Methodological Considerations for Sphenopalatine Ganglion Needling Trials in Allergic Rhinitis: Aligning Controls, Strengthening Physiologic Endpoints, and Extending Safety Assessment

To the Editor, We read with interest the multicenter randomized controlled trial by Liu et al. examining acupuncture (ACU), sphenopalatine ganglion needling (SPG-N), their combination (COM), and oral loratadine (MED) for persistent moderate-to-severe allergic rhinitis (AR). The reported week 8 response rates (≥30% reduction in TNSS) were higher in COM (82.5%) and ACU (71.4%) than in MED (45.3%), with earlier improvement observed in COM as soon as week 2 [1]. These results support the potential value of nonpharmacologic options for AR, yet several design features may influence how confidently the observed benefits can be attributed to specific physiologic effects. We outline considerations that could sharpen interpretation and inform future trials. A central issue concerns the comparability of treatment experiences across groups. Needling-based protocols—especially those delivered repeatedly and embedded in recognizable procedural rituals—carry an intensity of interaction, sensory input, and clinician contact that differs markedly from an oral medication comparator. Because key outcomes (TNSS, RQLQ and VAS) are patient-reported, they are inherently susceptible to expectation and contextual influences. Prior evidence indicates that placebo responses can vary with the invasiveness and complexity of an intervention, meaning that differences in “ritual” may inflate between-group contrasts even when specific physiologic effects are modest [2]. For this reason, incorporating an attention-matched control or a credible sham procedure, alongside formal assessment of blinding success and treatment expectancy, would strengthen causal inference. Trial planning and reporting could also be enhanced by following established guidance on sham controls in ACU research, which may improve transparency and interpretability [3]. Measuring expectancy and credibility would further allow quantification of contextual contributions rather than leaving them implicit. Alongside control symmetry, objective corroboration of nasal airflow changes would help connect symptom improvements to the proposed mechanism. The rationale for SPG-targeted interventions emphasizes autonomic modulation with downstream effects on turbinate edema and secretions [1]. However, subjective obstruction and global symptom ratings do not always track objective nasal patency, and discordance between perceived airflow and measured airflow has been documented [4]. Adding functional metrics—such as active anterior rhinomanometry, acoustic rhinometry, or peak nasal inspiratory flow—would allow triangulation between symptom scales and physiologic endpoints. Such measures could clarify whether benefits reflect measurable decongestion/airflow change, a shift in airflow perception, or a combination of both, while also improving cross-trial comparability. Given that SPG needling involves deep insertion toward the pterygopalatine fossa, safety characterization and durability of effect deserve particular emphasis. This region is anatomically complex and contains vascular and neural structures; therefore, absence of serious adverse events in a trial may still be compatible with clinically important rare complications, especially when sample size is insufficient to detect low-frequency harms [1]. More granular, procedure-specific adverse event reporting—capturing timing, severity grading, management, and delayed symptoms—would increase clinical usefulness. In parallel, AR is chronic and fluctuating, and a short follow-up window may not adequately distinguish transient improvement from sustained response. Extending follow-up (e.g., to ≥6 months), while documenting rescue medication use, would better characterize relapse patterns, longer-term effectiveness, and late-onset adverse events in a manner more aligned with real-world care. We congratulate the authors on completing a large multicenter RCT. Future studies that pair sham- or attention-controlled designs with objective airflow measures and longer safety follow-up should help clarify the specific efficacy, biological mechanism, and risk profile of SPG needling approaches for AR. Sincerely,