DISCUSSION
The opercular syndrome(OS) includes bilateral corticobulbar involvement
with voluntary facio-labio-pharyngo-glosso-laryngo-brachial paralysis
with well-preserved automatic and reflex movements.(8) It is a sequalae
of bilateral lesions of the anterior opercular area surrounding the
insula formed from gyri of the frontal, temporal and parietal lobes. It
is a form of cortical type of pseudobulbar palsy.(8)
The etiology encompasses vascular lesions including thrombotic or
embolic multiple strokes, particularly in adults; infections of the
nervous system, for example herpes simplex encephalitis, and
toxoplasmosis secondary to AIDS; acute disseminated encephalomyelitis;
head trauma; vasculitis; multiple sclerosis; perinatal difficulties; and
perisylvian cortical dysplasias.(1)(8)
OS is commonly associated with infectious cause in childhood (72.7)
including herpes simplex virus. The virus is the most prevalent cause
(37.5%). Likewise in adults OS is more commonly linked to cerebral
infarction.(53.3%)(9) with viral cause being less common. We found only
one previous case related to OS with EBV infection. EBV encephalitis
causes damage to the deep nuclei of the basal ganglia and thalamus,
which is different from our findings. Our patient’s PCR results showed
no amplification of EBV DNA. Only 75% of patients with a positive EBV
serological test show detectable EBV DNA. The remaining 25% can have
negative PCR results.(9)
The operculum includes the area covering the island of Reil, and is made
up of parts of the frontal, parietal, and temporal cortex and lesions
which disrupts the connections between these areas and the relevant
cranial nerve nuclei in the brainstem can cause the suprabulbar palsy of
the opercular syndrome. This explains the preservation of emotional and
automatic bulbar reflex movements, which relies on the use other neural
pathways.(10)
In contrast to pseudobulbar palsy, the opercular syndrome is
characterized by lack of sphincter disturbances, the rarity of
pathological laughing, the decreased tone of the affected muscles, and
the abolished gag reflex and it differs from bulbar palsy in the lack of
fasciculation, atrophy and denervation, and in the preservation of
involuntary innervation and of reflexes except for the gag reflex.(10)
The patient had mild residual dysarthria as seen in other studies.
Incomplete resolution of neurologic symptoms is consistent with prior
reports of HSV-induced FCMS.(15)
Weller et al classified opercular syndrome based on etiology; i.e. (a)
Classical form most often related to vascular etiology; (b) Subacute
form due to central nervous system infections; (c) Developmental form
most often related to neuronal migration disorders; (d) Reversible form
in children with epilepsy; and (e) Rare type related with
neurodegenerative disorders.(11)
Patient can present with opercular syndrome in the setting of initial
near normal cerebrospinal fluid (CSF) studies as seen in the early phase
of our case. HSV encephalitis should be suspected and treated in febrile
patients with otherwise unexplained neurologic deficits even if initial
CSF analysis is unremarkable.(12)
The clinical manifestation is fairly uncommon, however radiological
evidence of involvement of the operculum in HSE is commonly evident. MRI
is very sensitive in showing opercular damage, depending on the
etiology.(13)
The limbic system is usually affected by HSVE; the most commonly
affected areas are the medial temporal lobes, but it can also impact the
insular, cingulate, and fronto-basal cortex. The lesions are unilateral
or bilateral. On a brain MRI, regions of T2 and FLAIR hyperintensities
involving the cortex and white matter are commonly observed. Although a
few cases of basal ganglia involvement have been recorded in HSVE, basal
ganglia are typically avoided.(13)(14)
In terms of prognosis for HSE, it is critical to begin antiviral therapy
at an effective dose and time duration timely along with supportive
care. Inadequate dosing and treatment can lead to a poor prognosis. Many
authors believe that 21 days would be secure. Acyclovir and valacyclovir
are suggested as prophylaxis against HSE. We treated our case with
intravenous acyclovir for three weeks and continued for one more week
until the control CSF PCR findings came back negative. It is favorable
for prognosis to continue the intravenous treatment for at least four
weeks, even if the control CSF HSV-1 PCR goes negative.(2)