FINALS: CENTRAL NERVOUS SYSTEM INFECTIONS

Question 1

What are the primary types of meningitis under bacterial CNS infections?

Answer 1

Acute Purulent Meningitis:
Meningococcal Meningitis
Haemophilus Influenzae Meningitis
Pneumococcal Meningitis
Sub-acute Bacterial Meningitis:
Tuberculous Meningitis

Question 2

What are the classic triad symptoms of bacterial meningitis in adults and children?

Answer 2

Fever
Headache
Neck stiffness

Question 3

What signs indicate meningeal irritation?

Answer 3

Nuchal rigidity
Kernig’s sign
Brudzinski’s sign

Question 4

What are common complications of bacterial meningitis?

Answer 4

Immediate:
Septic shock
Subdural effusion/empyema
Infarcts/venous thrombosis
Hydrocephalus
Seizures
Delayed:
Cranial nerve deficits
Focal neurologic deficits

Question 5

What is the typical CSF profile in bacterial meningitis?

Answer 5

Increased pressure
Increased WBC count (pleocytosis)
Increased protein (>45 mg/dL)
Decreased glucose (<45 mg/dL)

Question 6

What is the most common pathogen for neonatal bacterial meningitis?

Answer 6

Group B Streptococcus Agalactiae
Escherichia coli

Question 7

What are the primary antiviral treatments for herpes simplex encephalitis?

Answer 7

Acyclovir

Question 8

What are the key symptoms of Tuberculous Meningitis?

Answer 8

Prodromal symptoms (2 weeks to 3 months):
Headache, vomiting, fever, irritability
Nocturnal wakefulness, anorexia, weight loss
Physical findings:
Meningeal irritation signs, altered DTRs
Increased ICP signs, focal deficits

Question 9

What is the prognosis of Tuberculous Meningitis without treatment?

Answer 9

Death in 6 to 8 weeks

Question 10

What is the typical treatment regimen for Tuberculous Meningitis?

Answer 10

RIPEs (Rifampicin, Isoniazid, Pyrazinamide, Ethambutol)
Duration: 18 to 24 months

Question 11

What is the hallmark symptom of a brain abscess?

Answer 11

Headache

Question 12

Pathophysiology of Bacterial Meningitis

Answer 12

Pathogens enter CNS through hematogenous spread, contiguous infection, or direct inoculation.
Inflammatory cytokines (IL-1, TNF-α) release causes blood-brain barrier dysfunction.
Leads to increased intracranial pressure (ICP), cerebral edema, and impaired cerebral perfusion.

Question 13

What is the mode of infection in poliomyelitis?

Answer 13

Oral ingestion → Pharynx and ileum → Lymph nodes
Spread to blood vessels and anterior horn cells

Question 14

Clinical Manifestations of Bacterial Meningitis

Answer 14

Fever, headache, neck stiffness (classic triad).
Altered mental status, photophobia, vomiting.
Positive Kernig’s and Brudzinski’s signs.
Seizures and focal neurological deficits in severe cases.

Question 15

Pathophysiology of Viral Encephalitis

Answer 15

Virus infects neurons or glial cells via hematogenous spread or retrograde transport along peripheral nerves.
Causes neuronal damage, inflammation, and edema.
Can lead to diffuse or localized brain dysfunction.

Question 16

Clinical Manifestations of Viral Encephalitis

Answer 16

Fever, headache, altered mental status.
Behavioral changes, seizures, focal neurological signs.
Symptoms depend on the affected brain region (e.g., temporal lobe involvement in HSV encephalitis leads to memory issues).

Question 17

Pathophysiology of Brain Abscess

Answer 17

Infection localizes in the brain parenchyma due to contiguous spread (e.g., sinusitis) or hematogenous seeding.
Formation of pus-filled cavity surrounded by a capsule.
Leads to mass effect, inflammation, and increased ICP.

Question 18

Clinical Manifestations of Brain Abscess

Answer 18

Headache (common), fever, focal neurological deficits.
Seizures and symptoms of raised ICP (nausea, vomiting, papilledema).
Progression may cause altered consciousness

Question 19

Pathophysiology of Fungal CNS Infections (e.g., Cryptococcal Meningitis)

Answer 19

Spores inhaled into the lungs spread hematogenously to the CNS.
Fungi evade immune response and proliferate in cerebrospinal fluid.
Causes chronic meningitis with granulomatous inflammation.

Question 20

Clinical Manifestations of Fungal CNS Infections

Answer 20

Subacute onset of fever, headache, and neck stiffness.
Visual disturbances, cranial nerve palsies, and altered mental status.
Common in immunocompromised individuals (e.g., HIV/AIDS).

Question 21

Pathophysiology of Tuberculous Meningitis

Answer 21

Mycobacterium tuberculosis spreads to CNS via blood, forming tubercles.
Tubercles rupture into subarachnoid space, causing inflammation and granuloma formation.
Leads to hydrocephalus, vasculitis, and cranial nerve involvement.

Question 22

Clinical Manifestations of Tuberculous Meningitis

Answer 22

Gradual onset of fever, headache, and malaise.
Altered mental status, cranial nerve deficits, seizures.
Signs of raised ICP and long-term complications like hydrocephalus.

Question 23

Case: A 25-year-old presents with a 3-day history of fever, severe headache, and neck stiffness. He also reports sensitivity to light and nausea. On examination, he has altered mental status and a positive Brudzinski sign.
Diagnosis? Pathopysio?

Answer 23

Diagnosis: Bacterial Meningitis
Pathophysiology: Bacterial pathogens (e.g., Streptococcus pneumoniae) cause an inflammatory response in the meninges, leading to increased intracranial pressure, cerebral edema, and dysfunction of the blood-brain barrier.
Clinical Features: Fever, headache, neck stiffness, photophobia, altered mental status, vomiting. Kernig’s and Brudzinski signs may be positive.

Question 24

ase: A 50-year-old with a history of uncontrolled diabetes presents with confusion, fever, and a headache for the past week. On MRI, there is a localized lesion in the temporal lobe.
Diagnosis?

Answer 24

Diagnosis: Viral Encephalitis (likely Herpes Simplex Virus)
Pathophysiology: HSV invades the CNS via retrograde transport along the olfactory or trigeminal nerves, causing inflammation, neuronal injury, and edema.
Clinical Features: Fever, headache, confusion, altered mental status, seizures, and focal neurological deficits (often affecting the temporal lobe, leading to memory issues).

Question 25

A 45-year-old patient with a history of recent travel to an endemic area presents with fever, headache, neck stiffness, and confusion. CSF analysis reveals an elevated white blood cell count with a predominance of neutrophils and a high protein level.

Answer 25

Diagnosis: Meningococcal Meningitis
Pathophysiology: Neisseria meningitidis enters the CNS through the bloodstream, causing acute purulent inflammation in the meninges and leading to cerebral edema and raised ICP.
Clinical Features: Rapid onset of fever, headache, neck stiffness, photophobia, vomiting, altered mental status, and potential for sepsis. CSF shows high WBC count, elevated protein, and decreased glucose.

Question 26

Case: A 32-year-old male presents with a history of sinusitis followed by the sudden onset of severe headache, fever, and confusion. CT scan reveals a localized mass in the right frontal lobe.

Answer 26

Diagnosis: Brain Abscess secondary to Sinusitis

Question 27

Case: A 28-year-old immunocompromised patient presents with fever, headache, and stiff neck. On examination, they have a positive Kernig sign, and MRI shows leptomeningeal enhancement.

Answer 27

Diagnosis: Fungal Meningitis (likely due to Candida or Aspergillus)