Sensory manifestations of diabetic neuropathies: Anatomical and clinical correlations

Background: Diabetes mellitus is among the most common causes of peripheral neuropathy worldwide. Sensory impairment in diabetics is a major risk factor of plantar ulcers and neurogenic arthropathy (Charcot joints) causing severe morbidity and high health-care costs. Objective: To discuss the different patterns of sensory alterations in diabetic neuropathies and their anatomical basis. Study design: Literature review. Methods: Review of the literature discussing different patterns of sensory impairment in diabetic neuropathies. Results: The different varieties of diabetic neuropathies include typical sensorimotor polyneuropathy (lower extremity predominant, length-dependent, symmetric, sensorimotor polyneuropathy presumably related to chronic hyperglycemic exposure, and related metabolic events), entrapment mononeuropathies, radiculoplexus neuropathies related to immune inflammatory ischemic events, cranial neuropathies, and treatment-related neuropathies (e.g. insulin neuritis). None of these patterns are unique for diabetes, and they can occur in nondiabetics. Sensory alterations are different among these prototypic varieties and are vital in diagnosis, following course, treatment options, and follow-up of treatment effects. Conclusions: Diabetic neuropathies can involve any segment of peripheral nerves from nerve roots to the nerve endings giving different patterns of abnormal sensation. It is the involvement of small fibers that causes positive sensory symptoms like pain early during the course of disease, bringing subjects to physician's care. Clinical Relevance This article emphasizes on the fact that diabetic neuropathies are not a single entity. They are rather different varieties of conditions with more or less separate pathophysiological mechanisms and anatomical localization. Clinicians should keep this in mind when assessing patients with diabetes on the first visit or follow-up.