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 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