CNS Infections Indian Medical PG Practice Questions and MCQs
Practice Indian Medical PG questions for CNS Infections. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
CNS Infections Indian Medical PG Question 1: A young male develops fever, followed by headache, confusional state, focal seizures and a right hemiparesis. The MRI performed shows bilateral frontotemporal hyperintense lesion. The most likely diagnosis is
- A. Acute pyogenic meningitis
- B. Carcinomatous meningitis
- C. Cerebral abscess
- D. Herpes Simplex Encephalitis (Correct Answer)
CNS Infections Explanation: ***Herpes Simplex Encephalitis***
- The constellation of **fever**, **headache**, **confusional state**, **focal seizures**, and **right hemiparesis** points strongly to an encephalitic process [1].
- The MRI finding of **bilateral frontotemporal hyperintense lesions** is highly characteristic of Herpes Simplex Encephalitis (**HSE**) [1].
*Acute pyogenic meningitis*
- Typically presents with fever, headache, and **meningeal signs** like nuchal rigidity, which are not explicitly mentioned as predominant features.
- While it can cause confusion, focal neurological deficits and seizures are less specific, and the MRI findings would typically show **leptomeningeal enhancement** rather than frontotemporal parenchymal involvement.
*Carcinomatous meningitis*
- This condition usually develops in patients with a known or occult malignancy and is characterized by a more **insidious onset** of neurological symptoms.
- MRI findings would typically show **leptomeningeal enhancement** or nodular seeding, not focal bilateral frontotemporal hyperintensities.
*Cerebral abscess*
- A cerebral abscess can cause fever, headache, focal deficits, and seizures, but its onset is often more protracted, and the MRI would typically show a **ring-enhancing lesion** with surrounding edema.
- The description of bilateral frontotemporal hyperintense lesions is not characteristic of a single or multiple discrete abscesses.
CNS Infections Indian Medical PG Question 2: Which of the following statements is true regarding HSV encephalitis?
- A. Hemorrhagic lesions are seen (Correct Answer)
- B. Caused by HSV-1
- C. Eosinophilic inclusion bodies are seen
- D. Caused by Varicella zoster virus
CNS Infections Explanation: ***Hemorrhagic lesions are seen***
- **Hemorrhagic necrosis** of the **temporal lobes** is the pathognomonic feature of HSV encephalitis [3]
- The hemorrhagic nature helps differentiate it from other viral encephalitides
- Classically affects the **medial temporal lobes** and **inferior frontal lobes** bilaterally [2]
- MRI shows hemorrhagic changes with mass effect in these regions
*Caused by HSV-1*
- While **HSV-1** causes >90% of HSV encephalitis cases in adults and children, this statement is technically correct
- However, **hemorrhagic lesions** are the more distinctive pathological feature being tested
- HSV-1 is the causative agent, but the hemorrhagic pathology is the key diagnostic finding
*Eosinophilic inclusion bodies are seen*
- **Cowdry type A intranuclear inclusion bodies** are indeed seen in HSV encephalitis [1]
- These are **eosinophilic** with a clear halo around them
- While true, this is a microscopic finding, whereas hemorrhagic lesions are the macroscopic hallmark
*Caused by Varicella zoster virus*
- VZV causes **varicella** (chickenpox) and **herpes zoster** (shingles) [2]
- VZV can cause encephalitis but with different clinical and pathological features
- HSV encephalitis is specifically caused by **herpes simplex virus**, not varicella zoster virus
**References:**
[1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 365-366.
[2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1278-1279.
[3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, p. 1278.
CNS Infections Indian Medical PG Question 3: Which of the following is the classical CSF finding seen in tubercular meningitis?
- A. Increased protein, decreased sugar, increased lymphocytes (Correct Answer)
- B. Increased protein, sugar and lymphocytes
- C. Decreased protein, increased sugar and lymphocytes
- D. Increased sugar, protein and neutrophils
CNS Infections Explanation: ***Increased protein, decreased sugar, increased lymphocytes***
- In **tubercular meningitis**, the **inflammatory response** leads to increased protein in the CSF due to vascular permeability and breakdown of the blood-brain barrier [2].
- **Mycobacterium tuberculosis** consumes glucose, resulting in **decreased CSF sugar**; the immune response is primarily **lymphocytic**, leading to elevated lymphocytes [1].
*Increased protein, sugar and lymphocytes*
- While **increased protein and lymphocytes** are consistent with tubercular meningitis, **increased CSF sugar** is not, as the bacteria actively consume glucose.
- This pattern is generally not seen in **bacterial or tuberculous infections** of the meninges [2].
*Decreased protein, increased sugar and lymphocytes*
- **Decreased protein** is atypical for infectious meningitis, where inflammation usually causes protein elevation.
- **Increased CSF sugar** is also inconsistent with tubercular meningitis, which classically causes hypoglycemia in the CSF [3].
*Increased sugar, protein and neutrophils*
- The presence of **increased neutrophils** is characteristic of **acute bacterial meningitis**, not tubercular meningitis, which typically involves lymphocytes [2].
- **Increased sugar** is also incorrect for tubercular meningitis; moreover, acute bacterial meningitis usually presents with **decreased CSF sugar** as bacteria consume it.
CNS Infections Indian Medical PG Question 4: The typical CSF profile in cases of viral meningitis after 48 hours of onset is -
- A. Neutrophilic pleocytosis, raised glucose level, normal protein level
- B. Lymphocytic pleocytosis, low glucose level, low protein level
- C. Lymphocytic pleocytosis, normal glucose level, normal or slightly elevated protein level (Correct Answer)
- D. Neutrophilic pleocytosis, normal glucose level, elevated protein level
CNS Infections Explanation: ***Lymphocytic pleocytosis, normal glucose level, normal or slightly elevated protein level***
- After 48 hours, the **CSF analysis** in viral meningitis typically shows a predominance of **lymphocytes** (lymphocytic pleocytosis) as the immune response shifts from neutrophils to mononuclear cells [1].
- Glucose levels remain **normal** in viral meningitis because viruses do not consume glucose, and protein levels are usually **normal to slightly elevated** due to mild inflammation and increased blood-brain barrier permeability [1].
*Neutrophilic pleocytosis, raised glucose level, normal protein level*
- **Neutrophilic pleocytosis** is characteristic of **bacterial meningitis**, especially in the initial stages, not viral meningitis.
- **Raised glucose levels** in CSF are not a feature of meningitis; glucose levels are typically normal or low in infectious meningitis.
*Lymphocytic pleocytosis, low glucose level, low protein level*
- While **lymphocytic pleocytosis** is seen in viral meningitis, a **low glucose level** (**hypoglycorrhachia**) is more commonly associated with **bacterial** or **fungal meningitis**, as these pathogens consume glucose.
- A **low protein level** is also atypical for meningitis, where protein levels are generally normal or elevated.
*Neutrophilic pleocytosis, normal glucose level, elevated protein level*
- **Neutrophilic pleocytosis** is characteristic of **bacterial meningitis**, not viral meningitis, particularly after 48 hours.
- Although **elevated protein levels** can be seen in both viral and bacterial meningitis, the presence of **neutrophilic pleocytosis** makes this option less likely for viral meningitis.
CNS Infections Indian Medical PG Question 5: A 10-year-old girl presented with fever, convulsions, and neck rigidity. CSF findings are protein 150 mg/dL, sugar 40 mg/dL with lymphocytic pleocytosis –
- A. Viral meningitis
- B. Pyogenic meningitis
- C. Tuberculous meningitis (Correct Answer)
- D. Cryptococcal meningitis
CNS Infections Explanation: ***Tuberculous meningitis***
- The combination of **fever, convulsions, neck rigidity** (suggesting meningitis), elevated **CSF protein (150 mg/dL)**, **low CSF sugar (40 mg/dL)**, and **lymphocytic pleocytosis** is highly characteristic of tuberculous meningitis.
- Tuberculous meningitis typically presents with a **subacute** or **chronic** course and CSF analysis reveals **elevated protein**, **low glucose**, and a **lymphocytic pleocytosis**.
*Viral meningitis*
- While viral meningitis presents with fever and meningeal signs, the **CSF protein** is usually mildly elevated (<100 mg/dL), and **CSF glucose** is typically normal.
- Often has a **benign and self-limiting course** with predominantly lymphocytic pleocytosis.
*Pyogenic meningitis*
- Characterized by very high **CSF protein (>100 mg/dL)**, very low **CSF glucose (<40 mg/dL)**, and a predominant **neutrophilic pleocytosis**.
- Symptoms are usually **acute and severe**, rapidly progressing over hours to days.
*Cryptococcal meningitis*
- This is more common in **immunocompromised individuals**, such as those with HIV/AIDS, and the clinical picture in a 10-year-old girl without immune compromise makes it less likely.
- While it can cause elevated CSF protein and low glucose, the presence of **lymphocytic pleocytosis** is less specific for cryptococcal infection compared to tuberculous meningitis in this clinical context.
CNS Infections Indian Medical PG Question 6: A patient has had recurrent optic neuritis bilaterally with transverse myelitis. Visual acuity in right eye is 6/60 and left eye is 6/18. Patient showed a 50% response to steroids. Diagnosis is?
- A. Neuromyelitis Optica (Correct Answer)
- B. Neuro-sarcoidosis
- C. Subacute combined degeneration of spinal cord(SACD)
- D. Multiple Sclerosis
CNS Infections Explanation: ***Neuromyelitis Optica***
- The combination of **recurrent bilateral optic neuritis** and **transverse myelitis** is highly characteristic of Neuromyelitis Optica (NMO).
- NMO is often associated with the presence of **aquaporin-4 (AQP4) antibodies**, although this is not mentioned, the clinical presentation is key.
*Neuro-sarcoidosis*
- While sarcoidosis can affect the nervous system (**neuro-sarcoidosis**) and cause **optic neuritis** or **myelopathy**, recurrent, bilateral severe optic neuritis and transverse myelitis in this pattern are less typical.
- Neuro-sarcoidosis often presents with other systemic features or cranial neuropathies.
*Subacute combined degeneration of spinal cord (SACD)*
- SACD is primarily caused by **Vitamin B12 deficiency** and typically manifests as progressive **paresthesias**, **ataxia**, and **weakness**, predominantly affecting the posterior and lateral columns of the spinal cord.
- It does not typically involve **optic neuritis** or a relapsing-remitting course like the one described.
*Multiple Sclerosis*
- Multiple sclerosis (MS) can cause **optic neuritis** and **transverse myelitis**, but the **severity** and **recurrence** of bilateral optic neuritis in this patient are more suggestive of NMO.
- While MS can present with similar symptoms, the profound visual loss and recurrent nature of both conditions make NMO a stronger differential, especially given the characteristic lesions for NMO in the spinal cord, which are often longer than in MS.
CNS Infections Indian Medical PG Question 7: Symptomatic neonatal CNS involvement is most commonly seen in which group of congenital intrauterine infections?
- A. Rubella and toxoplasmosis
- B. CMV and syphilis
- C. Rubella and HSV
- D. CMV and toxoplasmosis (Correct Answer)
CNS Infections Explanation: ***CMV and toxoplasmosis***
- Both **cytomegalovirus (CMV)** and **Toxoplasma gondii** are well-known causes of congenital infections that frequently lead to significant and symptomatic central nervous system (CNS) involvement in neonates.
- Congenital CMV can cause **microcephaly**, **periventricular calcifications**, **hearing loss**, and developmental delay, while congenital toxoplasmosis can result in **hydrocephalus**, **intracranial calcifications**, **chorioretinitis**, and seizures.
*Rubella and toxoplasmosis*
- While **toxoplasmosis** causes significant CNS involvement, **congenital rubella syndrome** typically presents with cataracts, heart defects (e.g., patent ductus arteriosus), and hearing loss, with CNS involvement being less consistently severe or frequently symptomatic in the immediate neonatal period compared to CMV or toxoplasmosis.
- Although rubella can cause **encephalitis** or **meningoencephalitis**, these are not as common or consistently severe as the direct destructive CNS lesions seen with CMV or toxoplasmosis.
*CMV and syphilis*
- **CMV** is a major cause of neonatal CNS symptoms. However, **congenital syphilis** primarily affects bones, skin, and mucous membranes (e.g., "snuffles"), with CNS involvement typically presenting as **meningitis**, **hydrocephalus**, or neurodevelopmental delays, but often not as overtly symptomatic in the immediate neonatal period as CMV or toxoplasmosis.
- While syphilis can cause neurosyphilis, the spectrum and severity of immediate symptomatic CNS involvement are distinct from the widespread calcifications and structural abnormalities seen with CMV or toxoplasmosis.
*Rubella and HSV*
- **Rubella** primarily causes classic congenital defects in eyes, ears, and heart, with CNS effects being less common and severe.
- **Congenital herpes simplex virus (HSV)** infection, while causing severe CNS disease (e.g., encephalitis) when disseminated, is relatively rare overall compared to CMV and toxoplasmosis, and often presents with skin, eye, and mouth lesions first.
CNS Infections Indian Medical PG Question 8: Symptomatic neonatal CNS involvement is most commonly seen in which group of congenital intrauterine infections?
- A. Rubella and HSV
- B. CMV and Toxoplasmosis (Correct Answer)
- C. CMV and Syphilis
- D. Rubella and Toxoplasmosis
CNS Infections Explanation: ***CMV and Toxoplasmosis***
- **Cytomegalovirus (CMV)** is the **most common congenital infection** causing symptomatic neonatal CNS involvement, affecting 0.5-2% of live births and being the leading cause of non-genetic sensorineural hearing loss and neurological disability.
- CMV causes **microcephaly, periventricular intracranial calcifications, ventriculomegaly, seizures**, and developmental delay.
- **Toxoplasmosis** is the second most common, presenting with the classic triad of **hydrocephalus, diffuse intracranial calcifications, and chorioretinitis**.
- Together, these two represent the **most frequently encountered** causes of symptomatic congenital CNS disease.
*Rubella and HSV*
- While both can cause neurological complications, they are **not the most common** causes of congenital CNS involvement.
- **Rubella** is now rare due to widespread vaccination programs.
- **HSV** as a true **congenital intrauterine infection is extremely rare**; most neonatal HSV is acquired **perinatally during delivery** or postnatally, not as a congenital infection.
*Rubella and Toxoplasmosis*
- While **Toxoplasmosis** is indeed a common cause of congenital CNS disease, **Rubella** is now uncommon due to vaccination.
- This combination doesn't represent the most frequently seen pair compared to CMV and Toxoplasmosis.
*CMV and Syphilis*
- **CMV** is correct as the most common cause, but **Syphilis** primarily causes multi-system involvement including hepatosplenomegaly, skin rashes, and bone abnormalities.
- While **neurosyphilis** can occur, CNS involvement is less consistently present compared to **Toxoplasmosis**, which characteristically causes the classic triad with prominent CNS features.
CNS Infections Indian Medical PG Question 9: A 6-year-old with recurrent febrile seizures presents lethargic with a high fever. What is the most appropriate next step in management?
- A. Perform lumbar puncture (Correct Answer)
- B. Consider using antipyretics for comfort
- C. Start anticonvulsants
- D. Order urgent EEG
CNS Infections Explanation: ***Perform lumbar puncture***
- The combination of **lethargy**, high fever, and a history of recurrent febrile seizures in a 6-year-old child raises suspicion for **meningitis or encephalitis**, necessitating a prompt **lumbar puncture** to analyze **cerebrospinal fluid (CSF)**.
- While febrile seizures alone are benign, **altered mental status (lethargy)** in conjunction with fever is a red flag for **central nervous system infection**.
*Consider using antipyretics for comfort*
- **Antipyretics** can help reduce fever and improve comfort but do not address the underlying cause of lethargy and potential CNS infection.
- Delaying definitive diagnostic steps like a **lumbar puncture** while waiting for antipyretics to work could worsen the patient's prognosis if a serious infection is present.
*Start anticonvulsants*
- **Anticonvulsants** are primarily used for managing ongoing seizures or preventing recurrent non-febrile seizures but are **not indicated as a first-line diagnostic or emergency treatment** for a child presenting with **fever and lethargy without active seizures**.
- There is no clinical indication of current seizure activity, and the immediate concern is detecting a potential **CNS infection**.
*Order urgent EEG*
- An **EEG (electroencephalogram)** is useful for evaluating seizure disorders or encephalopathy but is **not the most appropriate initial diagnostic step** when a **serious CNS infection like meningitis** is suspected.
- A **lumbar puncture** is crucial for diagnosing or ruling out meningitis, which requires immediate treatment.
CNS Infections Indian Medical PG Question 10: Eosinophilic meningitis is seen with all except:
- A. Cryptococcal meningitis (Correct Answer)
- B. Coccidioidomycosis
- C. Helminthic infections
- D. Leptomeningeal metastasis
CNS Infections Explanation: ***Cryptococcal meningitis***
- This is a **fungal infection** that typically causes a **lymphocytic or monocytic pleocytosis** in the cerebrospinal fluid (CSF), not eosinophilic meningitis.
- While it can occur in immunocompromised individuals, **eosinophilia in the CSF** is not a characteristic feature.
*Coccidioidomycosis*
- This **fungal infection** can cause meningitis with a notable **eosinophilic pleocytosis** in the CSF [1].
- It is known to produce a chronic meningitis that may present with CSF eosinophilia.
*Helminthic infections*
- **Parasitic infections** like **Strongyloides, Gnathostoma, and Angiostrongylus cantonensis** are well-known causes of eosinophilic meningitis [2].
- The host immune response to these parasites often involves a strong **eosinophilic infiltrate** [2].
*Leptomeningeal metastasis*
- **Leptomeningeal carcinomatosis** (metastasis) can cause a variety of CSF findings, including an **eosinophilic pleocytosis** [3].
- This is particularly true for certain types of cancers like **lymphoma** or **small cell lung cancer**.
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