Is ultrasonography useful in the diagnosis of the polyneuropathy in diabetic patients?
Mehmet Agirman, Ilker Yagci, Merve Akdeniz Leblebicier and 2 others
PMID 27799707WHAT IT FOUND
Ultrasound showed larger ulnar nerves at the elbow in diabetic patients with polyneuropathy or carpal tunnel syndrome.
The elbow measurement was the most effective ultrasound parameter for polyneuropathy diagnosis, but no diagnostic gold standard existed.
Key findings
01Median nerve cross-sectional area at the pisiform was 14.4 mm2 in diabetic patients with carpal tunnel syndrome and 12.5 mm2 in those with polyneuropathy and carpal tunnel syndrome, compared with 8.8 mm2 in controls.
02Ulnar nerve cross-sectional area at the medial epicondyle was 7.7 mm2 in controls and 9.2 mm2 in carpal tunnel syndrome, 9.2 mm2 in polyneuropathy, and 9.3 mm2 in polyneuropathy with carpal tunnel syndrome.
03An ulnar nerve cutoff of 8.5 mm2 at the medial epicondyle identified diabetic polyneuropathy with 70.4% sensitivity and 71.4% specificity.
STILL TO COME
How it was doneWhat they found
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What it does not show
There was no accepted gold standard for diagnosing carpal tunnel syndrome or diabetic polyneuropathy, so ultrasound was compared with clinical and nerve conduction tests that may themselves be imperfect. Some participants classified as normal by nerve conduction were classified as having carpal tunnel syndrome or polyneuropathy by ultrasound. Patients with ulnar entrapment or radiculopathy were excluded, so the findings may not apply to patients with those conditions. Focal entrapment neuropathies could be confused with polyneuropathy because the study could not accurately distinguish them. The study was single-center and used laboratory normative values, which may not transfer to other settings. Some enrolled patients were excluded from analysis, so the analysed sample was smaller than the recruited sample.
The easy way to misread this
Do not use ultrasound alone to diagnose diabetic polyneuropathy. The study had no gold standard, and ultrasound classified some people as having neuropathy when nerve conduction tests were normal.