Herpes simplex encephalitis: Difference between revisions
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==Classification== | ==Classification== | ||
Herpes simplex encephalitis may be classified according to origin of disease into 2 subtypes: oral (HSV-1) and genital (HSV-2). | Herpes simplex encephalitis may be classified according to origin of disease into 2 subtypes: oral ([[herpes simplex virus|HSV-1]]) and genital ([[herpes simplex virus|HSV-2]]). | ||
==Pathophysiology== | ==Pathophysiology== | ||
Herpes simplex encephalitis is thought to be caused by the [[Retrograde infection|retrograde transmission]] of virus from a peripheral site on the face to the brain along a nerve [[axon]] following HSV-1 reactivation.<ref name="pmid16675036"/> The virus lies dormant in the [[ganglion]] of the trigeminal or fifth [[cranial nerve]] but the exact pathogenesis remains unknown. The [[olfactory nerve]] may also be involved in herpes simplex encephalitis.<ref>{{cite journal | author = Dinn J | title = Transolfactory spread of virus in herpes simplex encephalitis. | journal = Br Med J | volume = 281 | issue = 6252 | pages = 1392 | year = 1980 | id = PMID 7437807}}</ref> | Herpes simplex encephalitis is thought to be caused by the [[Retrograde infection|retrograde transmission]] of virus from a peripheral site on the face to the brain along a nerve [[axon]] following HSV-1 reactivation.<ref name="pmid16675036"/> The virus lies dormant in the [[ganglion]] of the trigeminal or fifth [[cranial nerve]] but the exact pathogenesis remains unknown. The [[olfactory nerve]] may also be involved in herpes simplex encephalitis.<ref>{{cite journal | author = Dinn J | title = Transolfactory spread of virus in herpes simplex encephalitis. | journal = Br Med J | volume = 281 | issue = 6252 | pages = 1392 | year = 1980 | id = PMID 7437807}}</ref> | ||
==Causes== | |||
==Differentiating Herpes simplex encephalitis from Other Diseases== | ==Differentiating Herpes simplex encephalitis from Other Diseases== | ||
Herpes simplex encephalitis must be differentiated from other diseases that cause [[fever]], [[headache]], and [[altered mental status]], such as:<ref name="pmid14978145">{{cite journal| author=Kennedy PG| title=Viral encephalitis: causes, differential diagnosis, and management. | journal=J Neurol Neurosurg Psychiatry | year= 2004 | volume= 75 Suppl 1 | issue= | pages= i10-5 | pmid=14978145 | doi= | pmc=PMC1765650 | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=14978145 }} </ref> | |||
[[menengitis]], and other [[viral encephalitis|viral]] and [[bacterial encephalitis]] cases | |||
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! style="background: #4479BA; width: 120px;" | {{fontcolor|#FFF|Disease}} | |||
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| style="padding: 5px 5px; background: #DCDCDC;" | '''[[Encephalopathy]]''' | |||
| style="padding: 5px 5px; background: #F5F5F5;" | Presents with steady [[depression]], generalized [[seizures]]. Generally absent are [[fever]], [[headache]], [[leukocytosis]], and [[pleocytosis]]. [[MRI]] often appears normal. | |||
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| style="padding: 5px 5px; background: #DCDCDC;" |'''[[Brain abscess]]''' | |||
| style="padding: 5px 5px; background: #F5F5F5;" |Presents with an [[abscess]] in the [[brain]] caused by the [[inflammation]] and accumulation of [[infected]] material from local or remote infectious areas of the body; the infectious agent may also be introduced as a result of head [[trauma]] or [[neurosurgery|neurological procedures]]. | |||
|- | |||
| style="padding: 5px 5px; background: #DCDCDC;" | '''[[Bacterial meningitis]]''' | |||
| style="padding: 5px 5px; background: #F5F5F5;" |Presents with [[inflammation]] of the [[meninges]], which may develop in the setting of an [[infection]], physical injury, [[cancer]], or certain drugs; it may have an indolent evolution, resolving on its own, or may present as an rapidly evolving [[inflammation]], causing neurologic damage and possible [[mortality]]. | |||
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| style="padding: 5px 5px; background: #DCDCDC;" | '''[[Viral encephalitis]] ''' | |||
| style="padding: 5px 5px; background: #F5F5F5;" | Presents with acute [[inflammation]] of the [[brain]], caused by a [[viral infection]]; it may complicate into severe [[brain]] damage as the inflamed [[brain]] pushes against the [[skull]], potentially leading to [[mortality]]. | |||
|- | |||
| style="padding: 5px 5px; background: #DCDCDC;" | '''[[Epidural abscess]]''' | |||
| style="padding: 5px 5px; background: #F5F5F5;" | Presents with an [[abscess]] in the [[epidural space]], between the [[vertebrae]] and the [[dura mater]] of the [[spinal canal]]; it may complicate into [[spinal cord]] dysfunction, leading to [[paralysis]]. | |||
|- | |||
| style="padding: 5px 5px; background: #DCDCDC;" | '''Cerebral [[thrombophlebitis]]''' | |||
| style="padding: 5px 5px; background: #F5F5F5;" | Presents with [[inflammation]] of a cerebral [[vein]], related to a [[blood clot]] or [[thrombus]]; it can cause [[chronic pain]], leg [[swelling]], and [[pulmonary embolism]]. | |||
|- | |||
| style="padding: 5px 5px; background: #DCDCDC;" | '''[[Superior sagittal sinus thrombosis]]''' | |||
| style="padding: 5px 5px; background: #F5F5F5;" | Presents with [[thrombosis]] affecting the [[dural venous sinuses]], which drain blood from the [[brain]]; it can cause [[headache]]s, [[fever]], and increased [[intracranial pressure]]. | |||
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| style="padding: 5px 5px; background: #DCDCDC;" | '''[[Acute disseminated encephalomyelitis]]''' | |||
| style="padding: 5px 5px; background: #F5F5F5;" | Presents with scattered foci of [[demyelination]] and perivenular [[inflammation]]; it can cause focal neurological signs and decreased ability to focus. | |||
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Revision as of 13:29, 9 February 2016
Template:DiseaseDisorder infobox
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Herpes simplex Microchapters |
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Herpes simplex encephalitis On the Web |
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Risk calculators and risk factors for Herpes simplex encephalitis |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Cafer Zorkun, M.D., Ph.D. [2]; Anthony Gallo, B.S. [3]
Overview
Herpes simplex encephalitis is a severe viral infections of the central nervous system.
Classification
Herpes simplex encephalitis may be classified according to origin of disease into 2 subtypes: oral (HSV-1) and genital (HSV-2).
Pathophysiology
Herpes simplex encephalitis is thought to be caused by the retrograde transmission of virus from a peripheral site on the face to the brain along a nerve axon following HSV-1 reactivation.[1] The virus lies dormant in the ganglion of the trigeminal or fifth cranial nerve but the exact pathogenesis remains unknown. The olfactory nerve may also be involved in herpes simplex encephalitis.[2]
Causes
Differentiating Herpes simplex encephalitis from Other Diseases
Herpes simplex encephalitis must be differentiated from other diseases that cause fever, headache, and altered mental status, such as:[3]
menengitis, and other viral and bacterial encephalitis cases
| Disease | Findings |
|---|---|
| Encephalopathy | Presents with steady depression, generalized seizures. Generally absent are fever, headache, leukocytosis, and pleocytosis. MRI often appears normal. |
| Brain abscess | Presents with an abscess in the brain caused by the inflammation and accumulation of infected material from local or remote infectious areas of the body; the infectious agent may also be introduced as a result of head trauma or neurological procedures. |
| Bacterial meningitis | Presents with inflammation of the meninges, which may develop in the setting of an infection, physical injury, cancer, or certain drugs; it may have an indolent evolution, resolving on its own, or may present as an rapidly evolving inflammation, causing neurologic damage and possible mortality. |
| Viral encephalitis | Presents with acute inflammation of the brain, caused by a viral infection; it may complicate into severe brain damage as the inflamed brain pushes against the skull, potentially leading to mortality. |
| Epidural abscess | Presents with an abscess in the epidural space, between the vertebrae and the dura mater of the spinal canal; it may complicate into spinal cord dysfunction, leading to paralysis. |
| Cerebral thrombophlebitis | Presents with inflammation of a cerebral vein, related to a blood clot or thrombus; it can cause chronic pain, leg swelling, and pulmonary embolism. |
| Superior sagittal sinus thrombosis | Presents with thrombosis affecting the dural venous sinuses, which drain blood from the brain; it can cause headaches, fever, and increased intracranial pressure. |
| Acute disseminated encephalomyelitis | Presents with scattered foci of demyelination and perivenular inflammation; it can cause focal neurological signs and decreased ability to focus. |
Epidemiology and Demographics
It is estimated to affect at least 1 in 500,000 individuals per year.[1] Approximately 50% of individuals that develop HSE are over 50 years of age.[4] About 1 in 3 cases of HSE result from primary HSV-1 infection predominantly occurring in individuals under the age of 18. Although 2 in 3 cases occur in seropositive persons, few of these individuals have history of recurrent orofacial herpes.
Risk Factors
Natural History, Complications and Prognosis
Without treatment, HSE results in rapid death in around 70% of cases.[1] Even with the best modern treatment, it is fatal in around 20% of cases treated, and causes serious long-term neurological damage in over half the survivors. For unknown reasons the virus seems to target the temporal lobes of the brain. Only a small population of survivors (2.5%) regain completely normal brain function.[4]
Diagnosis
History and Symptoms
Most individuals with HSE show a decrease in their level of consciousness and an altered mental state presenting as confusion and changes in personality. Some patients with HSE will have seizures.
Physical Examination
Laboratory Findings
Increased numbers of white blood cells can be found in their cerebrospinal fluid without the presence of pathogenic bacteria and fungi, and they typically have a fever.[1]
MRI
CT
CT or MRI scans changes as the disease progresses, first showing abnormalities in one temporal lobe of the brain, which spread to the other temporal lobe 7–10 days later.[1]
Other Diagnostic Studies
The electrical activity of the brain (detected using EEG changes as the disease progresses, first showing abnormalities in one temporal lobe of the brain, which spread to the other temporal lobe 7–10 days later.[1]
Treatment
Medical Therapy
Surgery
Primary Prevention
Secondary Prevention
References=
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Whitley RJ (2006). "Herpes simplex encephalitis: adolescents and adults". Antiviral Res. 71 (2–3): 141–8. doi:10.1016/j.antiviral.2006.04.002. PMID 16675036.
- ↑ Dinn J (1980). "Transolfactory spread of virus in herpes simplex encephalitis". Br Med J. 281 (6252): 1392. PMID 7437807.
- ↑ Kennedy PG (2004). "Viral encephalitis: causes, differential diagnosis, and management". J Neurol Neurosurg Psychiatry. 75 Suppl 1: i10–5. PMC 1765650. PMID 14978145.
- ↑ 4.0 4.1 Whitley RJ, Gnann JW (2002). "Viral encephalitis: familiar infections and emerging pathogens". Lancet. 359 (9305): 507–13. PMID 11853816.