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Idiopathic Intracranial Hypertension Here we make some comments on the state-of-the-art article by Friedman and Jacobson (1) on idiopathic intracranial hypertension. The authors did not mention the echographic examination of the optic nerve as one of the most important diagnostic procedures to diagnose the presence of high intracranial pressure and to monitor the clinical course of this disease (2). With this technique, it is possible to detect an increase of subarachnoidal fluid within the optic nerve sheaths that is caused by the presence of high intracranial pressure (3–4). The authors noted that ‘‘in some patients, papilledema never resolves completely despite resolution of symptoms and stabilization of visual function.’’ The reason for this was described several years ago by Hayreh (5), who implanted balloons in the brains of monkeys and showed that papilledema takes 1 to 5 days to appear after intracranial pressure elevations. Acutely elevated cerebrospinal fluid pressure for up to 2 hours or sudden lowering of the pressure to normal does not produce immediate resolution of papilledema. This is caused by the slow process of axoplasmic accumulation, the cause of swelling of the axons in the optic nerve head. Echography is much more sensitive than optic nerve ophthalmoscopic examination, because it can detect a sudden increase or decrease of intracranial pressure by measuring the diameter of the optic nerve sheath. This diameter depends on the amount of perineural subarachnoid fluid, which increases during high pressure and returns to normal when there is a normalization of intracranial pressure. Echography can thus avoid the need for frequent intracranial pressure measurements that are not risk-free. Nicola Rosa, MD Luigi Capasso, MD Michele Lanza, MD Department of Ophthalmology Second University of Naples Naples, Italy
REFERENCES 1. Friedman DI, Jacobson DM. Idiopathic intracranial hypertension. J Neuro Ophthalmol 2004;24:138–45. 2. Rosa N, Giamundo A, Jura A et al. Mesalazine-associated benign intracranial hypertension in a patient with ulcerative colitis. Am J Ophthalmol 2003;136:212–3. 3. Green R, Frazier Byrne S. Ultrasound of the eye and orbit. St Louis: Mosby Publishing; 2002:419–22.
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4. Ossoinig KC. Standardized echography of the optic nerve. In: Till P, ed. Ophthalmic Echography 13. Dordrecht, The Netherlands: Kluwer Academic Publishers; 1993:3–99. 5. Hayreh MS, Hayreh SS. Optic disc edema in raised intracranial pressure: I. Evolution and resolution. Arch Ophthalmol 1977;95: 1237–44.
Author’s Reply: As pointed out by Drs. Rosa, Capasso, and Lanza, orbital echography is an extremely useful tool for determining the presence of papilledema, particularly when there is a question of pseudopapilledema from optic disc drusen or tilted optic nerves. The 30-degree test, a non-invasive and painless office technique, provides documentation of a distended subarachnoid optic nerve sheath in true papilledema that spares needless investigations in patients with other conditions that simulate it. I regret the inadvertent omission of this diagnostic modality in our article. The lack of resolution of papilledema in the shortterm, as described by Hayreh (1), is well-recognized. There are some patients with idiopathic intracranial hypertension who have persistent nerve fiber elevation indefinitely after their idiopathic intracranial hypertension seems to have otherwise resolved. Because the swelling does not progress, an ongoing disorder of axoplasmic flow seems unlikely. Perhaps there are gliotic changes in the nerve fiber layer that prevent the restoration of normal architecture at the anterior surface of the optic nerve. Regardless of the mechanism, from a clinical perspective, life-long ongoing intracranial pressure-lowering agents may not be necessary in these patients. Deborah I. Friedman, MD Departments of Ophthalmology and Neurology University of Rochester Rochester, New York
REFERENCE 1. Hayreh MS, Hayreh SS. Optic disc edema in raised intracranial pressure I. Its evolution and resolution. Arch Ophthalmol 1977;85: 1237–44.
Transient Monocular Visual Loss in Two Patients With Impending Central Retinal Vein Occlusion Transient monocular visual loss (TMVL) has been reported as a symptom of central retinal vein occlusion (CRVO) with its typical ophthalmoscopic findings (1,2). J Neuro-Ophthalmol, Vol. 25, No. 2, 2005
Letters to the Editor
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FIG. 1. Case 1. A. Moderately dilated retinal veins OD are the only abnormality at the initial examination for transient monocular visual loss (TMVL) OD. B. Two weeks later, retinal veins are more dilated and patchy retinal whitening is evident in the papillomacular bundle OD, signs of a central retinal vein occlusion.
We previously reported a patient with TMVL associated with dilated retinal veins as the only ophthalmoscopic finding (3), and now we report two additional patients. In these two patients, conventional signs of retinal vein occlusion appeared within 2 weeks of the original examination. Case 1 was a 43-year-old woman who experienced five episodes of painless TMVL in her OD. Each episode lasted from 10 to 40 minutes and resolved spontaneously. She described the episodes as ‘‘sudden blurry, dim vision with bright dots’’ that occurred over a 1-week period without precipitating factors. Initial evaluation, 2 days after onset of TMVL, showed normal visual function and isolated moderate retinal venous engorgement OD (Fig. 1A). Fluorescein angiography showed dilation of the retinal veins OD with delayed venous filling; Address correspondence to Vale´rie Biousse, MD, Neuro-Ophthalmology Unit, Emory Eye Center., 1365-B Clifton Road, NE, Atlanta, GA 30322; E-mail:
[email protected] This study was supported in part by a departmental grant (Department of Ophthalmology) from Research to Prevent Blindness, Inc, New York, New York, and by core grant P30-EY06360 (Department of Ophthalmology) from the National Institutes of Health, Bethesda, MD. Dr. Newman is a recipient of a Research to Prevent Blindness Lew R. Wasserman Merit Award.
arterial filling was normal. Carotid ultrasound was normal bilaterally. Aspirin 325 mg/d was prescribed. One week later, she reported decreased vision in her OD. Visual acuity was 20/20 OD with mild red desaturation and a small right paracentral scotoma OD on Humphrey visual fields. Ophthalmoscopy now showed mild disc edema with venous dilation, peripapillary retinal edema, and multiple small retinal hemorrhages OD consistent with a CRVO (Fig. 1B). Fluorescein angiography continued to show delayed venous filling OD. An extensive coagulation workup was initially negative (4). Magnetic resonance imaging of the brain and orbits was normal. She was maintained on aspirin. Three months later, visual function improved and the scotoma had resolved. Repeat coagulation workup led to the diagnosis of primary antiphospholipid syndrome. Aspirin was replaced with warfarin. One year later, her visual function and optic fundus remain normal. Case 2 was a 20-year-old man who reported two isolated painless episodes of TMVL in his OS. The first episode lasted 30 minutes, the second 4 hours. Both episodes were described as a ‘‘cloud over my OD.’’ He was examined during the second episode of TMVL, at which time visual acuity was 20/20 OD and
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FIG. 2. Case 2. Four days after an episode of TMVL OS, dilated retinal veins and intraretinal hemorrhages are evident OS. Four days earlier, the only ophthalmoscopic abnormality was dilated retinal veins OS (not pictured).
20/70 OS. He had a trace relative afferent pupillary defect OS. Ophthalmoscopic examination showed isolated retinal venous engorgement OS. A few hours later, visual acuity spontaneously returned to normal. Four days later, visual function and pupillary examination were normal. Ophthalmoscopy OS now showed two retinal flame hemorrhages in addition to the previously noted venous dilation (Fig. 2). Aspirin 325 mg/d was initiated. An extensive coagulation workup was negative (4). Brain and orbital magnetic resonance imaging and magnetic resonance angiography of the neck and brain were normal. The patient’s visual function remained normal and there were no further TMVL episodes after a 6-month follow-up. Our two patients experienced recurrent TMVL in the setting of dilated retinal veins as the only sign of a future CRVO that became ophthalmoscopically evident within 2 weeks of the initial symptom. The most common symptom of CRVO is acute and persistent monocular visual loss. Recurrent episodes of TMVL are occasionally described by patients, but are usually associated with the classic full-blown ophthalmoscopic appearance of CRVO, including scattered intraretinal hemorrhages (1,2). We previously reported a patient with isolated dilated retinal veins and recurrent TMVL lasting 2 to 4 hours (3) who had typical ophthalmoscopic signs of CRVO 3 weeks later and was found to have hyperhomocystinemia (4). Several characteristics of the TMVL should alert physicians to the diagnosis of a venous rather than an
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arterial cause. In the two cases we report here, and in our previously reported case, the TMVL episodes lasted 2 to 4 hours, longer than is typical for transient arterial retinal ischemia. TMVL from retinal arterial ischemia usually lasts no longer than 3 minutes (1). Also, our three patients described cloudiness of vision rather than the complete black-out of vision typical caused by arterial ischemia (1). Two of our patients mentioned positive visual phenomena (scintillations), which may signify a lower degree of retinal ischemia associated with slow venous flow (1). R. Keith Shuler Jr, MD Vale´rie Biousse, MD Nancy J. Newman, MD Departments of Ophthalmology, Neurology, and Neurological Surgery Emory University School of Medicine Atlanta, Georgia
REFERENCES 1. Shults WT. Ocular causes of transient monocular vision loss other than emboli. Ophthalmol Clin North Am 1996;9:381–91. 2. Clarkson JC. Central retinal vein occlusion. In Ryan SJ, Schachat A, Murphy R, eds. Retina, vol. 2, 2nd ed. St Louis: Mosby; 1994:1379–85. 3. Biousse V, Newman NJ, Sternberg P Jr. Retinal vein occlusion and transient monocular visual loss associated with hyperhomocystinemia. Am J Ophthalmol 1997;124:257–60. 4. Biousse V. The coagulation system. J Neuroophthalmol 2003;23: 50–62.
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