22. Meningitis, encephalitis

Question 1

Define meningitis

Answer 1

Inflammation of the meninges (dura, arachnoid, pia mater)

Question 2

Etiology of meningitis

Answer 2

1. Aseptic: viruses (enteroviruses), fungi, parasites, medications, tumors
2. Septic: bacterial
   - Infants: GBS, E. coli, listeria monocytogenes
   - Older: Neisseria meningitidis, strep. pneumoniae

Question 3

Aseptic meningitis

Answer 3

Negative CSF bacterial culture. 80% are caused by enteroviruses (coxsackie, echo). Outbreaks in early spring, late fall

Question 4

Bacterial meningitis CSF properties

Answer 4

High WBC count + high protein + low glucose in CSF

Question 5

Pathology of meningitis

Answer 5

Theres no MCH I or II antigens on neurons/astrocytes, so the immune system in CNS is weak. Pathogens cross the blood-liquid barrier to enter nervous system, penetrates CSF and spread through the brain. Most common route of infection is through nasopharynx – subdural space – subarachnoid space – meninges

Question 6

Signs of meningitis

Answer 6

• Positive meningeal signs = nuchal rigidity + Brudzinski’s sign + Kernig’s sign
• Petechiae (N. meningitis)
• Fever
• Increased ICP –> altered mental status + headache + seizures + nausea/vomiting

Question 7

Diagnosis of meningitis

Answer 7

• Lumbar puncture increased protein, cell count and decreased glc in bacterial
• Viral: PCR
• Bacterial: ELISA (PCR for listeria)

Question 8

Treatment of meningitis

Answer 8

Emperical: cefriaxone, amoxicillin, vancomycin
Confirmed N.meningitidis single dose ciprofloxacin to close contacts
Viral symptomatic treatment
Chemoprophylaxis = rifampicin
Autoimmune: corticosteroids

Question 9

Encephalitis

Answer 9

Inflammation of the brain parenchyma

Question 10

Types and etiology of encephalitis

Answer 10

• Infectious and non infectious
• Pure encephalitis = caused by viruses (arbovirus, enteroviruses, HSV, West-Nile, CMV)
• Meningoencephalitis = HSV + Naegleria fowleri
• Bacterial = neurosyphilis
• Paraneoplastic origin: tumor associated = SCLC + ovarian + breast

In 50% of acute encephalitis, caustive agent cannot be proven

Question 11

Arbovirus encephalitis pathology/mechanism/symptoms

Answer 11

• Summer, early fall
• 95% asymptomatic
• Two-phased: flu like symptoms, then neurological symptoms
• Mild, altered conciousness w. seizures for a short while

Question 12

HSV-1 encephalitis mechanism/pathology

Answer 12

• Temporal lobe dysfunction after latent phase and secondary activation
• Residual symptoms such as aphasia, memory and learning deficits and symptomatic epilepsy

Question 13

General clinical signs of encephalitis

Answer 13

• Fever, headache, seiure, altered conciousness

Question 14

Anti-NMDA encephalitis

Answer 14

Begins with flu like prodromal period, then disorientation, confusion, paranoid delusions, hallucinations. Later dyskinesia, seizures, autonomic dysfunction

Question 15

Diangosis of encephalitis

Answer 15

• EEG: diffuse slow waves
• CSF: mild lymphocytosis, increased protein
• Serology: pathogens
• CT/MRI

Question 16

Treatment of encephalitis

Answer 16

-HSV-1: acyclovir
- Autoimmune: IVIG, corticosteroids i.v.