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. 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