Neurology — MCQs

Neurology Indian Medical PG Practice Questions and MCQs

Question 61: In the ECG tracing shown below, which of the following is correct?

A. First degree AV block, intranodal
B. Second degree AV block type 1, intranodal (Correct Answer)
C. Second degree AV block type 2, infranodal
D. Second degree AV block type 2, intranodal

Explanation: ***Second degree AV block type 1, intranodal*** - The ECG shows **progressive lengthening of the PR interval** with each successive beat, followed by a **dropped QRS complex**, a classic pattern for Mobitz I (Wenckebach) AV block. - Mobitz I block is almost always due to a physiological delay within the **AV node (intranodal)**. *First degree AV block, intranodal* - First-degree AV block is characterized by a **constant, prolonged PR interval** (>0.20 seconds) without any dropped QRS complexes. - While it can be intranodal, the key feature of a dropped beat after progressive PR lengthening is absent here. *Second degree AV block type 2, infranodal* - Second degree AV block type 2 (Mobitz II) involves a **constant PR interval** for conducted beats, but with intermittent, **unheralded dropped QRS complexes**. - Mobitz II is typically due to disease in the **His-Purkinje system (infranodal)** and carries a higher risk of progression to complete heart block. *Second degree AV block type 2, intranodal* - Second-degree AV block type 2 is characterized by a **constant PR interval** with intermittently dropped beats. - While Mobitz II is usually infranodal, the hallmark of progressive PR lengthening seen in the tracing rules out Mobitz II entirely.

Question 62: A 65-year-old man loses consciousness at a Newyear party. On admission heart rate is 50 / min and BP is 170 / 110 mm Hg. JVP is normal. S2 is normal split and chest is bilaterally clear. The medic shows you his ECG. Troponin I value is <0.04 ng / dL. GCS is 7. Comment on the diagnosis.

A. STEMI
B. Stroke (Correct Answer)
C. Hyperkalemia
D. Stokes-Adams syndrome

Explanation: ***Stroke*** - The combination of **altered consciousness (GCS 7)**, **hypertension (BP 170/110 mmHg)**, and **bradycardia (HR 50/min)** in an elderly patient losing consciousness abruptly is highly suggestive of **Cushing's triad**, which is a sign of increased intracranial pressure often due to a stroke. - The **normal JVP and clear chest** rule out acute heart failure or pulmonary edema, and the **normal troponin I** rules out an acute myocardial infarction as the primary event. The provided ECG is essentially normal, lacking signs of acute ischemia or severe electrolyte disturbances. *STEMI* - An **ST-elevation myocardial infarction (STEMI)** would typically present with chest pain (though silent MIs can occur), and the ECG would show significant **ST-segment elevation** in at least two contiguous leads. - The patient's **troponin I is normal (<0.04 ng/dL)**, making STEMI very unlikely. *Hyperkalemia* - **Hyperkalemia** on ECG typically manifests as **tall, peaked T waves**, prolonged PR interval, wide QRS, and eventually sine wave patterns or asystole. - The provided ECG does not show these characteristic findings, rendering hyperkalemia an improbable primary diagnosis. *Stokes-Adams syndrome* - **Stokes-Adams syndrome** is characterized by recurrent syncopal attacks caused by transient **bradyarrhythmias or asystole** due to advanced AV block or sick sinus syndrome. - While the patient has bradycardia, there is no evidence of advanced AV block or asystole on the provided ECG, and the primary presentation points more strongly towards a neurological event.

Question 63: The most common cause of pontine hemorrhage is

A. Hypertension (Correct Answer)
B. Diabetes
C. Trauma
D. Aneurysmal rupture

Explanation: Hypertension - **Chronic hypertension** leads to the weakening and rupture of small perforating arteries in the pons, making it the most common cause of **pontine hemorrhage** [1]. - The elevated pressure damages the **endothelium** and smooth muscle layers of these vessels, predisposing them to bleeding. *Diabetes* - While diabetes can cause microvascular complications, it is not considered the most common cause of **pontine hemorrhage**. - Its primary cerebral vascular complications include increased risk of **ischemic stroke** rather than hemorrhagic stroke in the pons. *Trauma* - **Traumatic brain injury** can cause various types of intracranial hemorrhage, but isolated **pontine hemorrhage** directly due to trauma is less common than that due to hypertension [1]. - Trauma typically results in contusions, subdural, or epidural hematomas, often in superficial brain regions. *Aneurysmal rupture* - **Aneurysmal rupture** is a common cause of subarachnoid hemorrhage, particularly from the Circle of Willis, but pontine hemorrhages are rarely caused by aneurysms within the pons itself [1]. - The vessels supplying the pons are typically small and perforating, not commonly forming dissecting or saccular aneurysms.

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