Horwell neurothesiometer

Neurothesiometry was performed using hand-held neurothesiometer (Horwell Neurothesiometer, Scientific Laboratory Supplies Ltd., Nottingham, UK) to the read vibration perception threshold (VPT) from the apex of the big toe of both legs, with the subject in a supine position, feet elevated with pillow support, and eyes closed. The neurothesiometer is a validated battery-operated diagnostic instrument that assesses sensitivity thresholds to vibration corresponding to a particular voltage at various sites on the body surface. On the basis of the method of limits, participants were asked to indicate when they first perceived vibration sensation after the stimulus was applied to the distal pulp of the toe. The intensity of the stimulus was gradually increased at a rate of 0.5 V/s from null to a voltage at which vibration was first detected. VPT was performed on each participant about 3–5 times and, at least, three VPTs that differed ≤5 V were averaged and used for analysis. A null stimulus test was randomly performed to ensure that the participant understands and adheres to the test procedure. Participants who failed to provide 3 consistent values of VPT within 5 V after seven measurements were excluded from the analysis, considered as having conflicting VPTs.

Symptoms of peripheral neuropathy was assessed using the neuropathy symptom profile (NSP). Cold (CT) and warm (WT) perception thresholds were assessed on the dorsolateral aspect of the left foot (S1) using the TSA-II NeuroSensory Analyser (Medoc, Ramat-Yishai, Israel). Electrodiagnostic studies were undertaken using a Dantec Keypoint system (Dantec Dynamics, Bristol, UK). Vibration perception threshold (VPT) was established using a Horwell Neurothesiometer (Scientific Laboratory Supplies, Wilfrod, Nottingham, UK). Deep breathing heart rate variability (DB-HRV) was established using an ANX 3.0 autonomic nervous system monitoring device (ANSAR Medical Technologies, Philadelphia, PA, USA).

Clinical assessment for diabetic peripheral neuropathy included a history of neuropathic symptoms, physical examination as recommended by the American Diabetes Association, and assessment of vibration perception threshold (VPT).15 (link) Participants' feet were examined for deformities, ulcers, calluses, pinprick sensation, and vibration sensation using a 128-Hz tuning fork and the 10-g monofilament testing was done. According to the manufacturer's guidelines, VPT was assessed using the hand-held neurothesiometer (Horwell Neurothesiometer, Scientific Laboratory Supplies Ltd, Nottingham, UK). VPT was assessed at the metatarsophalangeal joint of both feet in a two-step manner, starting from 0 V with increasing stimulation and then starting from 50 V with decreasing stimulation. Patients with a VPT greater than 15V, with or without clinical features of peripheral neuropathy, were classified as having diabetic peripheral neuropathy. Nephropathy was diagnosed using the estimated Glomerular Filtration Rate (eGFR) of < 90ml/min/1.73m². Blood urea (Urease UV method), electrolytes (the ion selective electrodes and enzymatic method for bicarbonates), and creatinine (Jaffe IDMS Traceable method) were assayed with the AU480 Beckman Coulter, USA.