Greater occipital nerve block versus intranasal sphenopalatine ganglion block in chronic migraine with failure of at least two oral preventive treatments: a prospective, non-randomised patient-preference comparative study.

backgroundProspective comparative evidence for greater occipital nerve (GON) block and intranasal sphenopalatine ganglion (SPG) block is limited. This study describes the six-month course of two treatment cohorts of patients with chronic migraine in whom at least two oral preventive treatments had failed.

objectiveTo describe changes in migraine attack frequency, pain intensity, acute medication intake and associated symptoms after distal landmark-guided GON block or topical intranasal SPG block, and to examine whether the trajectories of the two cohorts differed.

methodsIn this single-centre prospective observational study, treatment followed the patient's acceptance or refusal of an injection; allocation was not randomised. Of 100 enrolled patients, 78 had complete baseline and month 1, 3 and 6 data (GONB group n = 45; SPG block group n = 33). Each procedure used 3 mL of 0.5% bupivacaine weekly for four weeks. Attack frequency, Numerical Rating Scale (NRS) pain intensity and triptan and NSAID intake days were analysed with linear mixed-effects models containing group, categorical time and their interaction, with Holm adjustment across the four outcomes and covariate-adjusted sensitivity models. Associated symptoms were self-reported and analysed only in patients with the symptom at baseline.

resultsBoth cohorts showed lower attack frequency, pain intensity and acute medication intake throughout follow-up (Friedman p < 0.001 in both groups). At month six, model-estimated attack frequency was 3.69/month (95% CI 3.40-3.98) in the GONB group and 4.24/month (3.90-4.58) in the SPG block group, and the NRS score was 4.56 (4.26-4.85) versus 5.48 (5.14-5.83). In the primary unadjusted models the group-by-time interaction was significant for attack frequency (p = 0.034) and NRS (p = 0.007) and not for triptan (p = 0.057) or NSAID days (p = 0.298); after Holm adjustment across the four outcomes only NRS remained significant (p = 0.030), and in the covariate-by-time sensitivity models no interaction remained significant after adjustment. A ≥ 50% reduction in attack frequency occurred in 40/45 (88.9%) and 28/33 (84.8%) patients (risk difference 4.0% points, 95% CI - 11.0 to 21.0). Baseline stabbing (p = 0.019) and electric shock-like pain (p = 0.009) were more frequent in the SPG block group. Reported adverse events were mild dizziness in three GONB patients and brief epistaxis in one SPG block patient.

conclusionBoth patient-preference cohorts showed within-group improvement over six months. Preference-based allocation, baseline phenotype differences, incomplete follow-up and the sensitivity of the between-group comparisons to multiplicity and covariate adjustment prevent conclusions about efficacy or superiority. Randomised, controlled studies using standardised headache-day endpoints are required.