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HSV1/2 infection of the CNS (encephalitis) - Coggle Diagram
HSV1/2 infection of the CNS (encephalitis)
prognosis
relapse 25% (9y!)
encephalopathy
choreoathetosis
seizures
white matter changes on MRI
anti-NMDA?
treatment: immunomodulation, aciclovid, neurorehabilitation
mortality 70% without aciclovir, 6-8% with aciclovir
morbidity 36-79% long-term sequale
developmental delay, cognitive impairment 15-58%
seizures 15-44%
motor deficits 19-37%
visual loss 21%
personality changes, behavioural problems 5-15%
speech difficulties 5-7%
unfavourable prognostic factors: young age, lower GCS, late adminstration of aciclovid, status epilepticus
clinical features
signs of encephalitis
fever
psychiatric symptoms: abnormal behaviour, olfactory hallucinations, anosmia
increased intracranial pressure 15%
brainstem encephalitis, acute myelitis - HSV2
seizures: frequent, recurrent, focal - face, upper limb, mya be
febrile seizure!
reduced consiousness: stupor, lethargy, coma
focal neurologic signs: hemiplegia, aphasia, acute opercular syndrome: orofacial palsy, dysarthria, dysphagia
some cases: fever+seizures without encephalopathy- favourable outcome
cannot be reliably distinguished from other less severe infections based on clinical symptoms!
prodrome: 60%
fever
malaise
herpetic lesions 8-25%
subtle changes in speech, memory, sensation
management of PCR positive HSV encephalitis
aciclovir iv for 14-21 days
repeat LP at the end of treatment
if CSF positive for HSV, then continue aciclovir and repeat LP weely
corticosteroid: marked cerebral edema, brain shift, increased ICP
decision to stop aciclovir
in case of initial negative CSF HSV PCR (p 591)
caution of false negative results are common! if CSF taken in the first 72 hours of illness
can be stopped if
no ongoing clinical suspicion of HSV encephalitis - alternative diagnosis made
CSF PCR negative more than 72 h after onset of neurological symptoms + child recovered + normal MRI+ normal CSF white cell count
more caution approach: + normal MRI and normal EEG after 96 h after onset of neurological symptoms
ongoing clinical suspition of encephalitis: repeat LP 24-48 h after the first LP, if both are negative, HSV encephalitis is very unlikely
otherwise continue aciclovir at least for 10 (14) days
if strong suspition of HSV encephalitis, i.e. focal abnormality on EEG - 21 day aciclovir
diagnosis
lumbar puncture
PCR: 96% specificity, 99% sensitivity
RBC: frequently haemorrhagic or xanthochromic
protein: mildly elevated
glucose: normal
WBC: may be normal 25% in the first few days, pleocytosis 0-500/ul, lymphocytes (neutrophils in the first 23-48h)
HSV-1 antibody in CSF 10-14 d (first IgM, then IgG), oligoclonal band - may persist for years
neuroimaging - MRI
normal first 24-48 h
findings
bilateral, asymmetrical gyral oedema on T1, T2 hyperintensity in the medial temporal lobe and limbic structures, inferior frontal lobes, insula, cingulate gyrus
parietal lobes, extra-temporal regions 60%
lentiform nucleus and basal ganglia are spared
Involvement of the cingulate gyrus and contralateral
temporal lobe is highly suggestive
Early: of focal gyral oedema on T1, progress to extensive cortical necrosis +/-haemorrghagia, later atrophy
pseudotumoral features
differential diagnosis
mesial temporal sclerosis
mitochondrial encephalopathy,lactic acidosis and stroke-like episodes (MELAS)
neurosyphilis
EEG: 86% abnormal
high amplitude slow waves
temporal spikeand-
wave activity
most often PLED 2-5 days after onset
may be low amplitude over one/more regions
asymmetrical
references
Aicardi's Diseases of the Central Nervous System in Childhood (2018) p. 598
etiology
HSV1: encephalitis (90%)
HSV2: meningitis, perinatal meningoencephalitis
pathophysiology
70% reactivation (anti-HSV IgG pos)
olfactory bulb, trigeminal ggl - retrograde neuronal transport
susceptibility: AR defect in TLR3-interferon innate immune response
basal frontal,
mesial temporal, cingulate and insular cortex - close proxemity to olfactory bulb
HSV meningitis
primary HSV2
sexually active adolescents
mild HSV1 with recovery in 7-14d
Mollaret meningitis
20% of HSV2 meningitis
recurrent, multople episodes of aseptic, lymphocytic meningitis
benign, no permanent symptoms
treatment: iv aciclovir followed by oral valaciclovir prophylaxis, indomethacin