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Show Journal of Neuro- Ophthalmology 17( 4): 247- 249, 1997. © 1997 Lippincott- Raven Publishers, Philadelphia Magnetic Resonance Imaging of Optic Perineuritis Aaron M. Fay, M. D., Steven A. Kane, M. D., Ph. D., Michael Kazim, M. D., William S. Millar, M. D., M. S., and Jeffrey G. Odel, M. D. Optic perineuritis, an uncommon variant of orbital pseudotumor, may be clinically indistinguishable from retrobulbar optic neuritis. Because treatment and prognosis for these two entities are different, early diagnosis is important. We report a case of a 47 year- old woman with clinical findings suggestive of retrobulbar optic neuritis, but whose magnetic resonance images suggested optic perineuritis. A dramatic clinical response to oral corticosteroids was observed. Optic perineuritis should be considered in cases of presumed retrobulbar optic neuritis. MRI may differentiate these two entities in the acute stage, and should be considered before treatment is decided. Key Words: Optic perineuritis- Orbital pseudotumor- Magnetic resonance imaging. Optic perineuritis is an idiopathic, noninfectious inflammation of the optic nerve sheath and perineural orbital fat ( 1). The neural sheath is the site of a hypocel-lular, polymorphous lymphoid infiltrate consisting of lymphocytes, plasma cells, macrophages, and polymorphonuclear cells( l, 2). The perineural fat may also be involved. The disorder classically presents as an orbital apex syndrome with optic neuropathy, proptosis, and ophthalmoplegia. Lid swelling may be present as well. Some optic perineuritis patients, however, have neither proptosis nor ophthalmoplegia ( 3). In such cases, the signs and symptoms mimic retrobulbar optic neuritis. Treatment of optic perineuritis with oral corticosteroids is often dramatically effective; intravenous corticosteroids are rarely required ( 4). Treatment of presumed demyelinating retrobulbar optic neuritis is more controversial. Results of The Optic Neuritis Treatment Trial ( ONTT) suggest that administration of intravenous corticosteroids may decrease the incidence of future neurologic recurrences, whereas oral corticosteroids may increase the likelihood of neurologic recurrences ( 5). Be- Manuscript received December 23, 1996; accepted April 23, 1997. From the Orbit and Plastics ( A. M. F., M. K.) and Neuro- Ophthalmology ( S. A. K., J. G. O.) Services, The Edward S. Harkness Eye Institute, Columbia- Presbyterian Medical Center; Department of Neuroradiology ( W. S. M.), Columbia- Presbyterian Medical Center; and Columbia University College of Physicians and Surgeons ( A. M. F., S. A. K., M. K., J. G. O.), New York, New York, U. S. A. Address correspondence and reprint requests to Dr. Steven A. Kane, The Edward S. Harkness Eye Institute, Columbia- Presbyterian Medical Center, 635 West 165th ST., New York, NY 10023, U. S. A. cause current treatments of these two diseases are significantly different, it is important to distinguish patients with optic perineuritis from patients with demyelinating retrobulbar optic neuritis. We describe a patient who presented with pain, dys-chromatopsia, and visual field loss suggestive of retrobulbar optic neuritis but in whom magnetic resonance imaging ( MRI) suggested the diagnosis of optic perineuritis. MRI, utilizing fat suppression techniques in conjunction with gadolinium Gd- DTPA ( Magnevist, Berlex Laboratories, NJ, U. S. A.) contrast enhancement, affected our treatment plan and should be considered in cases of suspected retrobulbar optic neuritis, especially for patients who would not otherwise be treated with corticosteroids and those with atypical features. CASE REPORT A 47- year- old Black woman complained of left eye pain and visual loss for 3 days. The pain consisted of a constant, deep, dull ache within the left eye that began suddenly while she was reading and was increased by palpation and eye movements. The patient was otherwise healthy. There was no previous visual loss, similar pain, weakness, numbness, dysarthria, urinary dysfunction, fever, sinusitis, subconjunctival hemorrhage, ptosis, renal disease, or carcinoma. She had no human immunodeficiency virus ( HIV) risk factors and there was no family history of neurologic disease. The patient appeared well and in no distress. Visual acuity was 20/ 20 OU at distance. A marked left relative afferent pupillary defect was present and the left globe was exquisitely tender to palpation. There was neither proptosis nor resistance to retropulsion. Rotations were full, but she experienced pain on extremes of horizontal gaze. Confrontation visual field testing revealed a markedly constricted field in the left eye with altitudinal loss above the horizontal midline. She missed two of six American Optical Hardy, Rand, and Rittler pseudoisochromatic color plates with her left eye. The remainder of her examination, including slit- lamp and dilated fundus examinations, was normal. Humphrey 24- 2 automated perimetry confirmed the field defect. ( Fig. 1) Erythrocyte sedimentation rate, complete blood count, serologic tests for syphilis, and angiotensin converting 247 248 A. M. FAYETAL. FIG. 1. A: Humphrey 24- 2 automated perimetry obtained at the time of presentation showing dense visual field loss respectful of the horizontal midline. B: One week after starting prednisone, the visual field defects had resolved. enzyme levels were all normal. Chest roentgenographs were normal. MRI was performed on a 1.5- Tesla system ( GE Signa, Milwaukee, WI, U. S. A.) using intravenous Gd- DTPA at 0.1 mmol/ kg and demonstrated abnormal enhancement of the anterior left optic nerve, surrounding optic nerve sheath, and perineural orbital fat ( Fig. 2). MRI of the brain ( not shown) revealed no evidence of abnormal signal intensity or contrast enhancement to suggest a demy-elinating process. The diagnosis of optic perineuritis was made and oral prednisone, 100 mg daily ( 1.5 mg/ kg), was begun. One week later, all signs and symptoms had resolved, color vision was normal, and automated perimetry showed no defects. Prednisone was slowly discontinued over 4 weeks and she has since remained symptom- free. DISCUSSION Rapid onset, unilateral pain during ocular motion, afferent pupillary defect, dyschromatopsia, visual field FIG. 2. Coronal projection of a contrast enhanced T1- weighted MR image demonstrates abnormal enhancement of the left optic nerve sheath ( arrowhead), perineural fat ( straight arrow), and optic nerve ( bent arrow, below). loss, and normal optic discs in a 47- year- old woman usually suggest the diagnosis of retrobulbar optic neuritis. A similar presentation, with the addition of proptosis, ophthalmoplegia, and external inflammation, is more suggestive of orbital pseudotumor or optic perineuritis ( 3). The optic neuropathy of optic perineuritis is reported to result from compressive forces rather than direct inflammation ( 1) and may be accompanied by vascular occlusion, thus simulating malignant optic glioma ( 6). As in our case, some optic perineuritis patients have neither proptosis nor ophthalmoplegia. In the absence of proptosis or external inflammatory signs, it is difficult to distinguish clinically between optic perineuritis and demy elinating retrobulbar optic neuritis. It is important to establish the correct diagnosis for several reasons. Both optic perineuritis and demyelinat-ing optic neuritis are treated acutely with corticosteroids, but their treatment protocols differ critically. Optic perineuritis is almost always treated with oral steroids on an outpatient basis and generally responds so rapidly to high- dose oral corticosteroids that a treatment trial may be part of the diagnostic work- up. Initial treatment with oral corticosteroids is contraindicated in cases of demy-elinating optic neuritis ( 5). The natural histories of these two diseases are also different. Patients with demyelin-ating optic neuritis deteriorate rapidly over a period of days, and then tend to improve over weeks to months. Patients with nonspecific orbital inflammation continue to deteriorate visually and have persisting pain. Corticosteroids, therefore, more dramatically alter the clinical course in cases of optic perineuritis. Another important reason to distinguish between these two entities is prognosis and counseling. Although there is a chronic form, acute optic perineuritis is most frequently monophasic. Recurrence is rare and it is not considered to be the initial presentation of, or related to, systemic disease. In optic neuritis, however, recurrent episodes and progressive visual loss are not uncommon. Optic neuritis is the harbinger of multiple sclerosis in 11.5- 85% of cases, depending on the series ( 7). Because acute treatment, systemic investigation, prognosis, counseling, and follow- up care are significantly different for these two entities, it is important to identify those optic perineuritis patients whose symptoms clinically simulate those of retrobulbar optic neuritis from the larger group of patients with true retrobulbar optic neuritis. Ultrasonography has been used to distinguish increased subarachnoid fluid from optic nerve tumors ( 8), but does not have the resolution to detect subtle inflammatory changes in the perineural fat, such as are seen in optic perineuritis. Computed tomography ( CT) of the orbit has been useful ( 9) by virtue of its high resolution and tolerance for motion. However, high- resolution CT imaging of the orbit is associated with radiation exposure, and morbidity and mortality is associated with iodinated contrast. MRI is now the preferred diagnostic method for evaluating neural and soft tissue perineural processes since it provides better soft tissue contrast, produces mul- J Neuro- Ophthalmol, Vol. 17, No. 4, 1997 Magnetic Resonance Imaging of Optic Perineuritis 249 tiplanar images with ease, and is able to detect subtle regions of contrast enhancement. Current MRI protocols of the orbit use fat suppression techniques in conjunction with Gd- DTPA contrast enhancement to best examine the optic nerve sheath as well as the optic nerve ( 10). Fat suppression techniques are necessary because the abundance of high- signal retro- orbital fat on routine Tl-weighted images tends to obscure any contrast enhancement within the retro- orbital fat, sheath, and, occasionally, the optic nerve. In the current case, MRI demonstrated enhancement of the optic nerve sheath, orbital fat, and optic nerve ( Fig. 2). Pathologic processes reported to affect both the optic nerve and sheath include malignant optic glioma, peri-optic neuritis from infectious and granulomatous causes, leukemia, lymphoma, and metastatic tumor ( 11- 13). The shaggy outline of inflammatory lesions, typically seen in Herpes zoster ophthalmicus, sarcoidosis, and pseudotumor, can usually be distinguished from the smooth outline typically seen in perioptic nerve sheath meningiomas ( 10). The imaging characteristics of sarcoidosis of the orbit are very similar to those of pseudotumor ( 14). Lack of basal cistern enhancement along with negative clinical examination and laboratory tests make sarcoidosis unlikely in this case. Although the MRI characteristics of Herpes zoster ophthalmicus overlap those of pseudotumor, the clinical picture of Herpes zoster ophthalmicus is usually obvious ( 15). Increased signal intensity has been reported in both the optic nerve and sheath in optic neuritis ( 16). To our knowledge, contrast enhancement of the intraorbital fat surrounding the nerve sheath has not been reported in demyelinating optic neuritis when using fat suppression techniques. With intraorbital nerve sheath and fat enhancement, MRI is highly suggestive of optic perineuritis. MRI of the brain revealed no evidence of abnormal signal intensity or abnormal enhancement suggestive of demyelinating disease. This patient was not believed to be at increased risk for multiple sclerosis. CONCLUSION Optic perineuritis may be clinically indistinguishable from retrobulbar optic neuritis. Clinicians should consider the diagnosis of optic perineuritis in suspected cases of retrobulbar optic neuritis. Treatment, systemic investigation, prognosis, counseling, and follow- up care are significantly different for the two entities. MRI with fat suppression techniques in conjunction with Gd- DTPA can detect the presence of optic nerve sheath and perineural fat enhancement, and is the preferred tool for differentiating between the two disease entities. MRI should be considered in cases of clinically apparent retrobulbar optic neuritis. REFERENCES 1. Albert DM, Jakobiec FA, eds. Principles and practice of ophthalmology: clinical practice. Philadelphia: W. B. Saunders, 1994: 1923- 32. 2. Margo CE, Levy HL, Beck RW. Bilateral idiopathic inflammation of the optic nerve sheaths: light and electron microscopic findings. Ophthalmology 1989; 96: 200- 6. 3. Hykin PG, Spalton DJ. Bilateral perineuritis of the optic nerves. / Neurol Neurosurg Psychiatry 1991; 54: 375- 6. 4. Kennerdell- S, Dresner SC. The nonspecific orbital inflammatory syndromes. Surv Ophthalmol 1984; 29: 93- 103. 5. Beck RW, Cleary PA. Optic neuritis treatment trial: one year follow- up results. Arch Ophthalmol 1993; 111: 773- 5. 6. Winterkorn JM, Odel JG, Behrens MM, Hilal S. Large optic nerve with central retinal artery and vein occlusions from optic neuritis/ perineuritis rather than tumor. / Neuro- Ophthalmol 1994; 14: 157- 9. 7. Miller NR, ed. Walsh and Hoyt's clinical neuro- ophthalmology. 4th ed. Baltimore: Williams and Wilkins, 1982: 236- 8. 8. Byrne SF, Green RL. Ultrasound of the eye and orbit. St. Louis: Mosby Yearbook, 1992: 403- 9. 9. Trokel SL, Hilal SK. Submillimeter resolution CT scanning of orbital diseases. Ophthalmology 1980; 87: 412- 7. 10. Tien RD, Hesselink JR, Szumowski J. MR fat suppression combined with Gd- DTPA enhancement on optic neuritis and perineuritis. J Comput Assist Tomogr 1991; 15: 223- 7. 11. Millar WS, Tartaglino LM, Sergott RC, Friedman DP, Flanders AE. MR of malignant optic glioma of adulthood. Am J Neuroradiol 1995; 16: 1673- 1676. 12. Bilaniuk LT, Atlas SW, Zimmerman RA. The orbit. In: Lee SH, Rao KCVG, Zimmerman RA, eds. Clinical MRI and CT. New York: McGraw- Hill, 1992: 119- 91. 13. Rothfus WE, Curtin HD, Slamovits TL, Kennerdell JS. Optic nerve sheath enlargement: a differential approach based on high-resolution CT morphology. Radiology 1984; 150: 409- 15. 14. Carmody RF, Mafee MF, Goodwin JA, Haery C. Orbital and optic sarcoidosis: MR findings. Am J Neuroradiol 1994; 15: 775- 783. 15. Lexa FJ, Galetta SL, Yousem DM, Farber M, Oberholtzer JC, Atlas SW. Herpes zoster ophthalmicus with orbital pseudotumor syndrome complicated by optic nerve infarction and cerebral granulomatous angiitis: MR- pathologic correlation. Am J Neuroradiol 1993; 14: 185- 90. 16. Lee DH, Simon JH, Szumowski J, feasby TE, Karlik SJ, Fox AJ, Pelz DM. Optic neuritis and orbital lesions: lipid- suppressed chemical shift MR imaging. Radiology 1991; 179: 543- 6 J Neuro- Ophthalmol, Vol. 17, No. 4, 1997 |
