neuro - parkinsonism

Question 1

lesion in what structure causes movement disorders?

Answer 1

basal ganglia

lesion in basal ganglia can cause either:
(1) dyskinesia (ie. too much movement)
or (2) akinesia/bradykinesia (eg. parkinsonism)

Question 2

other than a lesion in the basal ganglia, what else may cause movement disorders?

Answer 2

changes in the neurotransmitters regulating the basal ganglia (especially dopamine!)

Question 3

what issues with regards to dopamine can result in parkinsonism?

Answer 3

• dopamine deficiency
• degeneration of dopaminergic neurons
• decrease in dopamine receptor sensitivity
• imbalance of dopamine and acetylcholine

Question 4

what is regulated by the basal ganglia?

Answer 4

• regulation of movement quantity
• learning
• emotion

Question 5

what is parkinsonism?

Answer 5

a clinical syndrome that is characterised by:

(1) resting tremors (tremours subside with voluntary movements, and worsen with stress)

(2) lead-pipe rigidity (rigid all the time)

(3) bradykinesia (immobility)

Question 6

what are some clinical presentations of bradykinesia in parkinsonism?

Answer 6

• postural instability! (Parkinson gait - shuffling gait with quickened and shortened steps)
• hypophonia (softer speech)
• hypomimia (slower blinking)
• decremental bradykinesia in the arm (worsens over time)
• decreased arm swinging when walking
• slower movements in general (eg. finger tapping, opening&closing of fists)

Question 7

is parkinsonism the same as Parkinson’s disease?

Answer 7

No!
parkinsonism is a clinical syndrome.
(idiopathic) Parkinson’s disease is a CAUSE of parkinsonism.

Question 8

what are the later-stage clinical presentations of Parkinson’s disease?

Answer 8

• autonomic dysfunction, constipation, pain
• sleep disturbances, fatigue
• mild cognitive abnormalities, dementia, depression
• increased fall risk

Question 9

what is idiopathic Parkinson’s disease?

Answer 9

a progressive movement disorder marked by degeneration of dopamine-producing neurons of the substatia nigra

Question 10

what are some causes of parkinsonism?

Answer 10

• idiopathic Parkinson’s disease
• wilson disease
• neuroleptic drugs (due to extrapyramidal side effect when blocks dopamine binding to D2 receptors; including: antipsychotics like risperidone, and antiemetics/anti-nausea like metoclopramide)
• infective encephalitis
• vascular parkinsonism
• parkinson-plus syndrome

Question 11

what is the treatment of Parkinson’s disease?

Answer 11

main treatment: L-DOPA + carbidopa

also can add anticholinergics (eg. benztropine) to reuce involuntary muscle movements

Question 12

why can is levodopa (L-DOPA) used instead of just dopamine?

Answer 12

DOPA cannot be used directly as the molecules are too large to cross the BBB

Question 13

what must be added on to L-DOPA? why?

Answer 13

carbidopa

carbidopa inhibits DOPA decarboxylase
it also prevents the conversion of L-DOPA into DOPA in the peripheries, as carbidopa is too large to cross BBB

Question 14

what are some consequences of long-term L-DOPA use?

Answer 14

• diminishing efficacy
• side effects ( nausea, daytime sleepiness, hallucinations/psychosis)

Question 15

in view of the adverse effects of prolonged L-DOPA treatment, what is the prescription standard for young patients with Parkinson’s?

Answer 15

• first: prescribe dopamine agonists (eg. pramipexole)
• if needed: L-DOPA

Question 16

in view of the adverse effects of prolonged L-DOPA treatment, what is the prescription standard for older patients with Parkinson’s?

Answer 16

• first: L-DOPA
• use as adjuncts: MAO-B inhibitors (eg. rasagiline, selagiline) or COMT-inhibitors (entacapone)

Question 17

how is wilson disease diagnosed?

Answer 17

high levels of urinary and liver copper

Question 18

what are parkinson-plus syndromes? what is an example and some features?

Answer 18

• parkinson-plus syndrome: parkinsonism + other symptoms
• eg. dementia with Lewy bodies (dementia with visual hallucinations), multiple system atrophy
• features:
• poorer prognosis
• does NOT respond well to levodopa

Question 19

what is rigidity?

Answer 19

resistance to passive movements
(a type of hypertonia)

Question 20

what is the difference between lead-pipe rigidity and clasp-knife rigidity?

Answer 20

lead-pipe:
- extrapyramidal
- hard all the time
- both agonistic and antagonistic sets of muscles are equally affected
- therefore tone is determined by BOTH sets of muscles

clasp-knife:
- UMN
- easy in some plane of movements
- due to some muscles being stronger than the antagonistic ones, so stronger muscle determines tones

Question 21

what is cog-wheel?

Answer 21

lead-pipe rigidity + tremours