Neuropad as a diagnostic tool for diabetic autonomic and sensorimotor neuropathy

• Published in: Diabetic medicine Vol. 26; no. 7; pp. 686 - 692
• Main Authors: Spallone, V., Morganti, R., Siampli, M., Fedele, T., D'Amato, C., Cacciotti, L., Maiello, M. R.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.07.2009; Blackwell
• Subjects: Adolescent; Adult; Aged; autonomic neuropathy; Biological and medical sciences; Cold Temperature; diabetes; Diabetes Mellitus, Type 1 - complications; Diabetes Mellitus, Type 2 - complications; Diabetes. Impaired glucose tolerance; Diabetic Neuropathies - diagnosis; diagnosis; Endocrine pancreas. Apud cells (diseases); Endocrinopathies; Etiopathogenesis. Screening. Investigations. Target tissue resistance; Feeding. Feeding behavior; Female; Fundamental and applied biological sciences. Psychology; Humans; Male; Medical sciences; Middle Aged; peripheral neuropathy; Polyneuropathies - diagnosis; Statistics as Topic; Thermosensing; Time Factors; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Vertebrates: endocrinology; Vibration; Young Adult; Endocrinopathy; Obesity; Nervous system diseases; Nutrition; Diabetes mellitus; Nutrition disorder; Metabolic diseases; Neuropathy; peripheral neuropathy; Autonomic nervous system; Diseases of the autonomic nervous system; Diagnosis; Peripheral nerve disease; Autonomic neuropathy; diabetes; Endocrinology; Nutritional status; Tool
• ISSN: 0742-3071; 1464-5491
• DOI: 10.1111/j.1464-5491.2009.02760.x

Aims  The aim of the present study was to determine the diagnostic accuracy of the Neuropad sudomotor test for diabetic cardiovascular autonomic neuropathy (CAN) and diabetic polyneuropathy (DPN), the latter assessed using a multi‐level diagnostic approach. Methods  In 51 diabetic patients, CAN, symptoms and signs of DPN, vibration perception threshold (VPT), cold (CTT) and warm thermal perception thresholds (WTT) were measured. Neuropad response was determined as normal (complete colour change) or abnormal (absent or incomplete colour change). The time until the complete colour change (CCC time) was recorded. Results  CCC time showed significant correlations with all the neurological parameters, the strongest of which were with Valsalva ratio (ρ = −0.64, P < 0.0001), symptoms of DPN (ρ = 0.66, P < 0.0001), postural hypotension (ρ = 0.54, P = 0.0001) and CTT (ρ = −0.54, P = 0.0001). CCC time showed moderate diagnostic accuracy for both CAN and DPN: the areas under the receiver operating characteristic (ROC) curves were 0.71 and 0.76, respectively. The diagnostic characteristics of three cut‐off values of CCC time, identified by ROC analysis (i.e. 10, 15 and 18 min), were analysed. Compared with 10 min, the 15‐min cut‐off value provided better specificity (from 27% to 52% and from 31% to 62% for CAN and DPN, respectively) and a better likelihood ratio for negative result (from 0.67 to 0.34 and from 0.58 to 0.33) without lowering sensitivity (from 82% to 82% and from 85% to 80%). Conclusions  Neuropad is a reliable diagnostic tool for both CAN and DPN, albeit of only moderate accuracy. Extending the observation period to 15 min provides greater diagnostic usefulness.