THU0358 Gray Scale and Power Doppler Ultrasound Assessment of the Median Nerve: A Biomarker That Can Help in Setting A Treat to Target Approach Tailored for Carpal Tunnel Syndrome Patients

Accuracy of Carpal Tunnel Injection: A Prospective Evaluation of 756 Patients

Background: Corticosteroid injection into the carpal tunnel is both a diagnostic test and a therapeutic modality in the treatment of carpal tunnel syndrome. Many injection techniques are described in the literature. Improper placement of injection may result in damage to neurovascular structures in the carpal canal or decrease efficacy of the test and/or therapy. The purpose of this study is to determine if carpal tunnel injection using anatomic landmarks is reproducible and safe. A review of the senior author's injection technique is presented. Methods: Over 8 years, there were 756 attempted placements of a 25-gauge needle into the carpal tunnel in a simulated carpal tunnel injection prior to open carpal tunnel release. The needle was inserted at the wrist crease, just ulnar to palmaris longus. Open carpal tunnel release was subsequently performed, and position of the needle was recorded. Results: In 572 patients (75.7%), the needle was found to be in the carpal tunnel without penetration of contents. The needle was in the carpal tunnel but piercing the median nerve in 66 attempts (8.7%). The carpal tunnel was missed in 118 attempts (15.6%). Conclusions: This is the largest study looking at accuracy of carpal tunnel injection using anatomic landmarks. Our injection accuracy (75.7%) is less than reported in previous studies, which note 82% to 100% accuracy using the same injection technique. This may indicate that carpal tunnel injection is less reliable than previously thought. Safety of carpal tunnel injection remains an important concern. The median nerve was penetrated in 8.7% of attempts.

Ultrasound assessment of the median nerve: a biomarker that can help in setting a treat to target approach tailored for carpal tunnel syndrome patients

Ultrasonography (US) is a valuable tool for confirming the diagnosis of carpal tunnel syndrome (CTS) as it enables the detection of changes in the median nerve shape and rule out anatomic variants as well as space-occupying lesions such as ganglion cysts or tenosynovitis. This work was carried out aiming at: 1. Ultrasonography assessment of the median nerve and its neurovascular blood-flow in CTS patients before and after management. 2. Verify the possibility of using baseline US parameters as a biomarker to predict likely outcomes and frame a treatment plan for CTS patients. 233 CTS subjects diagnosed based on clinical and electrophysiological (NCS) testing were included in this work. US measures at the tunnel inlet included: cross sectional area, flattening ratio and neural Power Doppler (PD) signals. Patients who had severe NCS outcomes or neurological deficit were referred for open surgical decompression; the remaining patients were given the choice of either conservative or surgical management. The main outcome variable was improvement >70% in CTS symptoms. Assessments were carried out at baseline, 1-week, 1-month and 6-months post treatment. Results revealed an inverse relation between the neural vasculature and CTS severity defined by NCS (r = - 0.648). In CTS cases treated conservatively, the US measures started to improve within 1-week, whereas in the surgically treated cohort there was an initial phase of post-operative nerve measures increase, before settling at 1-month time of follow-up. The risk of poor outcomes was significantly higher (RR 3.3) in patients with high median nerve flattening ratio. This risk was most marked in the cohort with nerve flattening associated with longer duration of illness (RR 4.3) and low PD signal (RR 4.1). The results revealed that in addition to the diagnostic value of US in CTS, the detection of increased median nerve neuro-vasculature has a good prognostic value as an indicator of early median nerve affection.