Do we get additional relevant findings by imaging CTS?

Researchers who have studied the utility of ultrasound imaging in CTS frequently claim that the imaging study often reveals structural anomalies, or even outright abnormalities which either help to explain why that patient has developed CTS or have some bearing on treatment. These findings include:

High branching of the median nerve

Invasion of the carpal tunnel by normal muscles on movement - either the lumbrical muscles from the palm on finger flexion, or the long flexor muscles of the forearm on finger and wrist extension

Anomalous muscles within the carpal tunnel - some individuals have 'extra' muscles which may extend into or pass through the carpal tunnel.

Evidence of inflammation of the flexor tendons

Space occupying lesions within the carpal tunnel - ganglion cysts, tumours, granulomatous deposits, gouty tophi.

Anomalous vessels - persistent median artery, either patent or thrombosed.

The frequency with which such findings are present varies in different studies. We will add some figures from Canterbury here in due course.

It is often simply assumed that any anatomical peculiarity on the imaging constitutes important information but in practice some of these findings may make no difference at all to either the choice of treatment or the risk of complications while in other cases the significance of the imaging may depend on what course of treatment is proposed. A median nerve which branches proximal to the carpal tunnel may make endoscopic surgery more risky but for the traditional open operation it probably makes little difference. Those who argue that the ability of imaging to show these structural changes which NCS miss makes ultrasound a superior diagnostic modality to nerve conduction studies for CTS are generally neglecting the fact that the neurophysiology can show a variety of physiological changes which will be missed by ultrasound. At present the counsel of perfection appears to be to carry out both investigations where possible.

We have become convinced that ultrasound imaging can be helpful in analysing the nature of problems AFTER surgery. As this is a relatively complex topic this issue is covered in a separate page of the website.

As with other topics of interest we will continue to collect more data as patients pass through the clinic.

BACK - to the main ultrasound page

Revision date - 11th September 2017

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