Successful Surgical Management of an Intraorbital Hydatid Cyst through a Transmaxillary Approach: Case Report

ABSTRACT

A patient with an intraorbital hydatid cyst was treated successfully through a transmaxillary approach. Numerous procedures to remove intraorbital hydatid cysts are discussed.

The incidence of intraorbital hydatid disease is extremely low in all hydatid cysts.^{1, 2, 3, 4} The symptoms include progressive exophthalmos with or without pain, disturbance in ocular motility, visual deterioration, and chemosis.^{3, 4, 5} Surgery is the primary treatment in these cases,^{2, 6} but chemotherapy should be used if a cyst ruptures.^{2, 4, 6} We present a new case of a hydatid cyst of the orbit located inferiorly that we removed through a transmaxillary route.

CASE REPORT

Examination

A 76–year–old man sought treatment for worsening vision, positional amaurosis, and exophthalmos without pain that had persisted for 3 months. On examination, his left eye was exophthalmic with chemosis. Ocular motility in the left eye was restricted inward and outward. He had upper quadrant hemianopsia, and his vision was 6/10 in the right and 1/10 in the left eyes. He had also partial optic atrophy of the lower quadrant. Magnetic resonance imaging (MRI) revealed an intraorbital cystic mass located inferiorly (Fig. 1). Chest radiography and abdominal ultrasonography showed no hydatid cyst.

Figure 1A.

Axial T2–weighted MRI shows a well–defined biloculated hyperintense mass located inferior to the globe within the intraconal region.

Operation

The patient underwent surgery via a transmaxillary approach, the details of which are described elsewhere.^{2, 6, 7, 8} The patient was anesthetized via an orotracheal route and was positioned supine with the neck hyperextended and turned 30 degrees toward the surgeon. The oral cavity was cleansed with a povidine–iodine solution, and the gingiva was infiltrated with lidocaine containing 0.5 % epinephrine. A sublabial incision was extended from the lateral incisor to the third molar. Then, the left unilateral soft tissue was dissected up to the infraorbital foramen. The infraorbital nerve and artery were identified. A 2 × 2 cm maxillotomy was performed using a rongeur.

A microscope was introduced into the surgical field. The orbital floor was removed. The periorbita was incised, and the infraorbital nerve and artery and orbital fat were exposed. The orbital fat, which was very thin in this area, and the infraorbital nerve were carefully dissected medially. The inferior rectus and oblique muscles and the inferior branch of the oculomotor nerve were identifed. Nerve, muscle, and orbital fat were dissected off the cyst using hypertonic saline–soaked cotton patties. The cyst was removed completely, but the cyst wall ruptured during the resection. The periorbita was reapproximated with sutures, but complete reapproximation was impossible. No graft was used to repair the periorbita. Systemic albendazole was administered after surgery.

Postoperative Course

The patient's postoperative course was uneventful, and he was discharged on the third postoperative day. Eight months after surgery the patient was doing well and his ocular motility and vision had improved. On physical examination, no enophthalmos was detected. Follow–up MRI revealed no evidence of the cyst (Fig. 2).

Figure 2A.

Postoperative coronal MRI show no residual cyst.

DISCUSSION

Hydatid cysts of the orbit are rare and account for 1 % of all hydatid cysts.^{2, 3} Altınörs et al¹ surveyed the literature on central nervous system hydatidosis in Turkey and found that 22 of 336 cases were located in the intraorbital space. Typically, an orbital hydatid cyst is unilateral and occurs with or without hydatid cysts located elsewhere in the body.^{4, 5} The most frequent clinical findings are exophthalmos, chemosis, lid edema, visual impairment, and restriction of extraocular motility.^{3, 4, 5} An orbital hydatid cyst tends to involve the retrobulbar tissues either within the muscle cone or outside in the superolateral or superomedial angle.^{3, 9, 10}

Definitive treatment is total surgical excision.^{1, 2, 4} Various surgical approaches have been used to expose the orbital mass.^{11, 12, 13, 14} The proper surgical approach and understanding of the microanatomy of the orbit are very important in preventing surgical complications during the intraorbital procedure.¹¹ There are two main routes to expose the intraorbital lesion.^{11, 12, 14} The transcranial approach is often selected for lesions with an intracranial extension when it is necessary to expose the optic nerve and for lesions located superiorly to the optic nerve. The lateral orbital approach is the procedure most commonly used to treat intraorbital lesions located in the lateral compartment of the orbit such as lacrimal gland tumors. Arai et al¹¹ recommended the use of the lateral orbital approach for lesions located inferolaterally to the optic nerve, but they stressed that the ciliary ganglion and its nerve roots could be easily damaged. The lateral rectus muscle must be retracted, and this manuever can cause lateral gaze palsy. Removal of the lateral wall of the orbit could result in enophthalmos or exophthalmos with mastication. Forehead movement palsy can develop if the frontal branch of the facial nerve is transected.

In our patient, the cyst was located within the muscle cone inferiorly. To facilitate access to this region, we chose the transmaxillary approach. The transmaxillary route is used in neurosurgical clinics to excise masses involving the anterior clival region and sellar tumors invading the cavernous sinus.^{2, 7, 8} We find that the transmaxillary route provides excellent exposure of the cyst and prevents neural, vascular, and muscle injury. The most important complication in surgical treatment is rupture of the cyst during excision, which can cause a relapse.^{1, 2} However, complete extirpation of the cyst without rupture is almost impossible.² Given this possibility, some authors use treatment modalities other than surgery.^{4, 15, 16} If the cyst is accidentally ruptured, in situ irrigation with hypertonic saline solution should be performed.⁴ However, this procedure is thought to cause a local inflammatory reaction and atrophy of the optic nerve, and its efficacy is poor.^{4, 10, 17} Because of the possibility of the cyst rupturing, we dissected the mass and orbital fat over the cyst wall with hypertonic saline–soaked cotton. The cyst ruptured during removal, but the cystic contents floated into the maxillary sinus due to the effect of gravity. Thus, we believe that the risks of spreading the infection and recurrences associated with our technique are minimal.

Albendazole treatment is useful, especially if begun 14 to 28 days before surgery and is used as an adjunctive therapy to surgery.^{1, 4, 6} We administered albendazole to decrease the risk of a relapse. We believe that the transmaxillary route allows excellent exposure and removal of an intraorbital hydatid cyst located inferiorly without damaging the important surrounding orbital structures. The cosmetic outcome is excellent. Finally, the transmaxillary approach can be used safely in selected cases and may decrease the recurrence rate if the cyst ruptures accidentally.

Figure 1B.

Precontrast coronal T1–weighted MRI shows a hypointense mass.

Figure 1C.

Postcontrast axial T1–weighted MRI with fat suppression shows no enhancement.

Figure 2B.

Postoperative axial T–1 weighted MRI show no residual cyst.