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Orbital hydatid cyst a rare complication
Surgeons present case report and review of surgical techniques.
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| Marked right-sided axial proptosis with 6/6 visual acuity in both eyes. CT scan showing a unilocular, hypodense, thin-walled and fluid-filled orbital cyst. Complete removal of the inner germinal layer of cyst, leaving outer fibrous layer. All images courtesy of Roger Gray, MBBS, FRCS. |
Orbital disease is a rare complication of systemic hydatid infection, the treatment of which is traditionally surgical. Diagnosis is made largely on clinical and radiological appearances and in the current climate of international travel, nonendemic countries may be susceptible to isolated cases.
In 2002 a 60-year-old female patient presented to the Eye Department of CCBRT Hospital Dar Es Salaam (Tanzania) with a 6-month history of painless swelling around the right eye associated with diplopia. There were no other medical problems, and in particular, the liver was not enlarged. However, it was noted that the patient had previously lived in the arid northern region of Kenya and was from the nomadic Turkana tribe.
On examination, uncorrected visual acuity was 6/6 in both eyes, and marked axial proptosis was noted on the right (Figure 1). There was also restriction of eye movements in all positions of gaze. Orbital CT scanning showed a hypodense and thin-walled, fluid-filled cyst that was unilocular and placed laterally in the orbit (Figure 2).
A Kronlein-Berke lateral orbitotomy was carried out under general anesthesia, and after exposure and removal of the zygomatic arch, an encapsulated translucent cyst (endocyst) was identified and removed (Figure 3). The wound was then irrigated with saline before reattachment of the zygoma. Postoperatively, there was marked orbital edema, and she was treated with albendazole (400 mg twice daily for one month) and systemic steroids. She made a full and uneventful recovery.
Cause of hydatid cyst
Hydatid disease is caused by cestode larvae of the genus Echinococcus. The most common form that affects humans is E. granulosus (unilocular hydatid), which develops slowly and is adapted to large ungulates such as sheep and cattle that represent intermediate hosts. Dogs are the usual definitive hosts because they eat the flesh of infected sheep. Canine excrement may contain large numbers of eggs, and humans can become infected when in close contact with dogs or when handling and consuming food contaminated by feces.
Most hydatid cysts affecting humans grow in the liver, and orbital involvement is only present in about 1% of cases. The disease is more common among the nomadic Turkana tribe of Kenya because of close contact with their dogs, flocks of sheep, cattle and goats. Fortunately, the incidence is declining due to the intervention of the African Medical and Research Foundation (AMREF).
Surgical methods
The classical surgical method for hydatid cyst removal is described in “Manson’s Tropical Diseases.” The exposed surface of the wound is walled off with towels, and the contents of the cyst are evacuated through a large caliber needle and closed suction. Ten to 50 mL of 10% formalin are then injected into the cyst and aspirated after 5 minutes. The cyst and fibrotic pseudocapsule are then dissected and removed. The cavity is then irrigated with more formalin and obliterated with sutures where possible.
Kaymaz et al described an 8-year-old Turkish girl with an orbital hydatid cyst, and they commented “total evacuation of the cyst while avoiding rupture of the cyst walls is the only definite treatment for this disease.” However, Nahri described a simplified method in which the cyst is aspirated, and the fibrotic capsule carefully incised to a length of 5 to 10 mm. This reveals the glistening inner germinal layer, which is gripped with a cryoprobe and completely extracted. The outer fibrous layer is left behind, eliminating the need for potentially damaging orbital dissection. In two cases he reported no postoperative problems or recurrence. This was the technique employed by us. Akhan et al have recommended an even simpler approach in a 21-year-old patient. They drained the cyst percutaneously under ultrasound guidance, refilled it with 15% hypertonic saline and reaspirated after 10 minutes. Cyst involution was achieved by 9 months, and the patient remained asymptomatic 21 months after treatment.
Excessive postoperative inflammation and recurrence may both occur if there is significant spillage of cyst contents into the operative field. Because of this, antihelminthic drugs such as albendazole and praziquantel have been advocated postoperatively, along with systemic steroids.
For Your Information:References:
- Andrew Shaw, MBBS, can be reached at James Paget Hospital, Gorleston, Great Yarmouth, Norfolk, England, NR316LA; 0044-797-330-1524; e-mail: shawry@arcticmail.com.
- Roger Gray, MBBS, FRCS, can be reached at Taunton and Somerset Hospital, Taunton, Somerset, England, TA15DA; 0044-1823-342942; e-mail: roger.gray@tst.nhs.uk.
- Shougreg NM, Tabbara KF. Eye related parasitic disease. In: Tabbara KF, Hyndiuk RA, eds. Infections of the Eye. Boston, Mass: Little Brown; 1986:194-196.
- Wilcocks C, Manson-Bahr PEC. Chapter 13, Cestode infections. In: Manson’s Tropical Diseases. 17th ed. London, England: Bailliere Tindall; 1972:342-346.
- Aksoy FG, Tanrikulu S, Kosar U. Inferiorly located retrobulbar hydatid cyst: CT and MRI features. Comput Medical Imaging Graph. 2001;25:535-540.
- Kaymaz M, Dogulu F, et al. Orbital hydatid cyst. J Neurosurg. 2002;97:724.
- Nahri GE. A simplified technique for removal of orbital hydatid cysts. Br J Ophthalmol. 1991:75;743-745.
- Akhan O, Bilgic S, et al. Percutaneous treatment of an orbital hydatid cyst: A new therapeutic approach. Am J Ophthalmol. 1998;125:877-879.
- Jimenes-Mejias ME, Alarcon-Cruz JC, et al. Orbital hydatid cyst: Treatment and prevention of recurrences with albendazole plus praziquantel. J Infect. 2000;41(1):105-107.