See also: [[Meningitis]], [[Confusion]], [[Delirium vs psychosis]], [[schizophrenia#Drug-induced psychosis vs schizophrena|drug-induced psychosis vs schizophrenia]], [[Liver Failure#Hepatic encephalopathy grading|Hepatic encephalopathy]] See: [Dunn - Encephalitis](x-devonthink-item://69FEE9F4-E527-49FE-8192-5C44A9162AC3) >[!key points] >- If concern for HSV encephalitis, treat acyclovir 10mg/kg IV Q8h (do NOT wait for LP) >- Key aspect of diagnosis is [[Lumbar puncture]] (delays to treatment and LP are a frequent source of concern in case review/M&M cases involving encephalitis) # Overview ***Definitions*** **Encephalopathy** = altered consciousness persisting for longer than 24 h, including lethargy, irritability or a change in personality or behaviour - confusion, disorientation, hallucinations, lethargy (see [[#encephalopathy vs psychosis]]) - psychosis occurs in <5% of infectious causes **Encephalitis** = encephalopathy AND evidence of CNS inflammation, demonstrated by *at least two* of: - fever > 38 deg within 72 hours before/after presentation - seizures (generalised or partial not attributable to pre-existing seizure disorder) or focal neurological findings attributable to the brain parenchyma - CSF pleocytosis (more than 4 white cells per μL) - EEG findings suggestive of encephalitis - neuroimaging findings suggestive of encephalitis - *AND* no alternative cause identified ***Findings*** - CT usually normal - MRI with temporal lobe abnormalities favours HSV as cause - CT can exclude other changes - CT with contrast may show temporal or frontal lobe changes - 50% of cases have no definite cause identified - send large volume of CSF in 4 different tubes; 5mL children, 10mL adults - also send for PCR, including - HSV 1 and 2 - enterovirus - VZV - CMV - m/c/s - +/- cryptococcus in HIV - +/- measles, HIV, flu, adenovirus, lyssavirus, CSF immunoglobulin levels, Anti-NMDAR Ab, serum anti-VGKC complex Ab, serum anti-Hu, anti-Ma2 Ab > [!pearl] CSF findings in viral encephalitis > - similar to [[Lumbar puncture#interpretation|viral meningitis]] > - pressure normal or slightly ↑ > - usually clear or slightly turbid > - WCC 5-1000 x10\^6 > - usually lymphocyte predominance > - a WCC < 10 in an immunocompetent patent nearly excludes HSV as cause > - normal glucose > - mild ↑ in protein ***Management*** - generally acyclovir 10mg/kg q8h cover for HSV/vzv while awaiting results - +/- high dose corticosteroids - +/- [[IVIG]] - Often get cover for [[meningitis]]/meningoencephalitis as well eg ceftriaxone 2g - Patients at risk for [[Listeria]] (<1 month, older than 50, pregnant, immunocompromised or alcoholic): benzylpenicillin 2.4 g IV Q4h - Bactrim if can’t have ben-pen # Encephalitis causes - Viral (25% of caess) - HSV most common (and [[Herpes zoster|VZV]] ) - Treat on spec aciclovir IV 10mg/kg q8hr - EBV - CMV - enteroviruses - adenoviruses - hendravirus - bat lyssavirus / [[Rabies]] - flavaviruses -- consider in northern australia, wet summer - murray valley encephalitis - west nile virus - japanese encephalitis - [[Dengue]] - Immune-mediated (~30% of cases) - post-infections eg influenza, [[measles]], rubella, varicella - cerebral [[Malaria]] if returning traveller from an endemic region - [[HIV]] - consider toxoplasmosis (meningitis may be cryptococcus) - Bacterial - [[Rickettsia]] - [[leptospirosis]] - Amoebic # encephalopathy vs psychosis Similar #tables : [[Delirium vs psychosis|delirium vs psychosis vs dementia]], [[schizophrenia#Drug-induced psychosis vs schizophrena|Drug-induced psychosis vs schizophrenia]] | Characteristic | Encephalopathy | Psychosis | | ----------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | ----------------------------------------------------------------------------------------------------------------------------------------------------- | | Age | Any, often older > 40 | Teens - mid-30s | | Symptoms | - confusion<br>- disorientation<br>- irritability<br>- change in personality | See [[schizophrenia]] | | Orientation | Generally impaired | Generally intact | | Short-term memory | Poor | Intact | | Hallucinations | Frequent visual, olfactory, or tactile hallucinations (auditory hallucinations are not common) | Very frequent and prominent *auditory* hallucinations, as well as overt delusional thinking (visual, olfactory, or tactile hallucinations not common) | | Paranoia | Variable degrees of paranoia or delusional thinking | Frequent | | Physical exam | Signs of neurologic dysfunction that might include tremor, nystagmus, seizures, myoclonus, muscle atrophy, weakness, dementia, and/or loss of consciousness or ability to swallow or speak | Generally normal physical exam<br><br>Signs of neurologic dysfunction might include tremor, stiffness, rigidity, tardive dyskinesia, and/or catatonia | | Risk factors | HIV, immunodeficiency, medical illness, [[Fever in returned traveller\|travel history]] | Drug use, social determinants of health, family history of mental illness |