Encephalitis: Difference between revisions

 
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*[[CMV]]
*[[CMV]]
*[[Rabies]]
*[[Rabies]]
*Arboviruses ([[West Nile]], St. Louis equine)
*Arboviruses ([[West Nile]], St. Louis equine) account for 50% of cases<ref>Somand D, Meurer W. Central Nervous System Infections. EMCNA 2009; 27: 89-100.</ref>


==Clinical Features==
==Clinical Features==
*New psychiatric symptoms (HSV)<ref>Loring KE, Tintinalli JE: Central Nervous System and Spinal Infections, in Tintinalli JE, Kelen GD, Stapczynski JS (eds): Emergency Medicine, A Comprehensive Study Guide, ed 7. New York, McGraw-Hill, 2011, (Ch) 168:p 1175-1176.</ref>
*New psychiatric symptoms (HSV)<ref>Loring KE, Tintinalli JE: Central Nervous System and Spinal Infections, in Tintinalli JE, Kelen GD, Stapczynski JS (eds): Emergency Medicine, A Comprehensive Study Guide, ed 7. New York, McGraw-Hill, 2011, (Ch) 168:p 1175-1176.</ref>
*Cognitive deficits
*Cognitive deficits
**Aphasia, amnesia, confusion
**Aphasia, amnesia, [[confusion]]
*[[Seizure]]
*[[Seizure]]
*Movement disorder (arboviruses)
*Movement disorder (arboviruses)
*[[Fever]] and meningeal signs are almost always present
*[[Fever]] and meningeal signs are almost always present
*[[Dysuria]] and pyuria (St. Louis encephalitis)
*[[Dysuria]] and pyuria (St. Louis encephalitis)
*Extreme lethargy (West Nile encephalitis)
*Extreme [[lethargy]] (West Nile encephalitis)


==Differential Diagnosis==
==Differential Diagnosis==
*[[Meningitis]]
*[[SAH]]
*[[SAH]]
*[[Lyme disease]]
*[[Lyme disease]]
*Brain abscess
*[[Brain abscess]]
*Bacterial [[endocarditis]]
*Bacterial [[endocarditis]]
*Toxic / metabolic encephalopathy
*Toxic / metabolic encephalopathy
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{{AMS and fever DDX}}
{{AMS and fever DDX}}


==Diagnosis==
==Evaluation==
[[File:Hsv encephalitis.jpg|thumb|Brain MRI showing high signal in the temporal lobes and right inferior frontal gyrus secondary to HSV encephalitis.]]
*Imaging identifies abnormalities in medial temporal and inferior frontal gray matter in HSV<ref>Howes DS et al. Encephalitis Workup. Oct 12, 2015. http://emedicine.medscape.com/article/791896-workup#showall</ref>
*Imaging identifies abnormalities in medial temporal and inferior frontal gray matter in HSV<ref>Howes DS et al. Encephalitis Workup. Oct 12, 2015. http://emedicine.medscape.com/article/791896-workup#showall</ref>
**CT Head - edema and petechial hemorrhage
**[[head CT|CT Head]] - edema and petechial hemorrhage
**MRI - increased T2 intensity
**[[brain MRI|MRI]] - increased T2 intensity
*[[LP]]
*[[LP]]
**Bloody tap consistent with HSV
**Bloody tap consistent with HSV
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[[Category:Neurology]]
[[Category:Neurology]]
[[Category:ID]]

Latest revision as of 13:25, 14 November 2020

Background

  • Infection of brain parenchyma of the temporal lobes and inferior frontal lobe causing distinct neurologic abnormality
  • Pathophysiology
    • Gray matter is predominantly affected (cognitive / psychiatric signs, lethargy, seizure)

Microbiology

Clinical Features

  • New psychiatric symptoms (HSV)[2]
  • Cognitive deficits
  • Seizure
  • Movement disorder (arboviruses)
  • Fever and meningeal signs are almost always present
  • Dysuria and pyuria (St. Louis encephalitis)
  • Extreme lethargy (West Nile encephalitis)

Differential Diagnosis

Altered mental status and fever

Evaluation

Brain MRI showing high signal in the temporal lobes and right inferior frontal gyrus secondary to HSV encephalitis.
  • Imaging identifies abnormalities in medial temporal and inferior frontal gray matter in HSV[3]
    • CT Head - edema and petechial hemorrhage
    • MRI - increased T2 intensity
  • LP
    • Bloody tap consistent with HSV

Management

Often it is unclear which type of encephalitis is present and starting Acyclovir empirically is appropriate. In addition to the pathogens below, possible causes can include West Nile Virus, EBV, HIV, toxoplasmosis, or rabies.

HSV encephalitis

  • Acyclovir 10mg/kg (10-15mg/kg for pediatrics) every 8hrs

HZV encephalitis

CMV encephalitis

Tick Associated (Borrelia burgdorferi, Ehrlichiosis or Rickettsia)

  • Doxycycline 200 mg IV once followed by 100 mg IV twice daily

Disposition

Admit in all cases

See Also

References

  1. Somand D, Meurer W. Central Nervous System Infections. EMCNA 2009; 27: 89-100.
  2. Loring KE, Tintinalli JE: Central Nervous System and Spinal Infections, in Tintinalli JE, Kelen GD, Stapczynski JS (eds): Emergency Medicine, A Comprehensive Study Guide, ed 7. New York, McGraw-Hill, 2011, (Ch) 168:p 1175-1176.
  3. Howes DS et al. Encephalitis Workup. Oct 12, 2015. http://emedicine.medscape.com/article/791896-workup#showall