The Flexor Pollicis Longus Reflex Interrater and Intrarater Reliability in Comparison With Established Muscle Stretch Reflexes

Objective: The aim of this study was to investigate the interrater reliability and intrarater reliability of the flexor pollicis longus muscle stretch reflex (FPLR) and compare it with clinically established reflexes. Design: A total of 71 healthy volunteers participated. The FPLR, biceps reflex, brachioradialis reflex, and patellar tendon reflex of each participant were tested bilaterally and rated by eight examiners (four experienced, four inexperienced). For intrarater reliability evaluation, five examiners rated the reflexes of four volunteers at four different points in time. Results: Analysis of the interrater reliability withGwet'sAC1 demonstrated almost perfect agreement for FPLR (Gwet's AC1 = 0.90), biceps reflex (Gwet's AC1 = 0.90), and patellar tendon reflex (Gwet's AC1 = 0.95) when using binary data (reflex present vs. absent). Only fair agreement was found for the brachioradialis reflex (Gwet's AC1 = 0.56). Experienced raters had a higher agreement than inexperienced raters did when rating the biceps reflex and the patellar tendon reflex. The intrarater reliability was almost perfect for the patellar tendon reflex (Gwet's AC1 = 0.94), followed by the FPLR (Gwet's AC1 = 0.83) with substantial agreement and the biceps reflex (Gwet's AC1 = 0.57) with moderate agreement. Conclusion: The FPLR is a reliable diagnostic neuromuscular test and may therefore be useful in the clinical examination for C8/T1 nerve root lesions or pathologies of the interosseous anterior nerve.