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Primary Solitary and Multiple Intracranial Hydatid Cyst Disease: Report of Four Cases

Hydatid disease is caused by Echinococcus granulosus or Echinococcus multilocularis during the larval stage of the tapeworms. The incidence of intracranial hydatid disease is 1-2% of all cases with hydatid disease in all ages. However 50-75% of cases involving the central nervous system occurs in the pediatric age group (1). Cerebral hydatid cysts are usually solitary and may be unilocular or multilocular. Multiple cerebral cysts are rare and usually occur as a result of surgical or traumatic rupture, but spontaneous rupture is also possible (2-9). Multiple cysts resulting from the rupture of a primary cyst are acepholeceles, they are infertile and have no broad capsule. However, very rarely a multiple larval intake may cause primary multiple cerebral hydatid cysts (7,10-12). Hydatid cysts may not cause focal neurological signs until they are very large. Öz


Introduction
Hydatid disease is caused by Echinococcus granulosus or Echinococcus multilocularis during the larval stage of the tapeworms. The incidence of intracranial hydatid disease is 1-2% of all cases with hydatid disease in all ages. However 50-75% of cases involving the central nervous system occurs in the pediatric age group (1). Cerebral hydatid cysts are usually sol-itary and may be unilocular or multilocular. Multiple cerebral cysts are rare and usually occur as a result of surgical or traumatic rupture, but spontaneous rupture is also possible (2)(3)(4)(5)(6)(7)(8)(9). Multiple cysts resulting from the rupture of a primary cyst are acepholeceles, they are infertile and have no broad capsule. However, very rarely a multiple larval intake may cause primary multiple cerebral hydatid cysts (7,(10)(11)(12). Hydatid cysts may not cause focal neurological signs until they are very large.
Secondary to mass effect, the first clinical sign is usually intracranial hypertension (13).
In this report, we describe four children with primary intracranial hydatid cysts drawing attention to rare and different features of intracanial hydatid disease. The clinical symptoms, medical treatment and surgical interventions of these four children were discussed within the literature.

Case Report
This study included four children who were treated for primary intracranial hydatid disease. The clinical and laboratory findings of the patients were reviewed. All four patients, a preoperative diagnosis of the disease was made thanks to cranial Magnetic Resonance Imaging (MRI) findings and indirect hemagglutination test for E. granulosus. All patients underwent a chest radiography, abdominal ultrasonography (USG) and echocardiography to reveal if any other localization of hydatid disease was present. Cysts were removed surgically. Histopathological and microbiological studies were performed for surgical specimens. Intraoperative and postoperative complications were documented. Outcome of all patients at least one year after surgical removal were evaluated.

Case 1
A 7-year-old boy was admitted to our emergency department with strabismus, headache and vomiting lasting for 3 months. On physical examination esotropia of both eyes and papiledema were detected. The examination of chest radiograph, complete blood count, urine analysis, and blood biochemistry revealed no abnormality. Cranial MRI revealed a large multiloculated intracranial cyst with dimensions of 5.5 x 5,5 x 5 cm in left parieto-occipital region ( Figure 1). Investigations for other organ involvement (abdominal ultrasonography, chest radiography and echocardiography) were performed but no other focus was found. Indirect hemagglutination test for E. granulosus was positive with 1/256 titer. Albendazole treatment of 10 mg/kg twice daily was started. Upon surgical exploration, the cyst was totally extracted without rupture. Histopathologic examination of the specimen revealed a hydatid cyst with scoleces. Albendazole treatment continued for 3 months till indirect hemagglutination test for E. granulosus become 1/32 in titer. The patient is being followed for 3 years and no recurrence of hydatidosis has been detected.

Case 2
A 14-year-old boy was admitted to our emergency department in a state of deep stupor. He was suffering from headache, vomiting, malaise and intellectual deterioration lasting for 15 days. The day before hospitalization he had three seizures lasting for about 5 minutes each. He had a history of surgical intervention for an intracranial hydatid cyst two years ago. On physical examination there was an operation skar on the left frontotemporoparietal area. He could hardly be awakened, without cooperation and orientation. He had bilateral papiledema. The examination of complete blood count, urine analysis, chest radiograph and blood biochemistry revealed no abnormality. Indirect hemagglutination test for E. granulosus was positive with 1/64 titer. Cranial CT imaging demonstrated multiple cystic lesions the biggest of which was 6 x 7 x 7 cm in diameter in the left frontotemporoparietal region ( Figure 2). Albendazole treatment of 10 mg/kg twice daily was started. Extensive screening for another cyst elsewhere in the body revealed negative results. Chest radiography, echocardiography and abdominal ultrasonography were all normal. A left frontotemporoparietal craniotomy and total excision of six cysts without rupture was done. Histopathologic examination confirmed the surgical specimens were hydatid cysts with scoleces. The postoperative course was uneventful, and the patient showed marked recovery in his neurological status. Postoperative CT confirmed complete excision of the cysts. He got albendazole treatment for three months after operation without any sign of new cysts elsewhere in the body.

Case 3
A 15-year-old boy presented to our pediatric outpatient clinic with the history of headache and vomiting of two days duration. He was complaining from headache for a year with augmentation on the last 2 months. On neurological examination he had right temporal hemianopsia and right hemiparesis. Chest radiograph, complete blood count, urine analysis, and blood biochemistry were all normal. Cranial MRI demonstrated multiple cystic lesion of 8 x 9 x 9 cm on the right parieto-occipital region which extended to the convexity causing shift effect on midline structures ( Figure 3). Indirect hemagglutination test for E. granulosus was positive with 1/2048 titer. Investigations for other organ involvement (abdominal ultrasonography, chest radiography and echocardiography) were performed and no other focus was found. Albendazole treatment of 10 mg/kg twice daily was started. Upon surgical intervention 10 cysts were extirpated without rupture. An external ventricular drainage catheter was placed on the second day after operation and a ventriculoperitoneal shunt was placed on the fifteenth day. Histopathologic examination confirmed the surgical specimens were hydatid cysts with scoleces. Albendazole treatment was given in a dosage of 10 mg/kg twice daily for 6 months. He was hospitalized two times for meningitis in the following year. Further diagnostic evaluations revealed defect in frontobasale part of duramater and he went under surgical repairment. After second operation, no problem is detected in a 2 years follow-up period.

Case 4
A 7-year-old boy was admitted to our pediatric emergency department with headache, intermittant vomitting and gait disturbances lasting for 3 weeks. Neurologic examination revealed bilateral papiledema, positive cerebellar signs on the left and cerebellar ataxia. The examination of chest radiograph, complete blood count, urine analysis, and blood biochemistry revealed no abnormality. Cranial MRI revealed a midline cer-ebellar cystic lesion of 4 x 4 cm, which was hypointense on T1-weighted images and hyperintense on T2-weighted images without contrast enhancement (Figure 4). The lesion was compressing the fourth ventricle causing dilation of the third and lateral ventricules. Laboratory studies including complete blood count, urine analysis and blood biochemistry revealed no abnormality. Extensive examination including chest radiography, echocardiography and abdominal ultrasonography for another hydatid cyts were all normal. Indirect hemagglutination test for E. granulosus was negative. Albendazole treatment of 10 mg/kg twice daily was started. Although the cyst capsule was ruptured during operation, total removal was achieved. Histopathologic examination of the specimen revealed a hydatid cyst with scoleces. Postoperative MRI confirmed complete excision of the cyst. He has been on albendazole medication for 3 months without any complication.

Discussion
In hydatid disease, the main pathogenic species for humans are E. granulosus and less frequently E. multilocularis. Humans become infected by ingesting tapeworm eggs passed from an infected carnivore; especially dogs; which most frequently happens when individual handle or have a contact with infected carnivores or inadvertently ingest food or drink which is contaminated with fecal material containing tapeworm eggs (14,15). The history of direct contact with dogs was  found in patients 2 and 4. However, because our country is an endemic region, all the children in our series may have been infected by eating ingested food or milk.
Intracranial hydatid disease is considered a childhood disease. Fifty percent to 75 percent of intracranial hydatid cysts are seen in children. Izci et al. reported a series of 17 patients with intracranial hydatid cysts and 13 (65%) of these patients were children (16). Cerebral hydatid cysts are often supratentorially localized in the distribution of the terminal branches of the middle cerebral artery, usually temporo-parieto-occipitally (17,18). In our series, three patients had cysts in the distribution of middle cerebral artery; one in left parieto-occipital region, one in right parieto-occipital region and one in left fronto-temporo-parietal region.
Intracranial hydatid cysts may also be classified as primary or secondary. The primary cysts are formed as a result of direct infestation of the larvae in the brain without demonstrable involvement of other organs. In primary multiple cysts, each cyst has a separate pericyst with brood capsule scoleces and these originate from multiple larvae affecting brain after crossing the gastrointestinal tract, liver, lungs and right side of heart without affecting them. The primary cysts are fertile as they contain scoleces and brood capsules, hence rupture of primary cyst can result in recurrence. The secondary multiple cysts results from spontaneous, traumatic or surgical rupture of the primary intracranial hydatid cyst and they lack brood capsule and scoleces. The secondary intracranial hydatid cysts are therefore, infertile and the resultant risk of recurrence after their rupture is negligible. Primary multiple cysts are uncommon and isolated case reports of primary multiple hydatid cysts have appeared in the literature (19,20). Onal et al. found only three cases of multiple cysts in their series of 33 cases and Lunardi et al. found 2 cases in their series of 12 cases. In our series, two patients had multiple intracranial hydatid cysts (21,22). One of these patients had 10 primary cysts in right parietooccipital region. The other child had a history of operation for a solitary intracranial hydatid cyst without rupture two years before being operated in our pediatric neurosurgery department. In the second operation 6 hydatid cysts, the biggest of which was 6 x 7 x 7 cm in diameter were removed from the left frontotemporoparietal region. Because the hystopathological evaluation of these cysts removed in the second operation revealed scoleces, and the surgical data of the first operation did not mention about rupture, we consider this patient has experienced recurrent intracranial hydatid disease due to multipl larval intake.
The patients with intracranial hydatid cysts usually present with focal neurological deficit and features of raised intracranial pressure; the latter may be due to the large size or due to interference with pathway of cerebrospinal fluid flow. Ersahin et al. observed that 18 out of 19 cases presented with raised intracranial pressure (1). In our series, all four patients had symptoms and signs of increased intracranial pressure. All our patients suffered from headache and vomiting. Three patients had bilateral papiledema, one of them had seizures. One patient had right temporal hemianopsia and right hemiparesis.
Radiological evaluations of hydatid cysts by cranial CT scan and MR images reveal solitary, homogeneous, spherical and large parenchymal cysts with well-defined borders, without perifocal edema and environmental contrast enhancement. The density of the cyst fluid is the same as that of cerebrospinal fluid (23). In our cases, three patients were evaluated with cranial MRI and one patient with cranial CT before operation. Both techniques were helpful in the diagnosis.
The treatment of hydatid cyst is surgical and the aim of surgery is to excise the cyst in total without rupture to prevent recurrence and anaphylactic reaction. Only a few reports are available mentioning the efficacy of drug therapy alone. Isolated case reports showed complete disappearance of multiple intracranial hydatid cysts with Albendazole therapy in a daily dose of 10 mg/kg, taken three times a day for four months (24)(25)(26). Preoperative and postoperative albendazole treatment may be considered to sterilize the cyst, decrease the chance of anaphylaxis, decrease the tension in the cyst wall (thus reducing the spillage during surgery), and reduce the recurrence rate (25,(27)(28)(29). Intact removal rate of hydatid cyst is around 60-70% (19). In our cases, all patients were operated and total surgical removal was possible. Albendazole treatment was started to all our patients before the operation and continued for at least 3 months after operation. The cyst capsule was ruptured in one patient.
In conclusion, infection with E. granulosus should be included in the differential diagnosis for unspecific neurologic symptoms such as progressive headache, especially in pediatric patients where hydatid disease is endemic. The most important issue in cases with intracranial hydatid cysts is whether hydatidosis will develop in the primary sites. These patients should be followed, paying close attention to this possibility. The authors declared that this study has received no financial support.