A practical guide to assessing functional motor weakness: a review of validated techniques

Functional neurological symptom disorder, specifically, functional limb weakness, is a commonly seen condition in clinical neurological practice and requires careful examination for diagnosis. Specific and detailed examination techniques have been developed and validated over the past 100 years to help clinicians differentiate functional limb weakness from objective neurological weakness. These techniques vary in sensitivity, specificity, clinical application, and limitations. However, over time, the studied and/or validated forms of these exam techniques may have been lost and often not performed or taught in the way it was originally studied, thus decreasing the reliability of the examiner's findings. With many new examination techniques for functional limb weakness having been studied in recent years, it is important to not only review the form of each of these examination techniques, but also discuss the clinical applications, limitations, and utility of each. To date, there has been no comprehensive review demonstrating the exact form of all the studied and/or validated examination techniques for functional limb weakness and their proposed clinical utility. This review analyzes 9 examination techniques for functional limb weakness that have been studied for validity and provides readers with the exact technique of examination used to study each. It also outlines their sensitivity, specificity, clinical applications, and limitations to help clinicians accurately diagnose functional limb weakness.