Semester 2 Neuro, Quiz 4 - Basal Ganglia

The most appropriate pharmacotherapy for this patient's condition is levodopa/carbidopa. This patient's symptoms of involuntary left-hand twitches, resting hand tremor, and the ability to stop the shaking by looking at his hand and concentrating are consistent with Parkinson's disease. The bilateral cogwheel rigidity further supports this diagnosis. Levodopa/carbidopa is the mainstay treatment for Parkinson's disease as it helps to replenish dopamine levels in the brain and improve motor symptoms. Alteplase is a thrombolytic agent used for treating acute ischemic stroke, carbamazepine is an antiepileptic drug, glatiramer and interferon beta-l alpha are used for multiple sclerosis, and sertraline is an antidepressant.

The patient's symptoms of severe tremor, bradykinesia, rigidity, and cognitive decline, along with the pigmented cell loss in the substantia nigra seen on the CT scan, suggest a diagnosis of Parkinson's disease. Parkinson's disease is a neurodegenerative disorder characterized by the degeneration of dopaminergic neurons in the substantia nigra. Dopamine is the primary neurotransmitter involved in this disorder, as its deficiency leads to the motor and cognitive symptoms observed in Parkinson's disease. Treatment with L-dopa/carbidopa aims to increase dopamine levels in the brain and alleviate the dyskinetic symptoms.

The substantia nigra is the correct answer because it is a prominent population of melanin-containing cells located immediately internal to the crus cerebri. It is part of the basal ganglia and is involved in the regulation of movement and reward. The locus ceruleus is located in the pons and is involved in the regulation of arousal and stress responses. The pontine nuclei are also located in the pons and are involved in motor coordination. The red nucleus is located in the midbrain and is involved in motor control. The reticular formation is a network of neurons located throughout the brainstem and is involved in various functions including sleep, arousal, and attention.

The most likely diagnosis for this patient is Parkinson's disease. The patient's symptoms of involuntary left-hand twitches, resting hand tremor, and the ability to stop the shaking by looking at his hand and concentrating are characteristic of Parkinson's disease. Additionally, the absence of tremor in the right hand and unaffected lower extremities further support this diagnosis. The presence of bilateral cogwheel rigidity is also consistent with Parkinson's disease, as rigidity is a common symptom of the condition.

The patient's symptoms of uncontrollable flailing movements of his left arm suggest a lesion in the subthalamic nucleus. The subthalamic nucleus is part of the basal ganglia circuitry and plays a role in motor control. Lesions in this area can result in hyperkinetic movements, such as the flailing movements seen in this patient. The other structures listed, such as the cerebellar cortex plus nuclei, lenticular nucleus, ventral lateral nucleus, and ventral posterolateral nucleus, are not typically associated with these specific symptoms.

The patient's symptoms of sudden, uncontrollable movements of her left arm suggest hemiballismus. Hemiballismus is typically caused by a lesion in the contralateral subthalamic nucleus. Since the symptoms are on the left side, the lesion is most likely on the right side. Therefore, MRI would most likely show an infarction in the right subthalamic nucleus.

The most likely location of the degenerative changes at this stage of the physician's disease is the right substantia nigra. This is because Parkinson's disease is characterized by the degeneration of dopaminergic neurons in the substantia nigra, which leads to a decrease in dopamine levels. The symptoms described, such as the resting tremor, slow gait, and lack of facial expression, are consistent with the motor symptoms associated with Parkinson's disease. The fact that the tremor is present in the left hand suggests that the degenerative changes have already affected the contralateral side of the brain, which is why the right substantia nigra is the most likely location.

Huntington's disease is a neurodegenerative disorder characterized by movement abnormalities, cognitive decline, and psychiatric symptoms. It is caused by a genetic mutation that leads to degeneration of the basal ganglia, particularly the caudate nucleus. The absence of the head of the caudate in an MRI would be consistent with the diagnosis of Huntington's disease.

MPTP (1-methyl-4-phenyl-l,2,3,6-tetrahydropyridine) is the correct answer because it is known to produce a syndrome similar to the one seen in this patient. MPTP is a neurotoxin that selectively damages the substantia nigra, which is the part of the brain that is affected in Parkinson's disease. The symptoms described in the patient, such as involuntary left-hand twitches, resting hand tremors that can be stopped by looking at the hand and concentrating, and bilateral cogwheel rigidity, are characteristic of Parkinson's disease. MPTP is a known toxin that can cause Parkinsonism symptoms, making it the most likely agent responsible for the patient's condition.

Tolcapone is a catechol-O-methyltransferase (COMT) inhibitor. COMT is an enzyme that breaks down dopamine in the brain. By inhibiting COMT, tolcapone increases the levels of dopamine in the brain, which can help improve symptoms of Parkinson's disease. This mechanism of action allows for better uptake of L-dopa into the brain, enhancing its therapeutic effects.

Neurologists specialize in diagnosing and treating disorders of the nervous system, which includes the brain, spinal cord, and nerves. Stroke, epilepsy, and multiple sclerosis are all neurological conditions that affect the nervous system. Glaucoma, on the other hand, is an eye disease that primarily affects the optic nerve, which is part of the visual system, not the central nervous system. Glaucoma is typically treated by an ophthalmologist, a medical doctor specializing in eye care.

The correct answer is a monoamine oxidase B inhibitor. This drug prevents the breakdown of dopamine by inhibiting the enzyme monoamine oxidase B, which is responsible for breaking down dopamine in the brain. By inhibiting this enzyme, the drug helps to maintain higher levels of dopamine in the brain, preventing the development of Parkinsonian symptoms in the monkeys.