Comparison of Neurodynamic Test Response Between Patients with Frequent Episodic Tension-Type Headache and Migraine: An Exploratory Comparative Study

Background/Objectives: Although migraine and frequent episodic tension-type headache (FETTH) may share sensory features, direct comparisons of responses to neurodynamic loading are scarce. Establishing whether responses differ may help distinguish shared from phenotype-specific features and guide future diagnostic research. The aim of this exploratory secondary analysis was to compare range-of-motion and pain responses during the Long Seated Slump Test (LSST), Seated Slump Test (SST), and Straight Leg Raise (SLR) in participants with migraine and FETTH and to explore their potential discriminatory performance. Methods: This cross-sectional observational secondary analysis included participants with FETTH (n = 31) and migraine (n = 33) classified by a neurologist according to ICHD-3 criteria. LSST outcomes were sacral flexion, cervical flexion, and pain at maximal cervical flexion; SST outcomes were active knee-extension angle and pain at maximal active knee extension in dominant and non-dominant limbs; and SLR outcomes were hip-flexion angle and pain intensity at a low-pain point (O1) and high-pain point (O2), assessed bilaterally with the ankle at 30° plantar flexion and neutral (0°). Results: In the unadjusted exploratory analyses, FETTH showed greater LSST sacral flexion than migraine (adjusted mean difference = 13.56°, 95% CI 8.58 to 18.54), whereas migraine showed greater pain at maximal LSST cervical flexion (adjusted mean difference = −1.45 NPRS points, 95% CI −2.42 to −0.48). An unadjusted between-group difference was also observed for the dominant-limb SLR angle at the high-pain point with the ankle neutral (adjusted mean difference = −10.17°, 95% CI −18.95 to −1.39). After Holm adjustment across the 23 neurodynamic ANCOVA comparisons, only LSST sacral flexion remained statistically significant. LSST sacral flexion also yielded the highest apparent AUC (0.881), with 78.8% sensitivity and 90.3% specificity at the same-sample exploratory cut-off. Conclusions: Neurodynamic responses differed selectively, with the clearest exploratory signal involving LSST sacral flexion. The same-sample cut-off is not a validated diagnostic threshold, and the sex imbalance between groups limits attribution to headache phenotype. Independent validation and assessment of incremental value beyond ICHD-3 classification are required before clinical use.