Anatomical considerations of US-guided carpal tunnel release in daily clinical practice

Abstract

Carpal tunnel syndrome is the most frequent compression neuropathy with an incidence of one to three subjects per thousand. As specific anatomical variations might lead to unintended damage during surgical interventions, we present a review to elucidate the anatomical variability of the carpal tunnel region with important considerations for daily clinical practice: several variants of the median nerve branches in and around the transverse carpal ligament are typical and must – similarly to the variant courses of the median artery, which may be found eccentric ulnar to the median nerve – be taken into account in any interventional therapy at the carpal tunnel. Unintended interference in these structures might lead to heavy arterial bleeding and, in consequence, even underperfusion of segments of the median nerve or, if neural structures such as variant nerve branches are impaired or even cut, severe pain-syndromes with a profound impact on the quality of life. This knowledge is thus crucial for outcome- and safety-optimization of different surgical procedures at the volar aspect of the wrist and surgical therapy of the carpal tunnel syndrome e.g., USguided carpal tunnel release, as injury might result in dysfunction and/or pain on wrist motion or direct impact in the region concerned. For most variations, anatomical and surgical descriptions vary, as official classifications are still lacking.

A transmuscular path of the medial branch of the high division of the median nerve: an anatomical variation of clinical and surgical importance

“…Ultrasonography (US) has been shown to be a reliable tool for detecting the morphology of the bifid MN, which is generally not an infrequent variation, particularly in hands with CTS [30][31][32]. It is also important in the diagnosis of CTS, based on the enlargement of the MN with an area greater than 9 mm² or 10 mm² at the level of the pisiform bone [33][34][35][36].…”