Mohamed Mahmoud Hamdy Abd Ellah MD, Presenter: Nothing to Disclose

Thomas Auer MD, Abstract Co-Author: Nothing to Disclose

Eberle Gernot MD, Abstract Co-Author: Nothing to Disclose

Lenka Gerencerova MD, Abstract Co-Author: Nothing to Disclose

Sylvia Strobl MD, Abstract Co-Author: Nothing to Disclose

Christian Kremser PhD, Abstract Co-Author: Nothing to Disclose

Gudrun Feuchtner MD, Abstract Co-Author: Nothing to Disclose

Fabian Plank MD, Abstract Co-Author: Nothing to Disclose

Mihra S. Taljanovic MD, Abstract Co-Author: Nothing to Disclose

Werner R. Jaschke MD, PhD, Abstract Co-Author: Nothing to Disclose

Andrea Klauser MD, Abstract Co-Author: Nothing to Disclose

To evaluate the role of high resolution US in prediction of carpal tunnel syndrome (CTS) severity compared to nerve conduction studies.

643 wrists of 427 CTS patients (325 females and 102 males), age ranged between 17-90 years (57.9+/-14.7, mean+/-Std) were included in this study. CTS was diagnosed clinically and confirmed by nerve conduction studies (NCS). US was performed using a 14-8-MHz (LA424, 14-8 MPX; Esaote, Genoa-Firenze, Italy) or 18-6-MHz (LA435, MyLab90; Esaote) linear array transducer. CTS severity was classified according to NCS. Cross sectional measurements (CSA) of the median nerve was done at the level of the carpal tunnel (CSAc) and more proximally at the level of the pronator quadratus muscle (CSAp). Two parameters were calculated; ∆-CSA which is the difference between the proximal and distal measurements, and R-CSA which is the ratio calculated by dividing the distal over the proximal CSA.

Patients were classified into three groups (mild, moderate, and severe) according to severity by NCS. The mean CSA was (12.5, 14.7, and 18.8), mean ∆-CSA was (4.2, 6.95, and 10.7), and mean R-CSA was (1.5, 1.95, and 2.4) in all groups respectively with a significant difference between all groups (p<0.001). The cut off value was 5.5, and 8.5 between groups 1 and 2, and groups 3 and 4 respectively for ∆-CSA, while it was 1.7 and 2.2 between the same groups for R-CSA.

By implementing cut off values for the calculated parameters (∆-CSA and R-CSA), high resolution US showed ability to predict CTS severity compared to NCS.

1. The difference between cross-sectional areas of the median nerve measured at the level of the carpal tunnel (CSAc) and at the level of the pronator quadratus muscle (CSAp) – Δ-CSA – and the ratio between the two values - R-CSA - increases with the severity of Carpal tunnel syndrome (CTS). 2. Those parameters showed significant difference between different patient groups, which were classified according to nerve conduction study results (mild, moderate, and severe). 3. Better severity determination with Δ-CSA and R-CSA is obtained with better sensitivity and specificity values compared tp measured CSAc alone especially for the differentiation between mild and moderate groups. 4. Cut off values were obtained for each parameter (Δ-CSA and R-CSA) between the different CTS severity groups.

Abd Ellah, M, Auer, T, Gernot, E, Gerencerova, L, Strobl, S, Kremser, C, Feuchtner, G, Plank, F, Taljanovic, M, Jaschke, W, Klauser, A, Sonographic Median Nerve Cross Sectional Area Measurement in CTS Patients: Can Delta and Ratio Calculations Predict Severity Compared to Nerve Conduction Studies?.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14009368.html