Orbital echinococcosis is a lesion of the orbit and paraorbital tissue caused by infection with larval stages of echinococcus. The main symptoms of the disease are discomfort and pain in the orbit, limited eye mobility, exophthalmos. The examination complex includes ophthalmoscopy, computed tomography of the orbits, ultrasound, Casoni test, IOP measurement, biomicroscopy of the eye, blood analysis. Treatment is reduced to surgical removal of cystic formations, followed by the appointment of antibacterial and nonsteroidal drugs. With a complicated course, glucocorticosteroids are additionally used.
Orbital echinococcosis is a pathology characterized by the formation of parasitic cysts in the orbital zone. For the first time , the primary contamination of the eye socket of an echinococcal nature was described by French scientists K. Onerom and I. Ovulem in 2001. In the general structure of echinococcosis, the prevalence of parasitic lesions of the orbit reaches 1%. The disease is found everywhere, but it is most often detected in agricultural areas. The ratio of sick men and women is 1:1. The disease can develop at any age, but is more often diagnosed in people over 40 years old.
The etiology of orbital echinococcosis is caused by infection with Echinococcus (Echinococcus granulosus) at the larval stage. Infection is carried out by fecal-oral (when ingesting parasite eggs with food or water) or by contact. A person acts as an “accidental” intermediate host and does not participate in further transmission of infection. The final hosts of echinococcus are carnivores. The larva can grow for decades in the human body, forming a cyst. Cystic formations are found not only in the eye socket, but also in other organs and systems.
At the larval stage, echinococcus has the appearance of a small one- or two-chamber bubble, penetrates the orbit hematogenically. The growth and development of the parasite leads to the formation of a cyst. The cystic cavity spreads to soft tissues and only in chronic course is soldered to the walls of the orbit. Often, an echinococcal cyst is closely associated with intraorbital muscle fibers, which limits the mobility of the eye. The presence of a parasite in the orbital cavity is accompanied by an inflammatory reaction and intoxication manifestations. The appearance of a volume formation in the orbit is associated with an increase in intraocular pressure (IOP).
The disease is characterized by a slowly progressive course. Initially, there is a long asymptomatic period. Subsequently, patients complain of discomfort and soreness in the projection of the eye socket. An increase in the lesion area causes pain syndrome and the occurrence of exophthalmos. The mobility of the eyeball is sharply limited. Since the lesion is one-sided in the vast majority of cases, visual dysfunction is manifested by the clinic of false strabismus. With monocular exophthalmos, the perception of the image in front of the eyes is distorted.
With a severe course of the disease, the phenomena of echinococcal intoxication increase in patients. There is a pronounced general weakness, deterioration of appetite, weight loss. The appearance of a headache, a feeling of “bursting” or strong pressure in the eye indicates the progression of the disease. Dizziness and nausea may occur. With a prolonged course of the disease, it is difficult to close the eyelids, there is redness of the eyes, excessive tearfulness and photophobia. Anaphylactic reactions in echinococcosis include local or generalized urticaria, accompanied by itching.
Orbital echinococcosis often leads to reactive inflammation of the optic nerve and turbidity of the vitreous body. There may be the appearance of subconjunctival and subretinal hemorrhages caused by damage to the vessels feeding the cyst capsule. Compression by volumetric formation of surrounding nerve fibers causes their atrophy. The severe course of the disease entails the development of xerophthalmia. A characteristic complication of the disease is the rupture of an echinococcal cyst with further dissemination of infectious agents. This can cause the formation of cystic neoplasms in organs such as the liver, lungs, and heart. Puncture is often complicated by anaphylactic shock.
Visual examination reveals hyperemia of the anterior segment of the eyeball, exophthalmos of varying severity. When an echinococcal cyst is located in the anterior or lateral parts of the orbit, the formation of a cyst-like structure with an elastic capsule is palpated. In some cases, a positive symptom of fluctuation is determined. To confirm the diagnosis, an ophthalmologist prescribes:
- Tomography of eye sockets. Single or multiple volumetric formations (1 large maternal cyst and several smaller daughter cyst) with clear uneven contours are visible on the CT of the orbits. The average diameter of an echinococcal cyst does not exceed 1 centimeter.
- Ophthalmoscopy. When examining the fundus, the disc of the optic nerve is visualized in pale pink color. The lumen of the veins is slightly dilated. Echinococcal formations are detected only in the case of their intraocular location.
- Ultrasound B-scan of orbits. Ultrasound of the eye makes it possible to identify a small cystic cavity of a rounded or oval shape with clearly limited edges in the eye socket area. Additionally, it is recommended to conduct an ultrasound of the abdominal organs to study the condition of the liver.
- Measurement of intraocular pressure. With a cyst diameter of more than 0.3-0.5 mm, intraorbital pressure increases, followed by intraocular pressure. Contactless tonometry is considered to be the optimal way to measure IOP in patients with echinococcosis.
- Biomicroscopy of the eye. Pathological changes from the anterior segment of the eye are observed only with a large diameter of formation and an increase in exophthalmos. In such cases, biomicroscopy can detect injection of conjunctival vessels and edema of surrounding tissues.
- The Casoni sample. An intradermal allergic test, for which an echinococcal antigen is used. In the presence of a living parasite in the body, a positive result is observed in 60-90% of patients. If the efficiency of the sample is low, the precipitation reaction is additionally used.
- Blood test. Echinococcosis, regardless of localization, is characterized by an increase in the level of eosinophils in the blood. At the initial stages, pathological changes in the croi analyses are not determined, with the progression of the disease, minor leukocytosis occurs.
Treatment involves the removal of echinococcal formations surgically. With a large cyst size, surgical intervention is preceded by a puncture. The resulting material is subject to immediate morphological examination. When confirming the echinococcal nature of the pathology, a transpalpebral orbitotomy with excision of the formation is performed. In the postoperative period, it is recommended to prescribe a short course of broad-spectrum antibiotics, nonsteroidal anti-inflammatory drugs. With the development of an anaphylactic reaction, parenteral administration of glucocorticosteroids is indicated.
Prognosis and prevention
The prognosis for orbital echinococcosis is favorable for life and work capacity. Timely surgical intervention ensures complete recovery. Specific methods of prevention have not been developed. Non-specific preventive measures are reduced to thorough washing of vegetables and fruits before eating them, hygienic treatment of hands after contact with animals and agricultural work. Do not drink unboiled water from natural reservoirs. If echinococcosis of intraorbital localization is detected, it is necessary to seek the help of a therapist to exclude damage to other organs.