Optic Disc Edema and Optic Nerve Head Drusen

We are concerned about the conclusions reported by Sarac et al (1) in their article entitled 'Differentiation of optic disc edema from optic nerve head drusen with spectral-domain optical coherence tomography' and the application of these conclusions to clinical practice.

was begun, and 3 weeks later, he had recovered com-pletely. Several follow-up MRIs were performed. The most recent MRI, 1.5 years after the onset of symptoms, revealed an increase in number and extent of the white matter hyperintensities (Fig. 2). Glatiramer acetate therapy was initiated. On occasion, a one-and-a-half syndrome can be accom-panied by a facial paresis if the fascicle or nucleus of the seventh cranial nerve in the lower part of the dorsal pontine tegmentum is also affected. Eggenberger (2) designated this as eight-and-a-half (1.5 1 7) syndrome. As mentioned by Connors et al (1), variations of this syndrome caused by pathology of the dorsal pontine tegmentum have since been described including a combination of a one-and-a-half syn-drome and a bilateral peripheral facial paresis which Bae and Song (3) designated fifteen-and-a-half (1.5 1 7 1 7) syndrome. Only 3 cases of isolated eight-and-a-half syndrome caused by MS have been described in the literature (4,5). In one of these cases (4), the eight-and-a-half syndrome was, as in our patient, the initial symptom of MS. A 16 syn-drome caused by MS has not been reported previously. Hennie Lee, MD Paul L.M. de Kort, MD, PhD Department of Neurology, St. Elisabeth Ziekenhuis, Tilburg, the Netherlands, [e-mail] The authors report no conflicts of interest. REFERENCES 1. Connors R, Ngan V, Howard J. A case of complete lateral gaze paralysis and facial diplegia: the 16 syndrome. J Neuroophthalmol. 2012. 2. Eggenberger ER. Eight-and-a-half syndrome: one-and-a-half syndrome plus cranial nerve VII palsy. J Neuroophthalmol. 1998;18:114-116. 3. Bae JS, Song HK. One-and-a-half syndrome with facial diplegia: the 15½ syndrome? J Neuroophthalmol. 2005;25:52-53. 4. Andreé C, De Castro AL, Vincent MB, De Mattos JP, Maranhao Filho Pde A, Novis SA. One-and-a- half syndrome: anatomical-clinical considerations apropos of a case. Ag Neuropsiquiatr. 1989;47:365-370. 5. Rufa A, Cerase A, De Santi L, Mandala M, Nuti D, Giorgio A, Annunziata P. Impairment of vertical saccades from an acute pontine lesion in multiple sclerosis. J Neuroophthalmol. 2008;28:305-307. Optic Disc Edema and Optic Nerve Head Drusen We are concerned about the conclusions reported by Sarac et al (1) in their article entitled "Differentia-tion of optic disc edema from optic nerve head drusen with spectral-domain optical coherence tomography" and the application of these conclusions to clinical practice. Sarac et al seek to answer an old and important neuro-ophthalmic question: How can one distinguish between optic disc edema and optic nerve head drusen? Most clinicians have no trouble diagnosing advanced optic disc edema, such as Frisen Stages 3, 4, and 5 (2). Most clinicians have no trouble diagnosing optic nerve head drusen that are visible on ophthalmoscopy ("visible drusen"). Where clini-cians do find themselves in a quandary is when they are asked to distinguish mild cases of optic disc edema (Frisen Stages 0, 1, and 2) from optic nerve head drusen that are not visible on ophthalmoscopy ("buried drusen"). Clinicians frequently look to new tools such as optical coherence tomography (OCT) to help sort out these difficult situations. FIG. 2. Axial fluid-attenuated inversion recovery (A) and sagittal T2 (B) scans reveal several areas of high signal intensity in the periventricular region and corpus callosum. 204 Letters to the Editor: J Neuro-Ophthalmol 2013; 33: 202-207 Letters to the Editor Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Using time domain OCT, Karam and Hedges (3) con-cluded that OCT could not be used to differentiate indi-viduals with congenitally crowded optic nerves from individuals with mild papilledema. Conversely, Johnson et al (4) argued that OCT could be used to differentiate optic disc edema from optic nerve head drusen, but these authors included subjects with disc edema that was "mild, moderate, and severe" and drusen that were both visible and buried. These authors also included subjects with papille-dema, ischemic optic neuropathy, and optic neuritis in their study population. Lee et al (5) claimed that spectral domain OCT may be used to differentiate optic disc edema from optic nerve head drusen, but they also included subjects in whom the edema ranged from "subtle to severe," and did not state the etiology of the disc edema in their subjects. In the study by Sarac et al, the optic nerve head drusen group contained eyes with both visible and buried drusen. The optic disc edema group was also heterogeneous, containing subjects with "subtle to severe" optic nerve swell-ing. In addition, the optic disc edema group contained subjects with papilledema, nonarteritic anterior ischemic optic neuropathy, and optic neuritis. However, most clini-cians would have no difficulty distinguishing a patient with optic nerve head drusen from a patient with anterior ische-mic optic neuropathy or optic neuritis. We do not dispute the results reported by Sarac et al. Our concern is that clinicians reading this article will inappropriately extrapolate these conclusions to clinical care. When faced with a patient in whom the differential diagnosis includes mild optic disc edema and buried optic nerve head drusen, the guidelines proposed by Sarac et al may not hold. Their study population was not relevant to the clinical question being asked. Currently, it appears that the conclusions reached by Karam and Hedges (3) still hold. Until a study is designed with a clinically relevant population of subjects, the ques-tion of the utility of OCT in the differential diagnosis of optic disc edema and optic nerve head drusen remains unanswered. Bradley J. Katz, MD, PhD Alison V. Crum, MD Kathleen B. Digre, MD Judith E. A. Warner, MD John A Moran Eye Center Department of Ophthalmology and Visual Sciences and Department of Neurology University of Utah Health Sciences Center Salt Lake City, Utah [e-mail] The authors report no conflicts of interest. Supported by an unrestricted grant to the Department of Ophthalmology and Visual Sciences by Research to Prevent Blindness, New York, NY. REFERENCES 1. Sarac O, Tasci YY, Gurdal C, Can I. Differentiation of optic disc edema from optic nerve head drusen with spectral-domain optical coherence tomography. J Neuroophthalmol. 2012;32:207-211. 2. Frisén L. Swelling of the optic nerve head: a staging scheme. J Neurol Neurosurg Psychiatry. 1982;45:13-18. 3. Karam EZ, Hedges TR. Optical coherence tomography of the retinal nerve fibre layer in mild papilloedema and pseudopapilloedema. Br J Ophthalmol. 2005;89:294-298. 4. Johnson LN, Diehl ML, Hamm CW, Sommerville DN, Petroski GF. Differentiating optic disc edema from optic nerve head drusen on optical coherence tomography. Arch Ophthalmol. 2009; 127:45-49. 5. Lee KM, Woo SJ, Hwang JM. Differentiation of optic nerve head drusen and optic disc edema with spectral-domain optical coherence tomography. Ophthalmology. 2011;118: 971-977. Subclinical Optic Neuritis in Neuromyelitis Optica We read with great interest the review of neuromye-litis optica (NMO) by Morrow and Wingerchuk (1). Even with proposed diagnostic criteria (2), establish-ing the diagnosis of NMO may be difficult. We describe a patient with white matter cerebral lesions, myelitis, and subclinical optic neuritis with negative NMO-IgG at the initial presentation. The diagnosis of NMO became cer-tain 5 months later when the patient developed overt bilateral optic neuritis and a positive NMO-IgG anti-body. A 46-year-old woman experienced the onset of dizzi-ness, nausea, and vomiting. Neurological examination was unremarkable except for horizontal gaze evoked nystagmus and mild weakness in her right leg. Muscle strength in the right lower extremity was at 4/5, patellar deep tendon reflexes were hypoactive, and the plantar reflex was indifferent on the right side. Vision was 20/20 bilaterally with normal color vision, funduscopy, and visual evoked potentials. Automated visual fields demonstrated mild generalized depression (Fig. 1). Brain magnetic resonance imaging (MRI) revealed enhancement of the entire length of the left optic nerve (Figs. 2A and 2B) hyperintensities in the dorsal medulla, around the fourth ventricle, in the periaqueductal gray matter, mammillary bodies, the thalamus, and in the vi-cinity of the third ventricle (Fig. 2C). MRI of the spine Letters to the Editor: J Neuro-Ophthalmol 2013; 33: 202-207 205 Letters to the Editor Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited.