ISR Autumn Meeting 2015

YOUNG INVESTIGATOR AWARD 2015

C. McDonagh
Department of Rheumatology, Tallaght Hospital, Dublin and Spinal Cord Injury, National Rehabilitation Hospital, Dun Laoghaire

Oral (15A166)

Ultrasound Assessment of The Median Nerve in Carpal Tunnel Syndrome Before and After Corticosteroid Injection

Author(s)

C. McDonagh (1,2), M. Alexander (3), D. Kane (1)

Department(s)/Institutions

1. Department of Rheumatology, Tallaght Hospital, Dublin; 2. Spinal Cord Injury, National Rehabilitation Hospital, Dun Laoghaire; 3. Department of Neurophysiology, Tallaght Hospital, Dublin, Ireland

Introduction

Carpal tunnel syndrome (CTS) is the commonest entrapment neuropathy.(1, 2) Ultrasound (US) has been used to assess the median nerve (MN) in carpal tunnel since 1992 by assessing the cross-sectional area (CSA) primarily.(3) However, there is very limited published research looking at the changes in the MN after treatment with corticosteroid injection. (4, 5) Elastography assessment of the MN after injection has not been documented.

Aims/Background

1. To assess the MN and carpal tunnel before and after corticosteroid injection by means of US, NCS and clinical assessment.

2. To establish if US findings can be used to predict whether a patient will respond to injection.

3. To establish what the clinical outcome is at 6 months to corticosteroid injection in CTS.

Method

Patient with symptoms and signs of idiopathic CTS based on clinical assessment were recruited from outpatients’. Patients were assessed with US (including elastography and power doppler), NCS and the Levine- Katz CTS questionnaire (LKQ) and visual analogue score (VAS) for pain at baseline, 6 weeks and 6 months. LKQ was the primary outcome measure. Healthy volunteers were also recruited to act as a control group.

Results

A total of 29 patients (40 wrists) and 12 controls (23 wrists) were included in the study. The LKQ scores improved significantly between baseline and 6 weeks (p= = <0.001) but this significant improvement was not maintained at 6 months. VAS improved significantly between baseline and 6 weeks. There was a statistically significant reduction in CSA of the MN at 6 weeks and 6 months (p= 0.002 and 0.038 respectively). Vascularity and MN stiffness as assessed by elastography did not change significantly during the study period. All six NCS parameters assessed improved significantly. CSA of the MN could not predict response to injection as there was no significant difference in CSA of the MN in responders versus non responders.

Conclusions

Corticosteroid injection leads to significant improvement in median nerve CSA as assessed by US and function as assessed by NCS up to 6 months. However patients’ subjective assessment of improvement in symptoms and function did not match the objective measures at 6 months. US cannot be used to predict response to treatment based on this study.