The CMAP scan: Collecting normal values in a healthy population

The CMAP scan is a noninvasive neurophysiological tool that records the
electrical activity of a muscle in response to repetitive transcutaneous
stimulation of the motor nerve. Patterns in or properties of this CMAP scan
provide clinically relevant information and the method is easy to apply and
interpret. For these reasons, the scan is a promising new diagnostic
instrument. A further description of the method can be found in the protocols
of previously approved studies MEC-2005-277 and MEC-2007-205. The former study
concerned the initial exploration of the approach and has led to a
peer-reviewed publication in 2007.1 The second study addressed the optimal
settings for performing a CMAP scan. A publication of this study is in
preparation, and its results will be applied in the present study.

The next step toward establishing the CMAP scan as a novel electrodiagnostic
instrument is the determination of the distribution of CMAP scan variables that
is present in a healthy population. This is an essential step in the validation
of the method, because to be able to qualify a scan as abnormal, limits to what
is normal need be known. Since normal values may be age-, gender-, side- and
muscle-dependent, normal values will be collected for each of these
subcategories.

Primary Objective:
Collection of CMAP scan normal values

Secondary Objectives:
Assessment of the influence of gender, age, and side on the CMAP scan and its
variables

In this cross-sectional observational multicenter study, we will record CMAP
scans bilaterally in 6 different muscles of 140 healthy subjects: 10 male and
10 female, in each of the categories 18-29, 30-49, 40-49, 50-59, 60-69, 70-79,
and >= 80 years of age.

The CMAP scan was initially designed in the Erasmus MC and continues to be
developed with three international centers: Mayo Clinics, Rochester, USA;
University of Utah, Salt Lake City, USA; and Royal Women*s and Children*s
Hospital, Brisbane, Australia. Each of these centers has agreed to study at
least 20 healthy subjects.

The investigations are noninvasive. There are no risks, nor are there immediate
benefits for individual subjects.