Small-fibre involvement in diabetic patients with neuropathic foot pain

• Published in: Diabetic medicine 2008-06, Vol.25 (6), p.692-699
• Main Authors: Vlckova-Moravcova, E., Bednarik, J., Belobradkova, J., Sommer, C.
• Format: Article
• Language: English
• Subjects: Adult; Aged; Biological and medical sciences; Diabetes Mellitus, Type 2 - diagnosis; Diabetes Mellitus, Type 2 - physiopathology; Diabetes. Impaired glucose tolerance; Diabetic Foot - diagnosis; Diabetic Foot - physiopathology; diabetic neuropathy; Endocrine pancreas. Apud cells (diseases); Endocrinopathies; Etiopathogenesis. Screening. Investigations. Target tissue resistance; Evoked Potentials, Somatosensory; Feeding. Feeding behavior; Female; Fundamental and applied biological sciences. Psychology; Humans; Male; Medical sciences; Middle Aged; Nerve Fibers - physiology; Neurons, Afferent - physiology; pain; Pain - etiology; Pain - physiopathology; Sensation Disorders - diagnosis; Sensation Disorders - physiopathology; Sensory Thresholds - physiology; Skin - innervation; skin biopsy; small-fibre; thermal threshold; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Vertebrates: endocrinology
• ISSN: 0742-3071; 1464-5491
• DOI: 10.1111/j.1464-5491.2008.02446.x

Aims  To assess small‐fibre involvement in diabetic patients with neuropathic pain. Methods  Peripheral nerve function was assessed in 30 patients with Type 2 diabetes mellitus (T2DM, n = 24) or impaired glucose tolerance (IGT, n = 6), and clinical symptoms of neuropathic pain in the feet, using nerve conduction studies, autonomic tests, thermal quantitative sensory testing (T‐QST) and quantification of intra‐ and subepidermal nerve fibre densities in skin punch biopsies. Results  Clinical signs of isolated small‐fibre sensory involvement were present in 13 patients [pure small‐fibre neuropathy (pSFN)], seven patients had isolated positive sensory symptoms without neurological deficits (pSFN–). Ten patients had concomitant electrophysiological and/or clinical signs of large‐fibre sensory involvement [mixed‐fibre neuropathy (MFN)]. Twenty‐seven patients (90%) had both reduced skin innervation and abnormalities of the T‐QST parameters. Two other patients displayed either abnormal skin innervation or T‐QST, and only one patient had normal findings on both tests. The criteria of small‐fibre neuropathy (SFN) were met in all 20 patients without large‐fibre involvement. Small‐fibre involvement was also present in the 10 MFN patients. Both T‐QST and skin biopsy parameters revealed significant differences between these clinical subgroups, with increased severity of small‐fibre involvement in the MFN group. Autonomic dysfunction was found in 43% of patients and did not correlate with either clinical, T‐QST or skin biopsy data. Conclusions  Although the exact mechanism of neuropathic pain in diabetic patients is not known, pain is almost invariably accompanied by small‐fibre dysfunction and pathology irrespective of autonomic or large‐fibre involvement.