Movement Disorders Flashcards

1
Q

What is the cause of Parkinson’s?

A

Degeneration of dopaminergic axons in the substantial nigra

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2
Q

What factors could contribute to early onset Parkinson’s?

A

Head trauma
Environmental factors
Virus

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3
Q

Name the 2 receptors that dopamine can bind to

A

D1
D2

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4
Q

Which motor pathway is the D1 receptor part of?

A

The direct (excitatory) pathway

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5
Q

What pathway is the D2 receptor part of?

A

The indirect (inhibitory) pathway

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6
Q

What is the action of dopamine on the direct pathway?

A

It activates the striatal neurones

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7
Q

What is the action of dopamine on the indirect pathway?

A

It inhibits the striatal neurones

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8
Q

Overall what does dopamine do motor activity?

A

Increases it, as it results in excitation in the cerebral cortex

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9
Q

What is akinesia?

A

Loss of voluntary movement

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10
Q

Why does muscle rigidity occur in parkinson’s?

A

Due to locking up of the basal ganglia

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11
Q

Which part of the indirect pathway does dopamine inhibit?

A

Inhibits the disinhibition from the striatal neurones to the globus pallidus, causing less overall inhibition to the excitatory neurones from the thalamus to the cerebral cortex

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12
Q

List 8 signs of Parkinson’s

A

Soft monotonic speech
Swallowing problems
Masked face
Shuffling gait
Stooped posture
Depression
Anxiety
Sleep problems

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13
Q

Name 5 pathways in the brain that dopamine is part of

A

Nigrostriatal pathway
Mesolimbic pathway
Mesocortical pathway
Median eminence to anterior pituitary
Chemoreceptor trigger zone

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14
Q

Which dopamine pathway in the brain is affected in Parkinson’s?

A

Nigrostriatal pathway

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15
Q

Describe the function of dopamine that leads to tremor in Parkinson’s

A

Loss of dopamine stops the inhibition of ACh neurones, leading to tremors as these now function

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16
Q

Describe the function of dopamine that leads to rigidity in Parkinson’s

A

Loss of dopamine inhibits the direct pathway and excited the indirect pathway leading to rigidity

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17
Q

Why can muscarinic antagonists be used in treatment of Parkinson’s?

A

Because they have a function to inhibit the ACh neurones (this is usually the role of dopamine)

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18
Q

Why does a precursor of dopamine have to be given to patients instead of pure dopamine?

A

Dopamine itself cannot pass the blood brain barrier, however the precursor can

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19
Q

List 5 side effects of L DOPA as a treatment for Parkinsons

A

Dyskinesia (uncontrolled movement)
Psychotic
Decrease in prolactin release
On and off effects due to all neurones in substantial nigra eventually degenerating
Increased dopamine in other dopaminergic pathways

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20
Q

What is the effect of dopamine in the ventral tegmental area and nucleus accumbens?

A

Increases the reward pathway in the brain, can result in gambling habits

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21
Q

Why are noradrenergic pathways also increased by dopamine?

A

Dopamine is a precursor for noradrenaline, so will excite these pathways aswell

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22
Q

List 2 peripheral side effects of dopamine

A

Hypotension
Nausea

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23
Q

How does dopamine cause hypotension?

A

Removes noradrenaline from the nerve terminal, inhibiting sympathetic tone

24
Q

How does dopamine cause nausea?

A

It activates the dopamine receptors on the CTZ (chemoreceptor trigger zone)

24
How does dopamine cause nausea?
It activates the dopamine receptors on the CTZ (chemoreceptor trigger zone)
25
How can dopamine be prevented from being converted to noradrenaline?
Inhibit the enzymes in the pathway that convert dopamine to noradrenaline
26
Name 3 enzymes in the dopamine to noradrenaline pathway that can be inhibited
DOPA decarboxylase Monoamine oxidase B Catechol-O-methyl transferase
27
Name 2 drugs that block DOPA carboxylase enzyme
Carbidopa Benserazide
28
Name 2 drugs that block DOPA carboxylase enzyme
Carbidopa Benserazide
29
Name a drug that blocks the monoamine oxidase B enzyme
Selegline
30
Name an enzyme that blocks the Catechol-O-methyl transferase enzyme
Entacapone
31
Does carbidopa and benserazide work on L DOPA in the brain or in the periphery?
Works in the periphery, so can be given at the same time as L DOPA being given and will not reduce its effectiveness
32
Does selegline work on L DOPA in the brain or periphery?
Works in the brain, protects the dopamine that has already been formed
33
What drug can be used to reduce the nauseous effects of L DOPA on the patient?
Domperidone
34
Which receptor does domperidone target?
D2 receptor
35
What kind of drug is domperidone?
D2 receptor antagonist
36
Why is the effect of giving L DOPA only effective for 2-10 years?
Because eventually too many neurones degenerate, so there are none left to take up the L DOPA
37
What are adjuncts?
Drugs that are added to something else as a supplementary element, but is not an essential part
38
Name 3 examples of muscarinic antagonists
Benzhexol Benztropine Atropine
39
Why are muscarinic antagonists not commonly used in Parkinsons?
Inhibiting cholinergic can be negative effects as it has other important functions in the brain
40
What type of drug can be used if L DOPA stops functioning?
Dopamine receptor agonists
41
Name 3 D2 receptor agonists
Ropinirole Bromocriptine Pergolide
42
Name a D1 and D2 antagonist
Apomorphine
43
Why is domperidone always given with D2 receptor agonists?
Because it causes a lot of nausea
44
Name an anti viral drug that can be used in the treatment of Parkinsons
Amantadine
45
What is the function of amantadine?
NMDA antagonist, blocks glutamate
46
Why are glutamate antagonists effective at reducing Parkinsons symptoms?
Excess glutamate is toxic to nerve cells, reduces the effect of this Also reduces the amount of ACh used in pathways so more dopamine is used
47
What is a non drug related way to treat Parkinsons?
Deep brain stimulation
48
Describe the process of deep brain stimulation
Electrodes placed into the brain on the thalamic area, and electrical stimulation is given
49
Which pathway is being unregulated through deep brain stimulation?
GABAergic pathways (increases inhibition)
50
Why are transplants not permanent solutions to Parkinson's?
The existing neurones will still continue to die alongside the healthy graft
51
Is Huntington's chorea a hypokinetic or hyperkinetic disorder?
Hyperkinetic
52
Why is Huntingtons chorea hyperkinetic?
Loss of inhibition of the GABAergic neurones and no inhibition of the dopaminergic neurones
53
What drugs are used to treat Huntingtons chorea?
D2 receptor antagonists (Tetrabenazine)
54
Name dopamine antagonist used to treat tics and tourettes
Haloperidol
55
What is tourettes syndrome?
Uncontrolled motor output to speech centres
56
Where in the brain is the chemoreceptor trigger zone located?
Medulla