Reply to: Idiopathic Duro-Optic Calcification

Letters to the Editor Idiopathic Duro-Optic Calcification W e read with interest the case report on idiopathic dural optic nerve sheath calcification by Roditi et al. (1) We would like to comment on this paper and underscore that this entity is surrounded by controversy. Roditi et al correctly state that only a few cases of idiopathic duro-optic calcification have been reported. Still, among their citations is a previous report of ours, which indeed not presents a case of idiopathic duro-optic calcification, but a bilateral optic nerve sheath meningioma initially misdiagnosed as idiopathic duro-optic calcification (2). This brings us to the key question: does idiopathic duro-optic calcification represent an actual entity? Evidently, asymptomatic calcification might affect the optic nerve sheath, as first described in this journal in 1995 (3). Contrarily to this incidental finding, the term idiopathic durooptic calcification was introduced to describe 2 cases of optic nerve calcification presenting with symptomatic optic atrophy; the authors raised the question as to whether idiopathic durooptic calcification could be a new entity (4). However, it should be noted that Dr. Moseley soon questioned the proposition in a letter to the editor, pointing out that the 2 cases most likely represented bilateral optic nerve sheath meningiomas, which commonly exhibit calcification (5). Similarly, we could not rule out the possibility of meningioma in any case after scrutinizing every idiopathic duro-optic calcification report (2). The calcification in the present paper by Roditi et al was an incidental finding on computed tomography, and the authors also state that borderline thinning of the retinal nerve fiber layer on optical coherence tomography could be unrelated to the calcification. Accordingly, we believe it should be reported as a case of incidental asymptomatic optic nerve sheath Reply to: Idiopathic Duro-Optic Calcification W e read with interest the letter submitted by Dr. Yngvil Solheim Husum et al in which the authors suggest that our case should be entitled “incidental asymptomatic optic nerve sheath calcification.” We agree with the authors that this title describes our case correctly. Although it is not clear to us why would the term idiopathic duro-optic calcification imply symptomatology, we join their efforts to consolidate the nomenclature of this rare entity. Husum et al correctly raised the concern in their case report that what initially was diagnosed as a symptomatic idiopathic duro-optic calcification, after long follow-up, revealed as an optic nerve meningioma (1). Our patient has 66 months of radiological follow-up without any change, and the calcifications have a peculiar multipatch appearance, disconnected one from the other, but longer clinical follow-up is needed. As expressed in both our cases, symptomatic and asymptomatic optic nerve sheath calcification must e204 calcification, not idiopathic duro-optic calcification, because the latter term implies the calcification to be symptomatic. On the other hand, concurrent dural calcification and optic neuropathy should always raise the suspicion of underlying pathology. In such cases, idiopathic duro-optic calcification should only be used as a diagnosis of exclusion, keeping in mind that the existence of this entity is questionable. Yngvil Solheim Husum, MD, Karoline Skogen, MD, Petter Brandal, MD, PhD, Pål Andre Rønning, MD, PhD, Andreas Reidar Wigers, MD, Johan Arild Evang, MD, PhD, Øystein Kalsnes Jørstad, MD, PhD Departement of Ophthalmology, Oslo University Hospital, Oslo, Norway, Department of Radiology and Nuclear Medicine, Oslo University Hospital, Oslo, Norway, Department of Oncology, Oslo University Hospital, Oslo, Norway, Department of Neurosurgery, Oslo University Hospital, Oslo, Norway, Departement of Ophthalmology, Oslo University Hospital, Oslo, Norway, Section of Specialized Endocrinology, Oslo University Hospital, Oslo, Norway; and Departement of Ophthalmology, Oslo University Hospital, Oslo, Norway The authors report no conflicts of interest. REFERENCES 1. Roditi E, Wasser LM, Ben-David E, Rappoport D. Bilateral idiopathic dural optic nerve sheath calcification. J Neuroophthalmol. 2022. 2. Husum YS, Skogen K, Brandal P, Ronning PA, Wigers AR, Evang JA, Jorstad OK. Bilateral calcification of the optic nerve sheath: a diagnostic dilemma. Am J Ophthalmol Case Rep. 2021;22:101106. 3. Murray JL, Hayman LA, Tang RA, Schiffman JS. Incidental asymptomatic orbital calcifications. J Neuroophthalmol. 1995;15:203–208. 4. Phadke RV, Agarwal P, Sharma K, Chauhan SS. Idiopathic durooptic calcification–a new entity? Clin Radiol. 1996;51:359–361. 5. Moseley I. Idiopathic duro-optic calcification. Clin Radiol. 1996;51:741. be a diagnosis of exclusion, after scrutinizing carefully other diagnoses. Eduardo Roditi, MD, Lauren M. Wasser, MD, Eliel BenDavid, MD, Daniel Rappoport, MD Department of Ophthalmology, Shaare Zedek Medical Center Affiliated with the Hebrew University, Hadassah School of Medicine, Jerusalem, Israel, Department of Ophthalmology, Shaare Zedek Medical Center Affiliated with the Hebrew University, Hadassah School of Medicine, Jerusalem, Israel, Department of Radiology, Shaare Zedek Medical Center Affiliated with the Hebrew University, Hadassah School of Medicine, Jerusalem, Israel; and Department of Ophthalmology, Shaare Zedek Medical Center Affiliated with the Hebrew University, Hadassah School of Medicine, Jerusalem, Israel The authors report no conflicts of interest. REFERENCE 1. Husum YS, Skogen K, Brandal P, Rønning PA, Wigers AR, Evang JA, Jørstad ØK. Bilateral calcification of the optic nerve sheath: a diagnostic dilemma. Am J Ophthalmol Case Rep. 2021;22:101–106. Letters to the Editor: J Neuro-Ophthalmol 2024; 44: e201-211 Copyright © North American Neuro-Ophthalmology Society. 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