Clinical Neurology and Neurosurgery 107 (2005) 113–116
The biﬁd visual evoked potential—normal variant or
a sign of demyelination?
Rossen T. Rousseff
, Plamen Tzvetanov
, Maria A. Rousseva
Department of Neurology, Medical University Hospital, G Kochev 8A, 5800 Pleven, Bulgaria
Department of Neurology, Regional Hospital, Russe Private Khan Omurtag St. 11, 8000 Russe, Bulgaria
Received 18 December 2003; received in revised form 23 May 2004; accepted 24 May 2004
Objective: To prospectively evaluate the diagnostic signiﬁcance of biﬁd VEP at initial presentation.
Materials and methods: A hundred and sixteen patients (46 males and 70 females, age 15–54, mean 28.8), with a clinical suspicion of multiple
sclerosis (MS), underwent pattern-shift VEP investigation between 1992 and 1998. They were further followed by clinical, CSF, MRI means
for at least 5 years (mean 7.2). Twenty-six patients remained healthy, while 90 developed demyelinating disease (in 71 MS and in 19 optic
neuritis was the ﬁnal diagnosis). Fifty healthy persons (20 males aged 18–51, mean 28.8 and 30 females aged 18–48, mean 26.2) represented
the control group. The number of persons with biﬁd VEP in each group are analyzed.
Results: In the controls one out of 50 exhibited biﬁd VEP conﬁguration. Of 26 patients with unconﬁrmed suspicion for MS again one had
such responses. Biﬁd VEP were signiﬁcantly more frequent in patients with demyelinative pathology (nine out of 90, 10.0%, P (chi-squared)
Conclusions: Biﬁd VEP is rarely observed in healthy persons. Its presence should suggest the possibility of demyelinating disease and prompt
further investigation and follow-up.
© 2004 Elsevier B.V. All rights reserved.
Keywords: Visual evoked potential; Multiple sclerosis; Optic neuritis
A biﬁd or W-shaped visual evoked potential (W-VEP)
after pattern-shift, checkerboard stimulation was ﬁrst recog-
nized in the 1970’s . Rather than appearing as a single un-
divided deﬂection, the W-VEP takes the form of two distinct
positive peaks (P
) separated by anegativecomponent
with an amplitude greater than 25% of the total P100-N150
W-VEP is generally associated with demyelinating dis-
ease, although the presence ofthis waveform insome healthy
persons is well established [4,5,6]. Most studies of the biﬁd
VEP have been performed cross-sectionally on populations
of patients with established MS or optic neuritis (ON).
Corresponding author. Tel.: +359 64 33292; fax: +359 64 890111.
E-mail address: firstname.lastname@example.org (R.T. Rousseff).
We attempt to deﬁnethediagnosticvalueofthiswaveform
when found at presentation.
2. Materials and methods
Patients in the current study were drawn from two tertiary
referral hospitals covering a population of about 1.0 million.
Ninety-seven patients with a clinical suspicion of multiple
sclerosis and 19 with ON, underwent VEP testing between
1992 and 1998. Cases of deﬁnite multiple sclerosis (MS), at
the time of testing, are not included. Follow-up ranged from
5 to 11 years (median 7.4 years).
The study population included:
1. A total of 26 patients with clinically suspected multiple
sclerosis (csMS) (11 males and 15 females, age 15–48,
mean 28.6) but for whom this diagnosis was eventually
0303-8467/$ – see front matter © 2004 Elsevier B.V. All rights reserved.