Repeated greater occipital nerve injections with corticosteroids in medically intractable chronic cluster headache: a retrospective study.

Introduction: Current prophylactic drugs for cluster headache are associated with limited efficacy, serious side effects and poor tolerability. Greater occipital nerve injection (GON-injection) has been proven effective and safe as a single, one-time injection in episodic (ECH), and to a lesser extent, chronic cluster headache (CCH). We aim to analyse the effectiveness and safety of repeated GON-injections in medically intractable chronic cluster headache (MICCH).

Methods: Clinical data of all cluster headache patients who had received at least one GON-injection between 2014 and 2018 in our tertiary headache centre were retrieved from patients' medical records. Clinical history was taken as part of routine care shortly before and 6 weeks after GON-injection.

Results: We identified 47 MICCH patients (79 injections), and compared results with 22 non-MI CCH patients (30 injections) and 50 ECH patients (63 injections). Nineteen MICCH patients received repeated injections (32 in total, range 2-8). Rates of clinical relevant improvement to a first injection were similar in all groups (MICCH: 60%, non-MICCH 73%, ECH 76%; attack freedom: MICCH: 30%, non-MICCH 32%, ECH 43%). Furthermore, no difference in response to the first and second injection was shown between groups (all p > 0.29). Median effect duration in MICCH was 6 weeks (IQR 2.8-12 weeks). Side effects were only mild and local.

Conclusion: In this retrospective analysis, first and repeated GON-injections were well-tolerated and equally effective in MICCH as in non-MICCH, and ECH.