Parkinson's & Huntington's Flashcards
What is Parkinson’s disease?
Degenerative disorder of the CNS, mainly affecting the motor system
What is the mean age onset of Parkinson’s?
45-60
What causes Parkinson’s?
Idiopathic usually
There are some genetic mutations that can cause it
Drugs
Trauma, boxing
Copper toxicity: Wilson’s disease
What is the pathogenesis of Parkinson’s?
Loss of dopaminergic neurons in the basal ganglia, mostly the substantia nigra
Surviving neurons contain aggregations of protein, called Lewy bodies
Symptoms are only seen when dopamine levels are 20-40% of normal
What is the significance of the presence of Lewy bodies in Parkinson’s?
If Lewy bodies are seen throughout the brain, then dementia will be seen in addition to the other features of Parkinson’s?
Clinical presentation of Parkinson’s?
Tremor
Rigidity
Bradykinesia
Bilateral, though one side is always more affected
Abnormal gait
Speech
They stare, with eyes that don’t blink as often
Depression
Dementia
Hallucinations
Describe the gait of someone with Parkinson’s?
Slow shuffling steps
Stooped posture
Reduced arm swinging
Narrow based: feet are close together
Appears as if they can’t get their feet off the floor
Describe the speech of someone with Parkinson’s?
Slow, monotonous
What type of tremor do Parkinson’s patients get?
Resting tremor
- Pill-rolling of thumb over fingers
What is bradykinesia?
Slowness of movement:
- slow to walk
- slow to perform tasks, write, do up buttons
What does rigidity mean?
Increased resistance to passive movement
Equal in extensors and flexors
Investigations of Parkinson’s?
Clinical
MRI is normal
What are some non-motor features of Parkinson’s?
Loss of sense of smell
Constipation
Increased urinary frequency + incontinence
Visual hallucinations
Dribbling
Depression
Dementia
Treatment of Parkinson’s?
Exercise + physio
L-dopa: main treatment
Other drugs that aim to increase dopamine levels in the brain
Surgery: rarely used
What is L dopa?
What is the full name of L-dopa?
A drug used to treat Parkinson’s
It is the precursor to dopamine, so it is able to cross the blood-brain barrier, get into the basal ganglia and increase dopamine levels there
Full name = Levodopa
What 3 different types of L-dopa are there?
Dispersable: gives a kick start in the morning
Standard release: day time medication
Slow release: keeps them comfortable at night time
Depression in Parkinson’s is simply reactive due to the diagnosis.
True or false?
False
It’s not just reactive depression
What are the problems with L-dopa?
It’s effect can start to wear off over time
Can cause impulsive behaviours, like gambling, sexual behaviours
What are some causes of Parkinsonism?
Dopamine antagonists
Wilson’s disease
Progressive supranuclear palsy
What is essential tremor?
A familial inherited condition causing a tremor of the arms and head
It often occurs in the elderly
It is benign
What is the inheritance pattern for benign essential tremor?
Autosomal dominant
How can you distinguish between essential tremor and Parkinson’s tremor?
Essential tremor is not usually seen at rest, more so when the hands adopt a posture (holding a cup for example)
Essential tremor may be improved by alcohol, anti-convulsants
Essential tremor can be made worse by anxiety
Parkinson’s tremor will be accompanied with other symptoms: stooped posture, abnormal gait
What does dyskinesia mean?
Problems that affect voluntary movement:
Uncontrollable movements, like chorea, tics
What does akinesia mean?
Loss of the power of voluntary movement
What are some conditions that cause dyskinesia?
Benign Essential Tremor
Chorea
Huntington’s disease
Hemiballismus
Myoclonus
Tics
Dystonia
What is chorea?
A continuous flow of jerky, partly purposive movements
Flitting from one part of the body to another
Cease during sleep
What is hemiballismus?
Violent swinging movements of one side of the body
What is myoclonus?
Sudden, involuntary jerking of a single muscle or group of muscles
Give an example of a common type of myoclonus?
Benign essential myoclonus
The sudden jerking of a limb or the whole body on falling asleep
What are tics?
Brief, repeated movements involving the face and shoulders usually
What is dystonia?
Prolonged spasms of muscle contraction
Occur focally, for example in the neck, they can cause the head to be held in an abnormal posture
What is the inheritance pattern of Huntington’s disease?
Autosomal dominant
If one parent has the disease, the child has a 50% chance of getting it
What is Huntington’s disease?
An inherited progressive, degenerative disorder of the nervous system
What is the usual age of onset of Huntington’s?
About age 40, but it can be earlier
Can even be below age 20: juvenile HD
What determines the age of onset of Huntington’s?
The number of CAG repeats, the more = the earlier the onset
What is the pathogenesis of Huntington’s?
A defect in the Huntingtin gene found on chromosome 4
In normal people, this gene contains a repeat sequence of CAG
If there are too many repeats you get Huntington’s
The defective protein produced by Huntingtin gene causes increased neuronal damage
Loss of GABA and ACh neurons causing atrophy of caudate nucleus + corpus striatum in basal ganglia
What does ‘anticipation’ mean, in terms of Huntington’s disease?
The CAG repeat can lengthen with subsequent generations
The longer the repeat, the earlier and more severe the disease is
Which gene is affected in Huntington’s and where is it found in the genome?
Huntingtin
Chromosome 4
Clinical presentation of Huntington’s?
Chorea Agitation + anti-social behaviour Dementia Seizures Death
Management of Huntington’s?
No cure
Supportive: anti-psychotics can help to reduce chorea and agitation, but they don’t slow progression
Counselling is vital for patient and family, especially any children who might want to receive genetic testing
