Evaluation of sonographic ulnar nerve cross-sectional area cutoff values at and around the medial epicondyle for diagnosing ulnar neuropathy at the elbow in wheelchair users.
Kittipong Kitisak, Siam Tongprasert, Niracha Luengutaisilp and 4 others
PMID 41342790WHAT IT FOUND
A 10 mm² ulnar nerve size on ultrasound is highly specific for cubital tunnel syndrome in wheelchair users, making it useful for confirming the diagnosis.
However, sensitivity was low, so a normal scan does not rule out the condition.
Key findings
01At the 2 cm proximal site, a 10 mm² cutoff had 39.3% sensitivity and 91.2% specificity.
02At the medial epicondyle, a 10 mm² cutoff had 25.0% sensitivity and 89.5% specificity.
03The 2 cm proximal location showed the best overall discriminative ability among the three measured sites.
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTsWhat it means for SLPs
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What it does not show
The study population was limited to wheelchair users from a single region in Thailand, which may affect generalizability to other ethnicities or populations. Only the cross-sectional area was measured; qualitative ultrasound features like nerve echogenicity or vascularity were not assessed. Sensitivity was low across all sites, meaning many cases of cubital tunnel syndrome would be missed if ultrasound were used alone for screening.
Declared interests
The authors declare no competing interests. The study was funded by the Faculty of Medicine at Chiang Mai University.
The easy way to misread this
Do not use a normal ultrasound measurement to rule out cubital tunnel syndrome. The sensitivity was low, so many patients with confirmed nerve damage had measurements below the diagnostic cutoff.
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