A Novel Electrophysiological Battery for the Assessment of Visual Dysfunction in Multiple Sclerosis

Background: Visual impairment is a key component of the MS disease process. MS lesions can affect any part of the neural networks involved in vision and, therefore, can often cause a variety of neuro-ophthalmic manifestations. While acute optic neuritis (AON) is often a primary manifestation, visual impairments characterized by structural, axonal and other neuronal loss do occur in patients without a history of ON. Compromised components of the visual system have been associated with worsening of the disease. The frequency with which the afferent visual pathway is involved in the disease process of MS makes it a useful model of the pathophysiological mechanisms involved.

Objectives: The current work aims to establish a battery of electrophysiological techniques that rapidly and objectively assess function in select neural pathways and mechanisms in patients with MS at both retinal and cortical levels.

Methods: Patients with relapsing-remitting MS and age-similar controls were tested on an electrophysiological battery using an EvokeDx device (Konan Medical USA), which presented visual stimuli on a calibrated organic LED display, recorded amplified electroencephalographic (EEG) and electroretinographic (ERG) signals, and applied multivariate statistical analyses on the data in the frequency domain following a discrete Fourier transform. Stimuli and analytic techniques were designed to tap select neural pathways and mechanisms (e.g., retinal ganglion cells, magnocellular ON and OFF pathways, lateral inhibitory processes).

Results:  Data collection is in progress and final results will be presented at the meeting. Preliminary findings indicate that frequency-domain techniques capture neural deficits in rigorous, quantitative measures that are sensitive to dysfunction in the visual pathways.

Conclusions: The objective, rapid electrophysiological tests included in this battery capture the effects of the disease process and may be of value in identifying early-stage cases ahead of conventional measures, and may be able to monitor the progression of the disease as well as evaluate the effects of various treatments.