This study will highlight and validate chiropractic spinal manipulative therapy (CSMT) for cervicogenic headache (CEH). If the method proves to be effective, it will provide a new non-pharmacological treatment option for CEH. This is especially important since pharmacological management has minor effect in CEH, and alternative treatment options are warranted. The applied methodology of the study will aim towards the highest possible research standards. This international study is a collaboration between Akershus University Hospital, Innlandet Hospital and University of Oslo (UiO), Norway and Macquarie University, Australia. The multidisciplinary professional backgrounds are physiotherapy, chiropractic and medicine. By increasing the methodological quality of the investigators research to a very high level, the investigators see the method to work as a guide to increase the quality of chiropractic research in the future, as previous randomized clinical trials (RCTs) of CEH used methodology showing room for improvement.

Study hypothesis:

CSMT using the Gonstead method reduces days with CEH by at least 25% as compared to placebo (sham manipulation, i.e. broad non-specific contact, non-directional, low velocity and low amplitude) and no intervention (control group).

Cervicogenic headache (CEH) is a symptomatic headache characterized by chronic unilateral headache and symptoms and signs of neck involvement. CEH is often worsened by neck movement, sustained awkward head position, external pressure over the upper cervical or occipital region on the symptomatic side. Abolition of the headache following diagnostic anesthetic blocks of cervical structures or local factors in neck give evidence that the pain is attributed to a neck disorder or lesion. The prevalence of CEH is 0.2% in the general population of Akershus County, i.e. 9,000 Norwegians have CEH. However, the prevalence varies between 0.4-4.1% in studies applying less rigorous diagnostic criteria. The efficacy of pharmacological management in CEH is poor. Patients suffering from CEH are commonly treated with CSMT, but the methodology has one or more shortcomings in all studies. In addition, the RCTs mostly included participant with infrequent CEH and did not follow the recommended clinical guidelines by the International Headache Society (IHS) of intervention of at least three months. An analysis of the literature as well as a recent pilot study suggests that CSMT has an effect on headache intensity and duration, and medication intake. However, a randomized controlled clinical trial with high methodological quality on CEH still remains to be conducted.

The RCT is single blinded, placebo-controlled trial of CSMT using the Gonstead method vs. sham manipulation and control group. If the treatment shows to be effective, the participants whom receive sham manipulation or control will be offered true intervention after the follow-up period and free of charge. This study will follow the recommendations set by the clinical trial guidelines from the IHS, while the methodological quality control will in general follow previous suggested criteria and the CONSORT statements.

Patients will be recruited through Akershus University Hospital and Innlandet Hospital, Norway as well as through media advertising in Akershus and Oslo County. The diagnose is set by a chiropractor and a neurologist with experience in headache.

The clinical trials consist of three stages: Run-in, intervention (treatment) and follow-up.

One month of base line data collection where participants will fill-in a diagnostic headache diary. Baseline demographics and clinical characteristics will be presented in tables with mean and standard deviation (SD) for each group.

The participants will be randomized by drawing prepared sealed lots. Each lot includes three different interventions, i.e active treatment, sham manipulation and control group. The first three participants will draw from the same lot until all three interventions are used. The next lot with three interventions is then followed by the next three participants.

The RCTs will be conducted by an experienced chiropractor. Active treatment consists of CSMT using the Gonstead method. A specific contact, high velocity, low amplitude, short lever, with no recoil post adjustment directed to spinal biomechanical dysfunction diagnosed by standard chiropractic tests.

Follow-up at 3, 6 and 12 months post-treatment. During this period participants continue to fill in a diagnostic headache diary. The control group will also be included in this phase of the study.

The data will be analyzed with SPSS using standard statistical techniques.

The investigators based our calculation of sample size on migraine days from recent group comparison studies of topiramate (38). The investigators calculated that a sample size of 16 patients was required to detect a difference in mean reduction in monthly headache days of 2.5 with 80% power, with p=0.05 as level of significance, and assuming a common SD of 2.5 for active treatment and broad-based treatment groups.

Insurance is through "The Norwegian System of Compensation to Patients" (NPE) which is an independent national body, set up to process compensation claims from patients who have suffered an injury as a result of treatment under the Norwegian health service.

The Regional Committee for Medical Research Ethics (REK) in Norway and Norwegian Social Science Data Services approved the full PhD research protocol. The declaration of Helsinski is followed.

Inclusion Criteria:

• CEH according to at least three major criteria of the CHISG not including occipital nerve blockage
• Age 18-70 years

Exclusion Criteria:

• Contraindication to spinal manipulation
• Chiropractic treatment within the last 12 months
• Radiculopathy
• Depression
• Pregnancy
• Participants whom become pregnant during the migraine trial will also be excluded from analysis from the time of pregnancy
• Participants who change their prophylactic medical regime for headaches will be excluded in the analysis from the time of change