The Occipital Nerves Applied Strain Test to Support Occipital Neuralgia Diagnosis

Introduction: Occipital neuralgia (ON) is a disabling cephalalgia form with demanding diagnostic workflow. We report the description and reliability analyses of the occipital nerves-applied strain (ONAS) test for occipital neuralgia (ON) early-stage diagnosis in cephalalgia patients. Methods: In a retrospective and observational study, we evaluated, among n = 163 consecutive cephalalgia patients, the sensitivity, specificity, and prior probability [positive (PPV) and negative (NPV) predictive values] of the ONAS test against two reference tests (occipital nerve anesthetic block and the painDETECT questionnaire). Multinomial logistic regression (MLR) and χ analyses verified the ONAS test outcome's dependence upon independent variables (gender, age, pain site, block test, and painDETECT outcomes). We assessed inter-rater agreement with Cohen's kappa statistic. Results: ONAS test showed sensitivity and specificity of 81 and 18%, respectively, against the painDETECT and of 94 and 46%, respectively, against the block test. PPV was > 70% against both tests, while NPV was 81% against the block test and 26% against the painDETECT. Interrater agreement Cohen's kappa was excellent. Significant association (χ analyses) and relationship (MLR) were found only between ONAS test and pain site but not with the other independent predictors. Conclusions: The ONAS test showed satisfactory reliability among cephalalgia patients; thus, it might be considered a valuable early stage tool for ON diagnosis in these patients.