Orbital computed tomographic characteristics of globe subluxation in thyroid orbitopathy.

OBJECTIVE: Axial globe subluxation may complicate thyroid orbitopathy. This acute event is defined by anterior displacement of the globe equator beyond the orbital rim, lid retraction behind the equator, and tethering of the optic nerve. The authors explored the factors leading to spontaneous globe subluxation in patients with thyroid orbitopathy. DESIGN: A clinical review. MAIN OUTCOME MEASURES: The medical charts and axial and coronal orbital computed tomographic (CT) scans of all the patients with spontaneous globe subluxation were reviewed. The patients were categorized according to their CT scans into type I ("lipogenic" variant) or type II ("myogenic" variant). RESULTS: Four (0.1 %) of approximately 4000 patients with thyroid orbitopathy presented with spontaneous globe subluxation. All of these patients had increased orbital fat without significant enlargement of the extraocular muscles. Thus, they represent type-I thyroid orbitopathy. CONCLUSIONS: Globe subluxation in thyroid orbitopathy requires compliance of the orbital soft tissues and extensibility of the extraocular muscles. These are characteristics of type-I orbitopathy. The increased fat content results in more compliance of the soft tissues, and the normal caliber of the muscles allows them to become more extensible. This permits the acute contraction of the eyelids posterior to the equator of the globe. Patients with type-I orbitopathy and extensive proptosis may be at relatively greater risk of having globe subluxation develop.

Graves' disease of the orbit.

Graves' disease, the most common orbital disorder, affects approximately 0.5 % of the population of the United States. It is the underlying cause in 15% to 28% of cases of unilateral exophthalmos and in 80% of cases with bilateral exophthalmos. Also called "thyroid-associated ophthalmopathy", autoimmune thyroid disease," "endocrine exophthalmos," and "thyroid eye disease", Graves' disease presents with enlargement of the extraocular muscles, increased orbital fat volume, and venous stasis caused by increased orbital pressure. This article discusses the clinical evaluation and radiologic findings of this common orbital disorder.

Endoscopic orbital decompression under local anesthesia.

Orbital decompression for Graves' disease has traditionally been performed with the patient under general anesthesia. Endoscopic instrumentation allows for removal of the medial orbital wall and floor through an intranasal approach with local anesthetic techniques. Twelve endoscopic orbital decompressions were performed on awake patients with uncovered eyes so that vision could be monitored throughout the procedure. Simultaneous lateral decompressions were performed in 11 cases. No intraoperative or postoperative complications occurred. Visual acuity remained stable or improved in all cases. Proptosis was reduced an average of 5.5 +/- 1.6 mm. In a comparable series of 29 endoscopic decompressions performed with patients under general anesthesia, proptosis was reduced an average of 4.8 +/- 2.0 mm. Endoscopic orbital decompression with patients under local anesthesia appears to be an effective technique that may provide an additional margin of safety in prevention of injury to the optic nerve.

Endoscopic orbital decompression.

Exophthalmos from Graves' disease can result in visual disability and cosmetic deformity. Surgical treatment of this disorder is now possible through an intranasal endoscopic approach that allows removal of the medial orbital wall and floor without an external incision. Endoscopic orbital decompression was performed on 22 orbits in 14 patients for treatment of progressive exophthalmos. Local anesthesia was used in five cases. Sixteen procedures involved a concurrent lateral orbital decompression performed through an external approach. There were no intraoperative or postoperative complications. Visual acuity remained stable or improved in all cases. Proptosis was reduced an average of 3.2 +/- 1.1 mm (range 2 to 4.5 mm) by endoscopic decompression alone. When a lateral decompression was also performed, proptosis was reduced by an additional 2.4 mm, for an average improvement of 5.6 +/- 1.7 mm (range 2 to 8 mm). Endoscopic orbital decompression appears to be a safe technique for the treatment of exophthalmos that can be performed effectively with the patient under general or local anesthesia.

Periocular xanthogranulomas associated with severe adult-onset asthma.

This article describes six patients who presented, usually bilaterally, with yellow-orange, elevated, indurated, and nonulcerated xanthomatous eyelid lesions, typically extending into the anterior orbital fat, and sometimes involving the extraocular muscles and the lacrimal gland. Because the eyelids remained intact and because the process did not reach the deep orbital and perioptic connective tissues, visual acuity was well preserved. There is cosmetic morbidity and occasionally motility restriction with advancing involvement of the extraocular muscles. All patients had variably severe adult-onset asthma that required treatment with systemic prednisone and inhalants. No evidence of Erdheim-Chester disease was found in any patient, but the appearance in one patient, after 25 years of follow-up, of a separate subcutaneous necrobiotic xanthogranulomatous lesion in the mandibular region with an associated paraproteinemia, suggests that at least some of our cases might be a mild form of necrobiotic xanthogranuloma. For this reason, we would suggest repeated periodic serum protein immunoelectrophoretic studies as well as evaluation for lymphoma. Therapy probably should consist of low doses of periorbital radiotherapy coupled with high doses of corticosteroids. Should this not be successful, then systemic administration of corticosteroids with chemotherapeutic agents might be efficacious, as in necrobiotic xanthogranuloma.

Computed tomography of lymphoproliferative disease of the orbit. Report of 50 patients.

Orbital lymphoproliferative disease is one of the most common causes of exophthalmos and palpable masses in the anterior part of the orbit. Axial and coronal computed tomography (CT) is the method of choice for localizing the lesion and determining the extent of involvement. The CT features are non-specific but are highly suggestive in the proper clinical setting. The most important CT findings consist of: round, oval or elongated lobular masses, commonly in the extraconal space, with intraconal extension in large tumors. In some lesions, linear infiltrates radiate from the bulk of the mass into the adjacent fascial compartments. Tumors in proximity to the globe, wrap around the scleral-uveal coat causing no indentation but displacement of the globe from the mass effect. Similar molding occurs along the orbital walls, especially laterally from extraconal lesions. Bone destruction or remodeling of bone is rarely seen in orbital lymphoma. No diagnostic enhancement patterns were observed following contrast infusion. The majority of lymphoid tumors were situated anteriorly and superiorly.

Lymphocyte surface markers in orbital lymphoid neoplasms.

Since the malignant nature of many orbital lymphoid infiltrates is difficult to assess from pathologic examination alone, over the past four years lymphocyte surface marker studies have been added to the evaluation of 23 such cases. Only 10 of the 23 could be confidently classified as malignant lymphoma by histology alone. However, monoclonal surface immunoglobulin was found in 15, supporting the pathologic diagnosis of malignancy in eight and adding seven that could not have been diagnosed otherwise. Clinical evaluation, including a median follow-up of 18 months, revealed manifestations of systemic lymphoma in six of those 15; two had been diagnosed only by surface markers. In contrast, only one of eight cases lacking monoclonal surface immunoglobulin exhibited clinical evidence of malignancy (that case was also indeterminate by histologic criteria). The addition of surface marker analysis permits more accurate diagnosis of orbital lymphoma than is possible from pathologic study alone. This technique can suggest the subtype of lymphoma.

Conjunctival cysts of the orbit following enucleation.

Four patients developed orbital conjunctival cysts following enucleation. The cysts were demonstrated by ultrasonography and computerized tomography and confirmed by histopathology. They were lined by a non-keratinizing stratified squamous epithelium without goblet cells and contained fluid with mucinous strands. They were excised at eight, seven, and seven, and 25 years post-enucleation, respectively, the latter being the longest interval yet recorded. A simple classification of conjunctival cysts of the orbit is proposed and the mechanisms of the development of cysts in anophthalmic sockets are discussed. The effects of secretory rate and cyst growth are reviewed and surgical management in prevention and treatment of these lesions is outlined.

CT and ultrasound in the diagnosis of cavernous hemangioma and lymphangioma of the orbit.

Eighteen cases of cavernous hemangioma and seven cases of lymphangioma of the orbit were evaluated with regard to contrast enhancement, hemogeneity, type of margin, anatomic location, and associated changes in he bone. Hemangiomas usually demonstrated homogeneous contrast enhancement, a relatively smooth margin, intraconal location, with occasional extension to the orbital apex, and focal bone expansion. Lymphangiomas showed either minimal heterogeneous or absence of contrast enhancement, irregular margins, and anterior and posterior locations. Ultrasonography of hemangiomas showed high amplitude and closely packed echoes from vessel walls adjacent to blood-filled spaces. Lymphangiomas had a similar ultrasound pattern, but with very wide separation of echoes due to larger fluid lakes.

Congenital orbital teratoma: report of a case with visual preservation.

Congenital orbital teratoma is a rare, but benign cause of unilateral exophthalmos in infants, and therefore a worthwhile differential diagnosis to consider. Despite the grotesque and alarming external appearance of the eye, both it and visual function can be effectively preserved in certain instances with early intervention. A review of the literature accompanies the report of one such case of a successfully salvaged eye following removal of the teratoma. Clinical recommendations are included.

Computed tomography of masses in the lacrimal gland region.

Twenty patients with mass lesions in the lacrimal gland region were evaluated with computed tomography (CT). The extent of the mass and its relationship to the globe, optic nerve, and extraocular muscles were clearly seen. The CT appearance on plain scan and the presence or absence of contrast enhancement, bone involvement, and cystic components often suggested the specific pathological diagnosis. Although orbital ultrasonography and CT were frequently complementary, ultrasonography was more definitive in inflammatory diseases, while CT demonstrated better extraorbital extension.

Immersion ultrasonography: simultaneous A-scan and B-scan.

In eyes with opaque media, ophthalmic ultrasound provides a unique source of information that can dramatically affect the course of patient management. In addition, when an ocular abnormality can be visualized, ultrasonography provides information that supplements and complements other diagnostic testing. It provides documentation and differentiation of abnormal states, such as vitreous hemorrhage and intraocular tumor, as well as differentiation of orbital tumors from inflammatory causes of exophthalmos. Additional capabilities of ultrasound are biometric determinations for calculation of intraocular lens implant powers and drug-effectiveness studies. Maximal information is derived from ultrasonography when A-scan and B-scan techniques are employed simultaneously. Flexibility of electronics, variable-frequency transducers, and the use of several different manual scanning patterns aid in detection and interpretation of results. The immersion system of ultrasonography provides these features optimally.

Reliability of orbital diagnostic tests: ultrasonography, computerized tomography, and radiography.

A series of 342 patients with unilateral exophthalmos underwent orbital diagnostic studies including ultrasonography, computerized tomography, radiographic studies, and vascular contrast studies. Each test was found to have diagnostic capabilities that complemented other studies depending upon the specific disease process involved. No one test was entirely adequate without supplementary information from the other tests. Radiographic studies demonstrated bony abnormality in 50% of the tumor cases, but in only 28% of the entire series of exophthalmos cases. Computerized tomography demonstrated diagnostic soft tissue abnormality in 86% of tumors, 43% of inflammatory diseases, and an overall yield of 62% positive results. Ultrasonography proved the most versatile test for evaluation of orbital soft tissues, with 80% positive results for tumors, 87% for inflammatory disorders, and 78% overall accurate orbital diagnosis. Erroneous tumor diagnosis of 7% with computerized tomography and 3% with ultrasonography were corrected by combining these two studies, because they tend to err in opposite directions. Combination of ultrasound and CT scan resulted in a 98% correct diagnosis of all types of orbital diseases.