ORBITAL CT SCAN FINDINGS IN MALIGNANT EXOPHTHALMOS Kiyoshi Ichikizaki 1 , Shigeo Toya 1 , Hayao Shiga 2 , Akira Yagishita 2 , Kunihiko Ito 3 , Yoichi Inoue 4 1Department of Neurosurgery, School of Medicine, Keio University 2Department of Diagnostic Radiology, School of Medicine, Keio University 3Ito Hospital 4Olympia Clinic pp.985-993
Published Date 1978/9/1
DOI https://doi.org/10.11477/mf.1406204304
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The following is a report on the comparative study of the ophthalmological symptoms and the orbital CT scan findings of malignant exophthalmos that were diagnosed by the established criteria of the Ministry of Health and Welfare. A total of 144 malignant exophthalmos that underwent CT scan at the Keio University Hospital in the 8 months from February to September 1977 were studied.

For orbital CT scan EMI-SCANNER CT-1000 was employed at a slice width of 8mm to take as a rule 2-3 scans at 1 cm interval with a parallel overlap on the Reid's baseline. The presence of the enlargement of the extraocular muscle wasdetermined on polaroid photographs obtained at window level of -20 EMI units and window width of 100 EMI units.

The Orbital CT scan findings of malignant ex-ophthalmos can be classified into those that reveal characteristic enlargement of the extraocular muscle and those that suggest increase in the retrobulbar fat tissue. The enlargement of the extraocular muscle was detected in 87 (60.4%) out of the 144 cases. The remaining 57 cases were considered to be due to the increase in the retrobulbar fat tissue. Hence, when possible causative lesions for exoph-thalmos are not detected on CT scan of patients with exophthalmos the presence of malignant ex-ophthalmos should be suspected.

Of the extraocular muscles the enlargement of the inferior rectus muscle was the most frequent (46.5%) followed by the medial rectus muscle (29.9 %) and the lateral rectus muscle (20.1%). Accord-ingly, the CT scan of malignant exophthalmos should be so devised to expose the inferior portion of the orbit in order to determine the presence of the inferior rectus muscle.

The muscle which caused the disturbance in the eye ocular movement often showed enlargement on CT scan study. The degree of the enlargement and the extent of the disturbance of the ocular movement, however, did not necessarily correspond with each other. Cases with visual disturbance often showed findings suggestive of optic nerve compression by the extraocular muscle enlarged at the apex of the orbit.

Unilateral malignant exophthalmos was detected in only 7 cases (4.9%). Even in the unilateral cases the changes in the extraocular muscle were often bilateral under CT scan.

Copyright © 1978, Igaku-Shoin Ltd. All rights reserved.


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