Multifocal Visual Evoked Potentials (mfVEP) in Diabetic Patients with and without Polyneuropathy

Abstract

Previously not shown this study support that mfVEP is an indicator of optic nerve neuropathy in diabetic patients and there could be a correlation between the optic nerve dysfunction and diabetic poly neuropathy. The early optic nerve involvement might explain some of the visual complain in this group of diabetic patients.

Purpose: To investigate the function of the visual pathway measured by mfVEP (multifocal Visual Evoked Potentials) in patients with diabetic retinopathy and neurophysiologically verified polyneuropathy

Subjects and methods: Thirty-two diabetic patients with the same degree of diabetic retinopathy were classified with neurography regarding polyneuropathy and further examined with mfVEP. The mfVEPs of eighteen patients with polyneuropathy were compared to those of fourteen diabetic patients without polyneuropathy and to those of ten nondiabetic subjects.

Results: Diabetic duration, and the number of patients who had undergone panretinal photocoagulation for proliferative diabetic retinopathy were similar in the two patient groups, 29±13 vs 25±7 years, p=0.3. Both groups of patients with diabetic retinopathy had significantly lower amplitudes in the mfVEP than the healthy subjects. In addition the mfVEP amplitudes, which reflect selected areas of the visual function, were significantly reduced in the lower nasal quadrant in patients with neuropathy compared to patients without neuropathy.

Conclusion: The results indicate that mfVEP could be an indicator of optic nerve neuropathy in patients with diabetic retinopathy. The early optic nerve involvement might explain some of the visual complaints in this group of diabetic patients.

Keywords: Diabetic retinopathy; multifocal VEP (mfVEP).; neuropathy.

Fig. (1)

A normal mfVEP. (A) Cortical responses to stimulation of 60 segments in the central visual field. The ring indicates sector C, the region with the highest amplitudes when measured with the midline electrodes. (B) The arrow indicates the peak-to-peak amplitude of the first two components according to VERIS program, which correlate to N 70 and P 100 in the classic VEP.

Fig. (2)

Responses on stimulation of the right eye in a normal eye. N1, N2, N3, N4 are the four segments in the nasal visual field with the highest signal-to-noise ratio.

Fig. (3)

MfVEP responses from the left eye two patients included in the study with neuropathy (red traces) and with out neuropathy (black traces). The traces comprise both central (a) and temporal (b) recordings.

Fig. (4)

MfVEP responses from nasal sections in patients with no diabetes in comparison to diabetes with or without neuropathy.