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Show Journal of Clinical Neuro-ophthalmology 13(2); 135-137, 1993. Spontaneous Rupture of an Intraorbital Hydatid Cyst A Rare Cause of Acute Visual Loss M. Memet Ozek, M.D., M. Necmettin Pamir, M.D., and Aydin Sav, M.D. 19 1993 Raven Press, Ltd., New York A very rare cause of acute visual loss due to the spontaneous rupture of an intraorbital hydatid cyst is presented. Acute onset was thought to be due to volume expansion and inflammatory reaction of orbital structures to ruptured cyst fluid. Key Words: Orbita-Echinococcosis-Hydatid cystOrbital hydatid-Proptosis--MRl. From the Department of Neurosurgery (M.M.a., M:N.P) and Pathology (A.5.), Marmara University School of Medlcme, Istanbul, Turkey. Address correspondence and reprint requests to Dr. M: Memet Ozek Marmara Universitesi Hastanesl, Noroslrurp Anabilim Dali: Tophanelioglu cad, No: 13-1581190 Altunizade, Istanbul, Turkey. 135 Two species of Echinococcus may infect the human nervous system: E. granulosus and E. muItilocularis (1,2). These two cestodes differ in life cycle, morphology, and epidemiology. Central nervous system infestation by E. granulosus, called hydatid cyst disease, usually occurs in the cerebrum, but may also occur in the spine (1,3). Only a few papers of orbital hydatid disease have been reported from different areas of the world where hydatid disease is prevalent (1,3--9). Orbital hydatid cyst disease is a very rare cause of proptosis and loss of visual acuity, even in densely endemic countries. Although possible spontaneous rupture of a hydatid cyst is not mentioned in the literature very often (10), we present a case of a unilateral orbital hydatid cyst, in whom an acute loss of visual acuity occurred secondary to spontaneous primary cyst rupture. CASE REPORT A 52-year-old female was admitted to our hospital with a 6-month history of painless proptosis of the right eye and a 4-day history of sudden visualloss accompanied by severe orbital pain. Neuro-ophthalmologic Examination Right eye: Examination revealed total visual loss without light perception and optic atrophy. A proptosis of 28 mm with inferior and lateral globe displacement and limited motility in all directions of gaze was observed. Left eye: Fundoscopic and visual field examination of her left eye was normal. General physical examination and laboratory tests were unremarkable except for a positive Ca- 136 M. M. OZEK ET AL. soni test. The Weinberg complement fixation test was normal. MRI showed multiple well-defined cysts occupying the superior aspect of the orbit, causing erosion of the orbital roof. The cyst signal was low intensity on Tl-weighted images and high intensity on T2-weighted images (Fig. 1). No other focus of infiltration was uncovered. Surgical Procedure The preoperative diagnosis was orbital hydatid cyst. A right Kronlein-Berke approach was used to explore the orbital cavity. After opening Tenon's capsule, the very edematous orbital contents protruded from the craniectomy site. There was a very thick irregular fibrous membrane that had a moderate number of adhesions to the orbital contents and seemed to be the remains of a former primary cyst. Within this thick ruptured capsule we found three large cysts. These daughter cysts were carefully removed without rupturing their very thin membranes. After the cysts were excised, the orbital cavity was irrigated with 3% NaCI. Mebendazole was initiated immediately following the operation. Pathology Serial sections were taken for histopathological examination from the surgically removed tissues of the orbit. Morphologically, there were four separate cysts, one of which had a very thick membrane with heavy lymphocyte infiltration, both suggesting chronicity. The remaining three cysts were multilayered structures, whose characteristics were consistent with classic hydatid cysts. It is unlikely these small-calibered cysts ("daughter" cysts) had no typical outermost layer consisting of fibrous tissue: however, they showed a relatively thick, laminated, and acellular outer membrane nucleated inner germinative membrane. But there were no accompanying brood capsules or scolies in the cyst fluid. Although the cyst fluid was centrifuged and examined repeatedly, no evidence of free hooklets or scolies was found. The theory of four particular cysts in the same vicinity might be formulated as the "mother" cyst which possibly gave birth to a couple of small-calibered "daughter" cysts, which really had no time to form a thick enwrapping fibrous capsule around them. Follow-up At 7 months following surgery, proptosis was decreased to 17 mm, ocular motility limitation was improved, and visual acuity of the right eye did not improve. There were no signs of recurrence on the follow-up MRI (Fig. 2). DISCUSSION Hydatid cyst, a lesion that appears during the evaluation of the parasite Echinococcus granulosus in man as an accidental host, can be found in various sites in the human body. Despite the fact that the CNS is affected in about 2% of all cases of hydatid I C1i/l Nmf(l-tll'htlmlmol. Vol. 1.J, No.2. 1993 FIG. 1. There are three hydatid cysts within the orbital cavity. Notice the severe proptosis. ORBITAL HYDATID CYST 137 FIG. 2. Seven months following surgery there are no signs of recurrence on the follow-up MRI. disease, there are limited reports of CNS infestation in the literature (1-10). Orbital hydatidosis is an even more unusual manifestation of E. granulosus infestation. Although subretinal, vitreal and anterior chamber hydatid cysts have been reported occasionally, the orbit is the most common site of ophthalmologic involvement (4,11). The prognosis of orbital hydatidosis is strongly influenced by early diagnosis on a relatively high index of suspicion of hydatidosis, and proper surgical treatment. In all reported cases, the chief complaint was a slowly progressive unilateral proptosis. Morales and colleagues (4) described the duration of symptoms before consultation as being from 3 months to 2 years. But in our case, total visual loss and severe orbital pain occurred in 1 day, and was thought to be due to a sudden volume expansion secondary to the cyst rupture and inflammatory reaction of the orbital content with the cyst fluid. Our surgical findings supported also this and made our case unique. The computed tomography (CT) appearance of orbital hydatid cyst is well defined (5,6). When examining a lesion on CT suggesting hydatid cyst, the differential diagnosis should always include chronic hematic cyst, abscess, dermoid and epidermoid cysts, and teratomas. Since these entities, along with hydatid cyst, typically produce a similar low-density image on CT, CT is not very helpful in diagnosing a hydatid disease in the orbit. However, the magnetic resonance image (MRI) appearance of a lesion with high intensity on T2 and low intensity on T1 helps to rule out other cystic lesions with less water content. In our opinion, MRI should follow CT for all intraorbital cystic lesions to avoid misdiagnosis and serious conse-quences, such as cyst rupture, with resultant anaphylactic reaction or local spread. A lateral approach into the orbital cavity will prevent the risk of intracranial seeding and is therefore recommended. We strongly believe that a transcranial orbital approach is contraindicated in orbital hydatid disease because of the potential danger of cranial seeding. In case of spontaneous or accidental cyst rupture during surgery, corticosteroids are recommended to avoid the ensuing inflammatory reaction. Sudden visual loss due to the spontaneous rupture may accompany orbital hydatid cyst disease. Therefore, all intraorbital hydatid cysts should be decompressed by a lateral orbitotomy immediately. REFERENCES 1. Lunardi P. Missori P, Di Lorenzo N, Fortuna A. Cerebral hydatidosis in childhood: a retrospective survey with emphasis on long-term follow-up. Neurosurgery 1991;29:515-8. 2. Pamir MN, Ozer AF, Keles GE, Tozun N, Gurmen N, KuUu S. Cerebral echinococcosis. JNeurosurg Sci 1991;35:161--4. 3. Pamir MN, Akalan N, Ozgen T, Erbengi A. Spinal hydatid cysts. Surg Neurol 1984;21:53-7. 4. Morales AG, Croxatto )0, Crovetto L. Hydatid cysts of the orbit. Ophthalmology 1988;95:1027-32. 5. Khalili AH. CT values in orbital hydatid cyst. Comput Radiol 2987;11:193-7. 6. Alparslan L, Kanberoglu K, Peksayar G. Orbital hydatid cyst: assessment of two cases. Neuroradiology 1990;32:163-5. 7. Lerner SF, Morales AG, Croxatto )0. Hydatid cyst of the orbit. Arch Ophthalmol 1991;109:285. 8. Guerinel CL, Roux FX, Bonin A. Kyste hydatigue intraorbitaire. Neurochimrgie 1991;37:200-5. 9. Rudwan MA, Khaffaji S. CT of cerebral hydatid disease. Neuroradiology 1988;30:496--9. 10. Carrea R, Dowling E, Guevara )A. Surgical treatment of hydatid cysts of the central nervous system in the pediatric age. Child Brain 1975;1:4-21. 11. Scherz W, Meyer-Schwickerath G, Piekarski G, Waubke TN. Echinococcus in der Vorderkammer. Klin Monatsbl Augenheilk 1973;163:66--70. I ClIII Neuro-ophtha/mol. Vol. 13, No.2, 1993 |
