The diagnostic yield of a standardized approach to idiopathic sensory-predominant neuropathy

Background: Peripheral neuropathy is a common problem that often prompts a lengthy and expensive diagnostic evaluation. A rational, evidence-based diagnostic approach to peripheral neuropathy is desirable. Prior studies have focused on all patients presenting to a tertiary referral center with a diagnosis of unclassified neuropathy. However, most patients with peripheral neuropathy have primarily sensory symptoms. This study focuses on patients with sensory-predominant neuropathy. The goal was to develop a focused diagnostic algorithm that can be easily applied in a general medical setting. Methods: Patients referred with predominantly sensory symptoms and no previously defined cause were included and evaluated using a standard diagnostic approach. Results: Among 138 patients, 25% had at least 1 first-degree relative with symptoms suggestive of neuropathy. Among laboratory studies, a 2-hour oral glucose tolerance test had the highest diagnostic yield (61%) and was more sensitive than other measures of glucose metabolism. Vitamin B-12 deficiency was identified in 2 patients. Results of serum protein electrophoresis, immunofixation, and antinuclear antibody testing were abnormal in less than 5% of patients, and these rates are similar to those found in the general population. Using this approach, only 31% of patients completing the recommended evaluation were found to have an idiopathic neuropathy. Conclusions: Patients with sensory-predominant neuropathy should be tested for glucose tolerance and vitamin B-12 concentration. The significance of abnormalities of serum protein electrophoresis and antinuclear antibodies is uncertain. Other tests should be performed only when the clinical scenario is suggestive. Patients with atypical features may benefit from referral to a peripheral neuropathy center.