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John P Kelly, Marcela Estrada, Jason Wright, James O. Phillips, Avery H Weiss; Monocular nystagmus in chiasmal tumors. Invest. Ophthalmol. Vis. Sci. 2018;59(9):5783.
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© ARVO (1962-2015); The Authors (2016-present)
Asymmetric, or monocular, nystagmus (AMN) can be a clinical sign of an optic pathway tumor (OPT) involving the chiasm/suprasellar region in young children. We compared clinical findings in subjects with AMN to subjects with a chiasmal/suprasellar OPT but with stable gaze.
A retrospective review of children with an OPT of the chiasm/suprasellar region pre and post treatment. Visual acuity was converted to log minimum angle of resolution (logMAR) and was corrected for age if measured with Teller cards. Binocular eye movements recorded by video-oculography were available in one subject.
We identified 8 children with an OPT and AMN at their initial evaluation (6 with monocular and 2 with binocularly asymmetric nystagmus). None had neurofibromatosis type 1 (NF1). Nystagmus in the AMN group was typically < 5 degrees with 1-8 Hz frequency and was rotary in 5 of 8 subjects. Eye movement recordings revealed a 1-3 degree, 3 hz oscillation in both the horizontal and vertical directions (out of phase). The findings from the AMN group were compared to 12 children with chiasmal/suprasellar OPT and stable gaze (without NF1). A biopsy in 12 of 20 subjects showed a pilocytic astrocytoma. At the initial examination, mean age was 2.0 years in the AMN group and 5.2 years in the stable gaze group (p < 0.01). In the more affected eye, LogMAR ranged from 0.2 to > 2.0 in the AMN group and ranged from 0.1 to no light perception stable gaze group (n.s., p > 0.4; Mann-Whitney). All subjects overlapped in severity of optic atrophy (mild temporal pallor to severely atrophic). No subject had head titubations. All had normal versions throughout the observation period. Hydrocephalus was more common in the stable gaze group (7/12) versus the AMN group (1/8). All subjects with AMN had resolution of their nystagmus after treatment (carboplatin/vincristine).
AMN is an usual clinical finding that should prompt evaluation for a chiasmal/suprasellar OPT. NF1 was not associated with AMN. Reduced visual acuity and severity of optic nerve atrophy does not reliably distinguish children with a OPT having stable gaze from those with AMN. Although spasmus nutans is associated with AMN, none of our subjects head shaking/titubations. Because AMN resolves after treatment, future work will examine the role of tumor size and location with respect to AMN.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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