Basal Ganglia — MCQs

10 questions

Loss of striatal fibres in caudate nucleus is associated with?

All the following apply to Parkinson disease except

A 60-year-old man has resting tremor, pill-rolling movements, rigidity, and bradykinesia. Which of the following is most likely to be decreased in this man?

Parkinson's disease results from a lesion in the

A patient is brought to the OPD by his wife, complaining about difficulty expressing emotions and lack of participation in daily activities. On examination, resting tremors and rigidity are noted. Given the possible diagnosis, which part of the brain is affected in this patient?

When blood pressure falls below 40 mm Hg, which mechanism of regulation is working?

Which of the following statements about Kernicterus is TRUE?

Lesion of globus pallidus causes-

A patient presented with violent, flinging movements. Where is the lesion causing the hemiballismus seen?

Q10

Lesion of globus pallidus causes

Basal Ganglia Indian Medical PG Practice Questions and MCQs

Question 1: Loss of striatal fibres in caudate nucleus is associated with?

A. Hemiballismus
B. Huntington's disease (Correct Answer)
C. Charcot-Marie-Tooth disease
D. Parkinson's disease

Explanation: ***Huntington's disease*** - This neurodegenerative disorder is pathologically characterized by **atrophy of the striatum**, particularly the **caudate nucleus** [1]. - The loss of striatal neurons, especially medium spiny neurons, leads to the characteristic **chorea** and cognitive decline [1]. *Hemiballismus* - Characterized by **unilateral, violent, flinging movements** of the limbs. - It is typically caused by a lesion in the **subthalamic nucleus**, not the caudate nucleus. *Charcot-Marie-Tooth disease* - A group of inherited disorders that affect the **peripheral nerves**, leading to muscle weakness and sensory loss. - This condition does not involve the degeneration of the striatal fibers in the caudate nucleus. *Parkinson's disease* - Primarily caused by the degeneration of **dopaminergic neurons** in the **substantia nigra pars compacta**. - While it affects the basal ganglia circuitry, its primary pathology is not the loss of striatal fibers in the caudate nucleus but rather a **dopamine deficiency**. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1299-1300.

Question 2: All the following apply to Parkinson disease except

A. tremors at rest and muscular rigidity
B. secondary involvement of the parietal cortex (Correct Answer)
C. involvement of dopaminergic neurons
D. primary involvement of the substantia nigra

Explanation: ***secondary involvement of the parietal cortex*** - Parkinson disease primarily affects the **basal ganglia** and associated dopamine pathways, leading to motor symptoms [1]. - While cognitive decline can occur, it's typically more related to **frontal-subcortical circuits** and less directly to secondary parietal cortex involvement [2]. *tremors at rest and muscular rigidity* - **Resting tremor** (often described as "pill-rolling") and **muscular rigidity** (lead-pipe or cogwheel rigidity) are two of the cardinal motor symptoms of Parkinson disease [1]. - These symptoms result from the **loss of dopaminergic neurons** in the substantia nigra [1]. *involvement of dopaminergic neurons* - The hallmark pathological feature of Parkinson disease is the **degeneration of dopaminergic neurons** in the substantia nigra pars compacta [1]. - This loss leads to a significant **reduction in dopamine** levels in the striatum, causing the characteristic motor symptoms [1]. *primary involvement of the substantia nigra* - The **substantia nigra** is the primary site of neurodegeneration in Parkinson disease [1]. - The degeneration of dopaminergic neurons within this brain region is the **origin of the motor deficits** observed in the disease [1].

Question 3: A 60-year-old man has resting tremor, pill-rolling movements, rigidity, and bradykinesia. Which of the following is most likely to be decreased in this man?

A. GABA neurons in the caudate nucleus and putamen
B. Serotonin neurons in the raphe nuclei
C. Acetylcholine neurons in the forebrain
D. Dopamine neurons in the substantia nigra (Correct Answer)

Explanation: ***Dopamine neurons in the substantia nigra*** - The symptoms described—**resting tremor**, **pill-rolling movements**, **rigidity**, and **bradykinesia**—are classic signs of **Parkinson's disease** [5]. - Parkinson's disease is pathologically characterized by the degeneration of **dopamine-producing (dopaminergic) neurons** in the **substantia nigra pars compacta**, leading to decreased dopamine levels in the **striatum** [1]. *GABA neurons in the caudate nucleus and putamen* - **GABAergic neurons** in the **caudate nucleus and putamen** are primarily affected in conditions like **Huntington's disease**, where their degeneration leads to increased involuntary movements (chorea) [4]. - While there can be secondary changes in these neurons in Parkinson's, the primary deficit is not in GABA but in dopamine. *Serotonin neurons in the raphe nuclei* - **Serotonin neurons** in the **raphe nuclei** are involved in mood regulation, sleep, and appetite, and their dysfunction is primarily linked to conditions like **depression**, anxiety, and certain sleep disorders [3]. - While some serotonergic involvement can occur in Parkinson's, it is not the primary neurological deficit explaining the motor symptoms. *Acetylcholine neurons in the forebrain* - **Acetylcholine neurons** in the **nucleus basalis of Meynert** (part of the forebrain) are primarily implicated in **Alzheimer's disease**, where their degeneration contributes to cognitive decline [2]. - While some cholinergic deficits may be present in advanced Parkinson's, they are not the hallmark pathology or the initial cause of the characteristic motor symptoms.

Question 4: Parkinson's disease results from a lesion in the

A. Thalamus
B. Substantia nigra
C. Hypothalamus
D. Striatum (Correct Answer)

Explanation: ***Striatum*** - Parkinson's disease is characterized by the degeneration of **dopaminergic neurons** in the substantia nigra, leading to a deficiency of **dopamine** in the **striatum** [1]. - The striatum, composed of the **caudate nucleus** and **putamen**, receives dopaminergic input from the substantia nigra and plays a crucial role in **motor control** [1]. *Thalamus* - The thalamus acts as a **relay station** for sensory and motor signals to the cerebral cortex [1]. - While it's involved in basal ganglia circuits, it's not the primary site of pathology in Parkinson's disease. *Substantia nigra* - The **substantia nigra pars compacta** is the anatomical location where dopaminergic neurons degenerate in Parkinson's disease [1]. - However, the *lesion* itself leads to insufficient **dopamine release** *into the striatum*, which is the area that becomes functionally impaired due to the depleted neurotransmitter [1]. *Hypothalamus* - The hypothalamus is primarily involved in **regulating autonomic functions**, hormone release, and maintaining homeostasis. - It is not directly implicated in the primary motor symptoms of Parkinson's disease.

Question 5: A patient is brought to the OPD by his wife, complaining about difficulty expressing emotions and lack of participation in daily activities. On examination, resting tremors and rigidity are noted. Given the possible diagnosis, which part of the brain is affected in this patient?

A. Basal ganglia (Correct Answer)
B. Hippocampus
C. Cerebellum
D. Premotor cortex

Explanation: **Basal ganglia (Correct)** - The symptoms described—**resting tremors**, **rigidity**, difficulty expressing emotions, and lack of participation—are classic features of **Parkinson's disease**, which is characterized by the degeneration of dopaminergic neurons in the **substantia nigra**, a component of the basal ganglia [1]. - The basal ganglia play a crucial role in motor control, learning, and emotion, and their dysfunction leads to the characteristic motor and non-motor symptoms observed [2]. *Hippocampus (Incorrect)* - The hippocampus is primarily involved in **memory formation** and spatial navigation. - Damage to the hippocampus typically results in **amnesia** or difficulties with new learning, not motor symptoms like tremors or rigidity [3]. *Cerebellum (Incorrect)* - The cerebellum is responsible for **coordination**, balance, and fine motor control [2]. - **Cerebellar dysfunction** typically manifests as **ataxia**, dysmetria, and intention tremors, which differ from the resting tremors and rigidity seen in this patient. *Premotor cortex (Incorrect)* - The premotor cortex is involved in the planning and preparation of movements, as well as the control of trunk and proximal limb muscles. - While it contributes to motor control, its primary dysfunction does not typically cause the combination of **resting tremors** and **rigidity** characteristic of Parkinson's disease.

Question 6: When blood pressure falls below 40 mm Hg, which mechanism of regulation is working?

A. CNS ischemic reflex (Correct Answer)
B. Chemoreceptor response
C. Baroreceptor response
D. None of the options

Explanation: ***CNS ischemic reflex*** - The **CNS ischemic reflex** is activated when blood pressure falls below 60 mmHg, with maximal activation below 40 mmHg, indicating severe ischemia in the brain's vasomotor center. - This reflex elicits an intense **sympathetic vasoconstriction** and cardiac stimulation to prioritize blood flow to the brain even at the expense of other organs. *Chemoreceptor response* - The chemoreceptor reflex is primarily activated by a decrease in **arterial pO2**, an increase in **pCO2**, or a decrease in **pH**. - While it can increase blood pressure, it is not the primary or most profound regulatory mechanism specifically triggered by extremely low blood pressure (below 40 mmHg) to prevent brain ischemia. *Baroreceptor response* - **Baroreceptors** are most sensitive to changes in blood pressure within the normal to moderately hypotensive range (e.g., 60-180 mmHg). - At very low pressures (below 40-50 mmHg), baroreceptors become **less sensitive** or "saturated," and their effectiveness in raising blood pressure significantly diminishes. *None of the options* - This option is incorrect because the **CNS ischemic reflex** specifically functions as a powerful, last-ditch mechanism to maintain cerebral blood flow during severe hypotension which is a life saving reflex during conditions like hemorrhage.

Question 7: Which of the following statements about Kernicterus is TRUE?

A. Prematurity is the primary cause of Kernicterus
B. Kernicterus is due to Unconjugated Hyperbilirubinemia (Correct Answer)
C. Kernicterus is not associated with increased morbidity.
D. Yellowish staining occurs primarily in the Cerebellum in Kernicterus

Explanation: ***Kernicterus is due to Unconjugated Hyperbilirubinemia*** - **Kernicterus** is a rare but severe neurological condition caused by **high levels of unconjugated bilirubin** in a newborn's blood. - **Unconjugated bilirubin** is lipophilic and can cross the **blood-brain barrier**, particularly when levels are excessively high or the barrier is compromised. *Prematurity is the primary cause of Kernicterus* - **Prematurity** is a **major risk factor** for kernicterus, as premature infants have immature livers, reduced albumin binding sites, and a less developed blood-brain barrier. - However, the primary cause is the **unconjugated hyperbilirubinemia** itself, which can occur in both term and preterm infants, though it is more common and severe in prematures. *Yellowish staining occurs primarily in the Cerebellum in Kernicterus* - While kernicterus does affect the **cerebellum**, the **primary and most characteristic sites** of bilirubin deposition are the **basal ganglia**, hippocampus, and brainstem nuclei. - The **basal ganglia** are the predominant target, not the cerebellum, making this statement anatomically incorrect. *Kernicterus is not associated with increased morbidity.* - Kernicterus is associated with **significant morbidity** and can lead to permanent neurological damage, including **cerebral palsy**, hearing loss, intellectual disabilities, and gaze abnormalities. - It is a medical emergency that requires prompt diagnosis and treatment to prevent long-term neurological sequelae.

Question 8: Lesion of globus pallidus causes-

A. Hemibalismus
B. Chorea
C. Athetosis (Correct Answer)
D. Flexion dystonia

Explanation: ***Athetosis*** - A lesion in the **globus pallidus**, particularly the *internal segment*, or its connections can lead to **athetosis**, characterized by slow, writhing, involuntary movements. - The **globus pallidus** plays a crucial role in regulating movement patterns by modulating the activity of the thalamus and cortex. *Hemibalismus* - **Hemiballismus** is typically caused by a lesion in the **subthalamic nucleus**, often due to stroke. - It involves violent, flinging, involuntary movements on one side of the body. *Chorea* - **Chorea** is characterized by brief, irregular, unpredictable, and rapid involuntary movements, often associated with lesions in the **caudate nucleus** or **putamen** (e.g., in Huntingdon's disease). - The globus pallidus is involved in the overall basal ganglia circuit but isn't the primary site for chorea. *Flexion dystonia* - **Dystonia**, including flexion dystonia, involves sustained or repetitive muscle contractions resulting in twisting and repetitive movements or abnormal fixed postures. - While basal ganglia dysfunction is implicated, lesions primarily causing flexion dystonia are more diverse and not exclusively localized to the globus pallidus.

Question 9: A patient presented with violent, flinging movements. Where is the lesion causing the hemiballismus seen?

A. Putamen
B. Subthalamic nucleus (Correct Answer)
C. Globus pallidus
D. Caudate nucleus

Explanation: ***Subthalamic nucleus*** - **Hemiballismus** is characterized by **violent, flinging movements** of one side of the body, most commonly affecting the proximal limbs [1]. - This involuntary movement disorder is typically caused by a lesion, often an **infarct** or **hemorrhage**, in the **contralateral subthalamic nucleus (STN)** [1]. *Putamen* - Lesions in the **putamen** are more commonly associated with other movement disorders such as **dystonia** or **chorea**. - The putamen is part of the **striatum** and plays a key role in the direct and indirect pathways of the basal ganglia. *Globus pallidus* - Damage to the **globus pallidus (GP)**, particularly the external segment (GPe), can lead to conditions like **dystonia** or contribute to Parkinsonian symptoms depending on the specific region affected [2]. - The globus pallidus is a central component of the **basal ganglia output** to the thalamus. *Caudate nucleus* - Lesions in the **caudate nucleus** are closely linked to **Huntington's disease**, which primarily manifests as **chorea** and cognitive decline [1]. - The caudate nucleus is primarily involved in **cognitive functions** and motor control planning.

Question 10: Lesion of globus pallidus causes

A. Chorea
B. Athetosis (Correct Answer)
C. Hemibalismus
D. Dystonia

Explanation: ***Athetosis*** - **Athetosis** is the **classic movement disorder** associated with lesions of the **globus pallidus**, often occurring with **putamen** involvement. - It is characterized by **slow, writhing, involuntary movements**, particularly affecting the **distal extremities** (hands and feet). - Commonly seen in **kernicterus** (bilirubin-induced damage to basal ganglia), **cerebral palsy**, and **status marmoratus** of the basal ganglia. - When combined with chorea, it forms **choreoathetosis**. *Chorea* - **Chorea** is predominantly associated with dysfunction of the **caudate nucleus** and **putamen**, as seen in **Huntington's disease**. - It involves brief, irregular, unpredictable, **involuntary movements** that flow from one body part to another. *Hemibalismus* - **Hemibalismus** is most commonly caused by a lesion in the **subthalamic nucleus** (nucleus of Luys), often due to a **lacunar stroke**. - It involves large-amplitude, **involuntary flinging movements** of the limbs on **one side of the body**. *Dystonia* - **Dystonia** involves sustained or repetitive muscle contractions leading to twisting movements or abnormal fixed postures. - It results from dysfunction of **multiple basal ganglia structures** including the globus pallidus internal segment, putamen, and thalamus, but is **not the classic presentation** of isolated globus pallidus lesions.

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