Observational studyEuropean radiology2020
Carpal tunnel ultrasound: is the "safe zone" on the ulnar side of the median nerve really avascular?
Observational study in European radiology, 2020. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 4 papers.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
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Who cites it
4 citing papers in PubMed, 6 citations in OpenAlex.
- Forearm position-dependent variations in the carpal tunnel safe zone: an ultrasonographic anatomical rationale for a pronation-based injection concept.Surgical and radiologic anatomy : SRA · 2026Observational
- Combination of morphological and multiparametric MR neurography enhances carpal tunnel syndrome diagnosis and evaluation.Scientific reports · 2025Article
- Intraneural vascularity of the median, ulnar and common peroneal nerve: Microvascular ultrasound and pathophysiological implications.Australasian journal of ultrasound in medicine · 2023Article
- Thenar and Hypothenar Muscle Coverage on the Transverse Carpal Ligament.Journal of wrist surgery · 2022Article
Corrections and comments
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Authors and funding
6 authors at 2 institutions in 1 country.
Funding
No grant is acknowledged in the PubMed record.
Abstract
introductionNumerous publications have studied the regional anatomy of the carpal tunnel to define a "safe zone" to reduce the risk of perioperative neurovascular complications. This zone, located between the ulnar neurovascular bundle and the median nerve, is considered to be safe mainly because of the absence of vascular structures. This study aims to assess the presence of arterioles within this area using superb microvascular imaging (SMI). MATERIALS AND
methodsThe images from patients who underwent a bilateral routine wrist ultrasound with SMI, between January 28 and February 28, 2019, were retrospectively reviewed by two radiologists to evaluate the presence and location of arterioles in the safe zone. In addition, cadaveric wrists injected with intra-arterial red latex underwent dissection of the carpal tunnel.
resultsThe images from 27 patients (54 wrists) were reviewed. In the safe zone, arterioles were seen superficial to the retinaculum in 36 wrists (36/54; 66.7%) and deep to the retinaculum in 21 wrists (21/54; 38.9%). The arterioles located deep to the retinaculum were more frequently found close to the median nerve (21/54; 38.9%) than to the ulnar artery (9/54; 16.7%). In five cadaveric wrists, arterioles were detected superficial to the retinaculum in 3 wrists (3/5; 60%) and deep to the retinaculum in 2 wrists (2/5; 40%).
conclusionArterioles can be seen in the safe zone both superficial and deep to the flexor retinaculum. Deep to the retinaculum, they are mainly observed in the proximal aspect of the carpal tunnel and more frequently close to the median nerve. KEY POINTS: • Superb microvascular imaging (SMI) enables the visualization of arterioles within the "safe zone" of the carpal tunnel (visible both superficial and deep to the flexor retinaculum). • Arterioles were more frequently observed in the proximal aspect of the carpal tunnel. • Deep to the retinaculum, arterioles were more frequently seen in proximity to the median nerve.
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