Key-words:
Extradural - hydatid cysts - multiple - primary
Introduction
Hydatid disease in humans is caused by a tapeworm, Echinococcus granulosus, which
forms larval cysts in the human tissue. Humans get infected through the feco-oral
route. Central nervous system (CNS) echinococcosis is rare with <4% of cases of hydatid
disease have CNS involvement. Intracranial hydatid disease is seen in three different
forms, those are intracerebral, extracerebral, and a combined form. An extradural
hydatid cyst is rare, and the exact cause is not clear. The incidence of hydatid disease
varies geographically; it is much more common in South America, Australia, the Middle
East, and parts of North Africa than in Europe and North America. In India, E. granulosus
is relatively common in Southeast Rajasthan.[[1]] Till date, only 11 cases of primary multiple hydatid cysts of the brain (intradural)
have been reported in the literature, but extradural multiple hydatid cysts we could
not found in literature, so this is probably the first one.[[2]]
Case Report
A 20-year-old female patient presented to us with intermittent headache since last
1 month which was gradually increasing in intensity. There was no history of recent
trauma, vomiting, convulsions, or any weakness. The patient had a history of prolonged
canine contact. Neurological examination was completely normal. Skull and chest films
were normal. Magnetic resonance imaging (MRI) of the brain with contrast was done
which showed T1 hypointense lesion with multiple septae; it was hyperintense on T2-weighted
images. It showed a typical cartwheel appearance as seen in hepatic hydatid cyst.
Pressure erosion of the adjacent bone was seen on computed tomography (CT) of the
brain [[Figure 1]]a, [[Figure 1]]b, [[Figure 1]]c. Hence, hydatid cyst was considered as a probable diagnosis. Ultrasound of the
abdomen was completely normal.
Figure 1: (a-c) Preoperative magnetic resonance imaging of the brain with contrast of the patient
showing lesion. Typical cartwheel appearance
As there was a significant mass effect over the underlying brain parenchyma, the patient
underwent surgical excision of lesion. Intraoperatively, multiple cysts were found
completely in extradural space with pressure erosion of the skull bone at some places.
Dura was completely normal with no intradural involvement. The inner table was eroded
by the mass, but there was no evidence to suggest that the cyst arose from the diploic
space. There was a yellow colored large mother sac with multiple daughter cysts. Complete
excision of cyst was achieved; savlon wash was given [[Figure 2]]a, [[Figure 2]]b, [[Figure 2]]c, [[Figure 2]]d. Postoperatively, the patient recovered well without any deficits and was discharged
on the 7th postoperative day. Postoperative CT scan of the brain showed complete excision
of lesion. Postoperatively, the patient was given albendazole and steroids. On follow-up
at 3 months, the patient was doing better with complete relief from headache and no
recurrence [[Figure 3]].
Figure 2: (a-d) Intraoperative images showing multiple cysts. Intact dura can be seen
Figure 3: Postoperative computed tomography scan of the brain showing complete excision
Discussion
Human hydatid disease is caused by E. granulosus and Echinococcosis alveolaris. E.
granulosus produces cystic lesions, whereas E. alveolaris produces invasive, solid
lesions. CNS hydatid disease is most commonly seen in children and in males. Hydatid
cyst in the brain is relatively rare, seen in only 2% of cases. Brain hydatid cysts
can be primary (single) or secondary (multiple). The primary cysts are fertile as
they contain scolices and brood capsules, hence rupture of primary cyst can result
in recurrence. The secondary multiple cysts result from spontaneous, traumatic, or
surgical rupture of the primary intracranial hydatid cysts, and they lack brood capsule
and scolices. The secondary intracranial hydatid cysts are therefore infertile. Primary
multiple cysts are uncommon, and isolated case reports of primary multiple hydatid
cysts have appeared in the literature. Nurchi et al. while reviewing the literature
found only 11 reported cases of primary multiple hydatid cysts.[[3]]
The most common presentation in children is with signs of raised intracranial pressure.
Adults present with focal neurological deficits such as hemiparesis, hemianopia, speech
disorders, or seizures depending on the location of the lesion.
Intracranial extradural hydatid cysts are very rare, and we were able to find only
12 previous cases reported in the literature till date. The exact pathogenesis of
extradural echinococcosis is not clear; following postulations have been made:
-
Infestation by direct extension from the calvarium
-
Infestation by intracerebral cysts through an apparently healthy dura
-
Rarely, infestation by the extradural vessels which may carry hexacanth embryos to
the extradural space.[[4]]
In our case, there was no calvarial involvement; also no intracerebral lesions were
seen. Samiy and Zodeh had encountered a case of extradural hydatid with normal skull
films that showed erosion of the inner table during surgery. It was interpreted as
a primary calvarial lesion, but the authors did not elaborate more on the relation
of the cysts to the bone.[[3]] Robinson claimed that extradural vessels that can carry the hexacanth embryo are
few or nonexistent, so with such sparse blood supply to this region, extradural space
is an extraordinary site of infestation. The only known way, however, by which the
hexacanth embryo travels in the body is through the bloodstream.[[5]]
The cyst is hypointense on T1-weighted and hyperintense on T2-weighted MRI. MRI also
shows perilesional edema. MRI is superior in determining the exact cyst location,
cystic contents, and also in surgical planning and ruling out other diagnostic possibilities.
Despite the advancements in microsurgical operative techniques, cerebral hydatid cysts
still pose a challenge for the neurosurgeons as they are usually large in size at
presentation; thin cyst wall and the neurological deficits are minimal at presentation
despite the location and the large size of the cyst.[[1]]
Definitive treatment is complete excision of the cyst without spillage, followed by
medical treatment with albendazole. It is very important to avoid rupture on cyst
intraoperatively with thorough savlon wash ready at hand. Furthermore, perioperative
anthelmintic treatment with albendazole is recommended for multiple cysts and is reported
to be quite effective in slowing down the increase in cyst volume or even in stopping
cyst growth completely.
Conclusion
A high index of suspicion is necessary to diagnose this rare lesion preoperatively
and to consider it as one of the differential diagnosis. It is important as surgical
removal of the intact cyst is required to prevent progressive neurologic deficit.
Removal of all the cysts without intraoperative rupture with medical management postoperatively
is necessary to prevent recurrence.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms.
In the form the patient(s) has/have given his/her/their consent for his/her/their
images and other clinical information to be reported in the journal. The patients
understand that their names and initials will not be published and due efforts will
be made to conceal their identity, but anonymity cannot be guaranteed.
