ERS3025. See it and Believe it! Ultrasound Accuracy for Brachial Plexus Pathology
Authors * Denotes Presenting Author
  1. Stefanie Wai Ying Yip *; Prince of Wales Hospital
  2. James Griffith; Prince of Wales Hospital
  3. Cina Tong; Prince of Wales Hospital
  4. Esther Hung; Prince of Wales Hospital
  5. Carita Tsoi; Prince of Wales Hospital
To determine accuracy of ultrasound in detecting extra-foraminal brachial plexus pathology and advantages and limitations of ultrasound compared to magnetic resonance imaging (MRI) for imaging the brachial plexus.

Materials and Methods:
103 cases with clinically suspected brachial plexus pathology were evaluated first by ultrasound, followed by MRI. Patients with known brachial plexus pathology or prior brachial plexus MRI or ultrasound were excluded. Ultrasound of the brachial plexus yielded a single diagnosis. Final diagnosis was based on a combination of MRI, clinical follow-up, and surgical findings. All MRI imaging datasets were anonymized and independently assessed on a second occasion in a blinded manner by a panel comprising six musculoskeletal radiologists. Ultrasound findings were compared to the final diagnosis to determine accuracy of ultrasound assessment. Mean clinical follow-up time was 1.4years.

Sixty-six (64%) of the 103 cases had normal brachial plexus ultrasound and MRI examinations. Thirty-seven (36%) of 103 cases had brachial plexus pathology on MRI comprising post-radiation fibrosis (n=19, 51%), nerve sheath tumour (n=7, 19%), traumatic injury (n=5, 13.5%), inflammatory polyneuropathy (n=4, 11%), metastatic infiltration (n=1, 2.7%), and neuralgic amyotrophy (n=1, 2.7%). Overall diagnostic accuracy of ultrasound for brachial plexus pathology was 98% (101/103), with two discordant cases (neuralgic amyotrophy n=1, inflammatory neuropathy n=1) regarded as normal on ultrasound assessment. Sensitivity, specificity, positive and negative predictive value of ultrasound for identifying brachial plexus pathology were 95%, 100%, 100%, and 97% respectively. Occasionally, ultrasound had additional benefit to MRI, either in enabling more precise localization of nerve injury or revealing unsuspected extra-plexal pathology which were accountable for patient symptoms.

Ultrasound identifies brachial plexus pathology with high accuracy and specificity, showing comparable diagnostic efficacy to MRI. Ultrasound can serve as a cost-effective first-line imaging investigation, or primary triage tool, for suspected brachial plexus pathology, thereby streamlining patient management.