Treatment and outcome
With the consideration of CNS vasculitis, the patient started high-dose
dexamethasone which resulted in a progressive improvement of his GCS to
15/15. His seizure was well-controlled, and he fully regained his motor
function. He was then discharged from the hospital and improved. He had
a follow-up at our hospital four months after the discharge date and was
back to his daily routine activities.
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Discussion
Herpes Simplex Encephalitis is a destructive inflammatory condition that
typically impacts the cortex and the underlying white matter found in
the temporal lobe. (1) A delay in treatment significantly increases the
potential for axonal spread of the infection (2) The diverse clinical
symptoms, delayed diagnosis, and persistent alterations in brain
structure following treatment can all contribute to the illness and
death associated with HSV encephalitis. In cases of suspected viral
encephalitis, the decision to start antiretroviral therapy is based on
clinical assessment. Serological testing should not cause a delay in
treatment initiation which was true, as well in our patient; he was
started on Acyclovir until a CSF sample was sent for serologic study. In
our patient, the clinical presentation, imaging, laboratory evidence,
and initial clinical response to Acyclovir provided strong support for
the diagnosis of HSV-1 encephalitis
Magnetic resonance imaging is more significant in the early detection of
HSV encephalitis compared to computed tomography scans, (3). Early
finding on MRI usually occurs in the cingulate gyrus and medial temporal
lobe(3). In the reported case, the Initial Brain CT scan shows
hypo-density in the right capsule and median temporal lobe with minimal
white matter edema characteristic of HSV encephalitis. There are no EEG
findings pathognomonic for HSV encephalitis, but certain EEG features
can be helpful in the diagnosis, including the presence of focal or
lateralized abnormalities (4). In our patient, the EEG (Image 1)
performed within 24 hours supported the diagnosis.
Cerebrovascular disease can develop as a complication of various central
nervous system (CNS) infections (5) even though HSV is one of the least
recognized causes. Since the early 1970s, it has been acknowledged that
Herpes Simplex Encephalitis (HSE) can, in some cases, manifest with a
cerebral infarction (6). An epidemiological study of HSE conducted in
the USA reported that ischemic complications occurred approximately
twice as frequently, at a rate of 5.6%, compared to hemorrhagic
complications (7). This complication can occur regardless of early
initiation of antiviral therapy. Our patient has both clinical and brain
MRI worsening after an initial brief improvement with acyclovir
treatment. Though vascular imaging is not done in this patient, taking
into account the course of the patient and bilateral MCA territorial
area of worsening on the imaging, we considered HSV-1-associated
vasculitis with bilateral ischemic stroke. The exact pathophysiology
underlying infectious vasculopathy has not been fully elucidated. Even
if the presence of vasculitis and seizure are markers of poor prognosis
in a patient with HSE(7) our patient’s neurological status returned to
their baseline after treatment.