EUNOS 2023 Practical Neuro-Ophthalmology Course: Groningen, The Netherlands, June 1st-2nd, 2023.

The European Neuro-Ophthalmology Society (EUNOS) practical neuro-ophthalmology course, henceforth referred to as the EUNOS course, took place in 2023 in Groningen, the Netherlands. This two-day international event featured a blend of plenary lecture sessions, workshops, and case reports, providing a practical update on fundamental neuro-ophthalmology topics for residents and young specialists in both neurology and ophthalmology.

Treatment evaluation by volumetric segmentation in pediatric optic pathway glioma: evaluation of the effect of bevacizumab on intra-tumor components.

PURPOSE: Progressive pediatric optic pathway gliomas (OPGs) are treated by diverse systemic antitumor modalities. Refined insights on the course of intra-tumoral components are limited. METHODS: We performed an exploratory study on the longitudinal volumetric course of different (intra-)tumor components by manual segmentation of MRI at the start and after 3, 6 and 12 months of bevacizumab (BVZ) treatment. RESULTS: Thirty-one patients were treated with BVZ (median 12 months, range: 2-39 months). During treatment the total tumor volume decreased with median 19.9% (range: - 62.3 to + 29.7%; n = 30) within the first 3 months, decreased 19.0% (range: - 68.8 to + 96.1%; n = 28) between start and 6 months and 27.2% (range: -73.4 to + 36.0%; n = 21) between start and 12 months. Intra-tumoral cysts were present in 12 OPGs, all showed a decrease of volume during treatment. The relative contrast enhanced volume of NF1 associated OPG (n = 11) showed an significant reduction compared to OPG with a KIAA1549-BRAF fusion (p < 0.01). Three OPGs progressed during treatment, but were not preceded by an increase of relative contrast enhancement. CONCLUSION: Treatment with BVZ of progressive pediatric OPGs leads to a decrease of both total tumor volume and cystic volume for the majority of OPGs with emphasis on the first three months. NF1 and KIAA1549-BRAF fusion related OPGs showed a different (early) treatment effect regarding the tumor enhancing component on MRI, which did not correlate with tumor volume changes. Future research is necessary to further evaluate these findings and its relevance to clinical outcome parameters.

An aggressive lactotroph pituitary tumor in a young male: A pituitary carcinoma without metastasis.

This case report concerns a 31-year-old male with an aggressive pituitary tumor who presented initially with bitemporal hemianopsia and slightly elevated prolactin. On magnetic resonance imaging of the brain, there was a sellar mass with parasellar invasion to the lateral aspects of the internal carotid arteries, compressing the optic chiasm. On histopathological analysis, the diagnosis was made of a densely granulated lactotroph pituitary tumor with a Ki67 proliferation rate of 15%, a mitotic count of 6/10 high-power fields, and p53 positivity. Based on these features, the tumor was classified as a grade 2b tumor according to the Trouillas classification, and a more aggressive behavior of the tumor could be expected. In order to anticipate a future need for alternative drug treatments, the following analyses were undertaken: MGMT methylation (present) as well as the expression of estrogen receptor (negative), programmed-death ligand 1 (60 - 70% positive tumor cells), vascular endothelial growth factor-A and somatostatin receptor 2 (both positive). There was regrowth of residual tumor tissue, and the treatment consisted thus far of repeat surgery, cabergoline, pasireotide, and radiotherapy. Chemotherapy with temozolomide could not yet be initiated due to a concurrent infertility treatment. This case is unique because the tumor displays atypical characteristics, both in terms of morphology and behavior. It also illustrates how pathologists can play an important role in determining the diagnosis, prognosis, and possibilities for targeted therapy.

LONGITUDINAL STUDY OF RPE65-ASSOCIATED INHERITED RETINAL DEGENERATIONS.

PURPOSE: To study the disease course of RPE65-associated inherited retinal degenerations (IRDs) as a function of the genotype, define a critical age for blindness, and identify potential modifiers. METHODS: Forty-five patients with IRD from 33 families with biallelic RPE65 mutations, 28 stemming from a genetic isolate. We collected retrospective data from medical charts. Coexisting variants in 108 IRD-associated genes were identified with Molecular Inversion Probe analysis. RESULTS: Most patients were diagnosed within the first years of life. Daytime visual function ranged from near-normal to blindness in the first four decades and met WHO criteria for blindness for visual acuity and visual field in the fifth decade. p.(Thr368His) was the most common variant (54%). Intrafamilial variability and interfamilial variability in disease severity and progression were observed. Molecular Inversion Probe analysis confirmed all RPE65 variants and identified one additional variant in LRAT and one in EYS in two separate patients. CONCLUSION: All patients with RPE65-associated IRDs developed symptoms within the first year of life. Visual function in childhood and adolescence varied but deteriorated inevitably toward blindness after age 40. In this study, genotype was not predictive of clinical course. The variance in severity of disease could not be explained by double hits in other IRD genes.

Three novel mutations in KIF21A highlight the importance of the third coiled-coil stalk domain in the etiology of CFEOM1.

BACKGROUND: Congenital fibrosis of the extraocular muscles types 1 and 3 (CFEOM1/CFEOM3) are autosomal dominant strabismus disorders that appear to result from maldevelopment of ocular nuclei and nerves. We previously reported that most individuals with CFEOM1 and rare individuals with CFEOM3 harbor heterozygous mutations in KIF21A. KIF21A encodes a kinesin motor involved in anterograde axonal transport, and the familial and de novo mutations reported to date predictably alter one of only a few KIF21A amino acids--three within the third coiled-coil region of the stalk and one in the distal motor domain, suggesting they result in altered KIF21A function. To further define the spectrum of KIF21A mutations in CFEOM we have now identified all CFEOM probands newly enrolled in our study and determined if they harbor mutations in KIF21A. RESULTS: Sixteen CFEOM1 and 29 CFEOM3 probands were studied. Three previously unreported de novo KIF21A mutations were identified in three CFEOM1 probands, all located in the same coiled-coil region of the stalk that contains all but one of the previously reported mutations. Eight additional CFEOM1 probands harbored three of the mutations previously reported in KIF21A; seven had one of the two most common mutations, while one harbored the mutation in the distal motor domain. No mutation was detected in 5 CFEOM1 or any CFEOM3 probands. CONCLUSION: Analysis of sixteen CFEOM1 probands revealed three novel KIF21A mutations and confirmed three reported mutations, bringing the total number of reported KIF21A mutations in CFEOM1 to 11 mutations among 70 mutation positive probands. All three new mutations alter amino acids in heptad repeats within the third coiled-coil region of the KIF21A stalk, further highlighting the importance of alterations in this domain in the etiology of CFEOM1.

Defects in RGS9 or its anchor protein R9AP in patients with slow photoreceptor deactivation.

The RGS proteins are GTPase activating proteins that accelerate the deactivation of G proteins in a variety of signalling pathways in eukaryotes. RGS9 deactivates the G proteins (transducins) in the rod and cone phototransduction cascades. It is anchored to photoreceptor membranes by the transmembrane protein R9AP (RGS9 anchor protein), which enhances RGS9 activity up to 70-fold. If RGS9 is absent or unable to interact with R9AP, there is a substantial delay in the recovery from light responses in mice. We identified five unrelated patients with recessive mutations in the genes encoding either RGS9 or R9AP who reported difficulty adapting to sudden changes in luminance levels mediated by cones. Standard visual acuity was normal to moderately subnormal, but the ability to see moving objects, especially with low-contrast, was severely reduced despite full visual fields; we have termed this condition bradyopsia. To our knowledge, these patients represent the first identified humans with a phenotype associated with reduced RGS activity in any organ.