Meningitis and Encephalitis

Question 1

Meningitis Definition

Answer 1

Inflammatory disease of the meninges and CSF

Question 2

Common Pathogens for Bacterial Meningitis

Answer 2

• Adults: Strep pneumo
• Children: N. meningitidis

Question 3

Bacterial Meningitis Risk Factors

Answer 3

• exposure to meningitis
• travel to endemic area
• respiratory tract infection
• injection drug use
• penetrating head trauma
• neurosurgery
• devices - shunt, cochlear implants
• chronic disease

Question 4

Bacterial Meningitis Pathophysiology

Answer 4

• Inflammation and irritation of meninges
• Meningeal signs
• Neurological complications
• Cerebral edema
  
  • blood-brain barrier injury
  • cytotoxins
  • inflammation impedes reabsorption of CSF
• Increased intracranial pressure (ICP)
• Neurological complications
• Systemic symptoms - bacteremia

Question 5

Meningeal Signs

Answer 5

• Nuchal rigidity - stiff neck
  
  • flexion of neck - inability to touch chin to chest
• Kernig’s sign
• Brudzinski’s sign

Question 6

Signs of Increased ICP

Answer 6

• Mild/moderate
  
  • headache
  • confusion
  • irritability
  • nausea
  • vomiting
• Severe
  
  • altered mental status
  • cushing’s reflex
  • papilledema
  • cranial nerve palsy
  • herniation

Question 7

Neurological Symptoms

Answer 7

• seizures
• focal neurological deficits
  
  • CN palsy - III, IV, VI, VII
  • monoparesis, hemiparesis, quadriparesis
  • visual field defects
  • aphasia
  • ataxia
• Cerebrovascular
  
  • thrombosis, vasculitis, acute cerebral hemorrhage, aneurysm
• Sensorineural hearing loss - damage to CN VIII, cochlea or labyrinth
• Cognitive Impairment

Question 8

Systemic Signs

Answer 8

• Fever
• Ill appearing
• N. Meningitidis
  
  • rash, arthritis
• Pericarditis
• Arthritis
• Sepsis/septic shock
• ARDS

Question 9

Meningitis Classic Triad

Answer 9

• Fever, stiff neck, mental status change
• +/- headache

Question 10

Bacterial Meningitis - Lumbar Puncture

Answer 10

• Opening pressure elevated
• CSF:
  
  • cloudy fluid.
  • WBC: 1000-5000 WBC/microL (>2000 WBC/microL)
  • %neutrophils: >80%
  • Protein: 100-500 mg/dl (>220 mg/dL)
  • Glucose: <40 mg/dL (<34 mg/dL)
  • CSF: serum glucose: <0.4

Question 11

Bacterial Meningitis - Treatment

Answer 11

• Supportive therapy - fluids
• Begin immediately after LP obtained
  
  • antibiotics
  • dexamethasone
• Chemoprophylaxis for contacts

Question 12

Aseptic Meningitis

Answer 12

• meningeal irritation
• fewer neurologic s/s
• less acute in onset and progression
• better survival
• negative routine bacterial culture

Question 13

Viral Meningitis Symptoms

Answer 13

• Viremia:
  
  • signs of virus (viral exanthem)
  • Nonspecific viral symptoms
    
    • fever, headache, malaise, myalgia, anorexia, nausea, vomiting, diarrhea
• CNS invasion/meningeal inflammation
  
  • meningeal signs
  • focal neurological deficits - less common

Question 14

Aseptic Meningitis - LP

Answer 14

• CSF findings
  
  • WBC: <250 cells/microL, may evolve into lymphocyte predominance
  • Protein: <100mg/dL

Question 15

Aseptic Meningitis Treatment

Answer 15

• symptomatic treatment
  
  • analgesics, antipyretics, antiemetics
  • fluids
• suspected viral
  
  • antibiotics: elderly, immunocompromised, recently received abx
  • observe: everyone else
• unclear viral or bacterial
  
  • empiric antibiotics
  • observe, repeat LP
• Etiology confirmed
  
  • specific treatment as indicated

Question 16

Chronic Meningitis

Answer 16

• meningitis lasting four weeks or more
• both infectious and noninfectious causes
• subacute onset of symptoms
  
  • fever, stiff neck, headache, cranial neuropathy, altered mental status, radiculopathy, increased ICP
• Multiple lab and diagnostic tests
• empiric therapy, steroids

Question 17

Encephalitis

Answer 17

• inflammation of the brain parenchyma
• abnormal brain function
  
  • change in mental status
  • motor or sensory deficits
  • change in behavior or personality
  • speech and movement disorders

Question 18

Encephalitis Symptoms

Answer 18

• abnormalities in brain function:
  
  • altered mental status - confused, agitated, obtunded
  • seizures
  • motor or sensory deficits
  • altered behavior and personality changes
  • speech or movement disorders
  • hemiparesis
  • flaccid paralysis
  • paresthesias
  • CN deficits
• Fever, headache, nausea/vomiting
• May have signs outside the CNS of specific virus

Question 19

HSV Encephalitis

Answer 19

• Rule out HSV-1 Encephalitis
  
  • hemorrhagic encephalitis (RBCs in LP)
  • respiratory symptoms followed by encephalitis symptoms
  • fatal but treatable
• MRI, EEG - temporal lobe
• LP with RBCs in absence of traumatic tap
• HSV PCR on CSF
• Empiric therapy with acyclovir