Biology Reference
In-Depth Information
In this way, the regenerating axons from the freshly transected nerve fascicles
need only to grow over a limited distance in an environment with sub-
optimal viable Schwann cells before the axons reach a target, such as a dener-
vated muscle.
3. CEREBRAL PLASTICITY THE IMPORTANCE OF
TIMING IN REHABILITATION
After a nerve injury, a substantial functional disorganization occurs at
the cortical and the subcortical levels in and close to the somatosensory cor-
tex in the central nervous system ( Rosen et al., 2012; Taylor, Anastakis, &
Davis, 2009 ). These changes are clearly seen in adults, but younger children
have an extensive adaptive cerebral plasticity. Therefore, age is an important
factor for the functional outcome after nerve injury and repair and recon-
struction. There seems to be a critical time around puberty at which the
cerebral plasticity after a nerve injury changes and responds as in adults
( Chemnitz et al., 2013 ). Before puberty, the functional recovery may return
to almost normal after a nerve injury and repair and reconstruction. The
most plausible explanation is the mechanisms of cerebral plasticity, where
the functional disorganization of the cortical map can be completely restored
in young children. Thus, the brain can in young children more easily inter-
pret the new information from the periphery although an extensive misdi-
rection of axonal outgrowth occurs ( Rosen et al., 2012; Taylor et al., 2009 ).
In addition, there has also been detected a reduction in the cortex after nerve
injury. A link between the functional recovery after nerve injury and repair
and the disorganization and reorganization of both the gray and white sub-
stances has been demonstrated. The described alterations, with a reduced
activation of certain brain areas with atrophy of the gray substance as well
as the disorganization of reorganization, are rapid. Thus, these changes
may also be the target for the factor timing after nerve injury and repair
and reconstruction, since they can be considered in the new rehabilitation
strategies ( Lundborg, Bjorkman, & Rosen, 2007; Weibull et al., 2008 ). The
timing for introduction of training after nerve repair has been highlighted
and has focused on the importance of immediate sensory relearning
( Rosen & Lundborg, 2007 ). To provide an alternative afferent inflow from
the hand early after nerve repair in the forearm, a “Sensor Glove System” can
mediate impulses through the hearing sense. This implies that the depriva-
tion of one sense, that is, perception of touch in a denervated skin area, can
be compensated by another sense, that is, sensory-by-pass using the “Sensor
Search WWH ::




Custom Search