Neuropad test: a visual indicator test for human diabetic neuropathy

• Published in: Diabetologia Vol. 51; no. 6; pp. 1046 - 1050
• Main Authors: Quattrini, C, Jeziorska, M, Tavakoli, M, Begum, P, Boulton, A. J. M, Malik, R. A
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Berlin/Heidelberg : Springer-Verlag 01.06.2008; Springer-Verlag; Springer; Springer Nature B.V
• Subjects: Autonomic neuropathy; Biological and medical sciences; Biopsy; Computers; Diabetes; Diabetes Mellitus, Type 1 - complications; Diabetes Mellitus, Type 1 - physiopathology; Diabetes Mellitus, Type 2 - complications; Diabetes Mellitus, Type 2 - physiopathology; Diabetes. Impaired glucose tolerance; Diabetic Neuropathies - physiopathology; Diabetic neuropathy; Endocrine pancreas. Apud cells (diseases); Endocrinopathies; Etiopathogenesis. Screening. Investigations. Target tissue resistance; Heart rate; Human Physiology; Humans; Internal Medicine; Medical sciences; Medicine; Medicine & Public Health; Metabolic Diseases; Middle Aged; Neurologic Examination - instrumentation; Neurologic Examination - methods; Pain; Reference Values; Skin innervation; Statistical analysis; Sudomotor dysfunction; Toes - innervation; Toes - physiopathology; United Kingdom > UK; Sudomotor dysfunction; Skin innervation; Diabetic neuropathy; Autonomic neuropathy; Endocrinopathy; Human; Nervous system diseases; Dysfunction; Diabetes mellitus; Innervation; Skin; Neuropathy; Autonomic neuropathy,Diabetic neuropathy· Skin innervation; Indicator
• ISSN: 0012-186X; 1432-0428
• DOI: 10.1007/s00125-008-0987-y

Aims/hypothesis The commercially available Neuropad test was developed as a simple visual indicator test to evaluate diabetic neuropathy. It uses a colour change to define the integrity of skin sympathetic cholinergic innervation. We compared the results of Neuropad assessment in the foot with established measures of somatic and autonomic neuropathy. Methods Fifty-seven diabetic patients underwent Neuropad assessment, quantitative sensory and autonomic function testing, and evaluation of intra-epidermal nerve fibre density in foot skin biopsies. Results Neuropad responses correlated with the neuropathy disability score (r s = 0.450, p < 0.001), neuropathic symptom score (r s = 0.288, p = 0.03), cold detection threshold (r s = 0.394, p = 0.003), heat-as-pain perception threshold visual analogue score 0.5 (r s = 0.279, p = 0.043) and deep-breathing heart rate variability (r s = -0.525, p < 0.001). Intra-epidermal nerve fibre density (fibres/mm) compared with age- and sex-matched control subjects (11.06 ± 0.82) was non-significantly reduced (7.37 ± 0.93) in diabetic patients with a normal Neuropad response and significantly reduced in patients with a patchy (5.01 ± 0.93) or absent (5.02 ± 0.77) response (p = 0.02). The sensitivity of an abnormal Neuropad response in detecting clinical neuropathy (neuropathy disability score >=5) was 85% (negative predictive value 71%) and the specificity was 45% (positive predictive value 69%). Conclusions/interpretation The Neuropad test may be a simple indicator for screening patients with diabetic neuropathy.