Encephalitis

Question 1

Encephalitis

Answer 1

Subacute, altered conscious state or behavioural changes due to an organic cause
- Infective, autoimmune or paraneoplastic
Involvement of brain parenchyma = focal neurology

Question 2

Encephalitis definition

Answer 2

Major (must have)
- altered mental state, personality change lasting >24hrs with no other cause found
Minor criteria (3 or mor confirmed)
- documented fever >38 within 72hrs before or after presentation
- generalised or focal seizures and no prior seizure disorder
- new focal neurological findings
- abnormal CSF
- abnormal MRI with brain parenchyma changes
- abnormal EEG

Question 3

Limbic encephalitis

Answer 3

Subacute psychiatric manifestations - psychosis, hallucinations, behaviour changes
Poor short term memory
Temporal lobe seizures
MRI changes in unilateral or bilateral lobes

Question 4

HSV encephalitis

Answer 4

Primarily HSV 1, majority of cases are due to reactivation
Acute focal necrotising encephalitis with swelling that predominantly effects medial temporal lobe
Symptoms
- acute to subacute onset of fever and altered mental state
- focal weakness, aphasia, focal neurology
- seizures (focal or generalised)

Question 5

Diagnosis of HSV encephalitis

Answer 5

LP
- lymphocyte predominant pleocytosis with raised protein
- herpes PCR
MRI
- T2 hyperintensity in medial and inferior temporal lobe extending up to insular cortex
- oedema, necrosis, haemorrhage & break down of blood brain barrier
EEG
- focal slowing
- periodic epileptiform discharges

Question 6

Treatment HSV encephalitis

Answer 6

IV acyclovir

Question 7

Investigations for encephalitis

Answer 7

CT brain
Lumbar Puncture
- biochemistry, microscopy & culture
- herpes multiplex, VZV, enterovirus, cryptococcus antigen
- Anti-neuronal antibodies (paraneoplastic), NMDA, LGI1, CASPR2, AMPA, GABA, GAD, oligoclonal bands
Serum: as above, blood cultures, thyroid antibodies
MRI with contrast
EEG
Malignancy screen
PET