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Show Journal of Neuro- Ophthalmology 15( 2): 122- 224, 1995. © 1995 Raven Press, Ltd., New York Feature Photo Magnetic Resonance Visualization of the Swollen Optic Disc in Papilledema Michael C. Brodsky, M. D. and Charles M. Glasier, M. D. Papilledema develops when elevated intracranial pressure is transmitted into the subarachnoid space surrounding the orbital optic nerves, leading to interruption of axonal transport at the lamina cribrosa and secondary venous congestion ( 1). Fluorescein angiography in papilledema shows diffuse capillary leakage on the surface of the disc ( 1). We report optic disc enhancement on magnetic resonance ( MR) imaging as a neuroimaging correlate of papilledema. An obese 12- year- old boy complained of daily headaches of 1- month duration accompanied by nausea and vomiting, pulsatile tinnitus, and dizziness. He noted that his peripheral vision would momentarily " black out" when he stood up quickly. Two weeks previously, he had been diagnosed as having serous otitis media and treated with amoxicillin. He was otherwise healthy. Corrected visual acuity was 20/ 20 in each eye. Color vision and pupillary responses to light were normal. Extraocular movements were full. Ophthalmoscopic examination showed bilateral symmetrical optic disc swelling, with venous distension, cotton wool spots, and flame hemorrhages on the surface of the optic discs. Results of a neurological examination were otherwise normal. Unenhanced Tl- weighted axial magnetic resonance images of the optic nerves obtained with fat suppression were normal. Following gadolinium From the Departments of Ophthalmology ( M. C. B.) and Radiology ( C. M. G.), University of Arkansas for Medical Sciences, Little Rock, Arkansas, U. S. A. This study was supported in part by a grant from Research to Prevent Blindness, Inc. Address correspondence and reprint requests to Dr. Michael C. Brodsky, Arkansas Children's Hospital, 800 Marshall, Little Rock, AR 72202, U. S. A. administration, similar images revealed focal, intraocular enhancement corresponding to the swollen, prelaminar portions of both optic nerves ( Fig. 1). No mass lesions or intracranial signs of venous sinus thrombosis were identified. Results of a lumbar puncture showed an elevated opening pressure ( 360 mmHzO) but no other abnormalities. The patient was diagnosed as having idiopathic intracranial hypertension ( pseudotumor cerebri) and treated with oral acetazolamide and a weight loss program. His headaches and papilledema resolved over a 2- month period. DISCUSSION When papilledema is suspected, MR imaging is routinely obtained to rule out an intracranial mass lesion or venous sinus thrombosis. In addition detecting causative intracranial abnormalities, MR imaging in papilledema frequently shows distended and tortuous intraorbital optic nerves, which are best visualized when fat suppression pulse sequences are used to diminish the bright signal from surrounding orbital fat ( 2- 5). Intraocular protrusion of the optic discs in papilledema does not produce a visible signal differential with the vitreous gel when viewed with routine MR imaging. Intravenous gadolinium administration produces Tl- and T2- shortening ( enhancement) in areas where the blood- brain barrier is absent or disrupted. Intraocular enhancement of the swollen optic disc is analogous to leakage of fluorescein dye from the surface of the disc; both result from diffuse prelaminar capillary leakage secondary to severe venous congestion ( 1). Although numerous studies of MR imaging in pap- 222 MRI OF SWOLLEN OPTIC DISC 123 i •* V » 1 •-': ^^*- » .. # -#* V i' J • / 4 ^ >\ F: IG 1. ( Top): Optic disc photographs demonstrating bilateral papilledema with venous congestion, cotton wool spots, and flame hemorrhages. ( Middle): Axial T1- weighted ( TE = 29; TR = 800) MR image of the orbital optic nerves with fat suppression shows no intraocular signal abnormality ( arrows denote the position of the optic discs). ( Bottom): Similar MR image following intravenous gadolinium administration shows enhancement of the swollen optic discs ( arrows). / Neuro- Ophthalmol, Vol. 15, No. 2, 1995 124 M. C. BRODSKY AND C. M. GLASIER illedema have failed to visualize the swollen optic discs within the globes ( 2~ 5), we have subsequently identified this sign in two additional patients with pseudotumor cerebri. We have been impressed, however, by its absence in some patients with florid papilledema. Detection of intraocular optic nerve enhancement in papilledema may be limited by several technical factors including ocular motion, the rate of prelaminar gadolinium leakage from the prelaminar capillaries, and the timing of the acquisition of axial optic nerve images relative to gadolinium injection. It is important to recognize that MR imaging occasionally demonstrates focal enhancement of the swollen optic discs in papilledema so that unnecessary systemic evaluations for infiltrative and de-myelinating disorders can be avoided. REFERENCES 1. Hayreh SS. Optic disc edema in raised intracranial pressure. V. Pathogenesis. Arch Ophthalmol 1977; 95: 1553- 65. 2. Moser FG, Hilal SK, Abrams G, et al. MR imaging of pseudotumor cerebri. Am J Radiol 1988; 150: 903- 9. 3. Silbergleit R, Junck L, Gebarski SS, Hatfield MK: Idiopathic intracranial hypertension ( pseudotumor cerebri): MR imaging. Radiology 1989; 170: 207- 9. 4. Sorensen PS, Thomsen C, Gjerris F, et al. Increased brain water content in pseudotumour cerebri measured by magnetic resonance imaging of brain water self diffusion. Neurol Res 1989; 11: 160- 4. 5. Connolly MB, Farrell K, Hill A, Flodmar KO. Magnetic resonance imaging in pseudotumor cerebri. Dev Med Child Neurol 1992; 34: 1091- 94. / Neuro- Ophthalmol, Vol. 15, No. 2, 1995 |
