Abstract
Dear Sir We thank Dr Vijayan for his comments on our paper (1). The mechanisms of action of greater occipital nerve (GON) blockade in cluster headache are uncertain. Many parameters such as volume, type of procedure (dry needling, saline or active drug injection), type of anaesthetic drug, type and dose of steroid injected, and injection site need further studies in cluster headache and other head pain conditions. A comparison of different steroid injection sites is not the only way to prove and understand the mechanisms of GON blockade effectiveness in cluster headache.
Furthermore, recent evidence on manipulating occipital nerve transmission was recently presented at the Migraine Trust (Dodick). In other pain conditions there is evidence that the blockade effect is independent of the injected substance (2).
We agree a possible explanation for Anthony's (3) patients having a better response could be the dose and steroid type used. The fact Anthony blocked GON in cluster patients with neck tenderness may also account for the results.
Therapeutic approaches which manipulate input into the cervico-trigeminal complex (4), including physical therapy, botox, and nerve stimulation (5), may benefit cluster headache patients. We hope to see more studies clarifying the issue.