Diabetic and nondiabetic lumbosacral radiculoplexus neuropathies: new insights into pathophysiology and treatment

Abstract

Diabetic lumbosacral radiculoplexus neuropathy (DLRPN) (also called diabetic amyotrophy) is a well-recognized subacute, painful, asymmetric lower-limb neuropathy that is associated with weight loss and type II diabetes mellitus. Nondiabetic lumbosacral radiculoplexus neuropathy (LRPN) has received less attention. Comparison of large cohorts with DLRPN and LRPN demonstrated that age at onset, course, type and distribution of symptoms and impairments, laboratory findings, and outcomes are similar. Both conditions are lumbosacral radiculoplexus neuropathies that are associated with weight loss and begin focally with pain but that evolve into widespread, bilateral paralytic disorders. Although both are monophasic illnesses, patients have prolonged morbidity from pain and weakness, and many patients become wheelchair-dependent. Although motor-predominant, there is unequivocal evidence that autonomic and sensory nerves are also involved. Cutaneous nerves from patients with DLRPN and LRPN show pathological evidence of ischemic injury (multifocal fiber loss, perineurial thickening and degeneration, neovascularization, microfasciculation, and swollen axons with accumulated organelles) and microvasculitis (mural and perivascular inflammation, separation and fragmentation of mural smooth muscle layers of microvessels and hemosiderin-laden macrophages). Controlled trials with immune-modulating therapies in DLRPN are in progress, and preliminary data suggest that such therapy may be beneficial in LRPN. It is likely that DLRPN and LRPN are immune-mediated neuropathies that should be separated from chronic inflammatory demyelinating polyneuropathy and from systemic necrotizing vasculitis.