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Optic Nerve Disorders - part 9

Theo một nghiên cứu của Lewis et al., 41 tuổi trung bình của bài trình bày đã được 23 năm và 60% những khối u này xảy ra ở phụ nữ. Ít hơn 10% là song phương. Thị lực thường bị ảnh hưởng, trừ khi các hố mắt có liên quan. Các lĩnh vực thị giác thường cho thấy một điểm mở rộng mù. | 9. Optic Disc Tumors 225 may be inherited in an irregular autosomal dominant pattern. According to a study by Lewis et al. 41 the average age of presentation was 23 years and 60 of these tumors occurred in women. Less than 10 were bilateral. Visual acuity is usually spared unless the fovea is involved. Visual fields often reveal an enlarged blind spot. Progression of these lesions is rare and vitreal hemorrhage is unusual. In contrast to capillary hemangiomas of the optic disc and retina yellow intraretinal and subretinal exudation is not associated with cavernous hemangioma.41 On histopathology cavernous hemangiomas consist of large vascular spaces lined with epithelial cells. These spaces replace the normal nerve tissue but do not extend posterior to the lamina cribosa. These tumors extend through the full thickness of the peripapillary retina but not to the choroid.42 On fluorescein angiography the flow through a cavernous hemangioma is slower and is often hypofluorescent in the early stages. The tumor may not entirely fill until the venous phase or later. Some saccules fill completely whereas others demonstrate an upper portion of dye and a lower portion of erythrocyte plasma. Some tumors may remain hypofluorescent even in the late stages. Slight staining may be seen but extravascular leakage from the tumor is not commonly seen.41 On B-scan ultrasonography the cavernous hemangioma appears as an elevated domeshaped mass with an anechoic area inside and no choroidal excavation. A-scan ultrasonography reveals a high initial spike and irregular reflectivity.31 In contrast to capillary hemangiomas cavernous hemangiomas may grow within the ret-rolaminar intracanalicular and intracranial optic nerve optic chiasm 43 44 or optic tracts to cause a gradual compressive optic neuropathy with subsequent visual loss. More commonly sudden hemorrhage of the cavernous hemangioma may cause sudden headache acute decrease in visual acuity and visual field defects. Up to one-third .