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The Diagnosis That Didn’t Quite Fit

By Alice Song, MD
Edited by Thomas A. Oetting, MD
 
 

When we first saw Eleanor Smith,* the 49-year-old Caucasian woman complained of progressive decreased vision, photopsias and intermittent pain in her right eye. Although she had a history of migraine headaches, she had experienced none recently, and she denied any ocular trauma. She had a history of floaters in both eyes but noted no recent changes.

In addition to the migraines, Ms. Smith had hypothyroidism, which was diagnosed over 10 years ago (and was never hyperthyroid by her account), and reactive hypoglycemia. Her medications include levothyroxine (Synthroid), ibuprofen and butalbital.

First Look
When we first examined her, Ms. Smith’s visual acuity was 20/20-2 in her right eye and 20/15 in her left. She had no relative afferent pupillary defect. However, she noted red desaturation in the right eye relative to the left eye. Scleral show in her right eye was present and Hertel exophthalmometry measurements were 21 millimeters on the right and 18 mm on the left. Her IOP was 12 mmHg in both eyes. Ocular motility was full. The dilated fundus examination revealed healthy pink optic nerves and normal vessels, macula and periphery.

Critical flicker fusion frequencies were 23 and 29.5, respectively. Visual field testing revealed generalized constriction in the right eye. Her orbital echography was consistent with thyroid ophthalmopathy without evidence of compressive optic neuropathy. Based on these findings, Ms. Smith was diagnosed with Graves’ ophthalmopathy.

Common Disease, Uncommon Presentation?
However, Ms. Smith had some atypical features, which prompted us to take a second look when she returned for a follow-up exam, reporting episodes of deep sharp pain in her right eye. In particular, three typical signs of thyroid ophthalmopathy were missing:

  • The most common finding in Graves’ disease, eyelid retraction, was not present.
  • Ms. Smith had no previous history of hyperthyroidism, unlike most patients with thyroid ophthalmopathy.
  • Thyroid ophthalmopathy usually affects the inferior rectus muscles; in Ms. Smith, the lateral rectus muscles were thickened.

At this exam, Ms. Smith’s visual acuities were 20/20 in both eyes, but she now had a 0.3 log unit afferent pupillary defect on the right. We ordered a CT scan, which showed hyperostosis of the greater wing of sphenoid consistent with meningioma, with calcification of the dura along the greater wing of sphenoid. A follow-up MRI showed displacement of the orbital contents near the apex medially. The correct diagnosis: Meningioma.

Orbital Meningioma
Meningiomas are slow-growing tumors that arise from the arachnoid villi and gain access to the orbit via direct extension through bone, the superior orbital fissure or the optic canal.

Intracranial meningiomas account for 15 percent of adult intracranial tumors, and approximately 18 percent of intracranial meningiomas occur in the sphenoid wing. They occur three times more frequently in women than men and usually present in the fifth decade.

Clinical features depend on tumor location. Proptosis and distortion of the orbit, as well as expansion of the temporalis fossa, may be present. Parasellar tumors cause earlier visual deficits. Eyelid edema, chemosis and cranial nerve palsies may be seen.

Meningiomas can be distinguished from fibrous dysplasia by the homogenous thickening of bone, feathered bony surfaces and soft tissue involvement.1 Fibrous dysplasia usually has a heterogenous appearance with smooth cortical boundaries and rarely has soft tissue involvement.

Surgical excision is effective for well-localized tumors. The transcranial orbitotomy approach allows for more complete removal of the tumor by providing access to the bone surrounding the orbital fissure and optic canal. Radiotherapy is offered after incomplete surgical removal.

Patient’s Progress
We discussed the options of surgery, radiotherapy and observation with Ms. Smith. She decided to proceed with surgery and underwent transcranial orbitotomy on the right side; tumor along the optic canal and in the superior orbital fissure was removed.

Postoperatively, Ms. Smith had no diplopia. Her visual acuity was 20/20 in the right eye and 20/25 in the left. An afferent pupillary defect of <0.3 log unit was noted in the right eye. Full extraocular motility was present.

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1 Katz, B. J. and J. A. Nerad. Ophthalmology 1998;105:2207–2215.

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Dr. Song is a fellow in oculoplastics surgery at the University of Iowa.

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* Patient name is fictitious.

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