Neuromuscular Consequences of Diabetic Neuropathy: Motor Unit Loss, Transmission Instability, and Alterations in Muscle Form and Function (P6.252)

Objective: To investigate how diabetic polyneuropathy (DPN) impacts the neuromuscular system in humans using a comprehensive and novel array of complementary measures. Background: The early stages of DPN typically result in length-dependent sensory impairments, but can eventually lead to dysfunction of the neuromuscular system. However, these DPN-associated neuromuscular deficits are studied less often and are more poorly understood. Our laboratory has undertaken a set of interrelated investigations using decomposition enhanced quantitative electromyography (DQEMG), dynamometry, and magnetic resonance imaging (MRI) to examine neuromuscular alterations in patients with severe DPN. Design/Methods: Patients with DPN (n = 12) were compared with age- and sex-matched controls (n = 12). Neuromuscular parameters related to the tibialis anterior (TA) and dorsiflexion were examined. DQEMG was used to derive: motor unit number estimates (MUNE), standard needle EMG parameters, and measures of neuromuscular transmission stability (e.g. jiggle, jitter, [percnt] blocking). Dynamometry and electrical stimulation were used to assess: contractile speed, muscle strength and endurance during a sustained isometric fatiguing task. MRI provided assessment of muscle quantity and quality. Associations between variables of interest (e.g. MUNE and muscle strength) were examined. Results: Patients with DPN were weaker (-35[percnt]), slower (-45[percnt]) and more easily fatigued (-21[percnt]) than controls (p 0.05). Conclusions: DPN may result in major changes to the neuromuscular system beyond weakness and muscle atrophy. Combined with sensory deficits, these changes likely contribute to decreased functional capacity and impaired mobility in this population. Disclosure: Dr. Allen has nothing to disclose. Dr. Doherty has nothing to disclose. Dr. Rice has nothing to disclose. Dr. Kimpinski has nothing to disclose.