Diagnostic Accuracy of Ultrasound for Digital Nerve Injuries
Ameya V Save, MD1; Ogonna K. Nwawka, MD1; Christian Victoria, MPH1; Steve K. Lee, MD2; Lydia Ko, MPH1
1Hospital for Special Surgery, New York, NY; 2Hand and Upper Extremity Surgery, Hospital for Special Surgery, New York, NY
Introduction:
The purpose of this study was to determine the accuracy of diagnostic ultrasound for the evaluation of digital nerve injuries. We hypothesized that there would be a high match rate between the pre-operative ultrasound assessment and intra-operative findings.
Materials and Methods:
A retrospective review was conducted of patients with clinically suspected digital nerve injuries who had a pre-operative diagnostic ultrasound of the finger prior to surgical exploration. Patients evaluated between March 2016 and March 2020 were included. Pre-operative clinical data, ultrasound reports, and operative findings were reviewed. In order to be considered accurate, the pre-operative ultrasound had to correctly identify the presence of a laceration, the degree of a laceration, and the presence or absence of neuroma formation based on subsequent intra-operative findings.
Results:
Twenty-nine patients and 33 clinically suspected nerve injuries were identified. Four patients had more than 1 nerve injury suspected. The average age was 38 years (range 11- 63 years). There were 11 male patients, and 18 female patients. There was a match between pre-operative ultrasound diagnosis and intra-operative findings in 26/ 33 cases (79%). There was a mismatch in 4/33 cases (12%). The pre-operative ultrasound was reported as inconclusive in 3/33 cases (9%). The accuracy rate improved with the amount of time that had elapsed between injury and when the ultrasound was performed. The four cases in which a mismatch was identified were all performed within 3 days of injury. The accuracy rate of ultrasound performed 0-3 days after injury was 67%, 4-7 days was 78%, and over 7 days was 92%. In cases where over 30 days had elapsed since injury, ultrasound correctly identified neuroma formation in 100% of cases. Poor visualization due to surrounding soft tissue edema was the most commonly identified reason for an erroneous or inconclusive ultrasound.
Conclusions:
Ultrasound evaluation of digital nerve injuries matched intra-operative findings in 79% of cases. The accuracy of ultrasound improved with the amount of time since the injury had occurred, with all cases of mismatch occurring within 3 days of injury. Chronic nerve injuries were readily diagnosed by the presence of neuroma formation.
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