Aseptic meningitis
2017757
224217246
2008-07-07T21:11:19Z
Chaldor
7312839
what image?
{{Infobox_Disease |
Name = Aseptic meningitis |
<!-- Commented out because image was deleted: Image = Meninges.jpg|
Caption = The image above shows the location and the layers of the meninges surrounding the brain| -->
DiseasesDB = 945|
ICD10 = {{ICD10|G|03||g|00}} Nonpyogenic meningitis|
ICD9 = {{ICD9|322.0}} Nonpyogenic meningitis |
ICDO = |
OMIM = |
MedlinePlus = |
eMedicineSubj = NEURO|
eMedicineTopic = 697|
}}
'''Aseptic meningitis''' is a condition in which the layers lining of the brain, or [[meninges]], become [[inflammation|inflamed]] and a [[pyogenic]] [[bacteria]]l source is not to blame. [[Meningitis]] is diagnosed on a history of characteristic symptoms and certain examination findings (e.g. [[Woldemar Kernig|Kernig's sign]]). Investigations should show an increase in the number of [[leukocytes]] present in the [[cerebrospinal fluid]] (CSF), obtained via [[lumbar puncture]], (normal being fewer than five visible per microscopic [[high power field]]).
The term ''aseptic'' is frequently a [[misnomer]], implying a lack of [[infection]]. On the contrary, many cases of aseptic meningitis represent infection with viruses or [[mycobacteria]] that cannot be detected with routine methods. While the advent of [[polymerase chain reaction]] has increased the ability of clinicians to detect viruses such as [[enterovirus]], [[cytomegalovirus]], and [[herpes virus]] in the CSF, many viruses can still escape detection. Additionally, mycobacteria frequently require special stains and [[culture]] methods that make their detection difficult. When CSF findings are consistent with meningitis, and [[microbiology|microbiologic]] testing is unrevealing, clinicians typically assign the diagnosis of aseptic meningitis—making it a relative [[diagnosis of exclusion]].
Aseptic meningitis can result from non-infectious causes; it is a relatively infrequent side effect of medications, and can be an early finding in autoimmune disease.
==Classification==
There is no formal classification system. It is usually by the causative [[organism]] if identified.
==Symptoms and Signs==
These are varied, depending on the causative organism. There are usually non-specific [[constitutional]] [[symptoms]] lasting for hours or days. These are then followed by [[meningitis]], characterised by headache, stiff neck, [[fever]], [[photophobia]], drowsiness, and [[myalgia]]. A [[rash]] may be present, which could suggest a particular virus - for example, ''[[varicella zoster]]''. However, a [[non-blanching]] [[purpuric]] rash is not associated with meningitis and suggests systemic bacterial infection.Realated to polio
==Complications==
[[Seizures]], [[encephalitis]] and [[cognitive problems]] can develop, although rarely.
==Cause/Etiology==
The cause can be infectious or non-infectious.
===Infectious===
====Viruses====
*[[Herpes simplex virus|HSV 1 and 2]]
*[[HIV]]
*[[Enterovirus]]es
*[[Varicella zoster]]
*[[Epstein-Barr virus]]
*[[cytomegalovirus|CMV]]
*[[Lymphocytic choriomeningitis|Lymphocytic choriomeningitis virus]]
*[[Poliovirus]]
*[[Coxsackie A virus]]
====Bacteria====
*Partially treated meningitis
*[[Endocarditis]]
*[[Mycoplasma]]
*[[Mycobacterium tuberculosis]]
*''[[Borrelia burgdorferi]]''
*''[[Treponema pallidum]]''
*''[[Brucella]]''
====Fungi====
*''[[Cryptococcus neoformans]]''
*''[[Blastomyces dermatitidis]]''
====Parasites====
*''[[Toxoplasma gondii]]''
===Non-infectious===
====Drugs====
*[[non-steroidal anti-inflammatory drugs|NSAIDs]]
*[[Amoxicillin]]
*[[Azathioprine]]
*[[Methotrexate]]
*[[Intravenous immunoglobulin]]
*[[Isoniazid]]
*[[Allopurinol]]
====Systemic Diseases====
*[[Sarcoidosis]]
*[[Meningioma]]
*[[Systemic lupus erythematosus|SLE]]
*[[Wegener's granulomatosis|Wegener's]]
*[[Vasculitis]]
*[[Behcet's disease]]
===Miscellaneous===
*[[Migraine]]
*[[Arachnoiditis]]
==Diagnosis==
Usually the history and examination will arouse suspicion. Confirmation is mainly through [[cerebrospinal fluid|CSF]] findings:
*Less than 500 [[Reticuloendothelial system|mononuclear cell]]s/mm³ ([[pleocytosis]]) should develop with 8-48 hours
*Normal [[glucose]]
*Elevated [[pressure]]
*Elevated [[protein]]
*No findings which suggest another [[diagnosis]] - e.g. negative [[bacteria]] [[antigen]] tests, no [[lactic acid|lactate]]
*[[polymerase chain reaction|PCR]] may identify a causative organism
Viruses may be cultured from swabs of other areas, such as the throat.
Blood tests are rarely helpful in establishing the diagnosis (but may be of use to establish [[Baseline (pharmacology)|baseline]] [[chemistry]]). Imaging is useful in excluding other diagnoses, or identifying other features of [[infection]] by an organsim - for example, a [[chest X-ray]] may be useful if [[tuberculosis]] is suspected.
==Pathophysiology==
[[Invasion]] into or past the [[meninges]] by a pathogen can set up a local [[inflammatory]] response. The [[clinical sign]]s are due to this meningeal [[irritation]] - for example, [[Kernig's sign]] is due to pain produced by stretching of the [[inflamed]] meninges.
==Treatment/Management==
===Anti-pathogenic===
If the causative organism has been identified and has a specific therapy, this should be started.
====Bacteria====
Even though true aseptic meningitis cannot be caused by [[pyogenic]] [[bacteria]], [[broad-spectrum]] [[antibiotic]] cover should be started as the consequences of misdiagnosing a bacterial meningitis are dire, and relatively easily avoided. For non-pyogenic bacteria, local sensitivities should be taken into account, but generally broad-spectrum is best. Some bacteria are normally sensitive to certain drugs - for example, [[rifampicin]] is good for ''[[Brucella]]''.
====Viruses====
[[Herpes simplex virus|HSV]], [[varicella]] and [[cytomegalovirus|CMV]] have a specific antiviral therapy; most other viruses do not. For HSV the treatment of choice is [[acyclovir]]<ref name=acyclovir>Tyler Kl. Herpes simplex virus infections of the central nervous system: encephalitis and meningitis, including Mollaret's. ''Herpes''. 2004 Jun;11 Suppl 2:57A-64A.</ref>
====Fungi====
[[Amphotericin B]] and [[fluconazole]] are the best antifungals in most situations.
===Supportive===
This will be the majority of the treatment. Fluids, [[analgesia]] and [[antiemetic]]s should cover most cases. [[Antipyretic]]s should be used judiciously - [[fever]] can be a natural response. [[Steroid]]s are not recommended unless raised [[intracranial pressure]] occurs. [[Phenytoin]] and other [[anticonvulsants]] can be used is seizures occur, but [[prophylaxis]] is not recommended.
==Prognosis==
In [[immunocompetent]] individuals, the disease is usually mild and [[self-limiting]]. Full recovery 5-14 days afterwards is normal.
==Prevention/Screening==
[[Vaccines]] are available for some organisms that cause aseptic meningitis. Good infection control in hospital, as ever, is recommended. If the causative organism is [[Infectious disease|contagious]], steps may need to be taken to isolate the individual and protect the community.
==Epidemiology==
Aspetic meningitis is relatively common, with an [[Incidence (epidemiology)|incidence]] of around 10/100,000. The male:female [[ratio]] is around 1:1.
==References==
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[[Category:Diseases]]