Abstract
OBJECTIVE:The aim of this study was to investigate the prevalence of anatomic variations of the bifid median nerve, persistent median artery and persistent median vein in Chinese individuals and their relationship with carpal tunnel syndrome.METHODS:One hundred and sixty median nerves were examined using ultrasonography and colour Doppler ultrasonography. The location, shape, and size of the bifid median nerve, persistent median artery and persistent median vein were recorded. The cross-sectional area of the bifid median nerve (two trunks) was measured at the level of the pisiform.RESULTS:Among the 160 wrists examined, a bifid median nerve was observed in 15 (9.4%) wrists, and a persistent median artery was observed in 12 (7.5%) wrists. These two variations either coexisted or were observed independently, and the probability of coexistence (6.3%) was higher than the probability of existing independently (bifid median nerve only 3.1%, persistent median artery only 1.3%). The cross-sectional area of the radial trunk was greater than (13 in 15, 86.7%) the cross-sectional area of the ulnaris trunk. Persistent median vein was observed in 9 wrists (5.6%).CONCLUSIONS:The persistent median artery and bifid median nerve tend to coexist, and the persistent median vein sometimes runs parallel to the persistent median artery. Their positional relationship in carpal tunnel is uncertain, and thus, preoperative ultrasound is necessary. These three variations do not present any additional risk for the development of carpal tunnel syndrome.
Highlights
In 1977, Lanz [1] described the bifid median nerve as an anatomic variation in the median nerve
It is important for surgeons to be aware of these structural variations when planning carpal tunnel release or other surgeries associated with carpal tunnel syndrome (CTS)
Among the 50 female patients and 30 male patients, a bifid median nerve was observed in 15 wrists (9.4%): 9 patients (5 right and 4 left) exhibited unilateral bifid median nerves, and 3 patients exhibited bilateral bifid median nerves
Summary
In 1977, Lanz [1] described the bifid median nerve as an anatomic variation in the median nerve. This condition occasionally coexists with a persistent median artery in carpal tunnel syndrome [2,3]. A persistent median artery is occasionally accompanied by persistent median veins. It is important for surgeons to be aware of these structural variations when planning carpal tunnel release or other surgeries associated with carpal tunnel syndrome (CTS). Several studies have implicated bifid median nerve and persistent median.
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