Background Though there are various carpal tunnel syndrome (CTS) treatment options, their outcomes and long-term effects are still debatable. An accurate understanding of the predictive factors of CTS management outcomes would enable physicians and patients to make more informed decisions about an approach tailored to the patient's condition and develop more accurate expectations of outcomes.

Objectives 1. To assess the median nerve both by Gray-scale US and intra-neural vascular flow (using Power Doppler (PD) before and after management in subjects with CTS, and 2. to verify the feasibility of initial US parameters for prediction of management outcome.

Methods 233 subjects, mean age 55.6 years, diagnosed with CTS established by clinical and electrophysiological (NCS) findings. Baseline clinical, electrophysiological severity (grade 1-6 score) and self-assessment scoring of symptoms (using the modified Boston questionnaire were recorded. US measures included: the median nerve area at tunnel inlet, the flexor retinaculum, and the flattening ratio as well as Intra-neural PD signals (grades 0-3). Surgical decompression was offered to the patients who had neurological deficit or severe NCS outcome (grade 5/6) whereas the rest were given the choice of being treated either conservatively (including local steroid injection) or surgically. The main outcome variable was improvement >25% in CTS symptoms questionnaire score and >50% of the patient's overall satisfaction score. US assessments were performed at baseline, 1-week, 1-months and 6-months post treatment (whether conservative or surgically). Logistic regression analyses was used to assess the best predictive combination of preoperative findings.

Results There was an inverse relation between intra-neural vasculature in the median nerve (PD score) and increasing CTS severity based on nerve conduction results (r= - 0.648). In the patients cohort treated conservatively, US measures of the median nerve started to improve within a week of local injection, whereas in those treated surgically there was an initial phase of post-operative increase of the median nerve measures, before settling at 1-month time of follow up. The risk of a poor outcome was significantly higher in the patients with high median nerve flattening ratio at the CT inlet (relative risk 3.3, 95% CI 1.73-6.43, P=0.0004). This risk was most marked in the cohort with nerve flattening associated with longer duration of illness (relative risk 4.3, 95% CI 1.82-10.29, P=0.006) and low PD signal (relative risk 4.1, 95% CI 1.71-9.47, P=0.005). Clinical predictors of poor outcome included: neurological deficit and predisposing medical conditions. Nerve conduction testing did not show significant response to management.

Conclusions In addition to the diagnostic value of US in CTS, the detection of increased intra-neural vasculature of the median nerve is an indicator of early median nerve affection and has a good prognostic value. Increased flattening of the median nerve with low vascularity assessed by PD has a poor prognostic impact. Nerve conduction studies are not a good tool to monitor response to therapy, whereas US can be used to monitor median nerve changes as early as 1 week of management.

Acknowledgements To Omar El Miedany for Data Recording and admin support

Disclosure of Interest : None declared

DOI 10.1136/annrheumdis-2014-eular.1410