Encephalitis

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Brain infection
)
Encephalitis
artificial respiration[1]
PrognosisVariable[1]
Frequency4.3 million (2015)[3]
Deaths150,000 (2015)[4]

Encephalitis is

memory problems, and problems with hearing.[1]

Causes of encephalitis include

blood tests, medical imaging, and analysis of cerebrospinal fluid.[2]

Certain types are preventable with

artificial respiration.[1] Once the immediate problem is under control, rehabilitation may be required.[2] In 2015, encephalitis was estimated to have affected 4.3 million people and resulted in 150,000 deaths worldwide.[3][4]

Signs and symptoms

Adults with encephalitis present with acute onset of

Stiff neck, due to the irritation of the meninges covering the brain, indicates that the patient has either meningitis or meningoencephalitis.[8]

Cause

Rabies virus

In 30%-40% of encephalitis cases, the etiology remains unknown.[9]

Viral

Main articles:
Herpesviral encephalitis

Viral infections are the usual cause of infectious encephalitis.

measles virus.[11]

Additional possible viral causes are

reovirus (Colorado tick virus), and henipavirus infections.[12][13] The Powassan virus is a rare cause of encephalitis.[14]

Bacterial and other

It can be caused by a bacterial infection, such as bacterial meningitis,[15] or may be a complication of a current infectious disease such as syphilis (secondary encephalitis).[16]

Certain

compromised immune systems. Lyme disease or Bartonella henselae may also cause encephalitis.[citation needed
]

Other bacterial pathogens, like

rickettsial disease, cause inflammation of the meninges and consequently encephalitis. A non-infectious cause includes acute disseminated encephalitis which is demyelinated.[17]

Limbic encephalitis

Main article: Limbic encephalitis

Limbic encephalitis refers to inflammatory disease confined to the

MRI imaging reveals T2 hyperintensity in the structures of the medial temporal lobes, and in some cases, other limbic structures. Some cases of limbic encephalitis are of autoimmune origin.[18]

Autoimmune encephalitis

Main article: Autoimmune encephalitis

Autoimmune encephalitis signs can include

ovarian teratoma in 58 percent of affected women 18–45 years of age.[20]

Encephalitis lethargica

Main article: Encephalitis lethargica

lethargica occurred worldwide.[21]


Diagnosis

Spinal tap on a newborn

People should only be diagnosed with encephalitis if they have a decreased or altered level of consciousness, lethargy, or personality change for at least twenty-four hours without any other explainable cause.[22] Diagnosing encephalitis is done via a variety of tests:[23][24]

  • Brain scan, done by
    MRI
    , can determine inflammation and differentiate from other possible causes.
  • EEG
    , in monitoring brain activity, encephalitis will produce abnormal signal.
  • Lumbar puncture (spinal tap), this helps determine via a test using the cerebral-spinal fluid, obtained from the lumbar region.
  • Blood test
  • Urine analysis
  • Polymerase chain reaction (PCR) testing of the cerebrospinal fluid, to detect the presence of viral DNA which is a sign of viral encephalitis.

Prevention

Vaccination is available against

Pertussis immunization should be observed in patients with encephalitis.[28]

Treatment

An ideal drug to treat brain infection should be small, moderately lipophilic at pH of 7.4, low level of plasma protein binding, volume of distribution of litre per kg, does not have strong affinity towards binding with P-glycoprotein, or other efflux pumps on the surface of blood–brain barrier. Some drugs such as isoniazid, pyrazinamide, linezolid, metronidazole, fluconazole, and some fluoroquinolones have good penetration to blood brain barrier.[29]Treatment (which is based on supportive care) is as follows:[30]

  • Antiviral
    medications (if virus is cause)
  • Antibiotics
    , (if bacteria is cause)
  • Steroids
    are used to reduce brain swelling
  • Sedatives
    for restlessness
  • Acetaminophen
    for fever
  • Occupational and physical therapy (if brain is affected post-infection)

highly active antiretroviral therapy (HAART), in conjunction with the established pyrimethamine-based maintenance therapy, decreases the chance of relapse in patients with HIV and TE from approximately 18% to 11%.[31] This is a significant difference as relapse may impact the severity and prognosis of disease and result in an increase in healthcare expenditure.[31]

The effectiveness of

double-blind studies with sufficient numbers of patients and sufficient follow-up.[32] There is the possibility of a benefit of intravenous immunoglobulin for some forms of childhood encephalitis on some indicators such as length of hospital stay, time to stop spasms, time to regain consciousness, and time to resolution of neuropathic symptoms and fever.[32] Intravenous immunoglobulin for Japanese encephalitis appeared to have no benefit when compared with placebo (pretend) treatment.[32]

Prognosis

Identification of poor prognostic factors include

encephalogram at the early stages of diagnosis is associated with high rates of survival.[33]

Epidemiology

Encephalitis deaths per million persons in 2012
  0-0
  1-1
  2-2
  3-4
  5-9
  10-14
  15-24
  25-45

The number of new cases a year of acute encephalitis in Western countries is 7.4 cases per 100,000 people per year. In tropical countries, the incidence is 6.34 per 100,000 people per year.[34] The number of cases of encephalitis has not changed much over time, with about 250,000 cases a year from 2005 to 2015 in the US. Approximately seven per 100,000 people were hospitalized for encephalitis in the US during this time.[33] In 2015, encephalitis was estimated to have affected 4.3 million people and resulted in 150,000 deaths worldwide.[4][3] Herpes simplex encephalitis has an incidence of 2–4 per million of the population per year.[35]

Terminology

Encephalitis with meningitis is known as meningoencephalitis, while encephalitis with involvement of the spinal cord is known as encephalomyelitis.[2]

The word is from Ancient Greek ἐγκέφαλος, enképhalos 'brain',[36] composed of ἐν, en, 'in' and κεφαλή, kephalé, 'head', and the medical suffix -itis 'inflammation'.[37]

See also

References

  1. ^ a b c d e f g h i j k "Meningitis and Encephalitis Information Page". NINDS. Archived from the original on 29 October 2017. Retrieved 29 October 2017.
  2. ^ a b c d e f g h i j "Meningitis and Encephalitis Fact Sheet". National Institute of Neurological Disorders and Stroke. Archived from the original on 29 October 2017. Retrieved 29 October 2017.
  3. ^
    PMID 27733282
    .
  4. ^
    PMID 27733281
    .
  5. ^ a b "Encephalitis". NHS Choices. 2016. Archived from the original on 22 September 2017. Retrieved 29 October 2017.
  6. PMID 29626021
    .
  7. ^ "Symptoms of encephalitis". NHS. Archived from the original on 5 January 2015. Retrieved 5 January 2015.
  8. ISBN 978-1-4381-3216-7. Archived
    from the original on 2015-10-30.
  9. ^ a b "Encephalitis". www.hopkinsmedicine.org. 2021-08-08. Retrieved 2024-01-09.
  10. ISBN 978-0-07-180215-4. Archived
    from the original on 2017-11-17. Retrieved 2017-11-17.
  11. PMID 24865261
    .
  12. PMID 14978145. Archived
    from the original on 2015-10-02.
  13. PMID 22481140
    .
  14. ^ "Symptoms & Treatment | Powassan | CDC". www.cdc.gov. 4 December 2018. Archived from the original on 26 June 2019. Retrieved 26 June 2019.
  15. ISBN 978-1-4557-0692-1. Archived
    from the original on 2015-11-29.
  16. PMID 18854635
    .
  17. ^ Howes DS, Lazoff M, Conrad SA, Hemphill RR, Huff JS, Pritz T, et al. (2018-08-07). Brenner BE (ed.). "Encephalitis: Practice Essentials, Background, Pathophysiology". MedScape. Archived from the original on 2015-08-03.
  18. ISBN 978-1-107-60760-6. Archived
    from the original on 2015-10-30.
  19. PMID 22935553
    .
  20. S2CID 3623281
    .
  21. ^ encephalitis_lethargica at NINDS
  22. PMID 23861361
    .
  23. ^ "Encephalitis: Diagnosis". NHS Choices. Archived from the original on 2015-07-16. Retrieved 2015-08-05.
  24. PMID 22120594
    .
  25. ^ "Tick-borne Encephalitis: Vaccine". International travel and health. World Health Organization. Archived from the original on 3 December 2013. Retrieved 2 April 2013.
  26. ^ "Japanese encephalitis". Immunization, Vaccines and Biologicals. World Health Organization. Archived from the original on 3 December 2013. Retrieved 2 April 2013.
  27. ^ "CDC Media Statement on Newly Discovered Smallpox Specimens". www.cdc.gov. January 2016. Archived from the original on 2016-05-20. Retrieved 2016-05-19.
  28. ^ "Contraindications and Precautions to Commonly Used Vaccines in Adults". Vaccines. Center for Disease Control. Archived from the original on 2015-08-23. Retrieved 2015-08-05.
  29. PMID 20930076
    .
  30. ^ MedlinePlus Encyclopedia: Encephalitis
  31. ^
    PMID 28090819
    .
  32. ^
    PMID 28967695
    .
  33. ^
    S2CID 21041693
    .
  34. PMID 18973679
    .
  35. PMID 21488834
    .
  36. ^ "Woodhouse's English-Greek Dictionary" (in German). The University of Chicago Library. Archived from the original on 2017-03-05. Retrieved 2013-01-10.
  37. ^ The word seems to have had a meaning of “lithic imitation of the human brain” at first, according to the Trésor de la langue française informatisé (cf. the article on “encéphalite” Archived 2017-11-05 at the Wayback Machine). The first use in the medical sense is attested from the early 19th century in French (J. Capuron, Nouveau dictionnaire de médecine, chirurgie…, 1806), and from 1843 in English respectively (cf. the article “encephalitis” in the Online Etymology Dictionary). Retrieved 11 March 2017.

Further reading

External links

Scholia has a topic profile for Encephalitis.
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