Ординатура / Офтальмология / Английские материалы / Clinical Ophthalmic Echography_Harrie_2008

KB was a 54-year-old woman who presented to her ophthalmologist with a history of increasing diplopia over several months. Examination found proptosis of her right eye of 4 mm compared to her left. She had 2 mm of left upper lid ptosis. Her driver’s license photo taken 3 years previously did not show these changes. CT scan showed marked enlargement of several extraocular muscles.

Echography was performed and demonstrated thickening of the right superior rectus (9.3 mm), the right medial rectus (8.4 mm), and borderline thickening of the left superior rectus (5.8 mm) and the left lateral rectus (4.5 mm). However, reflectivity on A-scan was low-to-medium and regular in the right superior and medial recti (Fig. 229).

The finding of low internal reflectivity in a markedly thickened extraocular muscle in conjunction with minimal pain was not typical for Graves’ disease, so a biopsy of the right superior rectus was performed. The pathological diagnosis was consistent with malignancy probably due to metastasis. Systemic evaluation found an infiltrative ductal carcinoma of the left breast.

FIG. 229. A-scan of markedly thickened muscle in metastatic cancer (vertical arrows)

Other malignant processes, such as lymphoma, can sometimes invade the extraocular muscles as part of systemic disease, but in some cases it acts as a local process confined to the orbit.

AG is an 81-year-old woman with a 3-month history of double vision on looking to the left. She reported minimal discomfort when she moved the eye horizontally. Examination found mildly reduced abduction of the left eye and focal injection at the insertion of the left lateral rectus tendon. The remainder of the ocular examination was unremarkable except for cataract formation consistent with her age.

Echography was performed and demonstrated thickening of the left lateral rectus muscle measuring 5.4 mm with low reflectivity on A-scan (Fig. 230). The tendon was not abnormally thickened. The differential diagnosis included an infiltrative process by inflammatory or malignant cells.

A systemic evaluation by her primary care physician was unremarkable. A conjunctival biopsy performed at the lateral rectus tendon was positive for B-cell lymphoma. She was treated with local radiation to the orbit and followed closely by an

FIG. 230. A-scan of lymphoma of extraocular muscle (vertical arrows)

oncologist for the development of any systemic signs of lymphoma.

The incidence of relapse at a distant site in the body is 20% to 25% for low-grade lymphoma of the ocular adnexae and 40% to 60% for higher grades.42 The probability of systemic lymphoma is relatively low when it is confined to the conjunctiva and increases when the eyelids are involved. According to Coupland et al., lymphomas of the ocular adnexa represent about 8% of all extranodal lymphomas.43 The incidence of systemic involvement summarized from several series is 35% for lymphoma of the orbit, 20% for that of the conjunctiva, and 67% for lymphoma of the eyelid. Lymphoma occurs systemically in 35% of cases where there is bilateral orbital involvement.

Orbital biopsy of lymphoid lesions may be read by the pathologist as “lymphoid hyperplasia” or “atypical lymphoid hyperplasia,” which is categorized as a benign process. This low-grade lesion is at one end of a spectrum with highly aggressive monoclonal lymphoma at the other end. However, the incidence of eventual systemic involvement is reported to be 25% to 30% for these “benign” lesions.44 The probability of systemic occurrence by lesions classified as reactive lymphoid hyperplasia is a function of the monoclonality of the B-cells.

Diplopia and proptosis can be due to vascular congestion that can cause extraocular muscle thickening and dysfunction simulating Graves’ disease. A high-flow arteriovenous fistula is usually readily diagnosable by its rapid onset with pulsating exophthalmos, an audible bruit, and a red eye with arterialization of the conjunctival and episcleral veins. They are often related to traumatic head injury and are responsible for about 75% of highflow carotid cavernous fistulas.

AM is a 52-year-old man who was knocked to the ground by falling canisters and bumped the back of his head on the cement floor. He did not recall losing consciousness and was cleared by the emergency room to return to work the next day. He was asymptomatic for a few months but then began to experience severe headaches. He was diagnosed with migraines and treated with beta blockers with partial relief. In the following year he began to see double and was seen by an ophthalmologist, who prescribed prisms in his glasses that allowed him to see without diplopia in primary gaze. During this time he also noted that his right eye was red much of the time. He did not appreciate any unusual noises in his head.

He returned to his ophthalmologist, who suspected the patient had Graves’ disease and ordered a thyroid workup and referred him for echography. A-scan revealed diffuse thickening of most of his

FIG. 231. B-scan of dilated superior opthalmic vein in carotid cavernous fistula (arrow)

FIG. 232. Doppler frequency analysis (small arrow) of arterialized superior opthalmic vein (large arrow)

extraocular muscles with heterogeneous reflectivity consistent with Graves’ orbitopathy. However, B-scan demonstrated a markedly dilated right superior ophthalmic vein with spontaneous vascularity (Fig. 231). This finding was confirmed with orbital color Doppler that demonstrated reversal of flow with arterialization of the vein with a flow velocity of 13.68 cm/s on the pulse tracing (Fig. 232). The other orbit appeared normal.

A stethoscope was applied to the eye through closed lids and a faint bruit could be heard. Blood was noted in Schlem’s canal on gonioscopy and the intraocular pressure was 20 mm OD and 15 mm OS. He was referred for angiography with the plan to close the fistula by the injection of embolic material through the catheter.

Dural sinus fistulas are generally subtler and may occur spontaneously in middle-aged women.

SJ is a 58-year-old woman who presented with intermittent diplopia over several months. She also mentioned that her eyes were always red with a mild aching sensation. She denied hearing her “pulse” at night while lying in bed. There was no history of trauma to her head. She had undergone radioactive iodine therapy for hyperthyroidism 10 years previously and her thyroid levels were maintained at normal levels by medication. Examination found vision in both eyes of 20/25 and intraocular pressures of 23 mm OD and 24 mm OS. Slit-lamp examination showed tortuous dilation of conjunctival vessels bilaterally. A stethoscope was applied to both globes through closed eyelids and no bruit was appreciated.

Echography revealed diffuse thickening of her extraocular muscles bilaterally with irregular reflectivity on A-scan (Fig. 233). Dilation of the superior

FIG. 233. A-scan of extraocular muscle in cartotid cavernous fistula (vertical arrows)

FIG. 234. Color doppler of dilated superior ophthalmic vein in low-flow fistula (arrow)

ophthalmic veins bilaterally was detected. Orbital color Doppler imaging substantiated venous dilation and showed reversal of flow with low-flow arterial pulse waves of 3 cm/s in the superior ophthalmic veins (Fig. 234).

Because of the elevated intraocular pressure and diplopia, the patient was advised not to wait for spontaneous closure of the fistula but to proceed with angiography. The diagnosis of a dural sinus fistula was confirmed and embolic material was injected through the catheter to close the fistula with resolution of her diplopia and reduction of her intraocular pressure to under 20 in both eyes.

Another symptom of orbital pathology in association with proptosis is reduction of visual acuity due to lesions that directly involve the optic nerve, such as glioma, or invade the optic nerve sheaths, as with meningioma.

SB is a 40-year-old woman who noted some reduction in vision in her left eye during pregnancy. Examination was performed and found visual acuity OD of 20/20 and OS of 20/40-1. A 1+ afferent pupil defect was present in the left eye and Hertel exophthalmometry showed 2 mm of proptosis on that side. Fundus examination on the left found slight pallor of the optic disc with a possible retinochoroidal “shunt” vessel at the inferior margin. It was considered inadvisable to do CT scanning, with its attendant radiation exposure, during her pregnancy. She was given the option for an MRI scan but did not want to risk the unknown effects of a strong magnetic field on her developing fetus and was referred for echography.

B-scan showed a possible widening of the optic nerve shadow but this was not definitive. Calcification of the left nerve sheath could not be detected. A-scan measured optic nerve thickness on the right of 2.51 mm and on the left of 7.40 mm with widening of the optic nerve sheaths and a normal optic nerve parenchyma width (Fig. 235). The 30° test was negative for increased optic nerve sheath fluid so the differential diagnosis included a solid lesion of the nerve, such as meningioma, glioma, lymphoma, and metastatic tumor.

Her age at presentation and the appearance of the optic disc were most consistent with meningioma. It was elected to observe her without treatment and reevaluate after she delivered the baby. A CT scan was performed at that point and showed calcification of the optic nerve sheath that was highly consistent with nerve sheath meningioma.

FIG. 235. Top: A-scan of optic nerve sheath meningioma (vertical arrows). Bottom: Normal contralateral optic nerve (vertical arrows)

Her vision was stable at 20/40 and there was no evidence of posterior extension intracranially so no treatment was offered, but radiation was planned in the future if the vision decreased.

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Optic nerve sheath meninigiomas are generally slow-growing tumors and can be observed unless the vision progressively deteriorates. Nerve sheath biopsy to confirm the diagnosis is hazard-

Case Study 131. Optic Nerve Sheath Meningioma

ous and often results in profound loss of vision. Echography provides a cost-effective and safe technique to correlate the clinical findings with growth of the tumor.

VA is a 75-year-old woman who noted some blurring of her right eye over several months. Examination found vision OD of 20/50 and OS of 20/25. She had a 2+ afferent pupil defect in her right eye and 2 mm of proptosis. Fundus exam found slight pallor of the right optic disc.

Echography showed thickening of the right optic nerve sheath with a sheath-to-sheath diameter of 8.7 mm (Fig. 236) compared to 3.2 mm for her left nerve. The findings were consistent with an optic nerve sheath meningioma and were confirmed on CT scan with calcification of the nerve sheath (Fig. 237).

She was followed up with every 3 months without treatment, but was noted after 12 months to have reduction of vision to 20/70 on the right. Echography demonstrated further thickening of the sheath to 7.6 mm. She was referred for stereotactic radiation therapy with improvement in visual acuity to 20/30.

FIG. 236. A-scan of optic nerve sheath meningioma (vertical arrows)

FIG. 237. Computed tomography scan of optic nerve sheath meningioma (arrow)

A- or B-scan is not reliable in demonstrating calcification of the optic nerve sheaths in the orbit because of the high reflectivity of adjacent orbital tissue. This is not the case in the globe, where the high reflectivity of calcified lesions stands out in distinct relief against the low reflective vitreous gel. MRI scans are also not helpful in detecting sheath calcification. The imaging technique of choice to display orbital calcification is CT scanning.

An uncommon process that involves the nerve sheaths is an idiopathic process referred to in the literature by various names, such as perioptic hygroma, optic hydrops, or meningocele.45 In this condition, there is increased cerebrospinal fluid in the intrasheath space of unknown etiology. These patients may present with symptoms of reduced vision and can have fundus findings including atrophy of the optic disc, disc swelling, and choroidal folds.

HH is a 9-year-old child who failed his vision test in school. He had first noted problems the previous summer that he characterized as difficulty in seeing in dim light. His parents took him to an optometrist who documented vision in the right eye of 20/25 and the left of 20/20. Cycloplegic refraction was +1.00 OD and +0.50 OS. The fundus exam showed mild choroidal folds on the right while the optic discs had a normal appearance. Exophthalmometry measured 18 mm bilaterally.

Echography showed bilateral increased optic nerve sheath diameter with a slightly widened subarachnoid space on A-scan. B-scan demonstrated patulous retrobulbar optic nerve sheaths (Fig. 238).

A CT scan was performed and showed dilatation of the optic nerve sheaths. A spinal tap was performed and showed normal opening pressure. The diagnosis of optic nerve sheath meningocele was made and it was elected to follow the child with biannual eye exams and echography. His vision and optic nerve sheath diameter were unchanged over 5 years.

Choroidal folds are a variable finding in this condition. They are possibly due to a masslike effect of the increased nerve sheath fluid pushing on the posterior globe. However, choroidal folds are not generally found in other cases of excess sheath fluid, such as the papilledema associated with pseudotumor cerebri. Their presence on fundus examination should always prompt an investigation of the orbit to eliminate a mass lesion. This can easily be accomplished in the office as part of the initial examination.

FIG. 238. Top: A-scan of optic nerve sheath hygroma (vertical arrows). Bottom: B-scan of dilated optic nerve (arrow)

JJ is a 26-year-old man who complained of reduced vision in his left eye over several weeks. Examination by his ophthalmologist found uncorrected vision OD of 20/20 and OS of 20/60, but this eye could be refracted to 20/20 with a +2.50 lens. Hertel exophthalmometry showed 2 mm of proptosis OS. Fundus examination found choroidal folds in this eye.

Echography was performed at this time and showed a low reflective well-outlined lesion in the retrobulbar space (Fig. 239). The differential diagnosis included cystic lesions, such as a hematic cyst, dermoid, or lymphangioma. The patient gave no history of trauma. He opted for surgical removal of the lesion and a cystic structure was found

with blood breakdown products consistent with a hematic cyst. The patient experienced a complete resolution of his symptoms after surgery.

Hematic cysts are rare orbital lesions that are most often subperiosteal and may or may not be related to trauma.46 A fibrous capsule surrounds an area of inflammatory reaction to blood or blood breakdown products, such as hemosiderin.

Mass lesions in the orbit that are separate from the optic nerve can cause reduced vision by direct compression of the optic nerve. This is more common with slowly growing tumors that enlarge over time to the degree that they can press on the nerve with varying degrees of proptosis.

BC is a 10-year-old boy who failed his vision test in school and was referred to an optical shop to be fitted for glasses. The optometrist found visual acuity OD of 20/20 and OS of 20/40+2. Fundus examination revealed some swelling of the left optic disc so he was then referred to an ophthalmologist. Optic disc edema was confirmed and the presence of choroidal folds was also noted. Exophthalmometry measured 15 mm OD and 18 mm OS.

Echography was performed and B-scan revealed a round, well-outlined lesion in the muscle cone with some indentation of the posterior sclera. A-scan measured the lesion to be 9.92 mm in greatest diameter with medium internal reflectivity with a cavernous pattern. There was a moderate angle kappa (Fig. 240). Spontaneous vascularity was not detected. The lesion decreased in diameter by 2 mm with mild sustained pressure of the probe against the globe for 2 minutes through closed lids. These findings were highly characteristic of a cavernous hemangioma.

Computed tomography scan confirmed a round, well-outlined lesion in the muscle cone consistent with a hemangioma. He was referred to an orbital surgeon who completely removed the lesion with the aid of a cryoprobe. Follow-up examination found a reduction in the optic disc edema and improvement in visual acuity to 20/25+2.

The A-scan reflectivity of a cavernous hemangioma is based on the tissue architecture. The relatively large blood-filled cystic spaces provide a homogenous medium for the sound beam to traverse so the height of the echo spikes begins to drop towards baseline. However, the sound beam then encounters a septa and becomes high due to the

FIG. 240. Top: A-scan of cavernous hemangioma with angle kappa (arrows) (I). Bottom: B-scan of lesion (arrow)

interface reflection. This pattern is repeated as it travels through the lesion and gives a characteristic “sawtooth” or “honeycomb” pattern sometimes referred