Parkinsonism (Basal Ganglia)

Question 1

def parkinsonism

Answer 1

broad term that refers to various neurodegenerative diseases that usually affects the basal ganglia and usually manifests w/ motor symptoms

Question 2

what are the parkinsonism features (4)?

Answer 2

1. rigidity
2. tremors
3. bradykinesia
4. postural instability

Question 3

what could rigidity look like for parkinsonism?

Answer 3

increased tone: cogwheel or lead pipe rigidity

Question 4

what could tremors look like for parkinsonism?

Answer 4

resting pill rolling tremor
tremors exacerbated by stress

Question 5

what could bradykinesia look like for parkinsonism?

Answer 5

• mask-like facies: decrease facial expression
• decrease RAM
• dysarthria: difficulty speaking and soft spoke
• slowness of movement

Question 6

what could postural instability look like for parkinsonism?

Answer 6

1. shuffling gait
2. freezing gait
3. turn en block
4. decrease stride length

Question 7

what are the two most common primary diseases associated with parkinsonism features?

Answer 7

1. Parkinson’s disease
2. Drug-induced parkinsonism

Question 8

what are 3 secondary causes of parkinsonism features?

Answer 8

1. normal pressure hydrocephalus
2. vascular parkinsonism (MC HTN)
3. toxin-induced parkinsonism
4. brain tumour
5. chronic traumatic encephalopathy
6. parkinson-plus syndromes

Question 9

what are common drugs that can cause parkinsonism features?

Answer 9

• typical anti-psychotics - haloperidol
• atypical anti-psychotics - risperidone
• antiemetics
• dopamine-depleting drugs
• other: valproic acid, lithium

Question 10

basic pathophys of Parkinson disease

Answer 10

substantia nigra degeneration (in the basal ganglia) ➔ loss of dopaminergic neurons ➔ compensation attempt to increase dopamine levels ➔ compensation failure ➔ decrease dopamine levels ➔ increase inhibition of the motor cortex ➔ bradykinesia and postural instability

Question 11

basic pathophys of drug-induced parkinson disease

Answer 11

structurally or functionally blocked dopamine receptors ➔ decrease dopamine

Question 12

how to dx parkinson disease?

Answer 12

refer to neurologic ➔ clinical dx

do other ix to r/o other causes of parkinsonism

Question 13

what other s/s might we see in parkinson’s disease besides it’s classic 4 features?

Answer 13

• progressive (>10Y) where motor symptoms may start unilaterally
• micrographia
• autonomic: constipation, urinary urgency, anosmia (no smell), sleep disturbances, mood disorders (depression, apathy)
• ## dementia and cog impairment (lewy body dementia, irritability, impulsivity)

Question 14

tx for parkinson’s disease

Answer 14

refer to neurology
1. levadopa ➔ amino acid that can be metabolized into dopamine in the brain cause it can pass the BBB
2. carbidopa ➔ peripheral dopa decarboxylase inhibitor ➔ increase therapeutic effects
3. referral to OT, PT, SLP + cognitive training (improve memory, executive function, and attention)

other options
- COMT inhibitors, dopamine agonists, MAOIs

Question 15

how do COMT inhibitors work

Answer 15

Catechol-O-methyltransferase (COMT) inhibitors

MOA: blocks enzyme responsible for dopamine degradation

Question 16

how do dopamine agonists work?

Answer 16

MOA: stimulate dopamine receptors

Question 17

how do MAOIs work?

Answer 17

Monoamine oxidase inhibitors

MOA: ↓ dopamine metabolism by inhibiting enzyme MAO

Question 18

main role of the basal ganglia is to ____

Answer 18

regulate involuntary movements
fine tune voluntary movements
maintain posture

Question 19

activation of the the direct pathway used by the basal ganglia results in _________

Answer 19

increase voluntary movement ➔ allows movement
(an excitatory stimulus on the motor cortex)

Question 20

activation of the indirect pathway used by the basal ganglia results in ____________

Answer 20

decrease in voluntary movement ➔ prevents movement
(an inhibitory stimulus on the motor cortex)

Question 21

simply explain the direct basal ganglia pathway (main components)

Answer 21

1. The cerebral cortex sends the message that they want to initiate movement to the striatum via glutamate
2. The striatum sends inhibitory signals to the globus pallidus (internal) via GABA (this is further increased by activating dopamine from the substantia nigra pars compacta)
3. The thalamus is now NOT inhibited by the globus pallidus ➔ active ➔ thalamus sends excitatory signal to the motor cortex

Question 22

simply explain the indirect basal ganglia pathway (main components)

Answer 22

1. cerebral cortex signals to the striatum via glutamate that it wants a movement
2. striatum talks to the external globus pallidus (dopamine released from substantia nigra, wants to stop and is inhibitory bc dopamines end goal is to have movement) ➔ subthalamic nucleus then activates the internal globus pallidus
3. an activated globus pallidus ➔ inhibition of the thalamus ➔ inhibitory stimulus on the motor cortex