Basal Ganglia and Movement Disorders

Question 1

Functions of basal ganglia

Answer 1

Refinement of motor plan
Regulation of action selection
Facilitation of Habit Seeking
Reward Seeking

Question 2

Inputs to basal ganglia

Answer 2

Cortex (glutamate)
Thalamus
Midbrain (VTA and SN)
Raphe + LC in pons

Question 3

SNPc

SNPr

Answer 3

Compacta- dopamine

Reticulata- gaba

Question 4

Dorsal striatum

Ventral Striatum

Answer 4

Caudate and putamen
NAcc

Both have medium spiny neurons (gabaergic with D1 and D2 receptors)

Question 5

Why is basal ganglia a loop?

Answer 5

Because there are projections in from cortex, and back out to cortex

Question 6

Direct Pathway

Answer 6

Cortex + SNPc + Striatum - GPi/SNPr - VA/VL + Cortex

Question 7

Indirect Pathway

Answer 7

CTX + SNPc - Striatum - GPe- STN + GPi - VA/VL +CTX

Question 8

Hyperdirect Pathway

Answer 8

Fast inhibitory, activates STN directly

Question 9

PD

Answer 9

Degeneration of SNPc –> reduced activation of striatum, no inhibition of GPi so tonic inhibition. Usually asymmetric, rest tremor present.

Question 10

Huntingtons

Answer 10

Degeneration of striatal MSNs. Leads to activation of GPe, causing inhibition of STN, causing inhibition of GPi, causing movement.

Question 11

Lewy Bodies composed of?

Answer 11

Alpha synuclein

Question 12

Dementia with Lewy Bodies

Answer 12

Like parkinson’s but includes psychosis (hallucinations) and personality

Question 13

MSA-C

Answer 13

Pancerebellar dysfunction – wide based gait, ataxia, nystagmus, cerebellar atrophy

Question 14

MSA-A

Answer 14

Dysfunction in autonomics, get orthostatic hypotension, urinary dysfunction, severe constipation, erectile dysfunction, excessive sweating.

Question 15

MSA-P

Answer 15

Like parkinson’s but more symmetrical and with less control of postural reflexes so more falls. These falls also happen earlier in disease course.

Question 16

Progressive Supranuclear Palsy

Answer 16

Called toppling disease, most axial and symmetric of the parkinsonisms. Minimal response to levodopa, extension of the neck. Square wave visual jerks

Question 17

Corticobasal Syndrome/Degeneration

Answer 17

Alien limb syndrome, dystonia of the arm. Hyperphosphorylated tau protein.

Question 18

What improves essential tremor (f=6hz)

Answer 18

Alcohol

Question 19

What causes essential tremor?

Answer 19

Loss of purkinje cells in the cerebellum

Question 20

Dystonia

Answer 20

Involuntary movement. Agonist and antagonist muscles contract together.

Question 21

Tardive dystonia

Answer 21

Arises after medications that are Dopamine antagonists

Question 22

Myoclonus

Answer 22

Lightning fast jerky movements

Question 23

Sydenham chorea

Answer 23

Chorea after a streptococcal infection that resolves on its own.

Question 24

How to treat HTT

Answer 24

Tetrabenzine, deletes dopa by inhibiting VMAT.

Question 25

Ballism

Answer 25

Throwing movements of the limb

Question 26

Wilson’s Disease

Answer 26

Great imitator of movement disorders. Generally presents with parkinsonism, gait disturbance, and dysarthria. Kayser-fleischer rings around the eyes. Copper accumulation.