Acute weakness: A practical step-by-step approach to distinguishing myelopathy from neuropathy

PURPOSE: The primary care clinician may on occasion need to evaluate the patient who presents with acute or insidious weakness, which may be as a result of a myelopathy or neuropathy. The purpose of this article is to review a step-by-step practical approach to the diagnosis and treatment of these conditions based on available data and expert opinion. EPIDEMIOLOGY: Guillain-Barré syndrome is the most common type of acute neuropathy presenting with weakness or paralysis, and affects 10 to 20 individuals per million in the United States. Acute weakness secondary to spinal cord injury (myelopathy) is uncommon (32 cases per million population), but its impact on the individual, his family, and society are significant. REVIEW SUMMARY: This review highlights the various conditions that may result in a presentation of an acute neuropathy or myelopathy, and provides criteria to distinguish between them. A practical algorithm is provided, allowing the clinician, guided by key historical questions and data from the physical examination, laboratory, and neuroimaging studies, to determine probable underlying etiologies and initiate proper treatment in a timely fashion. TYPE OF AVAILABLE EVIDENCE: Systematic reviews, randomized, controlled trials, cohort studies, case reports, unstructured reviews, and textbooks. GRADE OF AVAILABLE EVIDENCE: Good. CONCLUSION: Although not every acute myelopathy has a clearly established treatment, the available evidence suggests that appropriate classification and treatment of patients with acute myelopathies eliminates unnecessary testing and can improve outcomes. Recent studies have identified key predictors of recovery in certain forms of myelopathy and ongoing studies are attempting to define diagnostic strategies that appropriately classify and prognosticate outcomes in patients with myelopathies.