Corticospinal tracts US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for Corticospinal tracts. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Corticospinal tracts US Medical PG Question 1: A 25-year-old man comes to the physician for severe back pain. He describes the pain as shooting and stabbing. On a 10-point scale, he rates the pain as a 9 to 10. The pain started after he lifted a heavy box at work; he works at a supermarket and recently switched from being a cashier to a storekeeper. The patient appears to be in severe distress. Vital signs are within normal limits. On physical examination, the spine is nontender without paravertebral muscle spasms. Range of motion is normal. A straight-leg raise test is negative. After the physical examination has been completed, the patient asks for a letter to his employer attesting to his inability to work as a storekeeper. Which of the following is the most appropriate response?
- A. “Yes. Since work may worsen your condition, I would prefer that you stay home a few days. I will write a letter to your employer to explain the situation.”
- B. You say you are in severe pain. However, the physical examination findings do not suggest a physical problem that can be addressed with medications or surgery. I'd like to meet on a regular basis to see how you're doing.
- C. I understand that you are uncomfortable, but the findings do not match the severity of your symptoms. Let's talk about the recent changes at your job. (Correct Answer)
- D. The physical exam findings do not match your symptoms, which suggests a psychological problem. I would be happy to refer you to a mental health professional.
- E. The physical exam findings suggest a psychological rather than a physical problem. But there is a good chance that we can address it with cognitive-behavioral therapy.
Corticospinal tracts Explanation: ***"I understand that you are uncomfortable, but the findings do not match the severity of your symptoms. Let's talk about the recent changes at your job."***
- This response acknowledges the patient's reported discomfort while gently highlighting the **discrepancy between symptoms and objective findings**, which is crucial in cases of suspected **somatoform or functional pain**.
- It also opens communication about potential **psychosocial stressors** related to his job change, which could be contributing to his symptoms, without dismissing his pain or making a premature diagnosis.
*"You say you are in severe pain. However, the physical examination findings do not suggest a physical problem that can be addressed with medications or surgery. I'd like to meet on a regular basis to see how you're doing."*
- While this option correctly identifies the lack of physical findings, it can be perceived as dismissive of the patient's pain, potentially damaging the **physician-patient relationship**.
- Suggesting regular meetings without a clear plan for addressing his immediate concerns or exploring underlying issues might not be the most effective initial approach.
*“Yes. Since work may worsen your condition, I would prefer that you stay home a few days. I will write a letter to your employer to explain the situation.”*
- This response would **validate the patient's claim of severe pain** without objective evidence, potentially reinforcing illness behavior and avoiding addressing the underlying issue.
- Providing a doctor's note for inability to work without a clear diagnostic basis or understanding of the pain's origin is **medically inappropriate** and could set a precedent for future such requests.
*"The physical exam findings do not match your symptoms, which suggests a psychological problem. I would be happy to refer you to a mental health professional."*
- Directly labeling the problem as "psychological" can be **stigmatizing and alienating** to the patient, leading to distrust and resistance to care.
- While a psychological component might be present, immediately referring to mental health without further exploration of the patient's situation or current stressors is premature and lacks empathy.
*"The physical exam findings suggest a psychological rather than a physical problem. But there is a good chance that we can address it with cognitive-behavioral therapy."*
- Similar to the previous option, explicitly stating a "psychological problem" can be **stigmatizing**.
- Jumping directly to recommending **cognitive-behavioral therapy (CBT)** without a comprehensive discussion and patient buy-in is premature and may lead to non-compliance.
Corticospinal tracts US Medical PG Question 2: A 78-year-old woman is accompanied by her family for a routine visit to her primary care provider. The family states that 5 months prior, the patient had a stroke and is currently undergoing physical therapy. Today, her temperature is 98.2°F (36.8°C), blood pressure is 112/72 mmHg, pulse is 64/min, and respirations are 12/min. On exam, she is alert and oriented with no deficits in speech. Additionally, her strength and sensation are symmetric and preserved bilaterally. However, on further neurologic testing, she appears to have some difficulty with balance and a propensity to fall to her right side. Which of the following deficits does the patient also likely have?
- A. Hemiballismus
- B. Hemispatial neglect
- C. Intention tremor
- D. Contralateral eye deviation
- E. Truncal ataxia (Correct Answer)
Corticospinal tracts Explanation: ***Truncal ataxia***
- This patient's symptoms of **difficulty with balance** and a **propensity to fall to her right side** are highly suggestive of truncal ataxia.
- While she had a stroke, her preserved speech, symmetric strength and sensation, and alertness rule out typical hemiparesis or aphasia, pointing towards a **cerebellar lesion** affecting balance and coordination.
*Hemiballismus*
- This condition involves **flailing, high-amplitude, involuntary movements** typically affecting one side of the body.
- The patient's description of balance issues and falling, without mention of such specific movements, makes hemiballismus less likely.
*Hemispatial neglect*
- Characterized by the **inability to attend to one side of the environment**, usually the left side following a right parietal stroke.
- The patient's presentation does not describe an indifference to one side of her visual or personal space.
*Intention tremor*
- An **intention tremor** is a tremor that worsens during purposeful movement towards a target.
- While it can be associated with cerebellar dysfunction, the primary deficit described is imbalance and falling to one side, not specifically a tremor.
*Contralateral eye deviation*
- This typically occurs in acute stroke scenarios as part of a **gaze preference**, where the eyes deviate towards the side of the lesion (or away from the hemiparesis).
- The patient is 5 months post-stroke and is alert with no acute focal deficits, making acute eye deviation unlikely as a chronic presenting symptom here.
Corticospinal tracts US Medical PG Question 3: An epidemiologist is evaluating the efficacy of Noxbinle in preventing HCC deaths at the population level. A clinical trial shows that over 5 years, the mortality rate from HCC was 25% in the control group and 15% in patients treated with Noxbinle 100 mg daily. Based on this data, how many patients need to be treated with Noxbinle 100 mg to prevent, on average, one death from HCC?
- A. 20
- B. 73
- C. 10 (Correct Answer)
- D. 50
- E. 100
Corticospinal tracts Explanation: ***10***
- The **number needed to treat (NNT)** is calculated by first finding the **absolute risk reduction (ARR)**.
- **ARR** = Risk in control group - Risk in treatment group = 25% - 15% = **10%** (or 0.10).
- **NNT = 1 / ARR** = 1 / 0.10 = **10 patients**.
- This means that **10 patients must be treated with Noxbinle to prevent one death from HCC** over 5 years.
*20*
- This would result from an ARR of 5% (1/0.05 = 20), which is not supported by the data.
- May arise from miscalculating the risk difference or incorrectly halving the actual ARR.
*73*
- This value does not correspond to any standard calculation of NNT from the given mortality rates.
- May result from confusion with other epidemiological measures or calculation error.
*50*
- This would correspond to an ARR of 2% (1/0.02 = 50), which significantly underestimates the actual risk reduction.
- Could result from incorrectly calculating the difference as a proportion rather than absolute percentage points.
*100*
- This would correspond to an ARR of 1% (1/0.01 = 100), grossly underestimating the treatment benefit.
- May result from confusing ARR with relative risk reduction or other calculation errors.
Corticospinal tracts US Medical PG Question 4: A 40-year-old man is brought to the emergency department after sustaining multiple lacerations during a bar fight. The patient’s wife says that he has been showing worsening aggression and has been involved in a lot of arguments and fights for the past 2 years. The patient has no significant past medical or psychiatric history and currently takes no medications. The patient cannot provide any relevant family history since he was adopted as an infant. His vitals are within normal limits. On physical examination, the patient looks apathetic and grimaces repeatedly. Suddenly, his arms start to swing by his side in an uncontrolled manner. Which area of the brain is most likely affected in this patient?
- A. Cerebral cortex
- B. Caudate nucleus (Correct Answer)
- C. Cerebellum
- D. Medulla oblongata
- E. Substantia nigra
Corticospinal tracts Explanation: **Caudate nucleus**
- The patient exhibits features like **worsening aggression**, **apathy**, and **uncontrolled, sudden movements** of the limbs, which are characteristic of Huntington's disease, a condition primarily affecting the **caudate nucleus**.
- **Huntington's disease** is an autosomal dominant neurodegenerative disorder linked to a trinucleotide repeat expansion (CAG) on chromosome 4, leading to atrophy of the **caudate and putamen**.
*Cerebral cortex*
- While damage to the cerebral cortex can cause personality changes and motor deficits, the specific combination of **choreiform movements** and progressive cognitive/behavioral decline seen here is more indicative of a basal ganglia disorder like Huntington's.
- Cortical lesions more commonly present with **focal neurological deficits** such as hemiparesis, aphasia, or sensory loss, which are not the primary features described.
*Cerebellum*
- Damage to the cerebellum typically results in **ataxia**, **dysmetria**, **intention tremor**, and problems with balance and coordination.
- The patient's **uncontrolled, sudden limb movements** are characteristic of chorea, not cerebellar dysfunction.
*Medulla oblongata*
- The medulla oblongata is crucial for vital autonomic functions such as **breathing, heart rate, and blood pressure regulation**.
- Lesions in this area would likely cause life-threatening symptoms, including **respiratory failure** or severe cardiovascular instability, which are not present in this patient.
*Substantia nigra*
- Damage or degeneration of the substantia nigra is primarily associated with **Parkinson's disease**, leading to symptoms like **bradykinesia**, **rigidity**, **resting tremor**, and **postural instability**.
- The patient's **hyperkinetic movements** (choreiform movements) are opposite to the hypokinetic presentation of Parkinson's disease.
Corticospinal tracts US Medical PG Question 5: A 21-year-old man was involved in a motor vehicle accident and died. At autopsy, the patient demonstrated abnormally increased mobility at the neck. A section of cervical spinal cord at C6 was removed and processed into slides. Which of the following gross anatomic features is most likely true of this spinal cord level?
- A. Cuneate and gracilis fasciculi are present (Correct Answer)
- B. Least amount of white matter
- C. Prominent lateral horns
- D. Absence of gray matter enlargement
- E. Involvement with parasympathetic nervous system
Corticospinal tracts Explanation: **Cuneate and gracilis fasciculi are present**
- At the **C6 level** of the spinal cord, both the **fasciculus gracilis** (carrying information from the lower body) and the **fasciculus cuneatus** (carrying information from the upper body) are present in the dorsal column.
- The fasciculus cuneatus typically appears at **T6 and above**, making it visible at C6.
*Least amount of white matter*
- The cervical spinal cord, particularly at C6, contains a **significant amount of white matter** because it carries all ascending and descending tracts to and from the brain, including those for the upper and lower limbs.
- The **sacral segments** typically have the least amount of white matter due to fewer tracts remaining.
*Prominent lateral horns*
- **Lateral horns** are characteristic of the **thoracic and upper lumbar (T1-L2/L3)** spinal cord segments, where they house preganglionic sympathetic neurons.
- They are generally **absent or poorly developed** in the cervical spinal cord.
*Absence of gray matter enlargement*
- The **cervical enlargement** of the spinal cord, particularly pronounced from C4 to T1, contains an increased amount of gray matter to accommodate the innervation of the **upper limbs**.
- Therefore, the C6 level would show **significant gray matter enlargement**.
*Involvement with parasympathetic nervous system*
- The **parasympathetic nervous system** exits the spinal cord at the **sacral levels (S2-S4)** and as cranial nerves, not primarily from the cervical spinal cord through distinct horns.
- The cervical spinal cord is primarily associated with **somatic motor and sensory pathways** for the neck, shoulders, and upper limbs, and receives some sympathetic input, but is not where parasympathetic outflow predominantly originates.
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