Obesity and peripheral neuropathy risk: a dangerous liaison

Abstract

This study investigates motor (MNCS) and sensory (SNCS) nerve conduction in a sample of non-diabetic obese people without symptoms suggestive of neuropathy and looks for a possible metabolic alteration. Twenty-one patients and 20 age-matched controls underwent (a) MNCS (median, ulnar, peroneal, and tibial) and SNCS (median, ulnar, and sural); (b) quantitative sensory testing to measure sensory threshold for vibration, warm and cold sensation (WS-CS), heat and cold-induced pain; and (c) blood sample analysis to evaluate glucose and insulin levels and calculate the quantitative insulin-sensitivity check index (QUICKI). The obese group showed significantly decreased compound muscle action potential amplitude of tibial and peroneal nerves and decreased sensory action potential amplitude of all nerves. Most of the sensory thresholds were altered in obese patients. Insulin serum levels were significantly increased while QUICKI decreased in obese patients. WS and CS from the index and little fingers and WS from the big toe significantly correlated with QUICKI. Thermal and pain thresholds from the index and thermal thresholds from the little finger correlated with QUICKI values. The non-diabetic obese patients showed a subclinical involvement of different diameter sensory fibers. Such impairment was related to hyperinsulinemia and insulin sensitivity. The increase in sensory threshold of obese patients might be due to a metabolic alteration, potentially leading to a future clinical neuropathy.

Body weight affects behavioural indication of thermal nociceptive threshold in adult domestic cats (Felis catus)

“…For humans the level of subcutaneous fat deposition is found to significantly decrease skin temperature around the abdomen (Savastano et al, 2009). This may translate into a longer duration for heavier individuals to respond to thermal stimulation as observed by Miscio et al (2005) and here in cats. The body weight of our subjects and the range of condition scores may mean that skin temperature did vary significantly between individuals.…”

“…In contrast, there is evidence that obesity affects latency to respond to thermal stimulation either as a result of obesity mediated inflammatory responses or thermal sensitivity. Some studies demonstrate a reduced latency of obese rats to respond to thermal stimulation following simulated inflammation (Iannitti et al, 2012), whilst other studies demonstrate increased latency of obese humans to respond following thermal stimulation of peripheral areas of skin (Miscio et al, 2005). The 9-point condition score system used in this study is a common measure of obesity in companion animals.…”

High-Fat Diet–Induced Neuropathy of Pre-Diabetes and Obesity

“…As one can conclude from the presence of thermal hypoalgesia and tactile allodynia, the HFD-fed mice developed small sensory nerve fiber neuropathy, i.e., a condition well documented in human subjects with IGT and the metabolic syndrome (2,4,9,10,22). Moreover, they also developed MNCV and SNCV deficits also reported in human subjects with prediabetes, overweight, and obesity (8), although studies of the association between IGT or obesity and nerve conduction changes resulted in contradictory findings (compare refs. 8 and 2).…”

“…A high BMI is a well-recognized risk factor for median nerve sensory conduction slowing and carpal tunnel syndrome (5-7). Furthermore, nondiabetic obese subjects have been reported to display significantly decreased compound muscle action potential amplitude of tibial and peroneal nerves and decreased sensory action potential amplitude of median, ulnar, and sural nerves compared with nondiabetic individuals (8). In the same study, warm and cold sensations from the index and little fingers, warm sensation from the big toe, and thermal and pain thresholds from the little finger directly correlated with the insulin sensitivity index, which was reduced in obese subjects.…”

Overview of the relationship between pain and obesity: What do we know? Where do we go next?

“…Overweight/obese individuals have an increased risk of various metabolic disorders, thus they have increased vulnerability to the neuropathic disorders associated with conditions such as diabetes [59]. However, altered sensory thresholds have been shown in nondiabetic obese individuals, which suggests that obesity alone may increase one's risk for peripheral neuropathic disorders [60]. For example, obesity has been found to be a risk factor for carpal tunnel syndrome [61].…”