Recurrent CTS

[PMR 4 MSK]

I often get orders for EMG in a pt s/p carpal tunnel Release several years ago, who has new hand numbness. If the EMG is normal, all is well and good. If, however, it suggests CTS, it presents a quandary, especially if mild, such as sensory-only.

This could be recurrent CTS, or could be chronic residual nerve damage from the original CTS. A post-op EMG would be ideal, but rare. Then we could compare what has changed since the surgery.

If the old EMG is available, and it is pre-op with no post-op, and the current findings are worse, one can conclude it is a continued or recurrent case. If the new EMG findings are improved, I often don't really know how to interpret that. If it just shows axonal loss with no demylination and no APB denervation, I usually will conclude this is old, residual axonal loss, with no evidence of current nerve compression.

More often, though, I get one like today, with delay of the median motor and sensory distal latencies, mild low amplitude, or just lower than ulnar and slightly low forearm NCV, but no APB abnormalities on needle exam. To me, this is inconclusive as to whether there is active nerve compression. Basically the surgeon wants to know if re-operation is likely to benefit the pt.

Often, an old EMG is not available, and I can only go by the current findings.

How do others here approach this?

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[RUOkie]

Often, these are the people where a more detailed history is needed. If they got initial relief for 4-6 months and then the sx returned, then a redo surgery could be beneficial. If they never got any better, then consider alternative pain generators. If sx were much worse postop, and then there is a low amplitude CMAP intraop nerve injury (especially if endoscopic release) needs to be considered.

Usually, though, these patients are being referred directly by the surgeon and I just state my findings and let him/her decide what to do

 

[Ludicolo]

Agree. Hard to make recs here without an earlier post-op EMG for comparison. Usually median DLs improve following CTS release, but don’t necessarily normalize. If the patient had residual numbness since surgery, then I would probably call any mild abnormal EMG findings as expected residua of CTS release. If however the patient has new onset hand numbness several months post-op, you certainly could argue clinically that there is new nerve compression. But will it progress? Who knows? I’d suggest a follow up study in a few months, and treat it conservatively in the meantime. Can’t imagine the surgeon (or the patient) minding waiting a few more weeks.

Wondering out loud - would diagnostic ultrasound, looking at the post-op cross-sectional area of the carpal tunnel, be more useful or additive in cases like this?

 

[SSdoc33]

Wondering out loud - would diagnostic ultrasound, looking at the post-op cross-sectional area of the carpal tunnel, be more useful or additive in cases like this?

thats a good question. my guess is that the actual size of the tunnel doesnt change all that much, but the pressure is relieved by just snipping that little flap of fascia. i nice little study might be to look at the cross sectional area of the nerve itself pre-op, and then post op, to see how much it shrinks, if at all.

 

[PMR 4 MSK]

thats a good question. my guess is that the actual size of the tunnel doesnt change all that much, but the pressure is relieved by just snipping that little flap of fascia. i nice little study might be to look at the cross sectional area of the nerve itself pre-op, and then post op, to see how much it shrinks, if at all.

In a lecture I saw of CTS US, the nerve was often flattened on it's way through the tunnel. Wonder if that normalizes either.

 

[SSdoc33]

whoops, looks like i am a little late. one of these days, ill come up with an idea no one has thought of. im giving myself 20-30 years until this happens.....

1: Muscle Nerve. 2008 Aug;38(2):987-91. Links

Carpal tunnel syndrome: clinical and sonographic follow-up after surgery.

Smidt MH, Visser LH.
Department of Neurology and Clinical Neurophysiology, St. Elisabeth Hospital, PO Box 90151, LC Tilburg, The Netherlands.
High-resolution sonography has the same accuracy as electrophysiological studies in confirming the diagnosis in carpal tunnel syndrome (CTS), but the value of sonographic follow-up after surgery requires prospective examination. The aims of the present study were to assess: (1) change in the size of the median nerve at the proximal carpal tunnel after surgery compared to conservative treatment, and (2) the correlation between sonographic characteristics and clinical outcome after surgery. Seventy-nine patients undergoing surgery for CTS were assessed at least 6 months after surgery. The patients completed questionnaires and underwent sonography. Postoperative improvement was scored by the patient on a 6-point ordinal transition scale ranging from "completely recovered" to "much worse." The median cross-sectional area of the median nerve at the proximal carpal tunnel decreased after surgery from 14 mm2 [interquartile range (IQR) 12-16 mm2] to 11.5 mm2 (IQR 11-13.5 mm2) (P < 0.0001); no significant changes in the cross-sectional area occurred in symptomatic hands treated conservatively or in asymptomatic hands. Sonography at the time of diagnosis was not a predictor of postoperative outcome, but in this study only a relatively small number of patients had a poor postoperative outcome.

 

[ostensibly]

check the following if you're interested (sorry I don't have the abstracts)

-Todnem and Lundemo, Median nerve recovery in carpal tunnel syndrome Muscle & Nerve 2000;23(10):1555-60

-Mondelli. CTS in elderly patients: results of surgical decompression. J periph nervous system 9;(2004 sept):168-76

-Prick, Neurology 2002;58(or is it 56?):1603

-stutz. Revision surgery after CT release-analysis of the pathology in 200 cases during a 2 year period. J hand
surg (british and european volume) 2006;31B:1: 68-71

-Thoma, systematic review of reviews comparing the effeectiveness of endoscopic and open carpal tunnel
decompression. plastic & reconstructive surgery 113 (2004, Apr1):1184-91

-Uchivama, Clinical Neurophysiology 113 (2002) 64-70