Biomedical subjects
Publications and source records attributed to R A Tang.
MR imaging is commonly used to evaluate orbital and facial soft-tissue disease. Although the eyelids are visible on these images, the radiographic appearance and the detailed anatomy of these structures has received little attention in the literature [1-4]. Anatomic correlation with MR images may be extremely helpful in the accurate interpretation and staging of eyelid malignancies and infections.
OBJECTIVE: To use modern computed tomography (CT) imaging to quantify the incidence of asymptomatic incidental orbital calcifications and describe their histological features. MATERIALS AND METHODS: One hundred orbital CT scans were reviewed. In addition, patients who had orbital calcification(s) detected on a brain CT scan were examined by the ophthalmology service. RESULTS: Of the orbital CT scans, 2% had bilateral drusen of the optic nerve head, 3% had calcified scleral plaques anterior to the medial or lateral rectus muscles, and 3% had bilateral ossification of the trochlear apparatus. Routine brain CT scans detected asymptomatic calcifications of the sclera and dura surrounding the proximal optic nerves. CONCLUSION: Incidental asymptomatic orbital calcifications are commonly encountered on modern high-resolution CT images of the brain and orbit. This article should help the clinician to confidently distinguish these densities from foreign bodies or pathological calcifications.
The syndrome characterized by papillomacular bundle damage, central or cecocentral scotoma, and reduction of color vision can be produced by toxic, nutritional, or hereditary causes. Patients who present with such a picture should be evaluated for toxic sources such as tobacco or alcohol use. Nutritional deficiencies must be considered and a good family history should be obtained to explore hereditary factors. DNA mutation analysis is available to detect genetic abnormalities. A trial of nutritional replacement may be advisable even in the face of normal laboratory values. Previous reports have shown dramatic visual improvement with intramuscular hydroxocobalamin and other oral vitamin B complexes, even when specific deficiencies are not found.
Interferon alfa is used to treat various systemic disorders and recently has been suggested as a possible treatment for choroidal neovascularization. We report 10 cases of retinal ischemia associated with the use of interferon alfa for various illnesses. The retinal findings include cotton-wool spot formation, capillary nonperfusion, arteriolar occlusion, and hemorrhage. The retinal complications may sometimes be reversible when treatment is stopped. Our findings emphasize the need to have patients who are receiving interferon alfa therapy monitored for these retinal complications, which may rarely be associated with permanent loss of vision secondary to closure of retinal capillaries.
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Arnold-Chiari malformation is a congenital malformation of the skull near the foramen magnum in which the cerebellum and the medulla are caudally displaced. This herniation of the brainstem causes down-beat nystagmus and oscillopsia, the most commonly presenting sign and symptom, respectively. Differential diagnoses for the Arnold-Chiari malformation include, but are not limited to, demyelinating disease, tumor, and vascular disorders. Symptoms will generally worsen with time and may even be brought on during exercise or valsalva maneuvers. A correct diagnosis can lead to timely surgical intervention which can improve the quality of eye movements. Treatment generally involves the surgical decompression of the surrounding spinal tissue.
The incidence of ocular metastases is approximately 300,000 cases a year, most often from breast or lung primaries. Usually, the primary has already been diagnosed, and the appearance of ocular metastases is an ominous sign. Sometimes ocular metastases may be the first sign of a systemic primary. The authors describe what to expect on ophthalmological examination of a patient with cancer, and what the findings can tell you.
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Intracarotid BCNU (100 mg/m2) and cisplatin (60 mg/m2) were administered to 36 patients with malignant brain tumors recurrent or progressive after cranial irradiation. Courses of therapy were repeated at 4-6 week intervals. Of 23 evaluable patients with recurrent glioma, 9 (39%) had tumor regression by CT scan and 3 had stable disease. The median time to tumor progression for responding patients was 37 weeks. For all patients with primary tumors it was 14 weeks. Six of 9 patients with no prior chemotherapy had a response and 1 had stable disease. Of 14 patients who had received prior chemotherapy, 3 had a response and 2 had stable disease. Survival ranged from 9 weeks to 95+ weeks (median 34 weeks) from start of therapy. Six of 23 patients with primary tumors are alive 1 year or more following therapy. Four of 11 patients with brain metastases had a response and 2 had stable disease. Major neurologic toxicity of intracarotid BCNU and cisplatin appeared cumulative and consisted of reversible hemiparesis in 3% of 118 courses, TIA in 1%, expressive aphasia in 9%, lethargy in 3%, seizures in 12%, and reversible confusion in 1%. Retinal toxicity consisted of mild blurring of vision in 4 patients and ipsilateral blindness in 5 patients. Three of 22 patients who had received supraophthalmic infusion later developed evidence of leukoencephalopathy. Intracarotid BCNU and cisplatin appears to have modest increase in activity over intracarotid cisplatin alone (Cancer 54:794, 1984), however, neurologic and retinal toxicity may also be increased.
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In an attempt to avoid toxic reactions of the eye as a complication of internal carotid arterial infusion of cisplatin, carmustine, or a combination of both for the treatment of brain tumors, a new Gore-Tex/Teflon coaxial catheter system has been used for supraclinoid placement. Catheter placement was successful in 14 of 16 attempts in eight patients. Two patients experienced eye pain and conjunctivitis--a result of the chemotherapeutic agent leaking through the Gore-Tex portion of the catheter at the infusion rate of 170 ml/h. No complications were noted as long as the infusion rate was maintained at 125 ml/h or lower.
A 29-year-old white man who complained of episodic pupillary distortion in his right eye brought on by strenuous exercise was found to have a segmental Horner's syndrome in association with a hypoplastic internal carotid artery.
Four patients had involvement of the anterior visual pathway by sarcoidosis. In two cases recognition of the systemic disease was delayed because only visual symptoms were present. Three cases had evidence of hypothalamic-pituitary axis dysfunction, with histologically proved granulomatous infiltration of this region. The chiasmal syndrome in sarcoidosis is characterized by a pattern of blindness in one eye, atrophy of the optic discs, and temporal visual field loss in the contralateral eye with variable degrees of pituitary dysfunction. The condition is medically treatable and simulates the clinical and even the roentgenographic appearance of a pituitary tumor.
A young woman was treated with topical and oral steroids for sarcoidosis manifested by systemic symptoms, involvement of the respiratory and musculoskeletal systems, and anterior uveitis. Her symptoms, ocular findings, pulmonary function, and serum angiotensin-converting enzyme level all improved in response to therapy. After tapering the steroid dosage retinal perivasculitis developed associated with a small but significant elevation of the serum angiotensin-converting enzyme level. Increasing the dosage of oral steroids resulted in prompt resolution of her retinal findings but no change in the level of the serum angiotensin-converting enzyme. This suggests that changes in the serum angiotensin-converting enzyme level may not parallel the course of ocular sarcoidosis limited to the posterior segment.
Two patients with mucoceles are described. The first case had exophthalmos, and the second had visual loss suggestive of retrobulbar optic neuritis. Possible ocular manifestations of mucoceles are discussed, and the computed tomography findings of these are shown. The treatment of mucoceles is reviewed, and it is stressed that a team approach involving ophthalmology, otorhinolaryngology, and radiology is essential for accurate diagnosis and treatment. Paranasal sinus mucoceles can present with a multitude of different symptoms. The type of presentation is usually determined by the original site of the mucocele, whether it be frontal, ethmoidal, or sphenoidal.
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Three patients had occlusion of preretinal loops and associated branch arterial occlusion. On fluorescein angiography all three eyes showed extensive cilioretinal circulation and that the occluded preretinal loops were part of the cilioretinal vascular anomaly. This supports the hypothesis that one form of preretinal arterial loop is associated with a malformation of the cilioretinal circulation.