What is a GON injection?
GON injection involves injecting a small dose of local anaesthetic (lignocaine) and steroid (Depo-Medrone) around the greater occipital nerve, which is located at the back of the head, at shown in the diagram.
Why is a GON injection done?
In people with chronic or disabling headaches, it has been shown that injecting the GON, as part of a headache management plan, can provide temporary benefits in approximately two out of three cases. These benefits are typically short-lived and may last a week or two, but on occasion people get considerably longer periods of relief. The headaches may ease in frequency or severity or stop for a period of time. In about one in three cases, the injection does not provide any benefits.
Please note that there is usually no advantage to giving the injection to someone whose headaches are in remission. If your headaches have settled down between the time of booking the injection and the appointment itself, please discuss this with us first.
Are there side-effects from a GON injection?
As with any injection, there is a small risk of bleeding or bruising at the injection site, and a theoretical risk of infection, which has not been a problem in our experience. On rare occasions, people describe a worsening of the headache, which is usually quite short lived. Some people can experience dizziness after the injection, which is why we advise you to remain for half an hour after the injection to ensure that you feel okay before going home.
On a couple of occasions (less than 1 % of injections to date) patients have experienced a small area of hair loss at the site of injection, (as shown in the photograph on our consent form). This is obviously more likely to be a cosmetic issue in those with short hair rather than long hair and is a rare complication of the injection.
If you have any questions or concerns about the injection, please feel free to discuss them with the doctor prior to proceeding with the injection.
What does it feel like having a GON injection?
Prior to carrying out the injection, the doctor will feel around the area to locate the tender spot which is suitable for injection. This process can be uncomfortable. The injection itself uses a fine needle and, while the local anaesthetic can sting a little, the procedure is generally well tolerated and only takes a couple of minutes. People often report hearing the fluid being injected, due to the site of the injection, but again this is not bothersome for most people. The area of skin is swabbed with alcohol prior to the injection and we will ask you to apply a little pressure to the area afterward to minimise bruising.
How soon can I go home?
Because some people can feel dizzy after the injection, we ask you to wait for half after the injection to ensure that you feel well, and to check with the nursing staff leaving.
Will a GON injection help my headache?
This is difficult to predict with any certainty, but your doctor will have arranged it because they felt that the injection is worth trying, and overall, most people do benefit from it. Please note that, in people who have had this injection previously, the benefit can vary a bit from one occasion to the next. Our experience is that the injection is most helpful when given at the point which is most tender, so establishing the ‘right spot’ prior to injection gives us the best chance of success.
What happens next?
When you are ready to go home you will be given a form to complete and return to us in due course. This gives us feedback as to whether the injection has been helpful or not. Usually, if there has been no benefit from the injection in the first seven to ten days, then it is unlikely to occur after this.
Arrangements for further follow-up and treatment options will be made separately to the GON appointment itself. If in doubt, please clarify these with the headache team.