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Carpal tunnel ultrasound: is the “safe zone” on the ulnar side of the median nerve really avascular?

  • Musculoskeletal
  • Published:
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Abstract

Introduction

Numerous 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 methods

The 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.

Results

The 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%).

Conclusion

Arterioles 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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Abbreviations

PACS:

Picture archiving and communication system

PD:

Pulsed Doppler

SMI:

Superb microvascular imaging

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Acknowledgments

The authors would like to thank Julien ADAM, Cassandre DUVINAGE, Benjamin LEJEUNE, and Quentin SION (medical students) who contributed to the cadaveric study.

Funding

The authors state that this work has not received any funding.

Author information

Authors and Affiliations

  1. Department of Musculoskeletal Radiology, Lille University Hospital, Lille, France

    Anne-Charlotte Sergeant, Sammy Badr, Xavier Demondion, Anne Cotten & Thibaut Jacques

  2. Department of Radiology, University Hospital of Poitiers, Poitiers, France

    Anne-Charlotte Sergeant

  3. Department of Orthopaedic surgery, Lille University Hospital, Lille, France

    Marc Saab

  4. Lille University School of Medicine, Lille, France

    Marc Saab, Xavier Demondion, Anne Cotten & Thibaut Jacques

  5. Laboratory of Anatomy, Lille University School of Medicine, Lille, France

    Marc Saab & Xavier Demondion

Authors
  1. Anne-Charlotte Sergeant
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  2. Sammy Badr
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  3. Marc Saab
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  4. Xavier Demondion
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  5. Anne Cotten
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  6. Thibaut Jacques
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Correspondence to Thibaut Jacques.

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The scientific guarantor of this publication is Thibaut Jacques.

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The authors of this manuscript declare no relationships with any companies whose products or services may be related to the subject matter of the article.

Statistics and biometry

No complex statistical methods were necessary for this paper.

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Written informed consent was waived by the Institutional Review Board.

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Institutional Review Board approval was obtained.

Methodology

• Retrospective

• Observational

• Performed at one institution

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Sergeant, AC., Badr, S., Saab, M. et al. Carpal tunnel ultrasound: is the “safe zone” on the ulnar side of the median nerve really avascular?. Eur Radiol 30, 887–894 (2020). https://doi.org/10.1007/s00330-019-06416-0

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  • DOI: https://doi.org/10.1007/s00330-019-06416-0

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