Corneal Anesthesia and Brun's Nystagmus Following Resection of Pilocytic Astrocytoma at the Inferior Cerebellar Peduncle

A 7-year-old girl initially presented with headaches and vomiting and was diagnosed with a right inferior cerebellar peduncle pilocytic astrocytoma with mild local mass effect on the medulla and right cerebellum. Six months following subtotal resection, she developed large amplitude right beating nystagmus in right gaze and fine left beating torsional nystagmus resembling Brun's Nystagmus and adopted a right head turn to minimize oscillopsia. Her neurological exam also revealed mild difficulties with tandem gait. Prisms were used to shift the null point and minimize her head turn in anticipation of future strabismus surgery. She later developed neurotrophic keratopathy and corneal ulceration from corneal anesthesia as well as a non-healing right sided nasal wound from trigeminal trophic syndrome. She was managed with tarsorrhaphy and corneal neurotization.

Poster 206 Corneal Anesthesia And Brun's Nystagmus Following Resection Of Pilocytic Astrocytoma At The Inferior Cerebellar Peduncle Natalia Binczyk 1, Imran Jivraj 1 1 University of Alberta Introduction: A 7-year-old girl initially presented with headaches and vomiting and was diagnosed with a right inferior cerebellar peduncle pilocytic astrocytoma with mild local mass effect on the medulla and right cerebellum. Six months following subtotal resection, she developed large amplitude right beating nystagmus in right gaze and fine left beating torsional nystagmus resembling Brun’s Nystagmus and adopted a right head turn to minimize oscillopsia. Her neurological exam also revealed mild difficulties with tandem gait. Prisms were used to shift the null point and minimize her head turn in anticipation of future strabismus surgery. She later developed neurotrophic keratopathy and corneal ulceration from corneal anesthesia as well as a non-healing right sided nasal wound from trigeminal trophic syndrome. She was managed with tarsorrhaphy and corneal neurotization. Description of Cases: The inferior cerebellar peduncle, trigeminal nerve nucleus and spinal tract, and inferior vestibular nucleus are in close proximity at the lateral medulla. Our patient developed two unusual neuro-ophthalmic and visionthreatening manifestations following resection of a lesion at this level, each requiring unique interventions. Our patient developed nystagmus similar to Brun’s nystagmus, though the lesion was at the level of the medulla; we suspect that it resulted from a lesion to the horizontal neural integrator and peripheral vestibular pathways (1, 2); management with prisms successfully improved her head turn. Corneal sensation is mediated by afferent fibers from the ophthalmic division of the trigeminal nerve whose cell bodies lie in the trigeminal ganglion and which course inferiorly to spinal trigeminal nucleus at level of the medulla. Corneal anesthesia has been reported to present with medullary pathology.(3) Following topical treatments and tarsorrhaphy, corneal neurotization was able to successfully restore corneal sensation and improve keratopathy.(4, 5) Conclusions, including unique features of the case: Dysconjugate gaze evoked nystagmus resembling Brun’s nystagmus and corneal anesthesia may result from a selective lesion at the level of the lateral medulla. References: 1. Biswas, Ray, Ball, Chakraborty. Bruns nystagmus: an important clinical clue for cerebellopontine angle tumours. BMJ Case Rep, 2018. 2. Venkateswaran, Gupta, Swaminathan. Bruns nystagmus in cerebellopontine angle tumor. JAMA Neurol, 70(5):646-7, 2013. 3. Pellegrini, Interlandi, Cuna, Mandarà, Lee. Corneal Involvement in Wallenberg Syndrome: Case Report and Literature Review. Neuroophthalmology, 44(1):548, 2020. 4. Solyman, Elhusseiny, Ali, Allen. A Review of Pediatric Corneal Neurotization. Int Ophthalmol Clin, 62(1):83-94, 2022. 5. Sepehripour, Lloyd, Nishikawa, Richard, Parulekar. Surrogate Outcome Measures for Corneal Neurotization in Infants and Children. J Craniofac Surg, 28(5):1167-70, 2017. Keywords: Nystagmus, Tumors, Pediatric neuro-ophthalmology Financial Disclosures: The authors had no disclosures. Grant Support: none Contact Information: None provided. 2023 Annual Meeting Syllabus | 269