Omorov T.M.

DIAGNOSIS AND TREATMENT OF CEREBRAL ECHINOCOCCOSIS

INTRODUCTION

Echinococcosis is a widely as distributed disease of low prevalence. The problems are not so much the numbers of patients, but the fact is hat the disease is highly pathogenic in affected patients. In the literature, between 43%-66% of cases present as liver disease, 32%-37% as pulmonary disease, 13,6% as concurrent pulmonary and liver disease, with 0,2% involving the lungs, liver and brain. (Akmatov 1994, Akshulakov et al 2000, Akhunbaev 1964, Kornyansky et al 1968, Petrovsky et al, Rosin 1991, Jimenes-Mejias et al 1991).

The prognosis for patients with echinococcosis depends on early and accurate diagnosis and prompt surgical or chemotherapeutic treatment. Whilst the problem of diagnosis in many organ systems has been solved, diagnosis of cerebral echinococcosis still represents a significant challenge. Frequently cerebral echinococcosis is misdiagnosed for other conditions such as tumours, abscesses or not parasitic cysts (Kariev et al 1990, Junarddi et al 1990). Late diagnosis of cerebral echinococcosis often leads to a poor prognosis. There are frequent complications during Suring to remove cerebral cysts. Rupture of the cysts can lead to an outpouring of contents that include germinal elements, pus and necrotic elements, into the serous cavities of patients. This can lead to serious complications such as allergic reactions, anaphylactic shock, epileptic attacks, suppuration and recurrence of disease (Akmatov et al 1994, Akshunbaev et al 2000, Kariev et al 1990, Petrovsky et al 1985, Jimenes-Mejias et al 1991, Kayu et al 1975). In addition, symptoms may worsen and central nervous system encephalitis may develop, intravascular coagulation and other problems associated with the disintegration of the cyst and the leakage of cyst fluid which contains acetic and lactic acid and other substances, into the blood. Serotonin, prostaglandin and kinins may be released in response this release of cyst fluid (Ersahim et al 1993). This can result in cerebral hypostasis and brain swelling (Akhunbaev 1964, Petrovsky et al 1985, Lunarddi et al 1990). Damage to the ventricular systems can alter the fluid dynamics in the brain, leading to pressure on aub-arachnoid tissues and angiospasm.

Epilepsy is a frequent complication of cerebral echinococcosis as cyst fluid is allergenic and irritant to the brain tissue and protoscolices are sometimes not completely removed leading to daughter cysts and relapses.

The underlying reasons for these pathogenic mechanisms is the space occupying lesion and the leakage of blood and necrotic or cyst material into the sub-arachnoid space. The important phase of the treatment with cerebral echinococcosis, after removal of the cysts, is adequate drainage of nercotic material and blood from the sub-arachnoid spaces. To remove blood, passive drainage using a polyethylene or rubber tube is required. However, this drainage requires close supervision as the tubes are frequently blocked with blood clots or detritus. Even wide bore tubes need constant supervision. A technique for the drainage of fluid from the brain has been devised. Blood and other detritus are flushed out of the sub-archnoid spaces by perfusion fluids. However, the technique has to be undertaken with great care to avoid increasing intracranial pressure or bleeding.

The purpose of this study was to define the clinical characteristics of cerebral echinococcosis, the rate of parasite growth and the topographical relationships with cerebral white and grey matter and the ventricular system, and then to study the active draining of the sub-arachnoid spaces following cyst removal.

MATERIALS AND METHODS

In the last 15 years, 105 patients have presented with cerebral echinococcosis. This represents 0.9 % of all patients treated with space occupying lesions of the brain. In a total of 65 patients external drainage from the cranial cavity was undertaken. In these patients the efficacy was assessed by changes in intra-cranial pressure and cerebral circulation by impedance radiography.

RESULTS AND DISCUSSION

Initial symptoms often appeared long before clinical diagnosis. A space occupying lesion was suspected based on evolving central and peripheral neurological symptoms. In 38 patients, cerebral echinococcosis was confirmed with the application of computer and nuclear magnetic resonance tomography. In all these patients neurological symptoms like exophthalmoses, paresis, titanic spasms of the neck muscles, horizontal nystagmus with rotary components, and problems of coordination were marked. In 12 patients the first symptoms observed were clonic epileptiform attacks up to 10 years before diagnosis. There developed into focal epileptiform attacks and localized pyramidal symptoms. In 43 patients the first symptoms were headaches. In 17 of these patients headaches occurred only a few months before diagnosis although this was many years after the first symptoms (such as epileptiform seizures). In 9 patients, headache was the presenting clinical symptom.

Marked eosinophilia was seen in 53 of the 65 patients. Radiological evidence of the development of cerebal hypertension includes an increase in the size of the cranium, impressions on the base of the cranium, funnel finger shaped depression, hypertrophy of ventricular veins and rarefaction of the skull. The radiological changes depend on the sizes of the hydatid cysts and disease duration. Intensity of headaches did not correlate with the hypertensive changes of the cranium.

Congestion of the ocular fundus was seen in 63 patients. In 11 of then, these had developed into secondary atrophy of the optic nerves. Development of this syndrome is often associated with massive intracranial pressure and obstruction of drainage from the ventricular and paraventricular systems by cysts with a volume of 200-250 cm³ The size of cysts from this series of patients varied between 13cm and 12cm in diameter.

Cerebral spinal fluid of 38 patients was normal and in 4 patients there was a moderate increase in lymphocytes.

According to the computer and nuclear magnetic tomography, the cysts are located in the white matter, mainly in the temporal occipital lobe (Ersahin et al 1993). Of 65 patients presenting with cerebral echinococcosis, 53 had single cyts, whilst 4 also had pulmaonary cysts and 4 had cyts in multiple locations. Single cysts were seen in the white matter of the frontal, parietal and temporal lobes and in the ventricular cavity. Patients with pulmonary cysts had 2*5 cerebral cysts in the white matter on the convex and basal loves of the brain. The severity of clinical signs was often not associated with the size but number and location of lesions. We compared the spontaneous chemiluminescence with composition of the protein in the cerebral spinal fluid . Weak fluorescence does not depend on (he quantity but type of protein present. When biological liquids are exposed to ultraviolet lights reactions of free radicals can lead to the formation of unidentified fatty acids. Thus the intensity of photo-induced chemiluminescence depend on processes at the cellular level and on the level of exposure.(pic I).

Pic 1.

In a series od cases of cerebrai echinococcosis and controls we have investigated the magnitude of chemiluminesce of the CSF. Comparison of the data suggests that CSF from cases with cerebral echinococcosis have more intense chemiluminescence than controls; this is an additional criterion that can be used in assessing a diagnosis.

When there is intracranial haemorrhage good drainage is required in 3 circumstances. In the first, which was encountered in 14 patients, good perfusion and drainage of the subarachnoid space and areas of surgical intervention were provided. Such conditions occur 2-3 hours after surgery. For rapid removal of the intracranial fluid, rapid perfusion is required with the drainage tube below the head of the patient. If the drainage tube is blocked, even partially, then there can be an uncontrollable increase in intracranial pressure with hypertensive syndromes developing.

The second situation arises when the outflow of fluid is greater then the inflow during perfusion drainage caused by the siphon, and thus creating negative intracranial pressure. This negative intracranial pressure can lead to haemorrhage. In 29 patients full haemostasis had been achieved within 30-60 minutes postoperatively as shown by the absence of blood from the perfusion tubes. The perfusion flow was decreased but in a number of patients haemorrhage commenced again within 20 minutes. This was controlled in 12 patients by increasing the perfusion rate again and adjusting the pressure of the drainage fluid. In 7 patients, haemostatic medical therapy was required. In 2 patients the surgical site was reopened and haemotoma was removed.

In the third situation complete or partial blockage of the drainage tubes by blood clots or brain detritus can lead to a rapid increase in intracranial pressure. Increase in intcacranial pressure was observed in 22 patients who clinically presented with intense headache, nausea, vomiting, shivering, psychomotor anxiety and excitation. Loss of consciousness, tachypnoea and tachycardia occurred in 5 patients. After emergency intervention to remove the excess fluid, the patients rapidly relopsed in to normaky.

Usually, even in the presence of such adverse pathological problems, providing adequate drainage is provided for 2 days, few long-term effects are witnessed in the majority of patients.

During non-con trolled perfusion drainage under negative intracranial pressure, fluctuations of the venous tension are not seen. Pulsatory and respiratory fluctuations on plethysmogram curves are not defined.

Only aperiodic changes in pressure are reflected by the bodily position. Gradual increases in intracranial pressure begin some 5-6 hours after surgery with an increase in the amplitudes of pressure changes.(pic 2).

Pic 2.

The long-tern follow-up of patients, who were given active intracranial perfusion, were investigated. In the first two groups, there were no relapses; in the third were 2 relapses out of 22 of interventions.

Good drainage of the intracranial cavity after sugery provides optimum conditions for the removal of debris (such as from the cyst), blood and necrotic material. This permits the establishment of normal intracranial pressure, blood circulation and brain metabolism. The condition of the patient improves, consciousness is restored, and clinical symptomatology decreases. Meningeal and fever responses do not develop, or only moderately, and then disappear within 2 days. There are decreased signs of thirst, headache, vomiting, psychomotor anxiety and excitement. Blood pressure is stabilized and respiratory and pulse rates return to normal.

Thus, adjustable perfusion-drainage of the cranial cavity is an important and effective postoperative treatment for cerebral echinococcosis. The patients condition is improved in the postoperative period and the time spent in hospital is reduced.

CONCLUSION

Based on our surgical experience, and others reported in the literature, the important features in die diagnosis and management of cerebral echinococcosis include: 1 )a history of episodic pyrexia of unknown origin 2)the presence of shot-term serous meningitis and epileptic attacks 3)slowly progressing focal neurological disease discrepancies between changes in the radiological appearance of bones of the cranium and duration of clinical neurological signs 5)data from computer tomography and magnetic resonance imaging in defining the number, size and location of cerebral cysts and any pathological changes in surrounding cerebral tissue 6)chemiluminescence of CSF 7)adjustablc perfusion drainage of the cranial cavity following removal of the cyst enables supervision of intracranial pressure during the post operative period 8)flushing out of protoscolices as a result of cyst rupture reduces the rick of recurrence.

References

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