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Flashcards in Disorders of the Basal Ganglia Deck (27)
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1
Q

What makes up the basal ganglia (aka the extrapyramidal system)?

A
  • striatum (caudate and putamen)
  • globus pallidus
  • substantia nigra
  • subthalamic nucleus
2
Q

what is the pyramidal system

A

corticospinal and corticobulbar tracts

3
Q

Parkinson’s disease pathophys

A

-loss of DA neurons in substantia nigra=less direct pw inhibition and more indirect pw stimulation of medial globus pallidus
=net increased inhibitory output of GPm to VL thalamic motor nuclei=less stim to motor cortex=clinically slow or absent movements

4
Q

hyperkinetic disorders of the basal ganglia

A

-there is a net decrease of medial globus pallidus (GPm) output=reduced inhibition of VL thalamic motor nuclei=greater stimulation of motor cortex=xs motor activity

5
Q

etiologies of parkinsonism

A
  • use of dopamine antagonist meds
  • toxic exposure to manganese of CO2
  • multiple ischemic infarctions of the basal ganglia
  • survivors of the encephalitis lethargica epidemic
  • Parkinson’s dz-progressive degenerative d/o of unknown cause
6
Q

What are the primary clinical signs of PD?

A
  1. resting tremor
  2. rigidity
  3. bradykinesia
  4. impaired postural reflexes
7
Q

resting tremor in PD

A
  • prominent when pt sitting or reclining
  • most often involves distal upper limbs asymmetrically (sometimes chin or lower limbs)
  • worse with stress
  • pill-rolling
8
Q

rigidity in PD

A
  • rigid arm may not naturally swing as the pt walks

- cogwheeling=ratchet or jerky feeling created by tremor when the rigid limb is moved

9
Q

bradykinesia in PD

A

=slowness or lack of movement

  • may rock several times to get off a cahir, stooped, multiple steps to tirn around
  • pt may freeze feet to the floor
  • manual tasks are slow and clumsy
  • eyeblinking slower
  • may drool
10
Q

impairment of postural reflexes in PD

A
  • balance instability while standing or walking

- least responsive to dopaminergic medication

11
Q

secondary signs found in pts with PD

A
  • masked facies
  • hypophonic speech
  • micrographia
  • ANS involvement: severe constipation, bladder dysfunction, or orthostatic hypotension
  • REM behavior sleep disorder
12
Q

how is PD diagnosed

A
  • primarily clinically

- at least 2/4 primary clinical signs should be present

13
Q

pathology of PD

A

-loss of pigmented dopaminergic neurons in the substantia nigra, many of which have alpha-synuclein-positive-eosinophilic-cytoplasmic inclusions called LEWY bodies

14
Q

what are the synucleinopathy?

A
  • Lewy body dementia, multiple system atrophy, PD

- accumulation of alpha-synuclein appears to play a central role in the degenerative process

15
Q

PD treatment

A

-L-dopa and Carbidopa (decarboxylase inhibitor, limits peripheral catabolism of L-dopa before it enters the brain)

16
Q

Levodopa SE in older pts

A

hallucinations or psychosis

17
Q

problem with L-dopa

A

-as dz progresses each dose provide less asymptomatic on time, and more off time with bradykinesia and rigidity sometimes alternating with xs movements (dyskinesia) like choreoathetosis or dystonia

18
Q

besides Carbidopa what else can increase L-dopa levels?

A
  • COMT inhibitor-Entacapone (helps with motor fluctuations)

- MAO-B inhibitor-Selegiline

19
Q

what provides some control of the resting tremor

A

anticholinergic drugs like trihexyphenidyl

20
Q

what can help reduce the longer term SE of dyskinesia?

A

dopamine agonists (Ropinirole, Pramipexole) when used as monotherapy

21
Q

sx fix for PD?

A

-pallidotomy could be placed in GPm, thereby counteracting its increased inhibition of the VL thalamic motor nuclei
OR
-deep brain stimulation-insert electrode into STN inhibiting it by means of repetitive electrical stimulations

22
Q

clinical presentation of Huntington’s Disease

A
  • choreoathetosis
  • dementia
  • behavioral syndromes (depression, anxiety, moodiness, agitation)
23
Q

tell me more about HD

A

-AD degenerative dz, manifests around 35-40 with early motor symptoms

24
Q

what is the clinical diagnosis for HD

A

-blood test demonstrating multiple trinucleotide repeats in huntingtin gene on chromosome 4

25
Q

path of HD

A
  • early: preferential loss of putaminal GABA-ergic neurons
  • later: cholinergic neurons are also lost
  • grossly: atrophy of caudate nuclei with less severe atrophy of cerebral cortex
26
Q

caudate atrophy in advanced HD

A

-detected on MRI or CT scans where frontal horns of the lateral ventricles appear relatively enlarged

27
Q

drugs for HD

A
  • dopamine antagonist drugs help less choreoathetosis and psych problems
  • Tetrabenazine, catecholamine depleter also helps reduce the choreoathetosis