What is a Greater Occipital Nerve Block?
A greater occipital nerve block is an injection of local anaesthetic and steroid around the nerves which supply the scalp. These nerves are located on the back of the head and the top of the neck.
How does it work in migraine and cluster headache?
Most primary heaaches happen because there is abnormal gain (amplification) of pain and other sensory messages in the trigeminal nucleus: an area in the brainstem. The greater occipital nerve feeds upwards into the trigeminal nucleus. The nerve block reduces traffic in this nerve, so the abnormal gain in the trigemonal nucleus is diminished, therefore reducing the symptoms of migraine and other primary headaches. The site of the injection might lead to the assumption that this treatment works for only pain at the back of the head but it can also work for pain at the front of the head, such as in cluster headache.
The injection itself only takes a minute or so. The injection is 2 ml of mixed local anaesthetic and steroid that stays at the injection site. The injection is just behind the ear so it can be heard going in. It can be performed whilst siting in a chair or lying down.
Following the injection
There is often a sensation of numbness in the head, part of the neck and shoulder. There can be bleeding at the site of the injection as the scalp is fairly vascular: this can be stopped by gently pressing tissue or cotton wool over the injection site. It is best to have someone accompanying you for the first injection but usually there is no reason not to carry on with your usual activities as normal.
What side effects might I get?
It is common to experience a lump at the injection site with an accompanying “bruised” sensation for a few or several days. About one in 30 patients experience transient worsening of their head pain. In theory, infection of the injection site could occur. Very rarely, patients can faint with injections: these patients should be lying down to have injections. Some people can experience temporary hair-loss at the site of injection.
How long will it be before I notice any benefit?
Benefit may start in a hour or so, though can take up to a week to begin.
How many do I need to have?
As many as you need, to fix your pain!
Exceptionally the injection can be repeated after a month if benefit is good but transient at that time. Other wise, it can be repeated as often as every two months. If the injections need to be repeated every two months for a year then it may be better to consider another treatment.
Not all treatments work the same every time; if you have two successive greater occipital nerve blocks with insufficient benefit, it’s probably best to try a different treatment.
Who cannot have a nerve block?
You cannot have this nerve block if you are allergic to any of the medications being injected or if you have an active infection near the injection site.
This information is provided as a general guide only. If you have any queries or concerns about your headaches or medications please discuss them with your GP or the Doctor you see at the National Migraine Centre.