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Selected Publication:
Marschall, A.
Ultrasound in Carpal Tunnel Syndrome
Predictive value of baseline B-Mode and Power Doppler assessment for long-term functional outcome
Humanmedizin; [ Diplomarbeit ] Graz Medical University; 2015. pp.
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- Authors Med Uni Graz:
- Advisor:
- Dejaco Christian
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- Abstract:
- Background: Carpal Tunnel Syndrome (CTS) is the most frequent syndrome of entrapment of peripheral nerves and is caused by an impairment of the median nerve due to compression as it passes through the Carpal Tunnel. The diagnostic value of ultrasound imaging in CTS by means of measurement of the Cross-sectional Area (CSA) of the median nerve has been established. However, reports on its prognostic value regarding the long term outcome are rare and contradictory. Objectives: To investigate the prognostic value of baseline B-mode and Power Doppler (PD) ultrasound assessment of the median nerve in CTS patients regarding their long-term functional outcome. Methods: Out of 136 patients with suspected CTS, we conducted a prospective study on 27 patients with confirmed CTS, who underwent baseline visit and two follow-up visits: short-term after 2.8 months, long-term after 26.8 months (mean). Clinical, neurophysiological (NCS) and sonographic evaluation was performed at each visit. Ultrasound was performed using a Logiq E9 ultrasound device with multifrequence linear transducer, measuring the CSA of the median nerve at the following anatomic levels: (1) proximal border of the Pronator quadratus muscle (CsP), (2) area of the proximal Third of the pronator quadratus muscle (CsT) and (3) in the carpal canal, level of the Scaphoid tubercle and pisiform bone (CsS). PD-signals were graded from 0-3. Clinical outcome was evaluated regarding patients clinical improvement, based on: (1) the DASH questionnaire, (2) the visual analogue scale for grading pain symptoms (painVAS), (3) the VAS for grading severity of the clinical condition, completed by the examiner (physVAS). We conducted multivariate inclusive logistic regression models (including age, gender, BMI, vascularisation and symptom duration as covariates) to determine the predictive value of CSA and PD for the binary dependent variable of outcome: improvement/no improvement of both at least 20% and 70%. Results: 42.2% and 33.3% of the CTS patients showed improvement of at least 20% and 70%, respectively regarding painVAS from baseline to long-term follow-up: 53.3% and 42.2% presented improvement of physVAS and 37.8% and 15.6% showed improvement of DASH. CsS, CsS/CsP and CsS/CsT were higher in patients without improvement compared to those with at least 20% or 70% improvement. CsS/CsP presented the most relevant predictive value for clinical improvement, being significant in all logistic regression models and yielding ORs of 0.000 – 0.012 (p<0.05) for an improvement of at least 20%. In models predicting an improvement of at least 70%, CsS/CsP showed to be significant for painVAS and almost reached significance for physVAS and DASH (p=0.069 and p=0.076 respectively). We found similar results for CsS/CsT (being significant in all regression models predicting an improvement of at least 20%) and CsS (being significant in models predicting an improvement of at least 20% of painVAS and DASH, and predicting an improvement of at least 70% of painVAS). PD scores were not linked with the clinical outcomes investigated. Conclusions: A higher CSA at baseline predicts a worse clinical outcome of CTS patients as determined by VAS and DASH. PD examination has no predictive value regarding CTS outcomes.