decreases
- Inhibitory inputs to thalamus increase
- Inhibition of thalamocortical output
- Results in rigidity & bradykinesia
8
Q
Clinical manifestations of Huntington’s disease
A
- Coordination deficits during voluntary movements can be detected using tests: RAM, rapid tongue movements, eye movements
- Muscle strength & reflexes are normal, rigidity can come as disease progresses
- Abnormalities in eye saccades, smooth pursuit, decrease in distance & velocity of eye movements
- Dysarthria
- Dysphagia (disrupted swallowing/breathing)
- Sleep disorders
- Urinary incontinence
- Cognitive deficits: memory, ideomotor apraxia
- Behavioral problems
9
Q
Clinical manifestations of Huntington’s disease related to chorea
A
- Abnormalities in gait: wide BOS with choreiform movements in UE & trunk
- Early stages minor choreic movements can be suppressed during exam
- Early chorea may seem like exaggeration of normal restlessness involving UE & face
- Chorea may increase during increased concentration, emotional stimuli, complex tasks
10
Q
Describe diagnosis of Huntington’s disease
A
- Depends on recognition of patterns of symptoms, patient’s Hx, & family Hx
- MRI can detect atrophy of striatum, not very helpful as atrophy is also seen with advancing age
- Genetic analysis & DNA testing
11
Q
Treatment of Huntington’s disease
A
- Genetic, psychologic, & social counseling should be started ASAP DX is confirmed
- Meds for symptomatic treatment: Nabilone for motor behaviors, anticonvulsants & antipsychotic agents that block dopamine provide most useful Sx relief from chorea
- Significant side effects to these drugs: dystonia, pseudoparkinsonism
- Hold drug therapy if chorea is slight
12
Q
Describe prognosis of Huntington’s disease
A
- Onset 15-40yrs
- Death occurs b/w 15-20yrs after onset
- Death can be from infection and/or suicide
- Earlier the onset the more severe the disease
13
Q
Implications for PT
A
- Center therapy around preserving abilities for functional ambulation & ADLs for as long as possible
- Surprising ability to maintain gait in the presence of chorea in limbs but start to lose balance & fall as chorea progresses to trunk
- Lower scores of Tinetti POMA & younger age are predictors for falls
- Use of metronomes for patients with rigidity can increase gait speed
- Intensive rehab as per tolerated have shown maintenance of functional mobility for as long as 3 years
