Severity of Autonomic and Sensory Neuropathy and the Impairment of Visual- and Auditory-Evoked Potentials in Type 1 Diabetes

Abstract

Is there a relationship?I t became clear in the last decades that neuropathy is not a separate clinical entity, but a component of several related complications (1). Although the functional consequences of neuropathy are well defined in various organ systems, the relationship of the alterations in the networks of the neuronal system is still poorly documented. Assessment of the potential common alterations of the different neuronal functions in patients with diabetic neuropathy may provide new pathogenetic and diagnostic considerations. Previously, we observed correlations between the delay of certain auditory-evoked potentials and the severity of autonomic and peripheral sensory neuropathy in patients with type 1 diabetes (2). In addition, we found a relationship between the latency of visual-evoked potentials and the peripheral neuronal function (3). The aims of this study were to analyze the possible correlations between the central auditory and visual afferentations and the severity of autonomic and sensory neuropathy in patients with long-standing type 1 diabetes.A total of 10 middle-aged type 1 diabetic patients with long-standing diabetes were included in the study (4 male and 6 female subjects aged 43.8 Ϯ 15.2 years [mean Ϯ SD], duration of diabetes 23.1 Ϯ 9.3 years, BMI 27.9 Ϯ 3.9 kg/m 2 ). Patients with abnormal hearing, proliferative retinopathy, impaired visual acuity, or neuropathy of origin other than diabetes were excluded. The quantitative characteristics of the brainstem function were evaluated by the detection of auditoryevoked potentials after the delivery of an audible click of short duration via an earphone (4). The latencies of the first five waves (I-V) were analyzed in this study.The central afferent visual function was evaluated via the delay of the major positive component (P100) of the visualevoked potentials that was generated following a pattern-reversal checkboard stimulation (5). Cardiovascular autonomic function was assessed by means of the five standard cardiovascular reflex tests (2,3,6). The heart rate tests (the heart rate response to deep breathing, the 30:15 ratio, and the Valsalva ratio) mainly reflect the parasympathethic function, whereas the systolic blood pressure response to standing up and the diastolic pressure change to a sustained handgrip predominantly characterize the sympathetic integrity. Detection of current perception thresholds (CPTs) with a neuroselective transcutaneous stimulator, the Neurometer (Neurotron, Baltimore, MD), allowed for the assessment of the sensory function at three different frequencies on the median and peroneal nerves (6). The analysis of the auditoryevoked potentials revealed negative relationships between the heart rate tests and the prolongation of the latencies of waves III and V (heart rate response to breathing-wave III, r ϭ Ϫ0.586, P Ͻ 0.01; 30:15 ratio-wave III, r ϭ Ϫ0.588, P Ͻ 0.01; heart rate response to breathingwave V, r ϭ Ϫ0.498, P Ͻ 0.05; Valsalva ratio-wave V, r ϭ Ϫ0.463, P Ͻ 0.05; and 30:15 ratio-wave V, r ϭ Ϫ0.599, P Ͻ 0...

Cochlear, auditory brainstem responses in Type 1 diabetes: relationship with metabolic variables and diabetic complications

“…Nevertheless, we detected a trend towards an association between peripheral neuropathy and/or cardiac autonomic dysfunction and the presence of wave IV. The latter may suggest early damage of small nerve fibres within the auditory pathway at the pons and midbrain level – lateral lemniscus and inferior colliculi – in line with evidence that small nerve fibres may be affected first in diabetic neuropathy . Our data build on recent research detecting an association with distal symmetric polyneuropathy .…”

Diabetic Gastroparesis: Functional/Morphologic Background, Diagnosis, and Treatment Options

“…In line with this, a recent study demonstrated altered central sensory processing in diabetic patients with upper abdominal symptoms [55]. A few clinical observations suggest the role of the central neuronal system in the regulation of certain visceral functions, including gastric motility [56]. The severity of the autonomic neuronal damage in humans is not yet measurable directly; therefore, reproducible and sensitive cardiovascular and sensory tests are applied to estimate the neuronal dysfunctions in patients with abnormal gastric emptying or GI symptoms.…”

Olfactory Dysfunction in Diabetes

“…The measurements of the auditory and VEPs led to a novel observation, as a correlation was found between the impairment of the latencies of both pathways. 21 This observation suggests that different central manifestations are related to each other. Based on the correlations with autonomic and sensory neuropathy, our findings also suggest that these abnormal central afferentations should be considered as early manifestations of neuropathy.…”