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'''Encephalitis''' is an [[Acute (medical)|acute]] [[inflammation]] of the [[brain]], commonly caused by a [[virus|viral]] [[infection]]. Sometimes, encephalitis can result from a [[bacteria]]l infection, such as bacterial [[meningitis]], or it may be a complication of other infectious diseases like [[rabies]] (viral) or [[syphilis]] (bacterial). Certain [[parasitic]] or [[protozoa]]l infestations, such as [[toxoplasmosis]], [[malaria]], or [[primary amoebic meningoencephalitis]], can also cause encephalitis in people with [[immune deficiency|compromised]] [[immune system]]s. Brain damage occurs as the inflamed brain pushes against the skull, and can lead to death. | '''Encephalitis''' is an [[Acute (medical)|acute]] [[inflammation]] of the [[brain]], commonly caused by a [[virus|viral]] [[infection]]. Sometimes, encephalitis can result from a [[bacteria]]l infection, such as bacterial [[meningitis]], or it may be a complication of other infectious diseases like [[rabies]] (viral) or [[syphilis]] (bacterial). Certain [[parasitic]] or [[protozoa]]l infestations, such as [[toxoplasmosis]], [[malaria]], or [[primary amoebic meningoencephalitis]], can also cause encephalitis in people with [[immune deficiency|compromised]] [[immune system]]s. Brain damage occurs as the inflamed brain pushes against the skull, and can lead to death. | ||
== | ==Risk Factors== | ||
Increased risk factors include increased age, weakened immune system, certain geographical locations, outdoor activities and some season of the year (summer and fall). | Increased risk factors include increased age, weakened immune system, certain geographical locations, outdoor activities and some season of the year (summer and fall). | ||
==Natural history, Complications, and Prognosis== | |||
== | |||
Its natural history, complications and prognosis depends on age of patient, immune status, type of organism and time to initiate medical therapy. Thus, depending on these factors it may present with complications like seizures, shock, cranial nerve palsy, and coma. | Its natural history, complications and prognosis depends on age of patient, immune status, type of organism and time to initiate medical therapy. Thus, depending on these factors it may present with complications like seizures, shock, cranial nerve palsy, and coma. | ||
== | ==Classification== | ||
It can be classified into primary and secondary post-infectious encephalitis(immune reaction to infection) | It can be classified into primary and secondary post-infectious encephalitis(immune reaction to infection) | ||
== | ==Causes of Encephalitis== | ||
It is an [[Acute (medical)|acute]] [[inflammation]] of the [[brain]], commonly caused by a [[virus|viral]] [[infection]]. Sometimes, encephalitis can result from a [[bacteria]]l infection, such as bacterial [[meningitis]], or it may be a complication of other infectious diseases like [[rabies]] (viral) or [[syphilis]] (bacterial). Certain [[parasitic]] or [[protozoa]]l infestations, such as [[toxoplasmosis]], [[malaria]], or [[primary amoebic meningoencephalitis]], can also cause encephalitis in people with [[immune deficiency|compromised]] [[immune system]]s. | It is an [[Acute (medical)|acute]] [[inflammation]] of the [[brain]], commonly caused by a [[virus|viral]] [[infection]]. Sometimes, encephalitis can result from a [[bacteria]]l infection, such as bacterial [[meningitis]], or it may be a complication of other infectious diseases like [[rabies]] (viral) or [[syphilis]] (bacterial). Certain [[parasitic]] or [[protozoa]]l infestations, such as [[toxoplasmosis]], [[malaria]], or [[primary amoebic meningoencephalitis]], can also cause encephalitis in people with [[immune deficiency|compromised]] [[immune system]]s. | ||
==Diagnosis== | ==Diagnosis== | ||
== | ==History & Symptoms== | ||
Adult patients with encephalitis may present with acute onset of fever, headache, confusion, weakness and sometimes seizures. Younger children or infants may present with irritability, anorexia and fever. Less commonly, photophobia, stiffness of the neck can occur if meningeal involvement occurs simultaneously with brain involvement. Rarely, patients may present with stiffness of the limbs, slowness in movement and clumsiness, and hallucination depending on which specific part of the brain is involved. The symptoms of encephalitis are caused by the brain's defense mechanisms activating to get rid of the infection. | Adult patients with encephalitis may present with acute onset of fever, headache, confusion, weakness and sometimes seizures. Younger children or infants may present with irritability, anorexia and fever. Less commonly, photophobia, stiffness of the neck can occur if meningeal involvement occurs simultaneously with brain involvement. Rarely, patients may present with stiffness of the limbs, slowness in movement and clumsiness, and hallucination depending on which specific part of the brain is involved. The symptoms of encephalitis are caused by the brain's defense mechanisms activating to get rid of the infection. | ||
== | ==Physical Examination== | ||
It may present as focal or diffuse neurological manifestations. The signs may include altered mental status, change in personality, meningismus, ataxia, seizures, and cranial nerve involvement. Stiff neck, due to the irritation of the meninges covering the brain, indicates that the patient has either meningitis or meningeoncephalitis. | It may present as focal or diffuse neurological manifestations. The signs may include altered mental status, change in personality, meningismus, ataxia, seizures, and cranial nerve involvement. Stiff neck, due to the irritation of the meninges covering the brain, indicates that the patient has either meningitis or meningeoncephalitis. | ||
== | ==Lab Tests== | ||
Diagnosis is often made with detection of antibodies against specific viral agent (such as herpes simplex virus) or by [[polymerase chain reaction]] that amplifies the [[RNA]] or [[DNA]] of the virus responsible. Other lab tests that might be useful are complete blood count with differential, coagulation profile, serum electrolyte, urine electrolyte, serum glucose, blood urea nitrogen and serum creatinine levels (to rule out confusion due to dehydration), liver function test (to rule out hepatic involvement), lumbar puncture and CSF examination. | Diagnosis is often made with detection of antibodies against specific viral agent (such as herpes simplex virus) or by [[polymerase chain reaction]] that amplifies the [[RNA]] or [[DNA]] of the virus responsible. Other lab tests that might be useful are complete blood count with differential, coagulation profile, serum electrolyte, urine electrolyte, serum glucose, blood urea nitrogen and serum creatinine levels (to rule out confusion due to dehydration), liver function test (to rule out hepatic involvement), lumbar puncture and CSF examination. | ||
== | ==MRI== | ||
== | ==CT== | ||
== | ==Other Diagnostic Studies== | ||
==Treatment== | ==Treatment== | ||
== | ==Medical Therapy== | ||
== | ==Primary Prevention== | ||
==See also== | ==See also== | ||
Revision as of 21:44, 14 February 2012
Template:Encephalitis Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editors-In-Chief: Priyamvada Singh, MBBS [2]
Overview
Encephalitis is an acute inflammation of the brain, commonly caused by a viral infection. Sometimes, encephalitis can result from a bacterial infection, such as bacterial meningitis, or it may be a complication of other infectious diseases like rabies (viral) or syphilis (bacterial). Certain parasitic or protozoal infestations, such as toxoplasmosis, malaria, or primary amoebic meningoencephalitis, can also cause encephalitis in people with compromised immune systems. Brain damage occurs as the inflamed brain pushes against the skull, and can lead to death.
Risk Factors
Increased risk factors include increased age, weakened immune system, certain geographical locations, outdoor activities and some season of the year (summer and fall).
Natural history, Complications, and Prognosis
Its natural history, complications and prognosis depends on age of patient, immune status, type of organism and time to initiate medical therapy. Thus, depending on these factors it may present with complications like seizures, shock, cranial nerve palsy, and coma.
Classification
It can be classified into primary and secondary post-infectious encephalitis(immune reaction to infection)
Causes of Encephalitis
It is an acute inflammation of the brain, commonly caused by a viral infection. Sometimes, encephalitis can result from a bacterial infection, such as bacterial meningitis, or it may be a complication of other infectious diseases like rabies (viral) or syphilis (bacterial). Certain parasitic or protozoal infestations, such as toxoplasmosis, malaria, or primary amoebic meningoencephalitis, can also cause encephalitis in people with compromised immune systems.
Diagnosis
History & Symptoms
Adult patients with encephalitis may present with acute onset of fever, headache, confusion, weakness and sometimes seizures. Younger children or infants may present with irritability, anorexia and fever. Less commonly, photophobia, stiffness of the neck can occur if meningeal involvement occurs simultaneously with brain involvement. Rarely, patients may present with stiffness of the limbs, slowness in movement and clumsiness, and hallucination depending on which specific part of the brain is involved. The symptoms of encephalitis are caused by the brain's defense mechanisms activating to get rid of the infection.
Physical Examination
It may present as focal or diffuse neurological manifestations. The signs may include altered mental status, change in personality, meningismus, ataxia, seizures, and cranial nerve involvement. Stiff neck, due to the irritation of the meninges covering the brain, indicates that the patient has either meningitis or meningeoncephalitis.
Lab Tests
Diagnosis is often made with detection of antibodies against specific viral agent (such as herpes simplex virus) or by polymerase chain reaction that amplifies the RNA or DNA of the virus responsible. Other lab tests that might be useful are complete blood count with differential, coagulation profile, serum electrolyte, urine electrolyte, serum glucose, blood urea nitrogen and serum creatinine levels (to rule out confusion due to dehydration), liver function test (to rule out hepatic involvement), lumbar puncture and CSF examination.