Neuro - Anat & Phys (Basal ganglia, Parkinson disease, Hungtington disease, & Movement disorders)

Question 1

What are 2 important functions of the basal ganglia?

Answer 1

Important in voluntary movements and making postural adjustments

Question 2

From where does basal ganglia receive input, and what does it provide in return?

Answer 2

Receives cortical input, provides negative feedback to cortex to modulate movement

Question 3

What parts of the basal ganglia make up the striatum? What is the main function of each of these parts?

Answer 3

Striatum = putamen (motor ) & caudate (cognitive)

Question 4

What parts of the basal ganglia make up the lentiform nucleus?

Answer 4

Lentiform = putamen + globus pallidus

Question 5

Describe the sequence of events in the excitatory pathway involving the basal ganglia. What is the ultimate consequence of this pathway?

Answer 5

Cortical inputs stimulate the striatum (putamen & caudate), stimulating the release of GABA, which disinhibits thalamus via the GPi/SNr (increased motion)

Question 6

Describe the sequence of events in the inhibitory pathway involving the basal ganglia. What is the ultimate consequence of this pathway?

Answer 6

Cortical inputs stimulate the striatum, which disinhibits STH via GPe, and STN stimulates GPi/SNr to inhibit the thalamus (decreased motion)

Question 7

What effect does Dopamine have on the excitatory versus inhibitor pathways of the basal ganglia, and how? What ultimate effect does Dopamine have?

Answer 7

Dopamine binds to D1, stimulating the excitatory pathway, and to D2, inhibiting the inhibitory pathway –> Increase motion

Question 8

What is the difference between the direct and indirect pathways via which dopamine impacts the basal ganglia?

Answer 8

Direct pathway (D1 receptor) facilitates movement; Indirect pathway (D2 receptor) inhibits movement; Think: “D1-Receptor = DIRect pathway; INdirect = INhibitory”

Question 9

What kind of disorder is Parkinson disease? What are 2 characteristic associations/findings with this disease?

Answer 9

Degenerative disorder of CNS associated with Lewy bodies (composed of alpha-synuclein - intracellular eosinophilic inclusion) and loss of dopaminergic neurons (i.e., depigmentation) of the substantia nigra pars compacta

Question 10

What are Lewy bodies? With what disorder are they associated?

Answer 10

Degenerative disorder of CNS associated with Lewy bodies (composed of alpha-synuclein – intracellular eosinophilic inclusion)

Question 11

What happens to dopaminergic neurons in the Parkinson disease? Where in the brain are they affected?

Answer 11

Loss of dopaminergic neurons (i.e., depigmentation) of the substantia nigra pars compacta

Question 12

What symptoms are associated with Parkinson disease?

Answer 12

Parkinson TRAPS your body - Tremor (at rest - e.g., pill-rolling tremor), cogwheel Rigidity, Akinesia (or bradykinesia), Postural instability, and Shuffling gait.

Question 13

What is the inheritance pattern of Huntington disease? With what type of mutation is Huntington disease associated, and on what chromosome is it found?

Answer 13

Autosomal dominant trinucleotide repeat disorder on chromosome 4.

Question 14

In what age range do Huntington disease symptoms manifest?

Answer 14

Symptoms manifest between ages 20 and 50

Question 15

What symptoms characterize Huntington disease? Which symptom is sometimes initially mistaken, and for what other condition?

Answer 15

Characterized by choreiform movements, aggression, depression, and dementia (sometimes initially mistaken for substance abuse)

Question 16

What are 2 neurotransmitters that have decreased levels in the brain with Huntington disease?

Answer 16

Decreased levels of GABA and ACh

Question 17

How does neuronal death occur in Huntington disease?

Answer 17

Neuronal death via NMDA-R binding and glutamate toxicity.

Question 18

What is a significant imaging finding in Huntington disease?

Answer 18

Atrophy of caudate nuclei can be seen on imaging.

Question 19

What genetic code change occurs in Huntington disease? Which nucleus in the brain is involved, and what 2 neurotransmitters does it lose?

Answer 19

Expansion of CAG repeats (anticipation). Caudate loses ACh and GABA; Think: “CAG = Caudate loses ACh and Gaba.”

Question 20

How does hemiballismus present?

Answer 20

Sudden, wild flailing of 1 arm +/- ipsilateral leg; Think: “Half-of-body ballistic”

Question 21

What is the characteristic lesion associated with hemibalismus?

Answer 21

Contralateral subthalamic nucleus (e.g., lacunar stroke); Note: Contralateral lesion

Question 22

What is the presentation of chorea?

Answer 22

Sudden, jerky, purposeless movements; Think: “Chorea = dancing”

Question 23

What is the characteristic lesion associated with chorea?

Answer 23

Basal ganglia (e.g., Huntington)

Question 24

What is the presentation of athetosis? Where in the body is it particularly seen?

Answer 24

Slow, writhing (snake-like) movements; especially seen in fingers

Question 25

What is the characteristic lesion associated with athetosis?

Answer 25

Basal ganglia (e.g., Huntington)

Question 26

What is the presentation of myoclonus? What are 2 examples of myoclonus?

Answer 26

Sudden, brief, uncontrolled muscle contraction; Jerks, hiccups

Question 27

In what kind of conditions is myoclonus common?

Answer 27

Common in metabolic abnormalities such as renal and liver failure

Question 28

What is the presentation of dystonia?

Answer 28

Sustained, involuntary muscle contractions

Question 29

What are 2 examples of dystonia?

Answer 29

(1) Writer’s camp (2) Blepharospasm (sustained eyelid twitch)

Question 30

What is another name for essential tremor? How does it present? What exacerbates it?

Answer 30

Essential tremor (postural tremor); Action tremor; Exacerbated by holding posture/limb position

Question 31

Which movement disorder is noted to have a genetic predisposition?

Answer 31

Essential tremor (postural tremor)

Question 32

With what do essential tremor patients often self-medicate, and why?

Answer 32

Patients often self-medicated with EtOH, which decreases tremor amplitude

Question 33

What is the treatment for essential tremor (postural tremor)?

Answer 33

Treatment: Beta-blockers, primidone

Question 34

What is the presentation of resting tremor? When does it occur? Where in the body is it most noticeable? How is it alleviated?

Answer 34

Uncontrolled movement of distal appendages (most noticeable in hands); Occurs at rest; Tremor alleviated by intentional movement

Question 35

What disease is characteristically associated with a resting tremor? What is the tremor called in this context?

Answer 35

Parkinson disease; “pill-rolling tremor” of Parkinson disease

Question 36

What is the presentation of intention tremor?

Answer 36

Slow, zigzag motion when pointing/extending toward a target

Question 37

With lesion of what part of the brain is intention tremor characteristically associated?

Answer 37

Cerebellar dysfunction

Question 38

What do each of the following basal ganglia acronyms mean: (1) SNc (2) GPe (3) GPi (4) STN (5) D1 (6) D2?

Answer 38

(1) Substania nigra pars compacta (2) Globus pallidus externa (3) Globus pallidus internus (4) Subthalamic nucleus (5) Dopamine D1 receptor (6) Dopamine D2 receptor