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Show Journal of Cli/llcal Neuro-ophthalmology 8(4): 281-282, 1988 Neuro-anatomical Feature Photo '9 1988 Raven Press, Ltd., New York Imaging Techniques In Optic Nerve Evulsion Lanning B. Kline, M.D., Marilyn M. McCluskey, M.D., and Harold W. Skalka, M.D. A 62-year-old man sustained multiple skull and facial fractures when a dumpster fell on him. He did not lose consciousness, and upon admission to University of Alabama Hospital he reported diminished vision in his right eye. Examination revealed acuity of no light perception 0.0. and 20/20 0.5. The right pupil was amaurotic, ductions on the right were absent, and there was bilateral chemosis, proptosis, and periorbital ecchymoses. Intraocular pressure was zero 0.0., and 17 mm Hg O.S. Funduscopic examination revealed a dense vitreous hemorrhage in the right eye while the left was normal. Cranial computed tomography (CT) confirmed the presence of multiple bony fractures, and images through the right orbit suggested optic nerve evulsion (Fig. 1). Orbital ultrasonography confirmed this diagnosis (Fig. 2). During the patient's hospitalization, the right vitreous hemorrhage sufficiently cleared to visualize the posterior pole (Fig. 3). COMMENT Optic nerve evulsion is an uncommon event caused by both penetrating and nonpenetrating injuries (1). In 1903, Salzman first described this entity as "the forceful backward dislocation of the optic nerve from the scleral canal without any break in the continuity of the adjacent coats of the globe" (2). The vitreous and retina separate from From the Combined Program of Ophthalmology, Eye Foundation Hospital-University of Alabama in Birmingham, University of Alabama School of Medicine, Birmingham, Alabama. Address correspondence and reprint requests to Dr. L. B. Kline at Suite 555, 1600-7th Avenue South, Birmingham, AL 35233, U.S.A. 281 FIG. 1. Orbital CT study demonstrates displacement of the right intraorbital optic nerve (arrow) as it attaches to the globe. Top, contrast-enhanced contiguous axial scans (1.5 mm thickness); bottom, reformatted image. G = globe, ON = optic nerve. 282 L. B. KLINE ET AL. FIG. 2. B-scan, sagittal view, shows lamina cribrosa (LC) posterior to the rest of the sclera and the optic nerve (ON) shadow separated from the scleral canal (SC). the optic disc; the retinal blood vessels are partially or totally interrupted; and the lamina cribrosa is ripped from its attachments to the choroid and sclera. Three mechanisms have been postulated for optic nerve evulsion due to nonpenetrating injury, as occurred in our patient (3). First, when struck by an object, the globe may be compressed against the bony orbit and/or orbital contents. The ensuing elevation in intraocular pressure may be so high that the optic nerve is pushed out of the scleral canal. Second, with orbital trauma, a sudden rise in intraorbital pressure forces the globe forward, I Clill Neuro-ophtlullmol, Vol. 8, No.4, 1988 FIG. 3. Two months following trauma, right fundus reveals absent optic disc. placing the optic nerve on stretch with resultant tearing of the nerves axons. Third, with extreme rotation and displacement of the globe within the orbit, there is disruption of the lamina cribrosa and laminar portion of the optic nerve. Since optic nerve evulsion is frequently accompanied by vitreous hemorrhage, the diagnosis may not be initially made by funduscopic examination. Our case illustrates the role orbital CT and ultrasonography may play in establishing the diagnosis of optic nerve evulsion early in the clinical course. Acknowledgment: Supported in part by an unrestricted development grant from Research to Prevent Blindness, Inc. REFERENCES 1. Williams CF, Williams GC, Abrams AW, Jesmanowicz A, Hyde JS. Evulsion of the retina associated with optic nerve evulsion. Am JOphthalmol 1987;104:5--9. 2. Salzmann M. Die ausreissung des Sehnerven (evulsio nervei optici). Z Augenheilkd 1903;26:489-505. 3. Sanborn GG, Gonder JR, Goldberg RE, Benwon WE, Kessler S. Evulsion of the optic nerve: a cliniopathologicaI study. Can JOphthalmol 1984;19:10--6. |
