Introduction
Hydatid disease in humans is an infrequent parasitic condition resulting from the
larval stages of tapeworms belonging to the Echinococcus genus, with cystic echinococcosis
being the predominant manifestation. The endemic areas of this disease encompass the
Mediterranean region, Australia, Africa, the Middle East, and specific regions of
South America, with an annual incidence rate of 1–200 per 100.000 inhabitants.[1]
Adult Echinococcus granulosus lives in the intestines of dogs. Eggs are released through
feces and are infectious. When ingested by intermediate hosts like sheep, eggs hatch
in the intestine, penetrate the intestinal wall, and migrate through various organs
of the body, with a particular affinity for the liver and lungs. Within these organs,
eggs mature into hydatid cysts containing protoscolices and daughter cysts. Dogs become
infected by consuming the organs of intermediate hosts. In humans, which are abnormal
hosts, the ingestion of eggs leads to the development of hydatid cysts in various
organs. If cysts rupture, protoscolices can form new cysts elsewhere in the body (secondary
echinococcosis).[2]
Hydatid infections can occur in various organs. The most common is the liver, followed
by the lungs and spleen. Other less common locations include the brain, spine, retroperitoneal
space, kidneys, and musculoskeletal system.[3]
Neurohydatidosis accounts for 1–2% of all primary hydatid cysts. Cysts within the
cranial region can be categorized as primary or secondary hydatid cysts.
Spontaneous rupture or rupture triggered by trauma or surgical intervention can occur
in primary hydatid cysts. When the cyst ruptures, the larvae are released into the
brain tissue, resulting in the formation of multiple secondary hydatid cysts. Another
potential scenario for the development of multiple cysts is if a cyst ruptures and
circulates through the left cardiac chambers, in the presence of cardiac pathology,
or within the major arterial vessels, thereby facilitating the dissemination of larvae
to the brain. In rare cases, multiple cerebral hydatid cysts can occur due to the
ingestion of multiple larvae, which then travel through the arteries and cause embolism
in the brain. These rare multiple secondary cysts are infertile, meaning they lack
the necessary structures for reproduction.[1]
Case Presentation
A 55-year-old male from a pastoral area, where he owns sheep and dogs, presented to
the hospital with a concerning history of neurological symptoms. He reported that
approximately one month before admission, he noticed subtle changes in his daily activities.
He observed a gradual decline in his right-hand coordination, making it difficult
for him to perform tasks such as buttoning his shirt and holding objects steadily.
This decline was accompanied by agraphia; he found it increasingly challenging to
write notes or even sign his name. Additionally, he experienced acalculia, leading
to difficulty with simple calculations.
One week prior to admission, the patient experienced a sudden loss of consciousness
and was transported to the hospital. This episode of loss of consciousness was brief
but concerning, lasting several minutes, and followed by confusion and disorientation.
Magnetic Resonance Imaging (MRI) revealed six distinct cystic lesions in the left
parietal lobe, extending toward the lateral ventricle. These lesions appeared well-defined
and non-enhancing with minimal perilesional edema ([[Fig. 1]]). The serological evaluation showed positive results for Echinococcus-specific
immunoglobulin G (IgG) antibodies. However, the complete blood count did not indicate
eosinophilia. A Chest-Abdomen-Pelvis Computed Tomography (CT) scan was conducted to
assess the presence of hydatid cysts in other organs, but no additional cysts were
detected.
Fig. 1 The MRI showing the cysts with minimal perilesional edema suggesting a possible cyst
rupture.
A left parietal craniotomy was performed, followed by a C-shaped durotomy. Intraoperative
ultrasound was used to locate the cysts. A minimal corticectomy was done at the posterior
border of the superior parietal lobule. Subsequently, a cluster of six hydatid cysts
was exposed at 1 cm subcortically. The cysts were carefully dissected and individually
removed using the Dowling-Orlando technique. We used an isotonic saline solution (0.9%
NaCl) for hydrodissection, which facilitates the separation of the hydatid cysts from
the surrounding brain tissue without damaging the delicate cyst wall. This technique
minimizes the risk of rupture during the dissection process by providing a gentle
and controlled method for cyst removal. During the procedure, a previously ruptured
seventh cyst membrane was discovered and exercised. The remaining cavity was flushed
with a hypertonic saline solution (3% NaCl), a standard scolicidal agent used to prevent
recurrence by destroying any residual protoscolices. Following this, the resection
cavity and the rest of the surgical field were irrigated with an isotonic saline solution
once again to ensure that any remaining debris was cleared without causing any other
complications ([[Fig. 2]]).
Fig. 2 Gross appearance of the hydatid cyst in the operative field and after intact removal.
The patient recovered well without any new neurological deficits or postoperative
complications. He received therapy with ceftriaxone, levetiracetam, dexamethasone,
and albendazole. Ceftriaxone was administered at a dose of 2 g intravenously once
daily, starting 60 minutes prior to surgery and continued for the next 48 hours postoperatively
until the removal of the epicranial drain. This was done as a prophylactic measure
to minimize the risk of infection due to potential contamination during surgery. Levetiracetam
was initiated at a dose of 500 mg twice daily (total 1000 mg/day) upon admission due
to the patient's sudden loss of consciousness, which raised concerns about potential
seizures. This treatment continued throughout the postoperative period for 3 weeks
to prevent any seizure activity, considering the brain manipulation during surgery
and the patient's neurological history. Dexamethasone was given at a dose of 4 mg
intravenously every 6 hours for 5 days, followed by a taper over the next 5 days.
This medication was initiated upon admission to manage cerebral edema and inflammation
associated with hydatidosis and the surgical procedure. Lastly, albendazole was initiated
on the day of surgery and administered at a dose of 400 mg orally twice daily (total
800 mg/day) for 28 days, with the patient being monitored for response to treatment
in the infectious disease department. Albendazole is a standard antiparasitic treatment
for hydatid cysts that is intended to prevent recurrence and eliminate any residual
parasitic material.
Histopathological examination confirmed the diagnosis of hydatid cysts. Postoperative
computed tomography showed complete removal of the hydatid cysts ([[Fig. 3]]). The patient was discharged on postoperative day 10, and parietal syndrome symptoms
were in remission.
Fig. 3 The postoperative CT scan showing the complete removal of the hydatid cyst.
Discussion
Hydatidosis is a rare parasitic disease with potentially fatal complications.[1]
[2]
Serological tests, such as ELISA or immunoblot assays detect immunoglobulin G antibodies
against specific antigens of Echinococcus species. These tests are used to diagnose
and monitor cases of echinococcosis.[4] Notably, in our case, while serology showed positive IgG antibodies for Echinococcus,
there was an absence of peripheral eosinophilia, which is consistent with reports
that eosinophilia is not always present in cerebral hydatidosis cases. Interestingly,
the literature suggests that eosinophilia is more commonly associated with complicated
cystic echinococcosis,[5] which could explain its absence in uncomplicated cerebral cases, as in our case.
Imaging studies, such as ultrasound, computed tomography (CT), and magnetic resonance
imaging (MRI), are valuable for visualizing hydatid cysts in various organs. These
imaging techniques can help identify cyst location, size, and number.
CT scans generally show hydatid cysts as well-defined, circular or oval lesions with
smooth walls that appear hypodense due to fluid content, similar to cerebrospinal
fluid. In cases where the cysts are infected, fluid-fluid levels or gas bubbles may
be visible. Edema and mass effects can occur around the cysts, particularly if they
exert pressure on surrounding brain tissue.[6]
Hydatid cysts are primarily concentrated within the watershed zone of the middle cerebral
artery. MRI displays cystic structures that exhibit a distinct and well-defined appearance.
These cysts are notably non-enhancing, indicating a lack of increased contrast uptake
in the imaging, and contain fluid that appears in isointense to cerebrospinal fluid
across all pulse sequences. Notably, there is an absence of calcification or surrounding
edema in the usual course, although the existence of perilesional edema may suggest
complications like rupture or secondary infection.[7]
Fine Needle Aspiration may be performed to obtain a sample of cyst fluid for analysis,
particularly in organs outside the brain. Microscopic examination of the fluid can
reveal characteristic structures such as protoscolices or hooklets, which help confirm
hydatid disease. In some cases, if the fluid analysis is inconclusive or additional
information is required, a biopsy of the cyst wall or the affected organ may be needed
for definitive diagnosis.[8]
Hydatid cysts have three main components: the laminated layer, germinal layer, and
cyst wall. The laminated layer is a dense outer layer that protects the cyst. The
germinal layer is where the parasite grows and produces protoscolices and daughter
cysts. The cyst wall consists of host tissue and often shows signs of chronic inflammation.
Protoscolices are infective structures within the cyst fluid, while daughter cysts
are smaller cysts formed within the germinal layer. The host's immune response leads
to inflammation and the formation of granulomas.[9]
The differential diagnosis of hydatid cysts encompasses various conditions that share
similarities in imaging characteristics. These include pyogenic or fungal abscesses,
which are infectious collections; cystic granulomas indicating inflammatory responses;
cystic astrocytoma, a type of primary brain tumor presenting with cystic components;
arachnoid cysts originating from the arachnoid membrane; and porencephalic cysts associated
with localized brain tissue loss. Discerning these conditions is crucial for accurate
diagnosis and appropriate management.[10]
[11]
Hydatidosis management strategies involve a diverse array of therapeutic choices tailored
to the specific characteristics and location of the cyst and the patient's condition.
Surgical resection, which involves complete cyst removal, is a fundamental treatment
option. Another technique, known as PAIR (puncture, aspiration, injection of protoscolicidal
agent, and respiration), involves a series of steps to puncture the cyst, aspirate
its contents, inject a protoscolicidal agent to neutralize any remaining larvae, and
then aspirate. Anti-helminthic agents like albendazole and mebendazole work to eradicate
larvae and reduce cyst size. This approach is crucial in cases where surgical options
may be limited or as a complementary treatment to minimize the risk of recurrence.
In cases in which the cysts are inactive and asymptomatic, a watchful waiting approach
is adopted, involving regular monitoring to assess any changes in the cyst's status.[12]
The management of cerebral hydatid cysts typically requires surgical intervention.
The preferred approach is Dowling's maneuver, which involves careful infusion of warm
saline to safely and separate the cyst from the brain, minimizing the risk of rupture.
If complete removal without rupture is challenging, an alternative approach involves
puncturing the cyst and aspirating its contents before removal.[13]
[14]
The choice of surgical technique depends on the specific characteristics of the cyst
and the assessment of the surgical team.
The Dowling technique is a highly effective surgical method for removing cerebral
hydatid cysts without causing rupture. It was described by Dowling in 1929, before
the introduction of microscopes in neurosurgery. Magnification is recommended during
the early stages of surgery to avoid damaging the fragile cyst wall and to establish
a precise surgical plane. A saline solution serves a dual purpose in the surgical
procedure, facilitating the dissection of the cyst wall from surrounding brain tissue
and aiding in the subsequent extraction of the hydatid. This irrigating solution not
only assists in maintaining tissue integrity but also contributes to a smoother and
more controlled removal process. Tilting the operation table toward the lesion site
and lowering the patient's head helps in the gravity-assisted removal of the cyst.[15]
In our case, the use of the Dowling-Orlando technique was highly effective for safely
removing multiple cerebral hydatid cysts. Given the proximity of the cysts to the
lateral ventricle and their subcortical location, the precise hydrodissection approach,
using isotonic saline, minimized rupture risk and facilitated separation from the
surrounding brain tissue. This step is particularly crucial in cerebral hydatidosis
because rupture can lead to serious complications, including infection, recurrence,
or systemic allergic reactions.[16]
Furthermore, the presence of a ruptured seventh cyst necessitated the use of hypertonic
saline as a scolicidal agent in the residual cavity to effectively reduce the risk
of recurrence by eliminating any remaining protoscolices. This application, supported
by literature as having a relatively safe, non-toxic profile for neural tissue and
being an effective scolicidal agent in neurosurgical cases of hydatidosis,[16]
[17]
[18] was integral to the treatment strategy.
Hydatid cysts are delicate and easily prone to rupture. The primary goal of curative
treatment is to meticulously remove the intact cysts, emphasizing the avoidance of
any unintended spillage. In the event of rupture, the surgical procedure necessitates
meticulous suctioning of the cyst contents and subsequent irrigation of the cavity
with a hypertonic saline solution to prevent recurrence and eliminate any residual
parasitic material.[17]
[18] It is crucial to acknowledge that hydatid cyst rupture not only increases the risk
of local complications and recurrence but also elevates the potential for systemic
reactions, such as anaphylaxis. Therefore, surgeons must be vigilant, employing preventive
strategies to avoid rupture and being prepared to manage anaphylactic reactions promptly.[19]
Specifically, cyst aspiration is a common procedure for brainstem lesions, with the
preference against Dowling's technique due to associated higher morbidity rates. For
asymptomatic and deeply situated lesions, medical treatment may be considered. However,
when surgically removing large cysts, a gradual approach is essential to mitigate
the risk of rapid decompression syndrome. This approach entails a careful and deliberate
process to minimize potential complications associated with rapid decompression during
surgery.[20]
Conclusion
Hydatidosis is an infrequent parasitic disease that poses the potential for severe
complications. The presence of multiple cerebral hydatid cysts without involvement
of other organs is uncommon. Early diagnosis and timely treatment are essential for
a favorable outcome. The primary objective of surgery is meticulous and complete removal
of the intact cysts. Postoperatively, a comprehensive treatment regimen entails the
administration of antibiotics and antihelminthic medications, strategically implemented
to forestall recurrence and promote a successful recovery.
