Ocular Neuromyotonia in Children and Adolescents Following Radiation Treatment of Pediatric Brain Tumors

Abstract

Purpose: To report five cases of ocular neuromyotonia in children and adolescents following radiation therapy for a variety of pediatric brain tumors. Notably, three cases occurred in children younger than 11 years. Methods: Case series of five patients with ocular neuromyotonia following proton beam therapy or conventional radiation. Results: Five cases of ocular neuromyotonia were identified following radiation treatment of various pediatric brain tumors. Onset ranged from 5 to 142 months after radiation treatment. The abducens nerve/lateral rectus muscle was affected in three patients, and the trochlear nerve/superior oblique muscle was affected in two patients. Ages at symptom presentation were 4 years (intermittent head tilt), 9 years (intermittent blurry vision and head tilt), 10 years (intermittent blurry vision progressing to intermittent diplopia), 15 years (intermittent diplopia), and 17 years (intermittent diplopia). One patient improved with gabapentin. Two patients experienced spontaneous resolution. One patient died due to meta-static disease, and one patient has planned follow-up. Conclusions: Ocular neuromyotonia occurs most commonly following radiation to the brain and skull base. Clinicians need to be aware that ocular neuromyotonia presents differently in children (who may not report diplopia) than in adults or adolescents (who typically report diplopia). Two children in this series never reported diplopia, only intermittent head tilt and blurry vision. Ocular neuromyotonia requires a high index of suspicion to diagnose, especially in children. Membrane stabilizers can be used effectively, but observation may be a valid option in children because spontaneous resolution was seen. [ J Pediatr Ophthalmol Strabismus . 2022;59(5):338–343.]

Ocular neuromyotonia: a review of diagnosis and treatment

“…Most cases of ONM described in the literature occur after radiation therapy for tumors, especially at the sellar and parasellar region [3]. Classic radiation, gamma knife radiosurgery, and proton beam therapy (PBT) all have been associated with ONM [12–14,15 ▪ ]. Through direct myelin and oligodendrocyte damage [2 ▪▪ ], radiation can lead to ephaptic transmission, with the time between irradiation and ONM onset ranging from 2 months to 18 years [16].…”

“…ONM has been described in patients ranging from 18 months to 78 years old [3,15 ▪ ]. While the majority of cases occur in adulthood, a number of case series also describe pediatric ONM cases [15 ▪ ,32,35–38].…”

“…ONM has been described in patients ranging from 18 months to 78 years old [3,15 ▪ ]. While the majority of cases occur in adulthood, a number of case series also describe pediatric ONM cases [15 ▪ ,32,35–38]. Importantly, children can present with symptoms differing from the regular adult presentation of ONM, including intermittent head tilt or blurry vision [15 ▪ ].…”

“…While the majority of cases occur in adulthood, a number of case series also describe pediatric ONM cases [15 ▪ ,32,35–38]. Importantly, children can present with symptoms differing from the regular adult presentation of ONM, including intermittent head tilt or blurry vision [15 ▪ ]. Spontaneous resolution of ONM can occur in children, more common than in adults, suggesting a possibility of age-dependent remyelination [15 ▪ ].…”

“…This is generally attributed to the higher incidence in underlying diseases of meningioma and TED in females. Cases have been reported in patients of various racial identities [7,15 ▪ ,22].…”