Cerebral echinococcosis is a disease caused by the penetration of echinococcus larvae into the brain with the formation of single or multiple cysts—bubbles. Depending on the location, it is manifested by headaches, epileptic seizures, paresis, visual impairment, mental disorder. The basis for the diagnosis is the presence of a cyst according to tomography, an increasing titer of antiechinococcal antibodies and a positive Casoni test. A complete removal of cysts with a capsule is performed in combination with anthelmintic and symptomatic therapy. After surgery, rehabilitation and long-term monitoring are required.
B67.9 Echinococcosis of other organs and unspecified
Cerebral echinococcosis is a rare parasitic lesion of cerebral tissues. According to various data, it accounts for from 0.4 to 9% of all cases of echinococcosis. Brain lesions in combination with echinococcosis of the liver and lungs occur in 0.2% of patients. The highest incidence is observed in endemic areas.
Most cases of cerebral echinococcosis are represented by single blisters containing larvae of the parasite. Multiple cerebral echinococcosis is extremely rare. Echinococcal foci are localized mainly in the white matter of the parietal, frontal and occipital lobes.
The cerebral form of echinococcosis occurs due to the penetration of larvae into the brain tissue. Human infection occurs in an alimentary way — by swallowing eggs (oncospheres) of echinococcus. The latter are released into the environment with the feces of infected animals: wolves, dogs, foxes. They persist in the soil for a long time, with its dried particles (dust) carried by the wind.
Eggs can get on the wool of livestock and dogs lying on the grass, on people’s clothes and hands. Persons associated with animal husbandry and butchering, hunters, owners of free-range dogs have the greatest risk of infection. A person with echinococcosis does not secrete parasites and is not dangerous to others.
The contamination of food occurs mainly through dirty hands. In endemic areas near slaughterhouses and livestock farms, dust from echinococcus oncospheres may get onto products standing openly. Getting into the human intestine, the larva leaves the egg and penetrates into the vascular bed. With the blood flow, it passes through the liver and lungs. Hematogenic larval entry into the brain is possible if it is not “hooked” in the tissues of previous organs or when a large number of eggs enter the body at once with a combined lesion of several organs.
A fibrous capsule forms in the brain tissues around the larva of echinococcus. A bubble is formed, sometimes surrounded by an inflammatory zone — the result of the reaction of cerebral cells to the introduction of a foreign organism. The cerebral membranes located near the cyst may be involved in the inflammatory process. The focus of echinococcosis has an irritating effect on brain neurons, which leads to the appearance of epileptic seizures. Gradually, the echinococcal bladder increases in size, exerting increasing pressure on the surrounding tissues.
Intracranial hypertension occurs — an increase in pressure inside the skull. The increase in pressure is reflected in all parts of the brain and underlies the progressive cerebral symptoms. The cerebral tissues and the vessels feeding them are compressed. Chronic hypoxia and ischemia develop, leading to metabolic disorders and neuronal death. First of all, the nerve cells located around the cyst suffer. The loss of their functions is manifested by focal neurological symptoms.
Cerebral echinococcosisn includes 2 main forms. In relation to each of them, different approaches to treatment are used in practical neurology and neurosurgery. The prognosis depends on the form of the disease.
- Solitary form is characterized by the presence of a single cyst. The formation often reaches significant sizes — up to 60 mm in diameter. Focal epiprimes and focal symptoms prevail in the clinical picture. Radical surgical removal is possible. Has a relatively favorable prognosis.
- Racymose form is characterized by the formation of a cluster-like conglomerate of blisters and the multifocality of the lesion. It is rare. Severe cerebral manifestations prevail in the clinic. Surgical treatment is difficult.
Solitary cyst is characterized by the gradual development of symptoms. The disease begins with a periodic headache. It hurts the temples, forehead or the whole head. The feeling of pressure on the eyes is characteristic. The duration and intensity of cephalgia gradually increase. It becomes persistent, accompanied by nausea and vomiting. In a number of patients, echinococcosis debuts with epileptic paroxysm. Then there are headaches. Multiple cerebral lesions manifest as a sharp cerebrospinal hypertension syndrome with intense cephalgia and repeated vomiting.
Focal manifestations of the disease directly depend on the location of the echinococcal bladder. Epileptic seizures are typical, which last for several years and do not respond to medical treatment. Paroxysms have the character of focal epilepsy in the form of numbness (sensory paroxysm) or convulsive muscle contractions (motor paroxysm).
The attack involves one or both limbs of the half of the body opposite to the localization of the cyst in the brain. Secondary generalization is possible: convulsions appear in one limb, gradually spread to the whole body. Subsequently, muscle weakness, spastic stiffness develops in the limbs exposed to focal motor epiprimes, pain sensitivity is lost.
Among other focal manifestations, there are various mental disorders (depression, aggressiveness, delirium), memory impairment, a decrease in intellectual abilities up to dementia. The picture of general cerebral symptoms is complemented by ataxia associated with damage to the vestibular analyzer. Dizziness with a sense of rotation of surrounding objects, instability during walking, coordination disorder are observed — with sharp turns, patients “drift” to the side. The severity and speed of progression of symptoms varies depending on the site of the lesion and the rate of increase in the volume of the cyst.
Accompanying echinococcosis intracranial hypertension causes compression of the visual tract and leads to atrophy of the optic nerves with a drop in visual acuity. Resistant to anticonvulsant therapy, the course of epilepsy in cerebral echinococcosis is often complicated by the development of epileptic status. The epiprimes that follow each other continuously are life-threatening, since they provoke a malfunction of the respiratory and cardiovascular system.
In the absence of timely diagnosis and adequate treatment of cerebral echinococcosis, an increasing cyst causes displacement of brain structures. Increasing hypertension causes compression of the brain with dysfunction of vital nerve centers and subsequent death. A rare complication is the rupture of the echinococcal bladder with the contamination of surrounding tissues.
Cerebral echinococcosis has a clinical picture similar to intracerebral tumors, which often leads to diagnostic errors. Therefore, it is important to consistently implement all stages of complex diagnostics:
- Detailing the anamnesis. Helps to identify the fact of being in an area endemic for echinococcosis, working in a livestock farm, etc. Establishes the features of the onset of the disease.
- Neurologist’s examination. It reveals signs of increased intracranial pressure, focal symptoms — the presence of hemiparesis, mental abnormalities, cognitive disorders.
- Examination by an ophthalmologist. It provides for ophthalmoscopy, with the help of which edematous discs of the optic nerves are detected, and with a long—term clinic – signs of atrophy.
- Skull x-ray. Finger depressions on the cranial bones, the divergence of sutures between them, signs of dilation of diploic veins indicate a long-term increase in intracranial pressure. In this case, the disease may have a short duration.
- CT or MRI. They allow to identify intracerebral formation with thin walls, determine its localization and volume. CT of the brain is more informative in relation to calcification of the capsule, MRI of the brain better visualizes the walls of the cyst.
- Laboratory tests. There are no inflammatory changes in the blood test, eosinophilia is observed. An enzyme immunoassay is being conducted for the presence of antibodies to echinococcus. The antibody titer matters: the higher it is, the more likely it is to confirm echinococcosis.
- Allergy tests with echinococcal antigen. An intradermal Casoni test is performed in its modern interpretation (the Schultz method). A positive result is observed in 85% of patients with cerebral echinococcosis.
- Examination of other organs. It is necessary to exclude a combined lesion. Liver ultrasound and lung x-ray are performed. If a change is detected, an in-depth study is carried out with the appointment of an MRI of the liver, CT of the lungs, consultations of a hepatologist, pulmonologist, etc.
The results obtained are evaluated in aggregate, comparing them with clinical symptoms and the course of the disease. It is necessary to differentiate cerebral echinococcosis from other volumetric formations: arachnoid cysts, cerebral cysticercosis, epidermoid cysts, intracranial tumors and abscesses.
The most justified method of treatment is surgical. Today it is effectively combined with etiotropic, symptomatic and rehabilitation therapy. Complex treatment is carried out by a number of specialists and includes:
- Surgical removal of a cyst. The generally accepted standard is radical microsurgical excision without damaging the walls of the bladder. The operation requires the neurosurgeon to carefully plan access. When the lesion is localized in functionally significant areas of the brain, intraoperative corticography is performed. The treatment of multiple foci is a difficult task, since it is necessary to remove all cysts.
- Conservative etiotropic therapy, which is carried out with anthelmintic pharmaceuticals from the benzimidazole group (for example, albendazole). Previously, anthelmintic treatment was prescribed in inoperable cases and was palliative in nature. Recently, the positive effect of postoperative anthelmintic therapy on the effectiveness of surgical treatment has been proven.
- Symptomatic treatment is carried out within the framework of preoperative and rehabilitation therapy. It is carried out with anticonvulsants, drugs that reduce intracranial pressure, painkillers, etc.
- Postoperative rehabilitation, consisting of pharmacotherapy (drugs to improve cerebral metabolism and blood flow), physical therapy, psychotherapy and classes with a speech therapist (for speech disorders).
Prognosis and prevention
The prognosis depends on the form of the disease, the number, size and localization of echinococcal blisters. The most favorable prognosis has timely operated solitary cerebral echinococcosis. The frequency of postoperative relapses is 15-30%. A relapse occurs if an opening of the bladder occurred during the operation. But it is mainly due to the parasite’s ability to spread microscopic screenings beyond the capsule, which are not diagnosed by modern methods of neuroimaging.
In order to diagnose relapse in a timely manner, operated patients should undergo regular examinations, including antibody analysis, liver ultrasound, cerebral MRI, chest x-ray. The WHO recommended follow—up period for patients is 10 years. Measures that can prevent echinococcosis include compliance with personal hygiene rules, wearing overalls when working with animals and butchering carcasses, improving the sanitary condition of farms, identifying and eliminating the source of infection.