RF Browne MD, DJ Tuite MD.
Brain involvement with hydatid disease occurs in 1–2% of all Echinococcus granulosus infections. Isolated cerebral hydatid disease is a rare manifestation of it. In this report, we analyze two cases of isolated cerebral hydatid cysts and discuss their mode of presentation, radiological features, operative procedure and outcome. In our two cases, radiological features and surgical approaches were different from one another. The literature concerning isolated cerebral hydatid disease is reviewed. Key words: Dowling‑Orlando technique, Echinococcus, isolated cerebral hydatid cyst
A 22‑year‑old male presented to us with complaints of headache for last 4 months, vomiting intermittently for 4 days and disorientation for 2 days. On physical examination, he was disoriented with bilateral papilledema and right sided hemiparesis. Computed tomography (CT) scan and magnetic resonance (MR) imaging of the brain [Figure 1a and b] were suggestive of a large multi‑cystic lesion in parieto‑occipital region. Lesion was removed by a large right parieto‑occipital craniotomy. Due to large size, in toto removal was not possible. Cyst wall was punctured; multiple daughter cysts removed one by one [Figure 1c]. After intra cystic decompression, laminated membrane was removed by irrigating warm saline between cyst wall and brain interface. Pathological examination confirmed it as hydatid cysts. X‑ray chest and USG of abdomen failed to show any lung or liver lesions. Five years after surgery, he remained well and free of disease.
Intracranial hydatid cyst may be classified as primary or secondary. Primary cysts are formed as a result of direct infestation of the larvae in the brain without demonstrable involvement of other organs. Lack of effective immune system in the brain, special architecture of brain tissue, patent ducts arteriosus and patent foramen ovale have been the proposed factors for isolated cerebral hydatid disease. In our two cases, echocardiography revealed no abnormality.
Magnetic resonance and CT scans characteristically show a spherical, well defined, non‑enhancing cystic lesion without peripheral edema.[2,3] The fluid density is generally equal to that of cerebro spinal fluid on both CT and MR scan. MR spectroscopy studies show pyruvate peaks besides lactate, alanine and acetate.
The treatment of hydatid cyst is surgical, and the aim of surgery is to excise the cyst in toto without rupture to prevent recurrence and anaphylactic reaction. Dowling‑Orlando technique remains the preferred method, in which the cyst can be delivered by lowering the head of the operating table and instilling warm saline between the cyst and the surrounding brain parenchyma. This is possible because of minimal adhesions around the cyst wall.
Isolated case reports showed complete disappearance of multiple intracranial hydatid cysts with albendazole therapy in a daily dose of 10 mg/kg, taken three times a day for 4 months.[6,7]
Incidence of primary hydatid cyst of brain is very rare. Patent ductus arteriosus and patent foramen ovale have been the proposed factors. In our cases, larvae might have passed through the capillary filter of the liver and lungs, entered into the systemic circulation and reached the brain. Aim should be in toto removal of the cyst. Sometimes because of large size, it is not possible, in that case intracystic decompression followed by removal of cyst wall by gentle traction and saline irrigation between cyst wall brain interfaces is a better option.
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Fig 1: Axial MR sections showing small multiple daughter cyst within large cyst, confirmed in surgery
Fig 2: Coronal MR sections showing multiple daughter cysts seen within.