Stéphanie Hostenbach Email: Stephanie.Hostenbach@uzbrussel

Stéphanie Hostenbach
Email: [email protected]
Telefoonnummer: 0477/65.01.77
ASO aan het UZ Brussel, opleiding Neurologie
MaNaMa aan de Vrije Universiteit van Brussel
Promotor: Prof. Dr. J. De Keyser
Titel van het werk : Full-Fiel Electroretinogram in patients with Multiple Sclerosis
Vorm van het werk: Prospectief Case Control onderzoek
Abstract:
Objective: Müller cells are the principal glial cells of the retina and contribute to the
generation of the b-wave of the full-field electroretinogram (ffERG). It has been postulated
that an astrocytic β2 adrenergic receptor deficiency might play a role in the pathogenesis of
Multiple Sclerosis (MS). FfERG abnormalities have been observed in MS patients and since the
Müller cells are thought to accomplish similar functions as the astrocytes in the Central Nerve
System (CNS), there might be a β2 adrenergic receptor dysfunction of the Müller cells as well.
The purpose of this study was to assess the functionality of the β 2 adrenergic receptors on
Müller cells in MS patients by looking at the differences in amplitude and implicit time of the
b-wave before and after the intake of propranolol.
Methods: Nine patients with definite MS and ten healthy controls were included in this study.
They all underwent a Visual Evoked Potential (VEP), an Optical Coherence Tomography (OCT)
and a ffERG, the last one performed before and 2.5 hours after the oral administration of
propranolol 40mg. Parameters of VEP, OCT and ffERG were compared between patients and
controls using the Mann-Whitney U-test.
The influence of propranolol 40 mg on the
parameters of the ffERG was evaluated using a paired Student’s t-test.
Results: The b-wave implicit times in the scotopic 3.0 ffERG were significantly delayed in
patients with MS (p= 0.0002). The other baseline results of the ffERG did not differ
significantly between MS patients and control subjects. Compared to the control subjects, MS
patients with a normal P100 latency (P100 < 115 ms) had significantly delayed b-wave implicit
times in the scotopic 3.0 ffERG (p=0.0005). There were no significant changes observed in
ffERG parameters between MS patients with a P100 normal and P100 delayed latency. After the
oral intake of propranolol 40 mg, there was a non-significant trend towards an increase in b-
wave amplitude in control subjects. The amplitudes of the oscillatory potentials were reduced
in the MS group (p=0.0013).
Conclusion: The delay of b-wave implicit times in patients with MS might represent a delay in
transcellular K+ currents in Müller cells, due to dysfunction of these cells. However, a
decreased photoreceptor activity in the outer nuclear layer (ONL) of the retina, is also needed
to be taken into account since atrophy of the ONL has already been described in MS patients.
Furthermore, it is possible that using β 2 adrenergic receptor blockers is not sufficient enough
to demonstrate an effect on the b-wave of the ffERG, since other neurotransmitter receptors
play a role in regulating the transcellular K+ currents.

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