Multifocal Visual Evoked Potential (mfVEP) and Pattern-Reversal Visual Evoked Potential Changes in Patients with Visual Pathway Disorders: A Case Series

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Paper

Link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5122941/
Year: 2015

Summary

• mfVEP may provide a more accurate assessment of visual defects when compared with PVEP
• demonstrates that mfVEP, as an objective test for visual fields, is potentially more sensitive than PVEP in detecting focal visual pathway pathology

Results

• mfVEP predominantly used in the assessment of patients with glaucoma and optic neuritis
• mfVEP provides a more accurate assessment of visual defects when compared with conventional PVEP
• mfVEP enables simultaneous recording from multiple regions of the visual field, allowing assessment of a much larger cross-sectional area of the optic nerve
• greater sensitivity of mfVEP compared with full-field PVEP
• mfVEP has the capacity to detect abnormalities in the posterior visual pathways that may be missed by conventional pattern-reversal
• good correlation between HVF defects and mfVEP in patients with retro-chiasmatic visual pathway lesions
• mfVEP uses a dartboard pattern of 58 segments that contains 4 × 4 checks cortically scaled to increase in size from the centre to the periphery in order to optimise the response from different parts of the visual field; therefore capable of greater resolution of visual pathway function including fibres from the peripheral visual field
• mfVEP techniques allow independent assessment of fibres sub-serving different regions of the visual field, minimising the susceptibility to phase cancellation and distortion
• mfVEP has some limitations, such as inter-subject variability, since the cortex is folded differently in every individual, the position of the primary visual area and its relation to the location of recording electrodes can result in noticeably different mfVEP responses
• mfVEP testing takes about 20 minutes to test both eyes, is well tolerated by patients

The purpose of this study was to evaluate multifocal visual evoked potential (mfVEP) and pattern-reversal visual evoked potential (PVEP) changes in patients with pathology at various levels of the visual pathway determined by other methods. Six patients with different visual pathway disorders, including vascular ischaemic events and compressive optic neuropathy, were reviewed. All patients were tested with both mfVEP and full-field and half-field PVEPs. Results were assessed in relation to other diagnostic tests such as magnetic resonance imaging, Humphrey visual field test, and optical coherence topography. The cases in this study demonstrate a potential higher sensitivity of mfVEP compared with conventional PVEPs in detecting lesions affecting the peripheral field, horizontal hemifields, and lesions of the post-chiasmal pathway. The limitation of the PVEP in this setting is probably due to phase cancellation and overrepresentation of the macular region. mfVEP provides a more accurate assessment of visual defects when compared with conventional PVEP. The independent assessment of different areas of the visual field improves the detection and localization of lesions and provides an objective topographical map that can be used in clinical practice as an adjunct to other diagnostic tests and to assess disease progression.