Giant pattern VEPs in children.

Our aim is to elaborate the clinical significance of giant amplitude pattern reversal visual evoked potentials (VEPs) in children. 'Giant' amplitude VEPs exceed the upper 97.5th centile, 90% CI for age. We scrutinised 2750 pattern VEPs recorded to international standards between Jan 2015 and 2017 from children aged 16 years and under, attending a specialist children's hospital. Twenty seven children, median age 6yrs, (range 1-16 yrs), were identified with giant VEPs (P100 amplitude range 65-163 µV). Most, 22/27 (81%), had conditions associated with a risk of raised ICP. Sixteen of these twenty two children had craniosynostosis; six multi-sutural and eight single suture disease. Others had Idiopathic Intracranial Hypertension, arachnoid cyst, NF1 with shunted hydrocephalus, chronic infantile neurological cutaneous and articular (CINCA) syndrome, nephrotic cystinosis and obstructive sleep apnoea. Five children presented with a range of conditions, some associated with seizures some symptomatic, but as yet undiagnosed. Frequent structural associations were optical coherence tomography measures of optic disc maximum anterior axial horizontal retinal thickness projection >160 µm and neuro-radiological findings of CSF effacement and copper beaten appearance. Ultrasonography measures of optic nerve sheath diameters varied, but in one child took 2 years to resolve after treatment for raised ICP. Optic disc gradings by fundoscopy were mostly normal, as were visual acuities. Raised ICP was confirmed by gold standard ICP bolt measurements in five of seven children tested. These data suggest that rICP should be considered if a child has sustained giant amplitude VEPs at normal latency.

ERGs on the brain: the benefits of simultaneous flash retinal and cortical responses in paediatric cerebral visual impairment.

PURPOSE: To highlight the importance of simultaneous flash electroretinogram (ERG) and visual evoked potential (VEP) recording to differentiate a true flash VEP response from an artefact caused by the intrusion of the ERG on a mid-frontal reference electrode in cases of severe cerebral visual impairment (CVI). METHODS: We report an observational case series of four children with severe CVI who underwent simultaneous flash ERG and VEP recordings. Flash VEPs from Oz-Fz and lower lid skin ERGs referred to Fz were recorded simultaneously to Grass intensity setting 4 flash stimulation. RESULTS: In all cases, atypical, but reproducible VEPs were evident. Comparison of the timing and waveform of the VEPs and ERGs showed the occipital responses were inverted ERGs and no true flash VEP was evident. CONCLUSIONS: While ISCEV and neurophysiology standards do not require the simultaneous recording of the flash ERG with the VEP, these cases highlight the usefulness of this non-invasive technique particularly in suspected paediatric cerebral visual impairment to differentiate a true VEP from an artefact caused by ERG contamination.