Flat panel detector-CT with endovenous injection. Description of a novel technique for obtaining cerebral arteries imaging: Technical note


Romanian Neurosurgery  |  Volume XXXI  |  Number 3 |  2017  |  July-September 

 
Article 

 
 Brain hydatidosis: review of the literature  

Johana Maraby-Salgado, Joulen Mo-Carrascal, Jorge Aquino-Matus, Willem Guillermo Calderon-Miranda,  

Amit Agrawal, Andrei F. Joaquin, Mohammed Al-Dhahir, Samer Hoz, Maria Teresa Pacheco-Hernandez,  

Huber Padilla, Luis Rafael Moscote-Salazar 
COLOMBIA, MEXICO, INDIA, BRAZIL, YEMEN, IRAK 

 

 

 

DOI: 10.1515/romneu-2017-0061 
 



 
 
 
 
 
378 | Maraby-Salgado et al - Brain hydatidosis 

 

 
 
 
 
 
 

DOI: 10.1515/romneu-2017-0061   

Brain hydatidosis: review of the literature 

Johana Maraby-Salgado1, Joulen Mo-Carrascal1, Jorge Aquino-Matus2, 
Willem Guillermo Calderon-Miranda3, Amit Agrawal4, Andrei F. 
Joaquin5, Mohammed Al-Dhahir6, Samer Hoz7, Maria Teresa Pacheco-
Hernandez1, Huber Padilla1, Luis Rafael Moscote-Salazar8 
1Universidad de Cartagena, COLOMBIA; 2Department of Internal Medicine, Universidad 
Nacional Autonoma de Mexico, Ciudad de Mexico, MEXICO; 3Department of Radiology, 
Universidad Nacional Autonoma de Mexico, Ciudad de Mexico, MEXICO; 4Department of 
Neurosurgery, Narayna Medical College Hospital, Chinthareddypalem, Nellore, Andhra Pradesh, 
INDIA; 5Department of Neurology, Neurosurgery Division, State University of Campinas, 
Campinas-São Paulo, BRAZIL; 6Neurosurgery, Al-Thawra Modren General Hospitakl, YEMEN; 
7Neurosurgery, Neurosurgery Teaching Hospital, Bagdad, IRAK; 8Neurosurgery, RED LATINO, 
Organización Latinoamericana de Trauma y Cuidado Neurointensivo, Bogota, COLOMBIA 

 
Abstract: Hydatidosis is a common disease worldwide. The causal agent may 
compromise any Organ of the body, the cerebral location is infrequent. The infection is 
caused by the larval form of Cestodo Echinococcus granulosus. The man is an accidental 
intermediary host for food consumption or water contaminated with eggs present in 
animal feces. We present a review of the literature. At the imaging level, the disease has 
a classic characteristic consisting of single, usually unilocular and less frequent 
multilocular, intra-axial and more frequently hemispheric cerebral lesions, 
compromising the vascular territory of the middle cerebral artery by the hematogenous 
dissemination of the parasite. 
Key words: Echinococcosis, Brain neoplasms, Cysts, Neurosurgery 

 
Introduction 

Hydatidosis (echinococcosis) is a global 
zoonotic parasitic disease produced by the 
larval phase of tenia Echinococcus (1, 2, 3). 
There are two types of Echinococcus 
infections: Echinococcus granulosus is the 
most common type, whereas Echinococcus 
multilocularis is less common but more 

invasive, generally with malignant behavior (1, 
2, 3, 4, 5, 6, 7, 8). 

Most cases of cystic echinococcosis are 
found in endemic areas such as Australia, New 
Zealand, the Mediterranean, the Middle East, 
and South America, and cases of alveolar 
echinococcosis are found in North America, 
Central Europe, Russia, China, and Turkey (6). 



 
 
 
 
 

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The overall incidence of organ infestation 
is highest in the liver reaching 50% to 77%, 
followed by lungs with 8.5% to 43%, and 10% 
found in other organs such as brain, muscles, 
pericardium, kidneys, ocular orbit, tibia, and 
bone marrow (4, 6, 7, 8). 

What is neurohidatidosis? 
Central nervous system (CNS) 

involvement is rare and occurs in 
approximately 2- to 3% of all cases, and 
accounting for only 2% of all lesions occupying 
the intracranial space (1, 3, 4). 

Neurohidatidosis is more frequent in 
children and young adults (approximately 50 
to this affects more men than women (62%) 
from 21- to 40 years -old in the general 
population (3, 4, 8). 

The cyst affects the CNS in 1% of cases and 
is usually diagnosed in childhood. It has been 
reported a prevalence of 60-93% in children 
with a male predominance (5, 8). 

Cycle 
The life cycle of the parasite requires two 

hosts: a definitive host and an intermediate 
host. The main definitive hosts are mainly 
dogs for E. granulosus and foxes, jackals and 
coyotes for E. multilocularis, which generally 
maintain the wild cycle. The main 
intermediate hosts are sheep for E. granulosus 
and wild rodents for E. multilocularis (6, 7). 

The adult worm lives in the intestine of the 
definitive host, which expels eggs in feces 
(infective form) that are ingested by the 
intermediate host. After the ingestion of eggs, 
the enzymes in the intestinal tract digest the 

outer lining of the eggs and the embryo is 
released. The embryos have small hooks and 
pacifiers with which they attach to the mucosa 
of the intestine, perforate the wall and 
disseminate through the circulatory and 
lymphatic system (1, 4, 5, 7, 8), and then to the 
liver, lungs, brain and other tissues. The 
embryo develops into a cyst within which 
protoscolices are produced. The cycle is 
completed when the final host ingests the 
larval form (5, 6, 7, 8). 

Humans may be infected incidentally as 
intermediary hosts after ingesting the eggs of 
the parasite directly by contact with a final host 
or indirectly with contaminated food or water 
(6, 7). 

Histopathology 
Histopathologically the E. granulosus cyst 

wall consists of a germinal inner layer 
(endochisis) and a laminated outer layer 
(exocyst). The host reacts to the cyst by 
forming a capsule of connective tissue 
(pericyst), vascularized that provides nutrients 
for the parasite. In the brain, the pericystic 
layer is thin because and exhibits minimal 
inflammatory reaction. E. granulosus cysts are 
usually solitary and commonly supratentorial, 
located in the distribution of the terminal 
branches of the middle cerebral artery, usually 
temporo-parieto-occipital (1, 8) 

E. granulosus cysts are usually unique and 
spherical, well demarcated from the 
surrounding tissue (which does not present 
major inflammatory changes), and have 
smooth and thin walls; they can reach a large 
size as a result of slow but continuous growth 
(7, 8). The cystic lesions are homogeneous 



 
 
 
 
 
380 | Maraby-Salgado et al - Brain hydatidosis 

 

 
 
 
 
 
 

with liquid content like that of cerebrospinal 
fluid, glycolipoproteins, carbohydrates, amino 
acids and metacestode metabolism salts. Some 
of its components, such as albumin and 
immunoglobulins are derived from the host. 
In the CNS, cysts can grow mainly from the 
direct implantation of oncospheres or from 
the metastatic dissemination of a visceral cyst 
(1, 6, 8). 

In contrast to the cyst of E. granulosus, the 
cyst of E. multilocularis grows by external 
budding of the germinal membrane with 
progressive infiltration of the surrounding 
tissue. Cysts are small, tend to aggregate in 
clusters resembling a bunch of grapes and 
proliferate rapidly eroding brain tissues; they 
have little fluid within a semi-solid structure 
and many small vesicles embedded in a calcified 
stroma.  They are commonly surrounded with 
connective tissue edema, and cause a severe 
immune reaction in the host. They usually do 
local and distant metastases, especially in the 
liver, lung, marrow, and brain. The extent of 
injury to brain tissue is characterized as "crab 
claws", which is extremely dangerous for the 
human body (4, 9, 10). 

Multiple brain hydatid cysts are rare. Most 
of the cases are due to surgical, spontaneous or 
traumatic rupture of a viable primary lesion 
with implantation of the scythe within the 
cerebral parenchyma. These lesions are called 
secondary and are infertile as they lack 
breeding and scolex capsules. It is believed that 
multiple cysts can also grow after rupture of a 
cyst located in a left heart cavity or large 
arterial vessels (4, 8, 9). In the literature, there 
are 81 patients reported with multiple cerebral 
hydatid cysts: 77 by Al Zain et al., 5 by Tu'zu`n 

et al., and 2 by Buktea et al. (3) Multiple 
primary cyst without any clinical or 
radiological evidence of hydatidosis in other 
parts of the body are rare and are usually result 
from arterial embolism secondary to the 
ingestion of multiple larvae (6, 7, 8). In both 
species, the larva of the parasite can be found 
within the cysts (7, 8, 9). 

Spinal hydatidosis is rarely seen and occurs 
in less than 1% of all cases of hydatid disease. 
Thoracic disease is more common with mainly 
vertebral and paravertebral involvement (1). 

Clinical manifestations 
The clinical manifestations of 

neurohydatidosis are closely related to their 
location. The lesions may remain asymptomatic 
until they become quite large (10). 

 The main symptoms are headache, 
vomiting, nausea, and other nonspecific 
symptoms such as hemiparesis, seizures, 
altered visual field and gait disorders; all of 
them varying with the intracranial location of 
the lesions. Neurological signs may also 
manifest as result of increased intracranial 
pressure (8, 11). 

The most common clinical manifestations 
of spinal hydatidosis include paraparesis 
(62%), paraplegia (26%), back pain and 
radicular pain (55%), hypoesthesia (36%), and 
loss of sphincter control (3%) (8, 9, 10, 11). 

Diagnosis 
The diagnosis of the disease hydatidosis is 

based on serological tests and imaging 
techniques. Immunological data are irrelevant 
for diagnosis, and the most reliable methods 



 
 
 
 
 

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are neuroradiological imaging and 
histopathological examination (6, 7, 8, 10, 12). 

Image Techniques 
Diagnostic methods useful for human 

hydatidosis include ultrasonography (US), 
computed tomography (CT) and magnetic 
resonance imaging (MRI) (13, 14, 15, 16). 
(Figure 1).  

CT (as well as MRI) is essential to the 
diagnosis of cerebral hydatid cyst. CT 
sensitivity ranges from 90% to 97%. MRI 
adequately shows the main characteristics of 
the hydatid cyst (6, 8, 12, 13). 

Although neurohydatidosis can locate in 
any part of the brain, there are most often 
found in both hemispheres, particularly in the 
territory of the middle cerebral artery. In 
younger patients, skull X-rays may 
demonstrate suture separation, unilateral and 
widening of the vault, or erosion of posterior 
clinoid processes (1, 6, 7, 8, 9, 10). 

The evaluations of hydatid cysts by cranial 
CT and MRI reveal a solitary parenchyma with 
homogeneous, most commonly 
supratentorial, spherical and large cysts with 
well-defined borders, and peripheral edema. 
The density of cyst fluid is the same as that of 
cerebrospinal fluid (8, 12). 

Although the lesion may cause extrinsic 
compression of the ventricle system with 
posterior hydrocephalus, there is associated 
edema as seen typically in abscesses and cystic 
tumors. The lesion does not improve after the 
intravenous administration of contrast material, 
and calcification is extremely rare (6, 7, 8). 

On non-contrast CT, the cyst wall is 
isodense or hyperdense to the brain tissue (7, 8). 

 In MRI the cyst wall usually shows a low 

intensity border in both T1 and T2-weighted 
images. In T2-weighted MRI, the presence of a 
hypointense border has been described as a 
characteristic of hydatidosis (6, 8).  

MRI is the preferred imaging modality 
when spinal hydatidosis is suspected. The 
walls of the cyst are thin and regular, with no 
septa. The presence of a markedly hypointense 
cyst wall in T1-weighted and T2-weighted 
images, and the absence of enhancement of the 
wall with gadolinium, are characteristic of 
hydatid disease (6, 8, 13, 14). 

It is believed that MRI should be 
considered as the imaging aid of choice in 
planning for surgical approach because of the 
ability to obtain coronal and sagittal images; 
and also, because it reveals the anatomical 
relationships of the lesions to the grooves and 
ventricles (7, 8, 10, 15). 

 

 
Figure 1 - Cerebral CT scan showing cysts of hydatidosis 



 
 
 
 
 
382 | Maraby-Salgado et al - Brain hydatidosis 

 

 
 
 
 
 
 

In imaging tests, cerebral alveolar 
hydatidosis are shown as solid, calcified 
lesions with surrounding edema, in the form 
of cauliflower. This pattern has also been 
reported in other studies and may help 
distinguish cerebral alveolar hydatidosis from 
other brain masses, particularly in 
cysticercosis, coenuresis, toxoplasmosis, 
fungal infections, brain abscesses and 
oligodendrogliomas (10, 12, 13, 16). 

Experimentally it has been shown that a 
cyst takes from 3 to 16 months to grow to 1 cm 
in diameter (12). 

Serological analysis is in most cases 
negative. The advantage of histopathological 
examination is that reveals the degree of 
infestation of the parenchyma around the cyst 
that contributes to the enlargement of the 
process. Although radiological characteristics 
are characteristic, the definitive diagnosis of 
hydatidosis is based on the histopathological 
examination of the surgical specimen (6, 11, 
12, 13, 15). 

Serology 
The test of choice for the serological 

diagnosis of hydatidosis is based on the 
detection of IgG antibodies against cyst fluid 
derived from native or recombinant B antigen 
subunits, either by enzyme-linked 
immunosorbent assay (ELISA) or in 
immunoblots. Antibodies are found up to 
92.2% against a new 32 kDa EPC1 antigen of 
the germ layer of the hydatid cyst of E. 
granulosus, compared to 84.5% against the B 
antigen (11, 12, 13, 14, 15, 16).  

E. granulosus has been shown to induce 
both cellular and humoral immune response, 

therefore increasing the number of CD8 in 
peripheral blood (10, 14, 15, 17). 

In other laboratory tests, the globular 
sedimentation rate is always high and 
peripheral eosinophilia could not be a 
significant feature. Lumbar puncture I usually 
avoided since changes in cerebrospinal fluid 
are not specific and the risk of complications 
due to increased intracranial pressure is high 
(14, 15, 18). 

Evidence for the fixation of the 
complement (Weinberg) and the reaction of 
Casoni (immediate hypersensitivity skin test) 
is limited; Weinberg is positive in 40 to 70% of 
patients, and false positives are frequently 
obtained with the Casoni reaction. (14, 15) 

Measurement of specific immunoglobulin 
E circulation is not a diagnostic test but may be 
used to monitor the response to medical 
treatment (14, 15, 17) 

The release of histamine from basophils 
and particularly the degranulation tests used 
to detect IgE binding to basophils, are more 
sensitive than common tests and may be used 
to confirm diagnosis in endemic regions (13, 
14, 15). 

Differential diagnosis 
The differential diagnosis of cerebral cystic 

echinococcosis includes brain abscess, cystic 
tumor, arachnoid cyst, and encephalic cyst. 
Hydatid lesions can be differentiated from 
brain abscess and cystic tumor by the absence 
of edema around the lesion and mural 
nodules. Other cystic lesions such as 
arachnoid cysts and brain cysts are not 
spherical and are not surrounded by brain 
matter (7, 8, 15, 16). 



 
 
 
 
 

Romanian Neurosurgery (2017) XXXI 3: 378 - 384 | 383 

 

 
 
 
 
 
 

The differential diagnosis of cerebral 
alveolar echinococcosis includes gliomas, 
metastases, tuberculomas and fungal 
infections. The diagnosis should be suggested 
by evidence of a primary hepatic foci, clinical 
history, patient clinical manifestations, 
geographic location with high prevalence of 
infection in the host, and laboratory data 
(include information about CSF, Western blot, 
or PCR before surgery (10, 11, 14, 15) 

Lack of transparency or sclerosis within 
adjacent bone in the absence of disc disease in 
vertebral hydatid disease may help to 
differentiate from tuberculous spondylitis. (1) 

Treatment 
The treatment of this infection consists of 

surgical intervention, medical treatment, and 
chemotherapy (19, 20, 21, 22). 

Medical treatment with mebendazole, 
albendazole and praziquantel have shown 
good results in the hydatid cyst of liver and 
abdomen. Few data have been published in the 
medical treatment of intracranial hydatidosis 
with respect to drug penetration through the 
blood-brain barrier and the intracranial 
hydatid cyst membrane, however reports of 
isolated cases showed complete disappearance 
of multiple intracranial hydatid cysts with 
albendazole therapy at a daily dose of 10 mg/kg 
three times daily for 4 months (7, 14, 15, 20, 
21, 22). 

 Nonetheless, surgical removal of the 
cerebral hydatid cyst remains the treatment of 
choice. The rate of intact removal of an 
intracranial hydatid cyst is about 60 to 70%. 
Intraoperative rupture of the cyst produces a 
high risk of recurrence and can be fatal due to 
the dissemination of scolex, which can lead to 

replantation, anaphylaxis, and chemical 
meningitis (14, 15, 21, 22, 23). 

Medical treatment with albendazole is 
beneficial in cases of recurrence, rupture of an 
intraoperative cyst, giant or multiple hydatid 
cysts, or both before and after surgery. Long-
term follow-up of patients with intracranial 
hydatidosis in whom rupture of the cyst 
occurred intraoperatively confirm the 
excellent prognosis reported previously (8, 
12). Currently the Dowling-Orlando 
technique is the technique most used in the 
surgical treatment of hydatid cysts. When the 
Dowling technique is combined with 
microsurgery, large cerebral hydatid cyst can 
be successfully removed without rupture (14, 
15, 21, 22, 24). 

The correct treatment of spinal hydatidosis 
and neurological compromise is laminectomy 
with removal of the cyst to achieve local 
decompression. However, cysts that 
compromise the spine may not be safely 
cleared, therefore the risk of recurrence is up 
to 40%, even after extensive surgery (4, 21, 22, 
23, 24). 

Currently, surgery is the accepted method 
for the treatment of cases of cerebral alveolar 
hydatidosis, but chemotherapy is mandatory 
after the surgical intervention (10) (Figure 2). 

 

 
Figure 2 - Appearance of a typical cyst at removal 



 
 
 
 
 
384 | Maraby-Salgado et al - Brain hydatidosis 

 

 
 
 
 
 
 

Correspondence 
Dr. Luis Rafael Moscote 
E-mail: mineurocirujano@aol.com 

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