Herpes Simplex Encephalitis
Due to the broad differential diagnosis, including encephalitis from other viral etiologies or post-infectious conditions, brain tumors, and paraneoplastic and autoimmune encephalitis, among others, the diagnosis can be quite challenging, particularly in an acute setting - MN Rayan
HWN Suggests
Herpes Simplex Encephalitis: Detection, Management, and Outcomes
Some common distinguishing clinical features that can raise suspicion for HSV encephalitis include olfactory hallucinations and feelings of déjà vu in the early stages due to temporal lobe involvement. HSV encephalitis can also cause limbic encephalitis, resulting in anterograde memory dysfunction, behavioral changes, seizures, headaches, and focal neurological deficits with evidence of temporal lobe involvement in neuroimaging.
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Herpes Encephalitis
Typical CSF findings include elevated protein, leukocytosis, and normal glucose. More useful is the HSV PCR assay, which is typically positive within 24 hours of symptom onset and is both highly sensitive and specific (98% and 94%, respectively). Neuroimaging with CT may be normal and therefore falsely reassuring in the early stages of HSVE. One study identified MRI abnormalities in 21% of patients with herpes encephalitis who had normal CT scans.
HSV Encephalitis
Herpes encephalitis (HE) is the most common form of sporadic encephalitis and the most lethal encephalitic disease5. One third of cases are caused by primary herpes simplex virus (HSV) infection while two thirds are caused by reactivation of the virus. MRI is considered the gold standard for neuroimaging in encephalitis. Temporal lobe involvement is typical of HE, but patients may also have frontal or parietal involvement. Lack of temporal lobe involvement does not rule out HE.
Articles of Interest
Encephalitis with herpes simplex virus
Encephalitis caused by herpes simplex virus can occur as a result of viral reactivation from the central nervous system, spread from other organs and as an immune reaction.
Herpes simplex virus encephalitis: A literature review
The most likely pathways include retrograde transmission through the olfactory or trigeminal nerves, as well as hematogenous spread. The most common presenting symptoms are encephalopathy, fever, convulsions, headache, and regional neurologic dysfunction.
Herpes Simplex Virus-1 in the Brain: The Dark Side of a Sneaky Infection
HSV-1 replication in the brain and the consequent activation of host immune responses may result in HSE.
HSV Encephalitis
Flu-like illness with malaise, N&V (50%), headache (80%) and fever (90%) followed by seizures (may be focal; 70%), cognitive impairment (25%), behavioural changes (70%), and/ or focal neurological deficits (33%). MRI is the diagnostic modality of choice.
Resources
Encephalitis Society
The rapid onset and development of HSE presents a dilemma to the clinician. During the early stages, when treatment would be most effective, the symptoms can be very general and so there may be several possible diagnoses.
NORD
Herpes simplex encephalitis (HSE) is a rare neurological disorder characterized by inflammation of the brain (encephalitis). Common symptoms include headaches, fevers, drowsiness, hyperactivity, and/or general weakness. The disorder may have some symptoms similar to those associated with meningitis, such as a stiff neck, altered reflexes, confusion, and/or speech abnormalities. Skin lesions usually are not found in association with herpes simplex encephalitis.
