Revista de Medicina Desportiva (English) March 2018 | Page 15

CT parallel to the second and third
tendons of the superficial flexor digi-
torum muscle. Along its path it orig-
inates several branches. In the proxi-
mal portion of the CT the anterior
interosseous nerve is responsible for
the innervation of all the flexors of
the forearm except the ulnar portion
of the deep muscle of the fingers
and the ulnar flexor of the carpus.
Palmar cutaneous nerve is respon-
sible for the cutaneous sensitivity
of the tenar eminence. In the distal
portion of the CT will give rise to the
recurrent motor branch responsible
for the innervation of the opposing
muscles of the thumb, short abduc-
tor of the thumb, short flexor of the
thumb and also to multiple palm
branches of the fingers. They are
responsible for the motor innerva-
tion of the two lateral lumbricoid
muscles and sensitive information
of the palmar and distal dorsal por-
tion of the first, second, third and
lateral of the fourth finger. 13
Figure 1 – O nervo mediano
Ref.http://2.bp.blogspot.com/-8Hp1VpNGsK4/UDz0aSHYt
HI/AAAAAAAAADY/9ab_kUnQj14/s1600/tuneld3.gif
Pathophysiology
The regions with the greatest predis-
position to MN entrapment are the
proximal boarder of the transverse
ligament or the hamatum “hook”.
The pathophysiological mechanism
of CTS is similar to a compartmental
syndrome. Normal pressure at the
CT scan is 2-10 mmHg. 14 Increased
pressure promotes the commit-
ment of neural microcirculation
and consequent destruction of the
blood-nerve barrier, myelin sheath
injury and axonal aggression, as
well as alterations of the supporting
connective tissue, namely the
endoneurium and epineurium. 15 The
destruction of the nerve-blood bar-
rier promotes the increase of capil-
lary permeability, with consequent
accumulation of proteins, inflam-
matory cells and intra-fascicular
edema. It is observed an increase
in oxygen perfusion distance with
associated hypoxia, which in turn
promotes Venue accumulation of
angiogenic factors, namely hypoxia-
inducible factor 1 and vascular
endothelial growth factor. As a
result, there is axonal degeneration
and demyelination. Nerve dam-
age generated by short-term com-
pressions is generally reversible,
given the regenerative capacity of
the peripheral nervous system. If
prolonged, compression eventually
results in epineural fibrosis. Com-
pression sustained for several years
without treatment can culminate in
irreversible injuries, namely destruc-
tion of the myelin sheath and axonal
disruption. 16 joint, responsible for the lumbri-
coid muscles, should also be tested.
Provocative tests, such as Tinnel,
Durkan and Phalen, are important
for diagnosis. Durkan test has sensi-
tivity and specificity of 85% and 95%
respectively. 18 It should be noted
that the more severe the MN injury,
the less symptomatology may be,
although marked functional disabil-
ity coexists. Longer and untreated
compression causes atrophy of the
tenar region muscles. Anatomical
variant, called Richie-Cannieu, is
highlighted in which the recurrent
motor nerve is the branch of the
ulnar nerve. In this case, despite
prolonged entrapment, no tenar
atrophy is observed.
Clinical features Figure 2 – Inervação do nervo mediano
The symptomatic pattern of CTS
is very diverse, justifying a rigor-
ous physical examination, com-
plemented by electrophysiological
study. Paresthesias and dysesthesias
in the palmar and dorsal portion of
the thumb, second and third fingers
are frequent. Pain in the ventral
region of the wrist and the sensation
of volume in the hand may also be
present. Symptomatology usually
arises at night, which is justified by
venous stasis derived from noctur-
nal hypotonia, tendency to flexion of
the wrist, increase of blood pressure
in the second half of the night and
decrease of cortisol levels. 17 Shak-
ing the hand repeatedly and quickly
is reported by patients as a way to
relie