Visual evoked potentials in children with neurofibromatosis type 1

A Systematic Review on Visual-Processing Deficits in Neurofibromatosis Type 1: What Possible Impact on Learning to Read?

This systematic review aimed to examine the possible implication of visual-perceptual, visuo-attentional and oculomotor processing in the reading deficits frequently experienced by children with Neurofibromatosis type 1 (NF1), as previously shown in dyslexia. Using PRISMA methodological guidelines, we examined 49 studies; most of these reported visual-processing deficits in this population, raising the importance of directly studying the visuo-perceptual and visuo-attentional processes and eye-movement control involved in the learning-to-read process in NF1. The discussion provides a reflection for a better understanding of how visual-processing skills interact with reading deficits in NF1, as well as new avenues for their screening and care.

Insights into Novel Choroidal and Retinal Clinical Signs in Neurofibromatosis Type 1

Neurofibromatosis type 1 (NF1) is a rare inherited neurocutaneous disorder with a major impact on the skin, nervous system and eyes. The ocular diagnostic hallmarks of this disease include iris Lisch nodules, ocular and eyelid neurofibromas, eyelid café-au-lait spots and optic pathway gliomas (OPGs). In the last years, new manifestations have been identified in the ocular district in NF1 including choroidal abnormalities (CAs), hyperpigmented spots (HSs) and retinal vascular abnormalities (RVAs). Recent advances in multi-modality imaging in ophthalmology have allowed for the improved characterization of these clinical signs. Accordingly, CAs, easily detectable as bright patchy nodules on near-infrared imaging, have recently been added to the revised diagnostic criteria for NF1 due to their high specificity and sensitivity. Furthermore, subclinical alterations of the visual pathways, regardless of the presence of OPGs, have been recently described in NF1, with a primary role of neurofibromin in the myelination process. In this paper, we reviewed the latest progress in the understanding of choroidal and retinal abnormalities in NF1 patients. The clinical significance of the recently revised diagnostic criteria for NF1 is discussed along with new updates in molecular diagnosis. New insights into NF1-related neuro-ophthalmic manifestations are also provided based on electrophysiological and optical coherence tomography (OCT) studies.

Visual-spatial and visuomotor functioning in adults with neurofibromatosis type 1

BACKGROUND

Neurofibromatosis type 1 (NF1) is a neurodevelopmental genetic disorder associated with visual-spatial and visuomotor deficits, which have not been studied well in adults with NF1.

METHODS

In 22 adults with NF1 and 31 controls, visuomotor functioning was assessed by measuring eye latency, hand latency and hand accuracy during visuomotor tasks. Visual-spatial functioning was assessed by measuring eye movement responses during the Visual Threshold Task.

RESULTS

The NF1 group had a significantly shorter eye latency than the control group and was less accurate in their hand movements during specific visuomotor tasks. The groups showed no differences in eye movement responses during the Visual Threshold Task and in hand latency during the visuomotor tasks.

CONCLUSIONS

In contrast to studies in children with NF1, we found no alterations in visual-spatial information processing in adults. Impairments in eye latency and hand accuracy during specific visuomotor tasks may indicate deficits in visuomotor functioning in adults with NF1.

The role of visual electrodiagnostics in management of children with neurofibromatosis type 1

PURPOSE

To evaluate the role of visual electrodiagnostic testing in children with neurofibromatosis type 1 (NF1) despite improved accessibility to magnetic resonance imaging (MRI).

METHODS

The records from 39 children (78 eyes, 15 boys, 24 girls, average age at last visit of 11.5 ± 4.3 years, average follow-up time of 7.8 ± 3.9 years) with genetically confirmed NF1 were retrospectively analysed. They all underwent a thorough ophthalmological investigation, including age-appropriate visual acuity testing, anterior segment evaluation for Lisch nodules and a dilated fundus examination. If children were cooperative enough, colour vision was tested using the Hardy-Rand-Rittler test, visual fields were evaluated with Goldmann perimetry. All performed MRI of the brain and orbits as part of the standard of care protocol. Visual electrodiagnostics included electroretinography (ERG) and visual evoked potentials (VEP) using a standard protocol in older children, whereas with less cooperative children a modified protocol according to the Great Ormond Street Hospital (GOSH protocol) was used.

RESULTS

The average visual acuity was 0.8 ± 0.3, colour vision was abnormal in 6%, perimetry in 8%, Lisch nodules were present in 62%, and the optic disc was pale in 66% of all eyes. Plexiform neurofibroma of the eyelid/orbit was present in 4%. Optic pathway glioma (OPG) was detected with MRI in 22 (57%) and in 6/22 treatment was indicated. Other intracranial NF1-related lesions were documented in 70% of children. VEP were abnormal in 16/39 of all children with NF1 (41%) comprising 14/22 (65%) of children with confirmed OPG and 2/17 (12%) of children without OPG. All full-field and pattern ERG responses were within normal limits. All individual VEP results are described and three cases from this cohort of children are presented in detail to illustrate the importance of VEP testing. In Case 1, VEP abnormality suggested subsequent MRI of the brain under general anaesthesia, which was otherwise contraindicated according to normal clinical findings and his young age. In Cases 2 and 3, VEP provided more precise functional information during the follow-up of OPG, while other psychophysical tests remained unchanged.

CONCLUSIONS

Electrodiagnostics has multifactorial role and importance in children with NF1, either when visual pathway function is impaired in young children, even before MRI under general anaesthesia and other psychophysical tests can be performed, as well as for a more precise monitoring of the visual pathway function before potential treatment of OPG, or after it, to evaluate its success.

Electrophysiological and Behavioral Evidence for Hyper- and Hyposensitivity in Rare Genetic Syndromes Associated with Autism

Our study reviewed abnormalities in spontaneous, as well as event-related, brain activity in syndromes with a known genetic underpinning that are associated with autistic symptomatology. Based on behavioral and neurophysiological evidence, we tentatively subdivided the syndromes on primarily hyper-sensitive (Fragile X, Angelman) and hypo-sensitive (Phelan-McDermid, Rett, Tuberous Sclerosis, Neurofibromatosis 1), pointing to the way of segregation of heterogeneous idiopathic ASD, that includes both hyper-sensitive and hypo-sensitive individuals. This segmentation links abnormalities in different genes, such as FMR1, UBE3A, GABRB3, GABRA5, GABRG3, SHANK3, MECP2, TSC1, TSC2, and NF1, that are causative to the above-mentioned syndromes and associated with synaptic transmission and cell growth, as well as with translational and transcriptional regulation and with sensory sensitivity. Excitation/inhibition imbalance related to GABAergic signaling, and the interplay of tonic and phasic inhibition in different brain regions might underlie this relationship. However, more research is needed. As most genetic syndromes are very rare, future investigations in this field will benefit from multi-site collaboration with a common protocol for electrophysiological and event-related potential (EEG/ERP) research that should include an investigation into all modalities and stages of sensory processing, as well as potential biomarkers of GABAergic signaling (such as 40-Hz ASSR).

Visual function tests including the role of optical coherence tomography in neurofibromatosis 1

Optic pathway glioma (OPG) is a common and significant complication of neurofibromatosis 1 (NF-1) that might lead to vision loss. The main reason to treat OPG is to preserve vision. Tumor location along the visual pathway largely dictates the presenting signs and symptoms. Clinical ophthalmic evaluation is focused on optic nerve functions including evaluation of pupils' reaction to light, visual acuity, color vision, and visual field, as well as optic nerve appearance. An important relatively new ancillary test is optic coherence tomography (OCT) that measures the volume of retinal nerve fiber layer around the optic nerve and the ganglion cell layer-inner plexiform layer (GCL-IPL) of the macula, both proved to be strongly associated with losing vision in OPG. Accurate evaluation of vision functions plays a critical role in the decision of treatment. In this review, we describe the ophthalmological assessment including new biomarkers in clinical use. We also outline prognostic factors and current recommendations for surveillance and indications for treatment.

NEUROFIBROMATOSIS TYPE 1 AND OPTIC PATHWAY GLIOMA

PURPOSE

Evaluate the effectiveness of treatment of patients with optic pathway glioma.

MATERIALS AND METHODS

Comparison of literature research on neurofibromatosis and optic pathway glioma with a cohort of pediatric patients treated at the Childrens Ophthalmology Clinic of the University Hospital in Brno from January 2013 until June 2018.

DISCUSSION

The main challenge of this and other retrospective studies is variable intervals between ophthalmologic examinations. In some pediatric patients it is also difficult to objectively assess visual functions. The main risk factors are age at the time of treatment and tumor localization. Tumor progression itself does not always correlate with worse visual acuity outcomes, and it remains to be evaluated whether some patients would be better off without treatment. As of now, there are no clinical biomarkers able to predict impending visual acuity loss.

CONCLUSION

The cohort outcome agrees with literature. Chemotherapy remains a treatment of choice and its most likely outcome is visual acuity stabilization. In order to properly evaluate the treatments effectiveness, better collaboration between medical specialists and regular standardized ophthalmology examinations are required.

Visual function assessed by visually evoked potentials in optic pathway low-grade gliomas with and without neurofibromatosis type 1

PURPOSE

To investigate the contribution of full-field transient pattern-reversal visually evoked potentials (PRVEP) on cross-sectional evaluations of visual function in patients with and without neurofibromatosis type 1 (NF1) affected by optic pathway low-grade gliomas (OPLGG).

METHODS

Participants were children and adolescents referred for visual function evaluation and receiving treatment for OPLGG, linked (NF1-OPLGG) or not to NF1 (Non-NF1-OPLGG). An age-adjusted control group was included for comparison. Monocular full-field PRVEPs were recorded from each eye in accordance with ISCEV standards. Parameters of peak-to-peak P100 amplitude (µV) and P100 peak time (ms) were measured. Cutoff normative values obtained from controls for 15' and 60' check sizes were ≥ 9.0 µV for N75-P100 amplitude and ≤ 103.0 ms for P100 peak time. The association of age, gender, tumor resection and NF1 with P100 amplitude reduction and P100 peak time delay was explored by Firth logistic regression modeling.

RESULTS

Participants were 30 patients (15 males, 60% Non-NF1) with ages from 3.6 to 19.9 years (mean ± SD = 9.2 ± 3.8 years; median = 8.4 years) and 19 controls (12 males) with ages from 3.7 to 19.9 years (mean ± SD = 10.4 ± 4.9 years; median = 9.5 years). Overall, 68% of tested eyes presented reduced P100 amplitudes for both check sizes (46% in the NF-1 and 83% in the Non-NF1) and delayed P100 for both check sizes (38% in NF1 and 89% in Non-NF1). Absence of NF1 adjusted for age, gender and tumor resection was significantly associated with marginally reduced P100 amplitude for 15' checks [odds ratio (OR): 6.26; 95% confidence interval (CI) = 0.96-40.94; p = 0.055].

CONCLUSIONS

Full-field PRVEP on cross-sectional evaluations contributed to detect visual dysfunction in two-thirds of patients with OPLGG by highlighting subclinical evidence of visual loss. Abnormalities were more frequent and more severe in OPLGG not linked to NF1 than in NF1-OPLGG; however, there was a difference in surgical management between these groups. PRVEP parameters may provide reliable evidence of visual pathway involvement in OPLGG, helping to hasten treatment before optic atrophy is detected.

Optical coherence tomography as a marker of vision in children with optic pathway gliomas

PURPOSE

Optic pathway gliomas (OPG) represent an important cause of visual loss in pediatric population. The indication of treatment is based on clinical or neuroimaging progression. Visual acuity loss is the most important symptom of disease progression, but children with OPG are frequently unable to complete the testing of visual function. Optical coherence tomography (OCT) was suggested as an objective tool for visual assessment. A literature review was performed in order to determine the role of retinal OCT as a surrogate marker of vision in children with OPG.

METHODS

The search was performed using PubMed, Embase, and Web of Science databases and was restricted to articles published in English between 2000 and 2016, with a minimum of ten participants enrolled.

RESULTS

Eleven studies met the eligibility criteria and were included in the present review. Both neurofibromatosis-1 associated and sporadic OPG were investigated.

CONCLUSIONS

Retinal OCT is a promising tool to be considered as a screening or follow-up test in children with OPG, and further multicenter research is encouraged.

Functional outcome measures for NF1-associated optic pathway glioma clinical trials

OBJECTIVE

The goal of the Response Evaluation in Neurofibromatosis and Schwannomatosis Visual Outcomes Committee is to define the best functional outcome measures for future neurofibromatosis type 1 (NF1)-associated optic pathway glioma (OPG) clinical trials.

METHODS

The committee considered the components of vision, other ophthalmologic parameters affected by OPG, potential biomarkers of visual function, and quality of life measures to arrive at consensus-based, evidence-driven recommendations for objective and measurable functional endpoints for OPG trials.

RESULTS

Visual acuity (VA) assessments using consistent quantitative testing methods are recommended as the main functional outcome measure for NF1-OPG clinical trials. Teller acuity cards are recommended for use as the primary VA endpoint, and HOTV as a secondary endpoint once subjects are old enough to complete it. The optic disc should be assessed for pallor, as this appears to be a contributory variable that may affect the interpretation of VA change over time. Given the importance of capturing patient-reported outcomes in clinical trials, evaluating visual quality of life using the Children's Visual Function Questionnaire as a secondary endpoint is also proposed.

CONCLUSIONS

The use of these key functional endpoints will be essential for evaluating the efficacy of future OPG clinical trials.

Detection of tumor progression in optic pathway glioma with and without neurofibromatosis type 1

BACKGROUND

We wanted to determine the sensitivity and specificity of serial changes in visual acuity and visual evoked potentials (VEPs) to detect radiological progression of tumor volume in children with optic pathway gliomas.

METHODS

From a retrospective review of a cohort of 69 patients, 54 patients met inclusion criteria (31 with primary chemotherapy, 4 with primary radiotherapy, and 19 with stable tumor volume and no treatment). Age at presentation ranged from 0.3 to 13 years. Patients were serially followed by MRI, age-corrected visual acuity in log minimum angle of resolution (logMAR), and pattern VEP. Longitudinal data averaged 7.9 years (range 0.5-16 y). Visual assessments were aligned with MRI data within 6-month intervals. Tumor progression was defined by 25% or greater increase in volume.

RESULTS

Visual acuity in the better eye had poor sensitivity and specificity for detecting tumor volume progression (0.5 and 0.5, respectively). Visual acuity in the worse eye showed worse sensitivity and specificity because false positives (visual decline without tumor progression) were more frequent than true positives (visual decline with tumor progression). VEPs showed slightly better sensitivity and specificity (0.69 and 0.58, respectively). In patients with stable tumors, visual acuity fluctuated ±0.55 logMAR (SD = 0.15) between examinations. VEP amplitude fluctuated -0.74 to 0.48 log units (SD = 0.19) between examinations.

CONCLUSIONS

Serial changes in visual function do not reliably detect tumor progression. Conversely, tumor progression does not reliably indicate decreased visual function. Objective visual function and serial MRIs are complementary in management of optic pathway gliomas.

Ophthalmological assessment of children with neurofibromatosis type 1

Neurofibromatosis type 1 (NF1) is a common autosomal dominant disorder, caused by mutations in the NF1 gene, located on chromosome band 17q11.2. In 1988, the National Institutes of Health created specific criteria for the diagnosis of NF1. Four cardinal criteria are assessed through ophthalmological screening: Lisch nodules, optic pathway glioma, a distinctive osseous lesion (sphenoid dysplasia), and the (orbital) plexiform neurofibroma. NF1 patients are prone to the development of central and peripheral nervous system tumors. Especially young children are at risk for growing optic pathway gliomas that can threaten their sight. From an early age, children with NF1 undergo regular ophthalmological examinations. Little is known about the natural progress of these clinical features and the guidelines for screening and follow-up are controversial. Several questions remain unanswered.

CONCLUSION

Most of these questions could be solved by better understanding of the natural history of optic pathway gliomas. There is a tendency towards using vision as a primary objective in clinical treatment trials; this way we can evaluate new treatment strategies and focus specifically on visual evolution so we will be able to select even more carefully which patient would benefit treatment. For future clinical trials, a standardized visual acuity assessment protocol is therefore mandatory.

Role of visual evoked potentials in the assessment and management of optic pathway gliomas in children

OBJECTIVE

The aim of this study is to investigate the role of pattern reversal visual evoked potentials (pVEPs) in the screening and monitoring of optic pathway gliomas (OPGs) in children with and without neurofibromatosis type 1.

METHODS

A review of the English literature published between 1980 and 2012 was performed, with comparison of results of retro- and prospective studies.

RESULTS

Pattern reversal VEPs have a high sensitivity (85.7-100 %) for the diagnosis of OPGs, moreover they are safe and cost-effective. Conversely, they have a low specificity (43-83 %) and are not widely available. Besides, pattern reversal VEP results can be unreliable in young children, because of the need for a good cooperation. The studies that were analyzed have drawbacks, including the small sample size, the retrospective design, the differences in gold standard for diagnosis, the different interpretation of small changes in VEP results and the lack of control groups.

CONCLUSION

There is still debate about the gold standard for the screening and follow-up of OPGs. The added value of pVEPs to the ophthalmic examination is controversial. Randomized controlled trials or prospective multicentre studies are necessary to assess with sufficient accuracy the sensitivity and specificity of pattern reversal VEPs in the screening for OPGs and its follow-up.

Bilateral paraneoplastic optic neuropathy and unilateral retinal compromise in association with prostate cancer: a differential diagnostic challenge in a patient with unexplained visual loss

We report a 77-year-old Caucasian man with a 1-year complaint of unexplained visual loss and a 4-year history of prostate cancer. A complete ophthalmologic exam, Goldmann visual fields (GVFs), intravenous fluorescein angiography (IVFA), macular and disc optical coherence tomography (OCT), pattern-reversal visual evoked potentials (PVEPs), and flash electroretinograms (ERGs) were performed. On examination, visual acuity was reduced bilaterally. Fundus exam showed juxtapapillary changes (OS > OD) and, in OS, disc pallor, peripheral RPE dropout and whitish retinal discoloration along the arcades. OCTs were normal OU. Cancer-associated retinopathy (CAR) was suspected. A flash ERG was normal OD and markedly reduced and electronegative OS. An IVFA showed bilateral juxtapapillary staining and changes highly suggestive of sequelae of central retinal artery occlusion (CRAO) OS , in which a cilioretinal artery existed along the papillomacular bundle. GVFs showed bilateral blind spot enlargement and centrocecal scotomas, and PVEPs were delayed. These findings suggested cancer-associated optic neuropathy (CAON), confirmed by presence of anti-optic nerve autoantibodies (auto-Abs). No anti-retinal auto-Abs were found. CAON is a less common paraneoplastic manifestation than CAR and it is rarely observed in association with prostate cancer. A combination of visual function testing methods permitted the recognition, in this highly unusual case, of the concurrent presence of unilateral ERG changes most likely attributable to CRAO complications in OS, in all likelihood unrelated to CAON, and not to be confused with unilateral CAR. Auto-Ab testing in combination with visual function tests helps achieve a better understanding of the pathophysiology of vision loss in paraneoplastic visual syndromes.

Longitudinal measures of visual function, tumor volume, and prediction of visual outcomes after treatment of optic pathway gliomas

PURPOSE

To examine longitudinal changes in visual acuity, tumor volume, and visual evoked potentials (VEP) before and after treatment in children with optic pathway gliomas.

DESIGN

Retrospective cohort study.

PARTICIPANTS

Twenty-one patients (0.7-9 years of age).

METHODS

Patients initially were treated either by chemotherapy (n = 18) or radiotherapy (n = 3). Patients were followed up with serial magnetic resonance imaging, age-corrected visual acuity measurements in logarithm of the minimum angle of resolution (logMAR) units, and pattern VEP. Longitudinal visual outcome data were obtained on average for 9 years (range, 4-16 years). Tumor volumes before and after treatment were estimated in 15 patients. Multivariate regression was used to predict visual outcomes.

MAIN OUTCOME MEASURES

Visual acuity, relative tumor volumes, and VEP.

RESULTS

Before treatment, 81% of patients had reduced visual acuity and 81% had optic nerve pallor, whereas all had a reduced VEP in 1 or both eyes. After initial treatment, tumor volume decreased in 53%, stabilized in 27%, and progressively increased in 20%. Treatment arrested the rapid decline in visual acuity loss and stabilized visual acuity for 4 to 5 years. The rate of visual acuity decline was not correlated with tumor shrinkage. Sixty-two percent of patients required additional treatment with either chemotherapy or radiation because of tumor growth or progressive loss of visual function. Visual acuity at last examination was stable or improved in 33% of patients, but on average declined 0.4 logMAR units. Visual acuity was 20/200 or better in 1 eye of 62% of patients. The rate of visual acuity decline was predicted weakly by tumor volume at presentation (R(2) = 0.19; P<0.009). Visual acuity at last examination was predicted best by visual acuity and tumor volume at presentation (R(2) = 0.66; P<0.001).

CONCLUSIONS

Systemic chemotherapy arrested the decline in visual acuity and stabilized vision on average for 5 years. At presentation, VEPs were a more sensitive indicator of optic pathway damage than visual acuity or optic nerve appearance. Although tumor reduction or stabilization was achieved in 80% of patients, pre-existing visual damage, indexed by objective measures of tumor volume and visual function, limited visual outcomes.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Clinical and instrumental (magnetic resonance imaging [MRI] and multimodal evoked potentials) follow-up of brain lesions in three young patients with neurofibromatosis 1

Diagnosis of neurofibromatosis 1 is based on clinical criteria. In a large number of children with neurofibromatosis 1, magnetic resonance imaging (MRI) reveals high-signal T(2)-weighted intensities in different brain regions, defined as unidentified bright objects. These lesions are asymptomatic; most of them regress spontaneously with age, but the presence of contrast enhancement or mass effect in them usually strongly suggests an increased risk of proliferative changes. To date, few studies have focused on evoked potentials in patients with neurofibromatosis 1, and the reported abnormalities did not have significant clinical correlations. We describe the clinical and instrumental (MRI and evoked potentials) follow-up of three patients with neurofibromatosis 1. MRI and evoked potentials showed subclinical involvement of the central nervous system. Some MRI T(2)-weighted hyperintensities showed enhancement and mass effect of uncertain significance. During follow-up, the MRI lesions spontaneously decreased in size or enhancement, allowing us to exclude the hypothesis of proliferative lesions; in the same way, some asymptomatic evoked potential abnormalities disappeared. These findings suggest that both MRI and evoked potentials could be useful in the detection and monitoring of cerebral complications of neurofibromatosis 1.

Utility of multimodal evoked potentials study in neurofibromatosis type 1 of childhood

A group of 21 children affected by neurofibromatosis type 1 has been investigated with the aim of studying multimodal (visual, brainstem auditory, and somatosensory) evoked potentials and their correlations with neurologic, electroencephalographic, and cranial magnetic resonance imaging. In the present series, cranial magnetic resonance imaging and evoked potentials were the most frequently abnormal instrumental tests. In approximately two thirds of the cases at least one of the evoked potentials (particularly visual and auditory evoked potentials) was compromised, always without clinical signs of related sensory (visual, auditory, and somatosensory) pathway pathology and sometimes in the absence of magnetic resonance imaging signs of central nervous system involvement. This study indicates that in patients with neurofibromatosis type 1, multimodal evoked potentials are useful and should be part of the diagnostic protocol of encephalic lesions together with magnetic resonance imaging. The use of both methods could aid in early detection of central nervous system dysfunction in both the initial evaluation of disease and its follow-up.