Local anesthetic placed where the occipital nerves emerge at the base of the skull. Minutes to perform, and when the diagnosis is right, often effective within minutes.
What it treats
The greater and lesser occipital nerves carry sensation from the back of the head. When they are irritated or compressed, the result is occipital neuralgia — sharp, electric, shooting pain from the base of the skull upward, often with scalp tenderness so marked that brushing your hair hurts.
A block is also used in cervicogenic headache, where pain originating in the upper cervical spine is referred into the head, and as an add-on during a cluster bout, where injection of the greater occipital nerve with a corticosteroid can shorten the run of attacks while a preventive medication is brought up to dose.
It is diagnostic as well as therapeutic
This is the part most people are not told. If numbing a specific nerve abolishes the pain, that nerve is implicated. If it does not, the pain is coming from somewhere else, and that is useful information rather than a failed treatment. A block that does not work redirects the diagnosis instead of ending the conversation.
How it is done
You sit leaning slightly forward. The landmarks are identified by palpation, the skin is cleaned, and a small volume of local anesthetic — sometimes with a corticosteroid — is injected. The needle is fine and the injection takes seconds. Scalp numbness over the back of the head afterwards is expected and wears off over several hours.
There is no sedation. You walk out and you drive yourself home.
How long it lasts
The anesthetic wears off in hours, but relief frequently outlasts it by weeks — longer than the pharmacology alone explains, probably because interrupting the pain signal lets an irritated nerve settle. Duration varies widely between people. There is no fixed course of three; the interval is set by how long the last one held and by what is happening clinically, not by a schedule.