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Utility of Ultrasound for Identifying Median Nerve Changes Indicative of Acute Carpal Tunnel Syndrome After Distal Radius Fracture.

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Publication details: 2023; ; ISSN:

2589-5141

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Online resources:

https://dx.doi.org/10.1016/j.jhsg.2023.03.013

Summary: Conclusions: ACTS should be suspected in patients with median nerves demonstrating increased CSA and adopting a more circular shape. Fracture positioning impacts median nerve CSA with wrist extension, causing the greatest change. Median nerve HWR may offer an easier ultrasonographic alternative to CSA.Summary: Methods: We used 10 upper-extremity specimens. We induced ACTS (carpal tunnel pressure >40 mm Hg) in a distraction-only model and then used a DRF model as a neutral position, under traction, or wrist extension. We measured the median nerve cross-sectional area (CSA), height, and width with ultrasound in each model. We used a novel calculation, height-width ratio (HWR), to describe nerve shape. A low HWR indicates an elliptical shape; as the HWR increases toward one, the shape becomes more circular. The CSA measurements and HWR at pressures >40 mm Hg were used to calculate a 95% confidence interval, which defined the threshold for ACTS.Summary: Purpose: Ultrasound offers a fast and inexpensive way to evaluate the median nerve. However, there is a paucity of data assessing ultrasound in acute trauma. Our study aimed to characterize median nerve changes indicative of acute carpal tunnel syndrome (ACTS) in a cadaveric distal radius fracture (DRF) model.Summary: Results: Wrist distraction created carpal tunnel pressures >40 mm Hg in all specimens. Distraction increased CSA compared with baseline (9.1 +/- 0.9 mm2 vs 6.3 +/- 1.2 mm2, P < .001). Under ACTS-level pressures, the thresholds for CSA and HWR were 8.5 mm2 and 0.41, respectively. HWR significantly increased with distraction compared with baseline (0.47 +/- 0.10 vs 0.28 +/- 0.09, P = .006). Most neutral DRF models (n = 8, 80%) met the CSA threshold for ACTS, whereas all specimens with a DRF extended or under traction had CSAs above the ACTS threshold. Compared to the baseline, the shape of the median nerve was more circular in all DRFs, including neutral (0.28 +/- 0.09 vs 0.39 +/- 0.13), under traction (0.43 +/- 0.09), and extended (0.45 +/- 0.09).Summary: Type of study/level of evidence: Diagnostic III. Copyright © 2023 The Authors.

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Item type	Current library	Collection	Call number	Status	Date due	Barcode
Journal Article	MedStar Authors Catalog	Article	37521560	Available		37521560

Conclusions: ACTS should be suspected in patients with median nerves demonstrating increased CSA and adopting a more circular shape. Fracture positioning impacts median nerve CSA with wrist extension, causing the greatest change. Median nerve HWR may offer an easier ultrasonographic alternative to CSA.

Methods: We used 10 upper-extremity specimens. We induced ACTS (carpal tunnel pressure >40 mm Hg) in a distraction-only model and then used a DRF model as a neutral position, under traction, or wrist extension. We measured the median nerve cross-sectional area (CSA), height, and width with ultrasound in each model. We used a novel calculation, height-width ratio (HWR), to describe nerve shape. A low HWR indicates an elliptical shape; as the HWR increases toward one, the shape becomes more circular. The CSA measurements and HWR at pressures >40 mm Hg were used to calculate a 95% confidence interval, which defined the threshold for ACTS.

Purpose: Ultrasound offers a fast and inexpensive way to evaluate the median nerve. However, there is a paucity of data assessing ultrasound in acute trauma. Our study aimed to characterize median nerve changes indicative of acute carpal tunnel syndrome (ACTS) in a cadaveric distal radius fracture (DRF) model.

Results: Wrist distraction created carpal tunnel pressures >40 mm Hg in all specimens. Distraction increased CSA compared with baseline (9.1 +/- 0.9 mm2 vs 6.3 +/- 1.2 mm2, P < .001). Under ACTS-level pressures, the thresholds for CSA and HWR were 8.5 mm2 and 0.41, respectively. HWR significantly increased with distraction compared with baseline (0.47 +/- 0.10 vs 0.28 +/- 0.09, P = .006). Most neutral DRF models (n = 8, 80%) met the CSA threshold for ACTS, whereas all specimens with a DRF extended or under traction had CSAs above the ACTS threshold. Compared to the baseline, the shape of the median nerve was more circular in all DRFs, including neutral (0.28 +/- 0.09 vs 0.39 +/- 0.13), under traction (0.43 +/- 0.09), and extended (0.45 +/- 0.09).

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