Bifid median nerve as an anatomical risk factor for carpal tunnel syndrome: A meta-analysis

Long-Term Outcomes of Ultrasound-Guided Thread Carpal Tunnel Release and Its Clinical Effectiveness in Severe Carpal Tunnel Syndrome: A Retrospective Cohort Study

Ultrasound-guided thread carpal tunnel release (TCTR) was proposed as an effective and safe surgical technique with faster recovery and fewer complications. This study was conducted to confirm the long-term outcomes after TCTR and verify its clinical effectiveness in severe carpal tunnel syndrome (CTS) for more insights into TCTR procedure. A total of 168 TCTR procedures were performed in 152 individual patients by two physiatrists during 36-month period. In an assessment of 82 hands, surgical outcomes of 2 years after TCTR could be obtained, and the grade 6 CTS group of 21 hands, classified as extremely severe grade by Bland's classification, was compared with other severity groups (grade 1-5). The Boston Carpal Tunnel Syndrome Questionnaire (BCTQ) was used to assess surgical outcomes. No adverse events occurred in all cases including the case of severe CTS and anatomical variants. TCTR showed significant improvement in BCTQ scale within 1-2 weeks, which continued up to 2 years with no recurrence (p < 0.01). Although slower and more progressive than the other severity group, there was also significant improvement relative to the BCTQ scale around 4 weeks after procedure in the grade 6 CTS group (p < 0.05). With the familiarity of ultrasound, ultrasound-guided TCTR is an effective and reliable surgical treatment for CTS in long-term outcomes and in severe CTS.

At-Risk Median Motor Branch to the Thenar Musculature Crossing Under the Flexor Carpi Radialis in the Forearm: A Case Report

CASE

A 77-year-old woman who sustained a distal radius and ulna fracture underwent open reduction internal fixation through a standard flexor carpi radialis (FCR) approach. On dissection, a proximal division of the median nerve was identified, with an aberrant motor branch crossing radial to ulnar deep to FCR and superficial to flexor pollicis longus.

CONCLUSION

Although many anatomic variants of the median nerve have been described, the current case demonstrates a particularly important median motor branch variant, imposing a substantial risk of iatrogenic injury during a standard FCR approach.

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

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., US-guided 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.

Persistent Median Artery, Bifid Median Nerve, and Reversed Palmaris Longus Encountered During Cadaveric Dissection: The First Reported Case

The median artery is a transient embryological structure that normally disappears with the development of the radial and ulnar arteries. In rare instances, though, it persists as the persistent median artery (PMA). The superficial and deep palmar arches are formed through the anastomoses of the radial and ulnar arteries, giving hand and digits their main blood supply. This complex network of vessels and their anastomoses are prone to anatomical variations based on how the anastomosis occurs and which arteries contribute to this anastomosis. While it normally forms through the anastomosis of the radial and ulnar arteries, the superficial palmar arch (SPA) may also form differently, as in our case here, where the median artery persisted and branched off the radial artery, anastomosing with the ulnar artery to give rise to the SPA. This may also interfere with the normal compartmental architecture within the hand, possibly contributing to various clinical pathologies like carpal tunnel syndrome (CTS). Notably, in addition to the persistent median artery, our findings revealed a reversed palmaris longus and a bifid median nerve. These two additional variations can potentially exacerbate the risk of CTS. Alone, the coexistence of the PMA and the reversed palmaris longus is deemed a rare anomaly, only reported once in the literature. The addition of a third variation to the existing ones, like the bifid median nerve, is first reported by us and calls for more investigation for a possible genetic mutation. In this case, we report a persistent median artery, reversed palmaris longus muscle, and bifid median nerve in the forearm of a male cadaver found during a routine anatomy teaching session.

Pilot Cadaveric Study of Anatomical Variations of the Median Nerve at the Wrist in the Lithuanian Population

INTRODUCTION

 Carpal tunnel syndrome (CTS) is known as one of the most common neurological disorders in the human body. Nowadays, the prevalence in the general population ranges between 1% and 5%. Due to its high prevalence and increasing incidence of carpal tunnel surgery, the anatomical variations of the median nerve at the wrist are important to know to avoid iatrogenic injury of the nerve.

PURPOSE

The objective of this study was to evaluate the anatomical variation of the median nerve at the level of the wrist in the Lithuanian population with a focus on its thenar motor branch based on the classifications of Lanz.

MATERIAL AND METHODS

A cadaveric study was performed, and 30 wrists of 15 adult Lithuanian cadavers ranging from 70 to 89 years of age were dissected and examined. Eight female and seven male cadavers were included in the study. Any anatomical finding was documented, and the results were compared with the classification of Lanz as well as with the data found in the literature.

RESULTS

All hands showed different patterns in comparison to the standard anatomical variation Lanz type 0. The most common result was dedicated to Lanz group 4A. Nineteen out of 30 hands (63%, p<0.01) had an accessory branch proximal to the carpal tunnel, while one of these hands showed a third thenar motor branch. Five hands (16%) were dedicated to Lanz group 2 with an accessory branch distal to the carpal tunnel. One hand (3%) showed a variation close to Lanz group 2, but in this case, the thenar motor branch had its origin under the flexor retinaculum instead of proximal to it. Two hands each (6%) were classified by Lanz groups 1B and 3A. Additionally, one variation showed a pattern of a combination of Lanz types 3A and 3B. The bifid median nerve had a connecting branch in between which started distal to the flexor retinaculum. Two anatomical variations (6%) were not described by the classification of Lanz.

Open Carpal Tunnel Release With a Z-plasty Rearrangement for Median Nerve Mononeuropathy Secondary to Traumatic Scar Contracture

We present the case of a 56-year-old woman who developed carpal tunnel syndrome and palmar scar contracture secondary to a left-hand palmar laceration in a pedestrian versus motor vehicle accident. The patient underwent carpal tunnel release and a Z-plasty rearrangement to restore normal thumb movement. The patient reported significant improvement in thumb mobility, resolution of median neuropathy symptoms, and no pain along the scar at her three-month follow-up. Our case illustrates the effectiveness of a Z-plasty in relieving tension along scars and potential management for traction-type extraneural neuropathy arising from scar contracture.