Hydatid disease has been widely prevalent in the developing countries, and it is both a medical and economic issue. Echinococcosis was generally rare in developed countries; however, it has still been a significant public health issue in endemic areas [1–3]. The prevalence of echinococcosis is also observed in western China. Echinococcosis is one of the most common zoonosis, which equally infects both genders. The younger populations were subjected to more serious infections [4]. The definite hosts of Echinococcus are a variety of carnivores, and dogs are the most common host. Sheep, cattle, and human beings can act as the intermediate host.
The transmission routes of echinococcosis are through contacting with definite host or consuming contaminated water or food. During the infection, the eggs of Echinococcus lose their enveloping layer in the stomach, and the embryos would be released. The embryos pass through the wall of the gut into the portal system, being transferred to the liver. Most larvae would be entrapped end encysted in the liver. Some larvae may occasionally reach the lungs, and some may enter the systemic circulation after passing through the capillary filter of the liver and lungs. Some of these larvae may reach the brain or spinal cord. Brain echinococcosis are often accompanied with liver and lung infections. In our study, 16 of the 28 patients showed hydatid cysts in other organs. For the cerebral hydatid cysts, most cases were supratentorial, while only a few were infratentorial lesions [5]. Brain hydatid can be rarely located in some special place, such as thalamus or ventricle [6, 7]. Intracranial hydatid cysts were generally solitary, while multiple cysts were rare [8, 9]. Intracranial hydatid cyst may also be classified as primary or secondary infection. The primary cysts resulted from direct infestation of the larvae in the brain, without significant involvement of other organs. The secondary multiple cysts resulted from spontaneous, traumatic, or surgical rupture of the primary intracranial hydatid cyst, which may lack brood capsule and scolices. In our study, the primary cyst was observed in 11 cases, and the secondary multiple cysts were found in 10 cases.
Hydatid disease of the spinal cord has been rare. The first case of spinal cord echinococcosis was reported in 1964, in Xinjiang. Notably, approximately 50% of the patients were under 30 years old [10–15]. Braithwaite and Lees [16] have classified this disease into 5 types: (1) primary intramedullary hydatid cyst, (2) intradural extramedullary hydatid cyst, (3) extradural intraspinal hydatid cyst, (4) hydatid disease of the vertebra, and (5) paraspinal hydatid disease. Based on this classification, the 2 cases of spinal cord echinococcosis in our study were classified as type 3, the extradural intraspinal hydatid cyst.
The clinical manifestations of echinococcosis are similar to those of increased intracranial pressure due to other causes. The early diagnosis of echinococcosis was difficult for those patients without apparently increased intracranial pressure [17]. Therefore, a detailed medical history record would be especially important, and it should be combined with an auxiliary examination. Attention should be paid for the following situations: (1) the patient comes from epidemic area, being exposed to patients in these regions, or reporting contact with cattle and pet; (2) the patients can be asymptomatic or show elevated intracranial pressure, epilepsy, and nervous system local functional defect; (3) imaging examinations may reveal characteristic findings of brain hydatid cysts, especially head CT and MRI [18–21]; (4) the diagnosis may be supported by positive hydatid immunological test, but cannot be excluded by negative result; (5) the exclusion of intracranial space-occupying lesions due to other causes is important; the diagnosis of intracranial cystic brain echinococcosis should be differentiated from intracranial arachnoid cysts, brain-perforating deformity, and brain abscesses. The MRI result can be enhanced for intracranial bubbly brain echinococcosis, which can be distinguished from intracranial strengthened TB tumor, glioma, brain metastases, and brain cysticercosis. In addition, spinal cord echinococcosis should be differentiated from spinal cord and arachnoid cyst, as well as hydatid vascular malformation, such as spinal cord bleeding.
The diagnosis of echinococcosis should be comprehensively made based on patient information, clinical features, imaging results, and laboratory data. The clinical features may not be obvious. The imaging results could be atypical and similar to those of other intracranial space-occupying lesions; the differential diagnosis would be difficult. The radiologists from non-epidemic area may lack experience in recognizing the characteristic echinococcosis images. The diagnosis may be missed without adequate information and laboratory data. Therefore, the good communication between radiologists and clinician is necessary. Even so, there were still false-positive results [22], and such misdiagnosis may result from cyst wall thickness, deep location, and small number of cysts. Misdiagnosis of parasites may also be observed in organs with physical barriers, like the brain. The laboratory data may be affected in immunodeficiency and immunocompromised populations, including children, people undergoing chemotherapy, patients with tumor cachexia, and AIDS patients, which may also lead to misdiagnosis.
Until now, echinococcosis could still not be cured with any drug. The early diagnosis and timely treatment are critical for controlling brain echinococcosis. The preferred therapy is surgery. The preoperative plan is important for the complete removal of hydatid lesions, such as accurate localization, proper surgical approach, and adequate bone window. The critical point for the treatment of Echinococcus granulosus was the removal of unruptured cyst. Once the cysts ruptured and entered the subarachnoid space, there would be widespread dissemination of scolices, leading to severe inflammation and anaphylactic reactions caused by the fluids containing numerous antigens. Dowling-Orlando’s technique has been widely applied in the removal of intraparenchymal cysts [23]. The cyst would be exposed by a wide incision, and saline irrigation was performed with a rubber catheter from an inclined position of the head. In our study, Dowling’s technique was conducted in 17 cases, and the cyst wall was removed from the surrounding brain parenchyma with irrigation. The cysts could be completely excised, and the prognosis was good. As an adjunct for therapy, albendazole was given to treat patients with multiple-organ involvement or gave up surgical treatment. The dose was 15 mg/kg/d PO divided into twice daily for 3–6 months.
