Role of Neurologists and Diagnostic Tests on the Management of Distal Symmetric Polyneuropathy

IMPORTANCE Distal symmetric polyneuropathy (DSP) is a prevalent condition that results in high costs from diagnostic testing. However, the role of neurologists and diagnostic tests in patient care is unknown. OBJECTIVE To determine how often neurologists and diagnostic tests influence the diagnosis and management of DSP in a community setting. DESIGN, SETTING, AND PARTICIPANTS In this retrospective cohort study, we used a validated case-capture method (International Classification of Diseases, Ninth Revision screening technique with subsequent medical record abstraction) to identify all patients with a new DSP diagnosis treated by community neurologists in Nueces County, Texas, who met the Toronto Diabetic Neuropathy Expert Group consensus criteria for probable DSP. Using a structured data abstraction process, we recorded diagnostic test results, diagnoses rendered (before and after testing), and subsequent management from April 1, 2010, through March 31, 2011. MAIN OUTCOMES AND MEASURES Changes in DSP cause and management after diagnostic testing by neurologists. RESULTS We identified 458 patients with DSP followed up for a mean (SD) of 435.3 (44.1) days. Neurologists identified a cause of DSP in 291 patients (63.5%) before their diagnostic testing. Seventy-one patients (15.5%) had a new DSP cause discovered after testing by neurologists. The most common new diagnoses were prediabetes (28 [6.1%]), vitamin B-12 deficiency (20 [4.4%]), diabetes mellitus (8 [1.7%]), and thyroid disease (8 [1.7%]). Management changes were common (289 [63.1%]) and usually related to neuropathic pain management (224 [48.9%]). A potential disease-modifying management change was made in 113 patients (24.7%), with the most common changes being diabetes management in 45 (9.8%), treatment with vitamins in 39 (8.5%), diet and exercise in 33 (7.2%), and adjustment of thyroid medications in 10 (2.2%). Electrodiagnostic testing and magnetic resonance imaging of the neuroaxis rarely led to management changes. CONCLUSIONS AND RELEVANCE Neurologists diagnosed the cause of DSP in nearly two-thirds of patients before their diagnostic testing. Inexpensive blood tests for diabetes, thyroid dysfunction, and vitamin B12 deficiency allowed neurologists to identify a new cause of DSP in 71 patients (15.5%). In contrast, expensive electrodiagnostic tests and magnetic resonance imaging rarely changed patient care.