The Journal of the Arkansas Medical Society Issue 2 Vol 115 | Page 16

deficits represent an ictal phenomenon or hypo-
perfusion of the involved area.
Early recognition of HSV encephalitis is im-
portant as it can unleash a variety of complica-
tions such as cognitive deficits, seizures, etc. 1 It is
one of the neuroinfectious diseases where timely
institution of treatment can prevent morbidity and
mortality. There are several learning points in this
case, namely the sudden onset of symptoms, de-
layed appearance of fever and partial seizures,
initial frontal lobe involvement on brain imaging,
and atypical CSF findings. The combination of
brain MRI, CSF, and EEG should be used in cases
of diagnostic confusion because it improves the
sensitivity of diagnosis. 1
References
1. Cag Y, Erdem H, Leib S, Defres S, Kaya S, et
al. Managing atypical and typical herpetic
central nervous system infections: results of
a multinational study. Clin Microbiol Infect.
2016 Jun;22(6):568.e9-568.e17. Epub 2016
Apr 13.
2. Vachalová I, Kyavar L, Heckmann JG. Pit-
falls associated with the diagnosis of her-
pes simplex encephalitis. J Neurosci Rural
Pract. 2013 Apr;4(2):176-179.
Figure 2. Demonstrates hyperintensity on DWI sequence (A and B) in bilateral parafalcine area. FLAIR
hyperintensity is also seen in bilateral temporal and parafalcine areas (C and D).
clinched by the amplification of HSV type 1 DNA
in CSF and improvement with Acyclovir. Earlier,
brain biopsy was considered to be the gold stan-
dard for the diagnosis of this condition, but this
has now been replaced by HSV PCR detection in
CSF. 3 Despite being very sensitive, HSV PCR can
be negative if CSF is obtained very early in the
disease course; the testing should be repeated
if the suspicion is very high. 3 The measurement
of intrathecal synthesis of immunoglobulin (IgG)
after one week into the disease course has been
suggested if the HSV PCR in CSF continues to
remain negative. 3 Despite the fact that brain im-
aging can be initially normal in 5-10% of cases 1 ,
Renard et al showed that DWI (diffusion-weight-
ed imaging) identified more areas of involvement
than FLAIR sequence when MRI is performed
early in the disease course. 4 Initially, HSV en-
cephalitis affects one hemisphere and involves
the contralateral side once it has extended in
the initially involved hemisphere. 4 Brain MRI is
not helpful to assess the response to therapy as
the lesions can progress despite treatment. 1 The
temporal lobe is most commonly as well as ini-
tially affected with HSV encephalitis but isolated
extra-temporal forms of HSV encephalitis have
been reported. 5 The frontal or parietal lobe can
also be initially involved with HSV encephalitis,
which can potentially delay the diagnosis of this
catastrophic condition. 5 EEG when used alone is
not helpful for making a diagnosis as non-spe-
cific changes are seen. 1 HSV encephalitis can
present with a sudden onset of symptoms which
can mimic a stroke. 6 It is possible that sudden
40 • THE JOURNAL OF THE ARKANSAS MEDICAL SOCIETY
3. Denes E, Labach C, Durox H, Adoukonou
T, Weinbreck P, et al. Intrathecal synthesis
of specific antibodies as a marker of her-
pes simplex encephalitis in patients with
negative PCR. Swiss Med Wkly. 2010 Oct
7;140:w13107.
4. Renard D, Nerrant E, Lechiche C. DWI and
FLAIR imaging in herpes simplex encephalitis:
a comparative and topographical analysis. J
Neurol. 2015 Sep;262(9):2101-2105. Epub
2015 Jun 20.
5. Fernandes AF, Lange MC, Novak FT, Zavala JA,
Zamproni LN, et al. Extra-temporal involve-
ment in herpes simplex encephalitis. J Clin
Neurosci. 2010 Sep;17(9):1221-1223. Epub
2010 Jun 11.
6. Tsuboguchi S, Wakasugi T, Umeda Y, Umeda
M, Oyake M, et al. Herpes simplex encephalitis
presenting as stroke-like symptoms with atyp-
ical MRI findings and lacking cerebrospinal
fluid pleocytosis. Rinsho Shinkeigaku. 2017
Jul 29;57(7):387-390. Epub 2017 Jul 21.
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