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ultrasound guidance in carpal tunnel syndrome surgery
Recently on the ASSH list serve a member mentioned using the Manos method to check the position of the device with Ultrasound. He also said he could identify the recurrent motor branch to the thenar muscles
I for one can not identify the median nerve in the carpal canal on either vertical or transverse images
I certainly can not identify the motor branch
Can anyone give me a hint on how to identify those structures
George Balfour
Van Nuys CA
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Replies to This Discussion
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Permalink Reply by Paxton Holt Daniel on -
Hey George,
I think this is a good site for explaining the anatomy: http://www.med.umich.edu/rad/muscskel/mskus/images/193/193_ct.html
As you know the nerve dives posteriorly from the carpal tunnel as you scan more proximally up the forearm. This helps me the most to differentiate it from the tendons. The nerve looks different from the tendons as it has the appearance of multiple small cables within the nerve itself. Some folks find it useful that nerves demonstrate less anisotropy than tendons and thus angling the transducer shows less of a change in the echogenicity of nerves versus tendons. I have not found that of much use.
It helps me to use the highest frequency for the transducer I have (linear 13 mHz), compound imaging turned on (big help), and focal zone at the back third of the carpal tunnel. I like using two focal zones in the wrist as I think I can see things clearer and yet this number of focal zones doesn't slow down the frame rate (which can make the image "smear" as you move the transducer). Lastly, you can have the patients flex their fingers during the study if you are still stuck, tendons move and the median nerve doesn't.....or better not.
Best of luck.
Holt Daniel
Radiology
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Permalink Reply by Syed Amir Gilani on -
I agree with details nicely provided by Dr Holt Daniel,just to add few point,In CTS I have seen that the nerve becomes flat,hypoechoic,area more than 15mm2, symmetry disturbed,no gliding on tendons by moving wrist as it is compressed under the thickened flexor retinaculum.
syed amir gilani
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