Overview
Echinococcosis is a disease caused by human infection with the larvae of Echinococcus. It is most common in liver infections. When a person swallows the eggs of Echinococcus granulosus, the six hook larvae in the eggs come out in the gastrointestinal tract and pass through the intestinal wall to the liver, heart, lungs and tissues and organs of the body, developing into echinococcosis (also known as worm) and causing the disease.
Cerebral echinococcosis, also known as cerebral echinococcosis, is caused by the invasion of the larvae of the dog tapeworm (Echinococcus granulosus) into the skull and the formation of cysts. The disease is mainly seen in livestock areas, and is disseminated in northwest China, Inner Mongolia, Tibet, western Sichuan, Shaanxi, Hebei and other places. It accounts for 1%~3% of the cases of encapsulated worm disease.
Etiology and pathogenesis]
Canine tapeworm is parasitic in the small intestine of dogs, and its eggs are excreted in the feces, contaminating drinking water and vegetables. Human and sheep, cattle, horses and pigs are the intermediate hosts. The eggs hatch in the duodenum and become six-hook larvae, which penetrate into the portal vein and travel with the blood to the liver, lungs and brain, where they develop into encysted cysts after several months. Cerebral encystment is often solitary, mostly in the middle cerebral artery supply area, frontoparietal lobe, but also in the cerebellum, ventricles and skull base. Most of the worms die after a few years and the cyst wall calcifies, while a few may continue to grow and form huge cysts.
Diagnostic points
Clinical manifestations
The main manifestations are increased intracranial pressure, seizures and limited neurological signs. The course of the disease is slowly developing. Headache, vomiting, and optic papillar edema appear after the increase of intracranial pressure. Focal signs depend on the location of the cyst, such as monoplegia, hemiplegia, hemianesthesia, aphasia, etc. Epileptic G seizures are also often partial. In young children, frontoparietal cysts may also present with contralateral or lateral developmental disorders, skull bulging on the affected side or localized skull thinning and softening.
Imaging
CT scan shows a large spherical cyst in a low-density area. MRI is similar to CT in that the signal change of the contents is similar to that of cerebrospinal fluid, and can also show the cyst and cephalic ganglion, with a high signal shadow on T1-weighted images and calcifications that are not easily visible.
Differential diagnosis
The disease should be considered based on living in a pastoral area, history of contact with dogs and sheep, presence of encapsulated worm disease in the liver or lungs, followed by focal brain symptoms and/or increased intracranial pressure. Positive intracutaneous tests of encapsulated fluid, blood, and cerebrospinal fluid encapsulated worm complement binding tests help to confirm the diagnosis; CT and MRI are valuable for localization. The disease should be differentiated from brain tumors with very similar presentation.
Treatment overview
Drug treatment
For giant cysts of the worm, surgery is the only way to cure them. The inner capsule can be carefully and completely removed by injecting saline floatation between two layers of the cyst wall. If the cyst fluid is inadvertently spilled, it may cause anaphylaxis and recurrence of cephalic transplantation.
In addition, the following drugs have been suggested.
(1) Thiabendazole (fenbendazole): 750mg twice daily for 42d;
(2) mebendazole: 400~600mg per time, 3 times daily for 21~30d;
③Albendazole: 400mg twice daily for 30d;
④Pyrazinone: can also be used for inoperable or postoperative recurrence.
Symptomatic treatment: Anti-epileptic drugs and dehydrating agents should be given to those with G seizures and increased intracranial pressure, respectively.
Prevention
Close contact with dogs should be avoided in endemic areas, and infected dogs should be treated or killed to reduce the source of infection; the carcasses of sick animals should be buried deeply or burned, and should not be disposed of at will; pay attention to dietary hygiene, wash hands before meals, and prevent dog feces from contaminating food.