Basal Ganglia Review Flashcards
Explain how the “striatum” got its name.
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.
The “lenticular nucleus” is made up of the ____ and ___.
Putamen and globus pallidus
The ____ and ____ are always medial to the internal capsule, while the _____ and ______ ______ are always lateral.
Caudate and Thalamus
Putamen and Globus Pallidus
ANATOMY ONE
A. Fornix
B. Internal Capsule (Posterior Limb)
C. Globus Pallidus (Internal Segment)
The _____ is the most important input nucleus of the striatum for motor control pathways.
Putamen
Most cortical inputs to the striatum are ____ and use _____ as the neurotransmitter.
Excitatory
Glutamate
Basal ganglia outputs arise from the _____ _____ of the _____ _____ and from the _____ _____ _____ _____.
Internal segment of the globus pallidus
Substantia nigra pars reticulata
The main output pathways of the basal ganglia are to the ventral lateral and ventral anterior nuclei of the thalamus via the _____ _____.
Thalamic fasciculus
Finish the Indirect Pathway
Cortex –> Striatum –> __________ –> _________ –> Internal Segment of the Globus Pallidus or Substantia Nigra Pars Reticulata
External Segment of the Globus Pallidus
Subthalamic Nucleus
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)
Excitation
Inhibition
(hint: Indirect Inhibits)
In Parkinson’s disease, _____-containing neurons in the _____ _____ _____ _____ degenerate.
Dopamine
Substantia nigra pars compacta
Explain why anticholinergic agents may prove beneficial in treating parkinsonism.
(If correct, pick two letters)
Removal of cholinergic excitation of the INDIRECT pathway produces a net decrease in inhibition of the thalamus. This in turn increases excitatory output.
_____ is characterized by unilateral wild flinging movements of the extremetieis contralateral to a lesion in the basal ganglia.
Hemiballismus
ANATOMY TWO
Subthalamic Nucleus
In Huntington’s disease, neurons in the _____ and _____ degenerate.
Caudate
Putamen
ANATOMY THREE
- Motor Channel
- Oculomotor Channel
- Prefrontal Channel
- Limbic Channel
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.
Ventral Tegmental Area
Schizophrenia
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.
- Which of the four parallel channels are abnormal in this patient?
- Does this patient have a predominantly hyperkinetic or hypokinetic movement disorder?
- Motor, Oculomotor, Limbic (and possible Prefrontal as well)
- Bilateral hyperkinetic movement disorder
What symptoms make up the classic triad of Parkinson’s disease?
- Resting Tremor
- Bradykinesia
- Rigidity
Rank these common movement disorders by movement speed. (SLOW to FAST)
Athetosis
Ballismus
Bradykinesia
Chorea
Dystonia
Myoclonus
Rigidity
Tics
Tremor
Bradykinesia
Rigidity
Dystonia
Athetosis
Chorea
Ballismus
Tics
Myoclonus
Tremor
Describe a festinating gait.
Small, shuffling steps
You assess a patient who you believe has Parkinson’s disease. The patient has a positive Myerson’s sign. What does this mean?
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.
_____ tremor is to Parkinson’s disease as _____ is to cerebellar appendicular ataxia.
Resting
Intention
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.
- What is the diagnosis?
- What might a neurologist prescribe?
- If those medications don’t work or result in negative side effects, what neurosurgical procedure might be considered?
- Parkinson’s Disease
- Levodopa, dopaminergic agonists
- Deep brain stimulation
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.
Wilson’s disease
ANATOMY FOUR
Parkinson’s Disease
Notice the pallor of the right substantia nigra caused by degeneration of pigmented dopaminergic neurons.
How does atypical parkinsonism differ from idiopathic parkinsonism?
(letter for naming at least 2 of the 4 ways)
- Relatively symmetrical symptoms (Idiopathic Parkinson’s typically affects one side more than the other)
- Absence of resting tremor
- Early appearance of postural instability
- Little response to dopaminergic agents
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.
Huntington’s disease
The pathologic hallmark of Huntington’s disease is progressive atrophy of the striatum, especially involving the _____.
Caudate nucleus
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.
- What is the diagnosis?
- ANATOMY FIVE
- ANATOMY SIX
- Atypical parkinsonism
- Stereotactic surgery (note stereotactically placed lesion – Left pallidotomy)
- DBS (note electrode in right subthalamic nucleus)
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.
- Localize the lesion (be specific)
- What is the most likely diagnosis? (extra letter)
- LEFT subthalamic nucleus or LEFT striatum
- Lacunar infarction or small hemorrhage in the above locations. OR, given his history of HIV, toxoplasmosis or primary CNS lymphoma are potential diagnoses.
