Year : 2004 | Volume
: 14 | Issue : 1 | Page : 81--83
Multiple central nervous system hydatidosis secondary to cardiac echinococcosis
AK Pillai, MV Pillai, S Vohra, EB Oommen
From the Post Box 883,Raknor Private Limited, Eas Ai Khaimah, United Arab Emirates
A K Pillai
From the Post Box 883,Raknor Private Limited, Eas Ai Khaimah
United Arab Emirates
|How to cite this article:|
Pillai A K, Pillai M V, Vohra S, Oommen E B. Multiple central nervous system hydatidosis secondary to cardiac echinococcosis.Indian J Radiol Imaging 2004;14:81-83
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Pillai A K, Pillai M V, Vohra S, Oommen E B. Multiple central nervous system hydatidosis secondary to cardiac echinococcosis. Indian J Radiol Imaging [serial online] 2004 [cited 2020 Jul 2 ];14:81-83
Available from: http://www.ijri.org/text.asp?2004/14/1/81/28562
Hydatid disease is endemic in cattle-and sheep- raising regions of the world such as Central Europe, the Mediterranean countries, the Middle East, South America, Australia, New Zealand, India and South Africa . The disease is caused by the infestation of the larval form of Echinococcus granulosus. Hydatid disease in the central nervous system orbit and heart are rare with a reported incidence of 1-2%, less than 1% and 0.5-2% respectively of all cases of hydatid disease ,. Majority of the reported series are in the pediatric age group and therefore cerebral echinococcusis is considered as a childhood disease. We report an unusual case of secondary multiple intracerebral and intraorbital echinococcosis in an adult, presumably caused by embolised fragments from a left ventricular hydatid cyst.
A 36-year-old housewife presented with progressive protrusion of the left eyeball since 3 months. In the past 2 weeks she had developed diplopia in all direction of gaze and also complained of dull pain and hyperemia on waking in the morning. She denied any previous systemic illness, trauma or previous eye disease. On closer interrogation she gave a 1-year history of headache. Personal and family histories were unremarkable. Local examination of the left eye revealed a visual acuity of 6/18 without improvement on correction. Pupils reacted normally to light. Ocular movements were restricted in all directions. Conjunctival hyperemia was observed with engorged episcleral veins. Ocular pressure was slightly elevated and fundal examination revealed papillodema. The right eye was normal. Systemic examination was unrevealing. Specifically, there were no signs of hyperthyroidism or neurological deficits.
Laboratory examination did not disclose any abnormality except a high hydatid serology (1:1024). A plain and contrast enhanced CT scan of the brain including both orbits was performed. The scans of the orbit showed a 24 x 38mm intraconal cystic mass, pushing the globe outwards [Figure 1]. The brain scans revealed multiple , well defined CSF attenuation cysts varying in size from 2 to 4centimeters, in either parietal regions [Figure 2]. The CT values of the cyst were below 10 suggesting clear fluid [Figure 3]. No perifocal edema, calcification on the cyst wall or contrast enhancement was noted. There was no evidence of midline shift or brain herniation. Considering the possibility of hydatid disease an ultrasound scan of the abdomen, radiograph of the chest and an echocardiography were performed. The ultrasound scan of the abdomen and the radiograph of the chest were unrevealing. The echocardiogram showed a 14x22 mm cystic mass on the left ventricular surface of the posterior mitral valve.
The orbital cyst was enucleated. Pathological examination of the specimen confirmed the diagnosis of hydatid cyst with cuticular membrane; no germinative membrane or scolices were observed. Medical treatment was commenced post-operatively and further surgery for the intracranial and intracardiac cysts were planned and the patient was discharged in a satisfactory condition after 12 days.
Hydatidosis in humans occurs when the eggs of Echinococcus granulosus from canine faeces are accidentally ingested. The eggs loose their enveloping layer in the stomach, releasing the larvae. The larvae pass through the wall of the gut into the portal system and are carried to the liver where 65% of the larval load is filtered. Of the rest, 25% are trapped in the lungs (second filter) and less than 10% reach various organs through the systemic circulation .
Cardiac contraction provides an unfavorable environment for the cysts in the heart, thus cardiac implantation is uncommon. The majority of patients with cardiac hydatidosis are asymptomatic and present due to embolic dissemination of hydatid cysts elsewhere as was the case in our patient. In a case report by Turgut et al the patient presented with cerebral hydatidosis and acute vascular occlusion of the right femoral and left internal carotid arteries, consequent to embolic dissemination from a left ventricular hydatid cyst. . Trehan et al reported a case, which presented with a left basal ganglionic infarct secondary to a left atrial hydatid cyst . However, sudden death resulting from anaphylactic shock and cardiac tamponade due to rupture of cysts into the blood stream or pericardium respectively has been reported. Location wise the left ventricle (75%), right ventricle (18%) and interventricular septum (7%) are the usual sites. Two-dimensional echocardiography is the best diagnostic procedure for demonstration of cardiac hydatid cysts .
Orbital hydatid cysts typically present with gradually progressive proptosis and diminished extra ocular motility. MR and CT imaging characteristics are non-specific and the differential diagnosis includes congenital cysts like colobomatous cysts, optic nerve sheath meningoceles and hematic cysts. Colobomatous cysts are usually associated with micropthalmia while a hematic cyst contains blood and has a typical appearance on MRI. An optic nerve sheath meningoceles may occur primarily or secondarily (in association a optic nerve pilocytic astrocytoma or meningioma). These meningoceles can be associated with empty sella or enlarged subarachanoid cistern, such as gasserian cistern.  In a hydatid endemic area, a unilateral intraconal cystic mass in the presence of a positive hydatid serology should prompt a diagnosis of orbital hydatid cyst .
Intracranial hydatid cysts are classified as primary or secondary. The primary cysts, which are the commoner variety, are formed as a result of direct infestation of the larvae in the brain without demonstrable involvement of other organs and are mostly solitary. Supratentorial location is most frequent with a preference for the parietal lobe. These primary cysts are fertile as they contain scolices and brood capsules, hence rupture of primary cyst (e.g. during surgery) can result in dissemination. The secondary cysts on the other hand are less common and are always multiple. They arise from the rupture of a primary hydatid cyst (which may be intracranial or extra cranial). These cysts lack brood capsule and scolices and therefore are infertile and the resultant risk of recurrence after their rupture is negligible. However, recurrent secondary cysts formation can occur from repeated embolic phenomenon from a viable primary source. In the case report by Turgut et al , the patient underwent 5 surgeries over a period of 8 years for recurrent multiple intracranial hydatid cysts before the primary cardiac source was detected. Thus, it is essential to look for a primary source in case of multiple intracerebral hydatidosis, as only by eradicating the primary cysts will a cure be achieved.
MR and CT cannot distinguish primary from secondary cysts. Generally, multiplicity of the cysts strongly favors the diagnosis of secondary cysts and should prompt a search for a primary source elsewhere. Both modalities characteristically show hydatid cyst as a spherical, well-defined, non-enhancing cystic lesion without peripheral edema,. The fluid density is generally equal to that of CSF on both CT and MR scan. A fine rim of peripheral enhancement with perilesional edema may be seen in the presence of active inflammation  MR scan may show a low density cyst wall  and relations with surrounding structures are better delineated than on CT scan ,. Kohli et al  performed in vivo and in vitro MR spectroscopy (MRS) studies in a patient of intracranial hydatid cyst. Besides lactate, alanine and acetate, a large resonance for pyruvate was observed. MRS pattern appeared different from the other cystic lesions of brain and they suggested MRS as an adjunct to imaging in the differential diagnosis of intracranial hydatid. Role of MRS in monitoring drug therapy was also discussed.
In conclusion, multiple hydatid cysts in the central nervous system are invariably secondary. A primary source should always be looked for. A cure can be achieved only by eradicating the primary source. An occult cardiac source can be overlooked and hence it is important to think about this possibility when dealing with central nervous system hydatidosis.
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