1. GON Block
DR David PB Watson
Hamilton Medical Group
Aberdeen

2. GON Block rationale
Convergence of sensory input to trigeminal nucleus caudalis (TNC) neurons from both cervical and trigeminal fibres
GON composed of sensory fibres mainly from C2 and lesser extent C3
Animal studies: stimulation of GON increases metabolic activity in TNC

3. Evidence for effect Few double blind placebo controlled trials
Placebo effects
Mainly case studies

4. Chronic TTH Study 1: 15 patients open label
10 patient no change
4 patients worsening headache
1 patient headache improved
Study 2: TTH (mixed headache 52 patients)
14% of patients headache improved

5. Migraine
Study 1: 97 patients refractory to pharmacological therapy. 54% patients significantly better.
Study 2: CDH (various) 101 refractory patients. 22% pain free, 31% partial response. Local tenderness at GON area associated with treatment response
Study 3: looked at allodynia. Of 19 patients 90% had response

6. Cluster
Study 1: 61% attacks disappeared in 72 hours for 4 weeks. Some patients had sustained response for 26 months
Study 2: 14 patients episodic and chronic cluster. 9 patients good response at 1 week. No longer follow up.
Study 3: 15 patients. 9 had minor improvement but only local no steroid

7. Post Traumatic Headache
One study: 87 patients . 63 (72%) significantly better at 6 months

8. Cervicogenic Headache
One Study: ? Patient numbers as mixed headache. 55% headache improvement

9. Side Effects Transient dizziness Syncope Worsening headache
Local alopecia and fat atrophy (2 in 100)

10. Summary Relatively easy Low incidence side effects
Can help migraine, cluster, cervicogenic and post traumatic headache
Works best if local tenderness
For most patients works few weeks to maximum a few months