Peripheral Neuropathy: Evaluation and Differential Diagnosis

Peripheral neuropathy, a common neurologic problem encountered by family physicians, can be classified clinically by the anatomic pattern of presenting symptoms and, if indicated, by results of electrodiagnostic studies for axonal and demyelinating disease. The prevalence of peripheral neuropathy in the general population ranges from 1% to 7%, with higher rates among those older than 50 years. Common identifiable causes include diabetes mellitus, nerve compression or injury, alcohol use, toxin exposure, hereditary diseases, and nutritional deficiencies. Peripheral neuropathy is idiopathic in 25% to 46% of cases. Diagnosis requires a comprehensive history, physical examination, and judicious laboratory testing. Early peripheral neuropathy may present as sensory alterations that are often progressive, including sensory loss, numbness, pain, or burning sensations in a "stocking and glove" distribution of the extremities. Later stages may involve proximal numbness, distal weakness, or atrophy. Physical examination should include a comprehensive neurologic and musculoskeletal evaluation. If the peripheral nervous system is identified as the likely source of the patient's symptoms, evaluation for potential underlying etiologies should initially focus on treatable causes. Initial laboratory evaluation includes a complete blood count; a comprehensive metabolic profile; fasting blood glucose, vitamin B12, and thyroid-stimulating hormone levels; and serum protein electrophoresis with immunofixation. If the initial evaluation is inconclusive, referral to a neurologist for additional testing (e.g., electrodiagnostic studies, specific antibody assays, nerve biopsy) should be considered. Treatment of peripheral neuropathy focuses on managing the underlying etiology. Several classes of medications, including gabapentinoids and antidepressants, can help alleviate neuropathic pain.