Revista de Medicina Desportiva (English) March 2018 - Page 14

Revista Medicina Desportiva informa, 2018; 9(2):12-15.
Carpal Tunnel Syndrome in
Sports
João L Pinheiro, 2 Prof. Doutor João Pinheiro, 3 Dr. Armando Rocha
Neurosurgery; 2 Physical and Rehabilitation Medicine; Sports Medicine. Centro Hospitalar e Universitário
de Coimbra.
1
1
ABSTRACT
Despite being a rare entrapment syndrome in athletes, the knowledge of this peripheral neuropathy
should not be overlooked. Functional disability and loss of performance are common consequences.
The modalities associated with repetitive wrist movements or the use of accessories such as wheel-
chairs, dumbbells, bows or cleats are the ones that most frequently predispose to this pathology. The
treatment of the lesion is divided between the conservative and the surgical approach. Although the
competitive recovery is demanding carpal tunnel syndrome has a good prognosis particularly when
diagnosed and treated early.
KEYWORDS
Median nerve, carpal tunnel, entrapment, sports.
Introduction
It was first described in 1854 by
a surgeon and pathologist James
Paget 1 , carpal tunnel syndrome
(CTS) is a mononeuropathy induce
by mechanical compression and
consequent entrapment of the
median nerve (MN) in its distal por-
tion, at the level of the carpal tunnel
(CT). 2 It is present in 3.8% of the gen-
eral population, being responsible
for 90% of all peripheral neuropa-
thies. 3 It is the most common injury
of the median nerve and usually it is
classified as a neuropraxia. Physical
mechanism responsible for periph-
eral neuropathies can be divided
into high, medium or low energy.
This mechanism of entrapment of
the peripheral nerve is included in
traumatic injuries of low energy. 4
Morphological classification of the
nerve injury, initially created by
Seddon, was later replaced by that
of Sunderland. The latter consists
of five groups, arranged in order of
increasing severity: 5
• Grade I (Neuropraxia) – nerve
conduction blockade and inflam-
matory reaction along the myelin
sheath, without microanatomy or
axonal degeneration;
• Grade II (Axonotmesis) – axonal
injury, but with endoneurium
preservation;
• Grade III (Axonotmesis) – axonal
and concomitant endoneurium
12 march 2018 www.revdesportiva.pt
injury;
• Grade IV (Axonotmesis) – axonal
injury associated with injury of
the endoneurium and perineu-
rium;
• Grade V (Neurotmesis) – complete
nerve transection.
Etiology
Etiological factors responsible for
CTS are multiple. Intrinsic factors,
such as female gender, family his-
tory, a constitutional CT stenosis
or a thick flexor retinaculum (FR),
are causes to be considered. Several
studies are underway to understand
the role of genes responsible for
the production of connective tissue
proteins, such as collagen type V. 6,7
Metabolic factors, such as diabetes
mellitus type I and II, amyloidosis,
hypothyroidism and autoimmune
diseases, should also be taken into
account. 6 Pregnancy alone may
trigger this path ology. 8 Taking drugs,
such as growth hormone or oral
contraceptives, can also induce
symptomatology. 9 Sports practice is
also a risk factor for CTS, consider-
ing particularly overuse movements
of the forearm flexor and extensor
muscles, the use of assistive devices
/ accessories, direct traumatic
pathology among others. 10
Anatomy of the peripheral nerve
The microanatomy of the periph-
eral nerve has a similar organization
to the skeletal muscle fibers. Involv-
ing the nerve is the outer epineu-
rium. Within the nerve groups of
fascicles are identified that are
supported by the internal epineu-
rium. Each fascia is surrounded by
perineurium and consists of axons
surrounded by the endoneurium.
Each axon is covered by a layer of
myelin, produced by Schwann cells.
The myelin sheath is not continued
to be intercalated by demyelinated
regions, called Ranvier’s Nodes. Also
note the existence of the blood-
nerve barrier, formed by the peri-
neurium cells and endothelial cells
of the microvessels that accompany
the MN, branches of ulnar and radial
artery. 11
Anatomy of the carpal tunnel
CT is an osteofibrous area in the
anterior portion of the wrist. It is
located between the FR and the
carpal bones. The transverse carpal
ligament, the middle part of the FR,
corresponds to the upper limit of the
tunnel. It is inserted medially in the
pisiform bone and the hook of the
hamatum and laterally in the tuber-
cle of the navicular and trapezius.
The carpal bones and the various
ligaments that join them correspond
to their floor. The TC is 4-6 cm long,
3-4 cm wide and 2.5-3.5 mm thick.
MN cross along nine flexor tendons
within the CT, usually in the mid-
line or with slight radial deviation.
Four of these tendons correspond to
the superficial flexor of the fingers,
another four to the deep flexor of
the fingers and one to the flexor of
the thumb. 12
Medium nerve
MN has its origin in the medial
(C5-C6) and lateral (C8-T1) branches
of the brachial plexus. It descends
along the medial portion of the
arm, crosses the ulnar fossa, pass-
ing between the two heads of the
pronator teres and then deeply to
the superficial flexor of the fingers
in the sublimis bridge. It enters the