What is encephalitis?
Inflammation of brain parenchyma assoc w neurological dysfunction, such as altered state of consciousness, seizures, personality changes, CN palsies, speech problems, motor and sensory deficits.
Serious, complex and potentially fatal
Non-infectious and infectious causes
Epidemiology of encephalitis?
Affects extremes of ages (under 1, over 65)
Aetiology of encephalitis?
Aetiological agent only identified approx 50%
Bacterial, viral (most common), parasitic, fungal
Viral causes of encephalitis?
- Herpes (HSV1, HSV2); most common
- Adenovirus
- Enterovirus
- Parechovirus
Bacterial causes of encephalitis?
- Neisseria meningitidis
- TB
- Syphilis
- Listeria
- Lyme disease (bact), typhoid fever, etc
Diagnostic criteria for encephalitis?
Major criterion needed:
- Altered mental state lasting 24h+ w no alternative cause identified
Minor criteria (2- possible encephalitis, 3- probable/ confirmed):
- Fever over 38C within 72h before or after presentation
- Generalised or partial seizures not fully explained
- New onset of focal neurological findings
- Cerebrospinal fluid WBC count over 5/mm3
- Neuroimaging abnormality of brain parenchyma
- EEG consistent with encephalitis
Risk factors for encephalitis? (4)
- Insect bites
- Foreign travel
- Intravenous drug use (IVDU)
- Immunosuppression
Signs and symptoms of encephalitis?
- Headache and fever
- Viral prodrome
- Raised ICP
- Meningism
- Level of consciousness (LOC) altered
- Altered GCS and mental state
What are some symptoms of raised ICP?
Headache, blurred vision, feeling less alert, vomiting, changes in behaviour, weakness or problems w walking or speaking, sleepiness
Ix: Investigations for encephalitis inclu?
Bloods, LP, EEG, brain CT/ MRI
Also: CXR routine for febrile work-up. Could detect cause, ie: TB, sarcoidosis
Ix: What investigations and findings are there for bloods in encephalitis?
- High lymphocyes (FBC)
- Low sodium (SIADH) (Serum electrolytes)
- Blood cultures
- ESR/ CRP
- Viral serology
Ix: What findings are there for LP in encephalitis?
- High lymphocytes
- Normal/ low glucose
- Viral PCR
Initial management for encephalitis?
- ABCDE
- Acyclovir (give to all w suspected encephalitis and then give appropriate antiviral or AB according to underlying aetiology)
Potential complications of encephalitis?
- Death
- SIADH
- Neuro sequelae: damage to the CNS resulting in cognitive, sensory, or motor deficits. May also manifest as emotional instability and seizures (most severe cases).
