Concordance between different measures of small sensory and autonomic fibre neuropathy in diabetes mellitus.
This study presents concordance data from 3 different tests of small nerve-fibre function on the same diabetic patients and also examines the effects of hyperglycaemia. Thus the TTT-Glasgow automated thermal threshold test, EAR-Electrically evoked axon reflex flare, and GOE-Gastric emptying of a mixed sold/liquid meal and oesophageal emptying of a solid bolus were all measured on 25 diabetic patients. The TTT, EAR and GOE all gave values ranging from within the normal reference range for non-diabetics to markedly dysfunctional readings. Mean warm perception (WPT) on the foot dorsum averaged 0.73 degrees C +/- 0.93 for normal controls, but was 4.67 degrees C +/- 3.99 in the 25 diabetics. Cold perception thresholds (CPT) were 0.48 degrees C +/- 0.55 for normal subjects and 3.75 degrees C +/- 4.28 for diabetics. In the same normal subjects the mean EAR flare laser flux responses (for 8 and 16 noxious TENS pulses) was 2.8 V.min, while for diabetics the mean was 0.2 V.min. Solid and liquid gastric 50% emptying times and oesophageal emptying for non-diabetics were within normal range (mean 78 min and 18 min, 18 sec respectively) but for the 25 diabetics emptying times ranged from normal to very prolonged (mean 114 min and 30 min, 68 sec respectively). A plot of 3 measured variables (TTT, EAR and GOE) showed a high degree of correspondence between the gastro-oesophageal emptying delays and the presence of reduced electrical axon reflex and elevated thermal thresholds. Of 25 patients, 6 could be classed as within normal limits on all 3 variables, but 8 of 25 displayed objective evidence of C-fibre neuropathy--thermal perceptual impairment (C- and A-delta sensory fibres), reduced neurogenic inflammatory flare (peptidergic nociceptive afferents) and delayed gastro-oesophageal emptying (vagal afferent/efferent fibres).
Westerman
R A
RA
Department of Physiology, Monash University, Clayton, Vic.
Delaney
C
C
Ivamy-Phillips
A
A
Horowitz
M
M
Roberts
A
A
D001341:Autonomic Nervous System / Q000503:physiopathology*; D001342:Autonomic Nervous System Diseases / Q000503:physiopathology*; D001369:Axons / Q000502:physiology; D003929:Diabetic Neuropathies / Q000503:physiopathology*; D004558:Electric Stimulation; D005746:Gastric Emptying; D006801:Humans; D009474:Neurons / Q000502:physiology*; D009475:Neurons, Afferent / Q000502:physiology*; D012684:Sensory Thresholds; D012867:Skin / Q000294:innervation; D014630:Vagus Nerve / Q000503:physiopathology; D014664:Vasodilation / Q000502:physiology