Abstract text (incl. figure legends and references)

Question: Peripheral nerve blocks are used in the acute and preventive treatment of primary headaches. Few studies have studied its effectiveness in tension-type headache (TTH), with contradictory results.

Methods: Observational study of patients followed in a headache-intervention consultation of a tertiary hospital (01/2021-04/2022), submitted to monthly greater and lesser occipital nerve blocks (GON, LON) with lidocaine 2% (2.5mL GON, 1.0mL LON).

Results: Peripheral nerve blocks were performed in 75 patients, median of 46 years (P25=36.0, P75=57.0), 63 (84.0%) were female. The most prevalent type of headache was migraine (38.7%), followed by cTTH (20.0%). Of the patients with cTTH (n=15), 13 (86.7%) were female and 10 (66.7%) were older than 50 years-old. Five (33.3%) had concomitant medication-overuse headache. Twelve patients (80.0%) were receiving concomitant prophylactic treatment. In 33.3% the block was performed due to refractory course, and in 33.3% due to treatment intolerance. Overall, in this group, there was a decrease in the number of headache days with treatment [p<.001; 23.9 (sd 8.6) pre-treatment vs. 10.0 (sd 11.1) post-one treatment]; only 4 (14.8%) had no response. An interaction with age (≤50/>50) (p=.001) was observed, with a higher reduction in headache frequency in patients >50y (Mprevious=22.7±9.1; Mpost-blockade=8.1±9.5), compared to ≤50y (Mprior=15.4±10.0; Mpost-block=9.2±9.6). There was an interaction with follow-up time (0-6/7-24/>24) (p=.029), with a greater reduction in frequency in the group with a follow-up time of up to 6months.

Conclusions: Patients with cTTH had a good response to monthly occipital nerve blocks. Treatment responsiveness seemed to be better in older patients and those that started this intervention earlier.