Basal Ganglia Review

Question 1

Explain how the “striatum” got its name.

Answer 1

The caudate and putamen are separated by the internal capsule but remain connected by cellular bridges. These bridges appear like striations, earning the name “striatum” for the caudate and putamen.

Question 2

The “lenticular nucleus” is made up of the ____ and ___.

Answer 2

Putamen and globus pallidus

Question 3

The ____ and ____ are always medial to the internal capsule, while the _____ and ______ ______ are always lateral.

Answer 3

Caudate and Thalamus

Putamen and Globus Pallidus

Question 4

ANATOMY ONE

Answer 4

A. Fornix

B. Internal Capsule (Posterior Limb)

C. Globus Pallidus (Internal Segment)

Question 5

The _____ is the most important input nucleus of the striatum for motor control pathways.

Answer 5

Putamen

Question 6

Most cortical inputs to the striatum are ____ and use _____ as the neurotransmitter.

Answer 6

Excitatory

Glutamate

Question 7

Basal ganglia outputs arise from the _____ _____ of the _____ _____ and from the _____ _____ _____ _____.

Answer 7

Internal segment of the globus pallidus

Substantia nigra pars reticulata

Question 8

The main output pathways of the basal ganglia are to the ventral lateral and ventral anterior nuclei of the thalamus via the _____ _____.

Answer 8

Thalamic fasciculus

Question 9

Finish the Indirect Pathway

Cortex –> Striatum –> __________ –> _________ –> Internal Segment of the Globus Pallidus or Substantia Nigra Pars Reticulata

Answer 9

External Segment of the Globus Pallidus

Subthalamic Nucleus

Question 10

The net effect of input from the cortex through the DIRECT pathway will be _____ of the thalamus, while the net effect of the input through the INDIRECT pathway will be _____.

(inhibition vs. excitation)

Answer 10

Excitation

Inhibition

(hint: Indirect Inhibits)

Question 11

In Parkinson’s disease, _____-containing neurons in the _____ _____ _____ _____ degenerate.

Answer 11

Dopamine

Substantia nigra pars compacta

Question 12

Explain why anticholinergic agents may prove beneficial in treating parkinsonism.

(If correct, pick two letters)

Answer 12

Removal of cholinergic excitation of the INDIRECT pathway produces a net decrease in inhibition of the thalamus. This in turn increases excitatory output.

Question 13

_____ is characterized by unilateral wild flinging movements of the extremetieis contralateral to a lesion in the basal ganglia.

Answer 13

Hemiballismus

Question 14

ANATOMY TWO

Answer 14

Subthalamic Nucleus

Question 15

In Huntington’s disease, neurons in the _____ and _____ degenerate.

Answer 15

Caudate

Putamen

Question 16

ANATOMY THREE

Answer 16

1. Motor Channel
2. Oculomotor Channel
3. Prefrontal Channel
4. Limbic Channel

Question 17

The _____ _____ _____ provides dopaminergic inputs to the nucleus accumbens as well as to other limbic structures and to the frontal lobes. Abnormalities in this circuitry are thought to underlie _____ and other psychiatric disorders.

Answer 17

Ventral Tegmental Area

Schizophrenia

Question 18

A 35 y/o man with a recent history of marital problems presented to a psychiatrist due to marital problems. The man and his wife had been having recent arguments. Additionally, the man had started struggling with irregular jerking movements of the head, trunk, and limbs. On exam, his affect was moderately blunted. Saccadic eye movements were moderately slowed. Tone was normal to slightly decreased and rare, brief, irregular movements of the face, neck, trunk, and upper extremities were observed. Tandem gait was slightly unsteady.

1. Which of the four parallel channels are abnormal in this patient?
2. Does this patient have a predominantly hyperkinetic or hypokinetic movement disorder?

Answer 18

1. Motor, Oculomotor, Limbic (and possible Prefrontal as well)
2. Bilateral hyperkinetic movement disorder

Question 19

What symptoms make up the classic triad of Parkinson’s disease?

Answer 19

1. Resting Tremor
2. Bradykinesia
3. Rigidity

Question 20

Rank these common movement disorders by movement speed. (SLOW to FAST)

Athetosis

Ballismus

Bradykinesia

Chorea

Dystonia

Myoclonus

Rigidity

Tics

Tremor

Answer 20

Bradykinesia

Rigidity

Dystonia

Athetosis

Chorea

Ballismus

Tics

Myoclonus

Tremor

Question 21

Describe a festinating gait.

Answer 21

Small, shuffling steps

Question 22

You assess a patient who you believe has Parkinson’s disease. The patient has a positive Myerson’s sign. What does this mean?

Answer 22

Inability to suppress blinking when the center of the brow ridge is tapped repeatedly

Note: The Myerson’s sign is a nonspecific finding that can be observed in other neurodegenerative conditions as well.

Question 23

_____ tremor is to Parkinson’s disease as _____ is to cerebellar appendicular ataxia.

Answer 23

Resting

Intention

Question 24

A 53 y/o right-handed man was referred due to a 10 year history of motor slowness and difficulty using his right arm. These motor symptoms progressed, leading him to change jobs (fireman to desk job). He developed occasional shaking of the right arm and right leg. On exam, the patient exhibited decreased facial expression and hypophonic voice. He had tremors in all extremities, right worse than left. Finger tapping and rapid alternating movements were slow bilaterally. He was unable to rise from a chair without assistance and exhibited a slow, stiff gait with stooped posture. No sensory abnormalities.

1. What is the diagnosis?
2. What might a neurologist prescribe?
3. If those medications don’t work or result in negative side effects, what neurosurgical procedure might be considered?

Answer 24

1. Parkinson’s Disease
2. Levodopa, dopaminergic agonists
3. Deep brain stimulation

Question 25

In what autosomal recessive disorder do patients experience progressive degeneration of the liver and basal ganglia? It is considered a disorder of biliary copper excretion. Neurologic manifestations include the gradual onset of dysarthria, dystonia, rigidity, tremor, and prominent psychiatric disturbance. Some patients develop a “wing beating” tremor.

Answer 25

Wilson’s disease

Question 26

ANATOMY FOUR

Answer 26

Parkinson’s Disease

Notice the pallor of the right substantia nigra caused by degeneration of pigmented dopaminergic neurons.

Question 27

How does atypical parkinsonism differ from idiopathic parkinsonism?

(letter for naming at least 2 of the 4 ways)

Answer 27

1. Relatively symmetrical symptoms (Idiopathic Parkinson’s typically affects one side more than the other)
2. Absence of resting tremor
3. Early appearance of postural instability
4. Little response to dopaminergic agents

Question 28

This disease is caused by multiple repeats of the trinucleotide sequence CAG on chromosome 4. Patients with over 40 CAG repeats will ultimately develop the disease.

Answer 28

Huntington’s disease

Question 29

The pathologic hallmark of Huntington’s disease is progressive atrophy of the striatum, especially involving the _____.

Answer 29

Caudate nucleus

Question 30

A 48 y/o woman gradually developed difficulty with writing and typing, stating that her fingers were stiff and slow. Her gait became unsteady adn she had several falls. The patient was prescribed a common medication for this disorder, but her symptoms did not improve. When examined again 5 years later, she had a normal mental status, slow saccades, masked facies, slow dysarthric speech, bilateral bradykinesia and rigidity (especially of the axial and neck muscles), no tremor, and a slow, shuffling gait.

1. What is the diagnosis?
2. ANATOMY FIVE
3. ANATOMY SIX

Answer 30

1. Atypical parkinsonism
2. Stereotactic surgery (note stereotactically placed lesion – Left pallidotomy)
3. DBS (note electrode in right subthalamic nucleus)

Question 31

A 65 y/o HIV+ man presented with involuntary flinging movements of the right arm and leg. These movemetns had become progessively worse over the course of 1 month, making gait and the use of his right hand difficult. On exam, he had continuous wild, uncontrollable flapping and circular movements of the right arm and occasional jerky movements of the right leg. He had an unsteady gait and was noted to fall to the right. The remainder of the exam was unremarkable.

1. Localize the lesion (be specific)
2. What is the most likely diagnosis? (extra letter)

Answer 31

1. LEFT subthalamic nucleus or LEFT striatum
2. Lacunar infarction or small hemorrhage in the above locations. OR, given his history of HIV, toxoplasmosis or primary CNS lymphoma are potential diagnoses.