| OCR Text |
Show f. Clin. Neuro-ophthalmol. 4: 181-184, 1984. Idiopathic Unilateral Disc Edema The Big Blind Spot Syndrome MICHAEL L. ROSENBERG, M.D. PATRICK O'CONNOR, M.D. JACK CARTER, M.D. Abstract Unilateral edema of the optic disc without any evidence of increased intracranial pressure or optic nerve dysfunction is an uncommon problem. We describe two patients with "the big blind spot syndrome'" who presented with unilateral disc edema and normal optic nerve function except for an enlarged blind spot. The course was self-limited in both patients. The presenting neuro-ophthalmologic signs and symptoms were similar to those of intracranial hypertension. It can be distinguished from other causes of a unilateral swollen disc by the lack of intracranial hypertension, normal optic nerve function, and the absence of marked venous engorgement or peripapillary hemorhages. Its early recognition may spare the patient unnecessary diagnostic procedures. Optic disc swelling with normal optic nerve function is strongly suggestive of papilledema secondary to intracranial hypertension. We present two cases with unilateral disc edema and visual symptoms suggestive of papilledema, but without headaches or other symptoms. Lumbar puncture and other studies were all normal, and the signs and symptoms resolved spontaneously within 6 months. Case Reports Patient 1 A 1;3-year-old girl presented with a 3-week history of intermittent blurring of vision in the left eye. These episodes lasted only seconds, and had steadily increased in frequency to more than 30 per day. The attacks were aggravated by standing up quickly, but could occur without any Chief, Neuro-ophthalmology Section (MLR), Departme': of Neurology, Wilford Hall Air Force Medical Center, San Antonio, Texas; and Departments of Ophthalmology (POC) and Neurology (JC), University of Texas at San Antonio, San Antonio, Texas. September 1984 change in position. No other neurologic or ophthalmologic symptoms were reported. The neurological examination was normal. Visual acuity was 20/20 in each eye. The pupils were normal without an afferent pupillary defect. Color vision was normal. Visual fields showed no abnormality other than an enlarged blind spot in the left eye. The fundus was normal on the right, but showed marked nerve fiber layer swelling on the left. There was mild venous engorgement, and no significant hemorrhages (Fig. la). CT scan, FTA-ABS, CBC, antinuclear antibody screen, and other laboratory studies were normal. The cerebrospinal fluid was under normal pressure, with normal protein and glucose. There were no cells and the BORL was negative. Over the ensuing 9 months the symptoms resolved, with the visual fields and the fundus appearance returning to normal (Fig. 1b ). Patiellt 2 A 57-year-old woman noted that, while reading, a blind area was present in the vision of her right eye. She had no visual symptoms in her left eye. There were no past or present medical illnesses. On examination the visual acuity was 20/20 in each eye. Color vision was normal bilaterally. The pupillary reactions to light were normal. Goldmann perimetry was normal with the exception of an enlarged blind spot in the right eye that corresponded to the patient's symptomatic "dark area." Ophthalmoscopy revealed well-developed optic disc edema in the right eye with normal arterioles and a mildly dilated venous system. Hard exudates were present in the retina ildjacent to the temporal aspect of the disc (Fig. 2«). The left fundus was normal, and demonstrated spontaneous venous pulsations. Laboratory studies including CBC, VORL, sedimentation rate, and antinuclear antibody testing were all normal. During follow-up over the next 3 months, the optic disc edema underwent gradual resolution (Fig. 2b). The symptomatic dark spot in the vision 181 Big Blind Spot Syndrome ,.) Figur" 18 lind lb. Posterior pole of p.1tWnt I lit tM ti~ of dillgnosi5 (.) lind lit follow-up 4 months l.1It"" (II). of her right eye resolved. and visual fields showed that the blind spot returned to normal size. Discussion These two cases are typical of the uncommon entity named by Miller "the big blind spot syn- 182 drome:1 It presents in otherwise healthy individuals with complaints of mild visual disturbances. who are found to have unilateral disc swelling. The symptoms are similar to those of true papilledema (although unilateral). with transient obscurations of vision or an enlarged temporal blind Journal of Clinical Neuro-ophthalmology Rosenberg. O'Connor, Carter (.) (b) figures 2M and 2b. PO!>Ieriof" pole of patient 2 at the time or dl<1gnosis (.) and at follow-up 6 months later (II). spot. Visual function is totally normal with the exception of an enlarged blind spot on the af~ fected side. All of !he cases have had a benign course with resolution of clinical signs and symptoms within 6 months.I ~Iember 1984 The differential diagnosis of unilateral disc edema is fairly large. but these patients can be distinguished on the basis of tht'ir clinical history and examination. Optic disc swelling without any effect on optic nerve function is classically seen 183 Big Blind Spot Syndrome in papilledema due to an increase in intracranial pressure. Similarly, the visual symptoms in the big blind spot syndrome may be suggestive of intracranial hypertension. Although papilledema is usually bilateral, unilateral or asymmetric disc swelling can be seen in the presence of contralateral optic atrophy, ocular hypotony, or an anomaly of the optic nerve sheath on one side? In patients with the big blind spot syndrome none of these associated problems have been present. The lack of associated clinical symptoms such as headache, nausea, or vomiting as well as the presence of a normal disc with spontaneous venous pulsations in the opposite eye all help to separate these patients from those with true papilledema. The final distinction between the big blind spot syndrome and unilateral papilledema may have to be made on the lack of increased intracranial pressure on a lumbar puncture. The most common causes of unilateral disc swelling are the various optic neuropathies. By definition these are characterized by some degree of optic nerve dysfunction, and thus they can be easily distinguished from the big blind spot syndrome. Although it is true that optic nerve disease can occur with intact visual acuity, some other evidence of dysfunction of the nerve (i.e., Marcus Cunn afferent pupillary defect, decreased color vision, and/or optic nerve type visual field defects) will be present in almost all cases. These are all simple office tests that may be neglected if their importance is not recognized. Previous reports regarding syndromes most similar to the big blind spot syndrome have used such terms as ·optic disc vasculitis: ·benign retinal vasculitis,· and ·papillophlebitis,· with some authors grouping these together as a single entity. J-8 We feel that this is a mistake. The patients with pathologically documented vasculitis can be readily distinguished from the big blind spot syndrome as they have all suffered a significant degree of visual impairment.9 - 11 Those with papillophlebitis are similar tp the big blind spot syndrome in that they have no significant visual dysfunction; however, the disc appearance is clinically much different. Papillophlebitis patients have shown such marked perivenous hemorrhages and venous engorgement that most authors have likened it to central retinal vein occlusion.u In contrast, those with the big blind spot syndrome have more mild venous 184 engorgement and hemorhages, similar to papilledema, and not at all suggestive of a primary venous obstructive syndrome. I We suggest that this condition can be easily separated from the other disorders mentioned by the clinical signs and symptoms. The terms idiopathic unilateral disc edema or ·the big blind spot syndrome,· as proposed by Miller, are superior to others in the literature as they best describe the condition without specifying an unsupported etiology. References I. Miller, N.R.: The big blind spot syndrome: Unilateral optic disc edema without visual loss or increased intracranial pressure. Neuro-ophthalmology Upda/r, J. L. Smith, Ed. Masson Publishing. New York, 1977, pp. 163-169. 2. Kirkham, T.H .. Sanders, M.D., and Sapp, G.A.: Unilateral papilledema in benign intracranial hy. pertension. Call. /. OpMIJalmol. 8: 533-538,1973. 3. Ellenberger. e., and Messner, K.H.: Papillophlebilis: Benign retinopathy resembling papilledema or papillitis. AmI. Neurol. 3: 438-440, 1978. 4 Miller, N.R.: Walsh & Hoyt's Clillical Neuro-ophIhalmology. Williams & Wilkins. Baltimore, 1982, pp. 222-223. 5. Hart, CO.. Sanders, M.D., and Miller, S.J.H.: Benign retinal vasculitis. Br. ,. Ophtha/mol. 55: 721733, 1971. 6. Hayreh, 5.5.: Optic disc vasculitis. Br. f. aphtha/mol. 56: 652-670,1972. 7. Lonn, L.L, and Hoyt, W.F.: Papillophlebitis. A cause of protracted yet benign optic disc edema. Eye Ear Nosr Tllfoa/ MOllth. 45: 62-68, 1966. 8. Lyle, T.K., and Wybar. K.: Retinal vasculitis. Br. f. Op/rtllalmol. 45: 778-788, 1961. 9. Appen, R.E., and Venecia, G.: Optic disk vasculitis. Am. J. aphthalmol. 90: 352-359, 1980. 10. Cogan, D.: Retinal and papillary vasculitis. In The William MacKelllir Celliellary Symposium 011 the Ocular CirCl/latioll ill Health alld Disease, J. S. Cant, Ed. C V. Mosby, St. Louis, 1969, pp. 249-270. 11. Lowenstein, A., Michaelson, I.e., and Hill, J.: Retinal vasculitis of the young. A pathological report. Tra'ls. aphthalmol. Soc. UK 66: 211-230, 1946. Write tilT Tt'J"i'lts to: Michael Rosenberg, M.D" Neuro-ophthalmology Section, Department of Neurology, Wilford Air Force Medical Center, San Antonio, Texas 78236. Journal of Clinical Neuro-ophthalmology |
