Neural plasticity in patients with brachial plexus avulsion after intercostal-musculocutaneous nerve transfer

Contrary to the classical view of a pre-determined wiring pattern, there is
considerable evidence that cortical function and representation of body parts
are continuously modulated in response to activity and behavior but also as a
result of peripheral injury such as amputation or a brain injury such as
stroke. These changes in plasticity may account for recovery of function. Both
functional and structural changes are thought to play a role in this process.
It is debated though, to what extent these changes cause recovery of function,
or whether they might even inhibit recovery.
In this study, we want to investigate the plastic changes in the central
nervous system underlying recovery of biceps function in patients with a root
avulsion of the brachial plexus leading to paralysis of an upper limb. In some
cases, transfer of intercostal nerves (ICN) to the musculocutaneous motor
branch can yield a favorable outcome. After transfer, central ICN motor
programs for respiration and posture control become connected to the biceps
muscle. Initially, biceps contraction can only be effected by means of a
voluntary respiratory effort. At the end stage of reinnervation, however,
volitional control over biceps muscle contraction can be achieved without
resorting to respiratory effort.

The primary objective of this study is to identify the brain changes following
peripheral nerve injury and establishing their functional role in recovery. The
secondary objective is to evaluate new fMRI methodology in a patient
population.

Three groups of subjects will be compared: a healthy control group, a patient
group with good biceps function after ICN-MCN transfer and one with no
functional recovery after this procedure. Different types of MRI data will be
collected. fMRI data will be acquired with two different functional paradigms,
one involving biceps contraction (real and imagined) and one involving cued
voluntary breathing. Additionally, resting state fMRI and DTI data will be
acquired to investigate functional and structural connectivity, respectively.

There are no known risks associated with participating in an fMRI study. This
is a technique involving no catheterizations or introduction of exogenous
tracers. Numerous children and adults have undergone magnetic resonance studies
without apparent harmful consequences. Some people become claustrophobic while
inside the magnet and in these cases the study will be terminated immediately
at the subject's request. The only absolute contraindications to MRI studies
are the presence of intracranial or intraocular metal, or a pacemaker. Relative
contraindications include pregnancy and claustrophobia. Subjects who may be
pregnant, who may have metallic foreign bodies in the eyes or head, or who have
cardiac pacemakers will be excluded because of potential contraindications of
MRI in such subjects.