L44 Movement Disorders Basal Ganglia

Question 1

what does the BG receive info about motor commands from?

Answer 1

prefrontal cortex
premotor cortex
primary motor cortex

Question 2

does the BG have any direct synaptic connections with motor neurons?

Answer 2

NO - through the thalamus, the BG participates in the initiation and control of voluntary movement

Question 3

what is the role of the BG?

Answer 3

initiation an control of voluntary movement through the thalamus

Question 4

what are the 4 nuclei of the BG?

Answer 4

straitum - caudate n. + putamen
globus pallidus - GPm, GPl
subthalamic n.
substantia nigra - pars reticulata and pars compacta

Question 5

are the motor neurons in the BG excitatory or inhibitory?

Answer 5

inhibitory

Question 6

what type of receptors are D1 receptors in the striatum?

Answer 6

excitatory

Question 7

what type of receptors are D2 receptors in the striatum?

Answer 7

inhibitory

Question 8

what is the effect of the direct pathway on movement?

Answer 8

facilitate movement

Question 9

what is the effect of the indirect pathway on movement?

Answer 9

inhibits movement

Question 10

describe Parkinson’s disease

Answer 10

bilateral degeneration of dopaminergic cells in SN

Question 11

what type of disorder of Parkinson’s disease?

Answer 11

HYPOkinetic

Question 12

what are the sx/sx of Parkinson’s disease?

Answer 12

bilateral...
akinesia 
bradykinesia
resting tremors
muscular rigidity 
.. see notes on video lecture

Question 13

describe Huntington’s Chorea?

Answer 13

bilateral degeneration/loss of strial GABA neurons that EXPRESS D2 receptors

Question 14

what type of disorder is Hungtinton’s Chorea?

Answer 14

HYPERkinetic

Question 15

what are the sx/sx of Huntington’s Chorea

Answer 15

irregular bilateral movements
dyskinesia
involuntary movement of head, arms, legs
marked change in mental status

Question 16

describe hemiballismus

Answer 16

lesion of the subthalamic n. usually from stroke

Question 17

what type of disorder is hemiballismus?

Answer 17

HYPERkinetic

Question 18

what are the sx/sx of Hemiballismus?

Answer 18

irregular movements of the limbs and trunk on contralateral side
involuntary flinging arms and writhing movements of the leg ON ONE SIDE

Question 19

what is parkinsonism?

Answer 19

describes symptoms involving any combo of resting tremors, muscular rigidity, bradykinesia, impaired postural reflex

Question 20

what are the 4 things that can look like parkinson’s disease (perhaps differential dx)?

Answer 20

drug induced 
vascular 
repetitive head trauma
postencephalitic 
neoplastic

Question 21

describe drug induced parkinsonism?

Answer 21

• antipsychotic drugs (DA receptor blockers)
• depletors of DA stores (reserpine - old BP med)
• toxic contaminants (MPTP) - homemade drugs toxin…

Question 22

describe vascular parkinsonism

Answer 22

strokes affecting the BG (nigrostriatal path)

affects lower body and gait

Question 23

describe reptitive head truma

Answer 23

boxing-like injury associated with dementia because of damage to the midbrain

Question 24

describe postencephalitic parkinsonism

Answer 24

virally induced degenerations of substantia nigra

Question 25

describe Sydenham's chorea

Answer 25

linked to childhood rheumatic fever | transient, but preg women are susceptible for recurrence

Question 26

describe drug induced chorea

Answer 26

caused by L-dopa, anticonvulsants or antipsychoics as a result of enhancing dopaminergic transmission within the BG

Question 27

what are drug therapies for parkinson's disease?

Answer 27

``` L-dopa dopamine agonist drugs that enhance dopamine release MAO inhibitors COMT inhibitors anticholinergic drugs ```

Question 28

what does L-dopa do?

Answer 28

increases rate of dopamine synthesis in the still functional SNc given orally with cabidopa to prevent dopamine synthesis outside of CNS effectiveness decreases over time as SNc neurons die out

Question 29

what do dopamine receptor agonists do?

Answer 29

D2 agonist - bromocriptine D1 and D2 agonist - pergolide bypass degenerating nigrostriatal neurons and acts directly on postsynaptic receptors

Question 30

what are drugs that enhance dopamine release?

Answer 30

anti-viral drug amantadine - good effect on akinesia and rigidity, but PSYCHO may promote release of dopamine or block ACh receptors

Question 31

what do MAO inhibitors do?

Answer 31

selegiline - block dopamine breakdown may delay the need for other therapies

Question 32

what do COMT inhibitors do?

Answer 32

inhibit dopamine breakdown-- increase dopamine effects may be given in addition to L-dopa and carbidopa

Question 33

what makes up the lentiform nucleus?

Answer 33

putamen and globus pallidus

Question 34

what makes up the striatum?

Answer 34

caudate n. + putamen

Question 35

what provides vital modulation to the direct and indirect pathways?

Answer 35

substantia nigra --- dopamine producing cells projects into the striatum to release DA

Question 36

what is the function of DA in the direct and indirect pathways?

Answer 36

regulates BG function -- thus, indirectly regulating cortical control of movement ALWAYS cortical excitation = increased movement!

Question 37

what type of feedback is seen in direct BG loop

Answer 37

positive - cortical input increases cortical activity

Question 38

what type of feedback in seen in indirect BG loop?

Answer 38

negative - cortical input supresses cortical activity

Question 39

describe neoplastic parkinsonism

Answer 39

tumors can disturb the nigrostriatal system

Question 40

describe athetosis

Answer 40

striatal or thalamic injury can yield continuous writhing

Question 41

what do anticholinergic drugs do?

Answer 41

muscarinic antagonists - suppress ACh mediated excitation of striatal neurons ACh makes parkinsonism WORSE!

Question 42

what sites are ablated (burned) in surgical ablation?

Answer 42

subthalamus medial globus pallidus both of them are way overactive = hyperkinesis

Question 43

what sites are involved in deep brain stimulation

Answer 43

thalamus golbus pallidus subthalamus

Question 44

what happens when you increase DA transmission (maybe from L-dopa drug)?

Answer 44

PSYCHOSIS

Question 45

what is therapeutically given for brain degeneration?

Answer 45

block D2 receptors