Different Scale, Different Pain? Discordant Pain Measurements After Surgery for Trigeminal Neuralgia

OBJECTIVE: Trigeminal neuralgia (TN) has been described as one of the worst pains known to humankind. However, pain severity in TN has been measured using several different scales, resulting in difficulty comparing illness burden and response to TN surgery across studies. We examined the degree of concordance between standardized scales evaluating pain severity in a cohort of patients undergoing surgery for TN. METHODS: In this cross-sectional study, we evaluated 39 surgical TN patients with 3 pain measurement instruments: a Visual Analog Pain Scale, the Brief Pain Inventory- Facial (BPI-F) Pain, and the Barrow Neurological Institute (BNI) Pain Intensity Score. Scores were transformed into a 0-10 scale, and grouped into 5 severity categories (none, mild, moderate, severe, and worst). Discordant patients were those classified in different severity categories by at least 2 pain measurement instruments. Level of agreement was assessed with the intraclass correlation coefficient. RESULTS: Almost 50% of patients (18/39) had at least 1 categorical discordance when comparing all 3 scores. We found 30% discordance between visual analog scale (VAS) and BPI-F, 33% discordance between BPI-F and BNI, and 35% discordance between VAS and BNI. The highest degree of discordance between BNI and either VAS or BPI-F occurred in patients with moderate pain (BNI IIIb). The degree of agreement across all 3 scores was moderate (intraclass correlation coefficient [ 0.72). CONCLUSIONS: TN patients with residual mild- moderate pain after surgery are often discordantly classified by different pain measurement scales. These findings argue for a more standardized method of reporting postoperative pain outcomes in the TN literature.