NOTE: Today we offer a double feature on the treatment of cervicogenic headache. My article is about a study that compared manipulation to mobilization; it is followed by retired chiropractor Sam Homola’s guest article on manipulation for cervicogenic headache. The two posts complement each other and also complement my post from last week on the possible risk of stroke with neck manipulation.
Cervicogenic headache (CGH) refers to headaches that are caused by problems in the neck, as opposed to headaches of non-neck etiology that may be accompanied by neck pain. There is controversy over whether CGH is even a valid diagnosis. Diagnostic criteria usually include unilateral headache triggered by head/neck movement or by pressure on the neck, headache that spreads to the neck, shoulder or arm; and often limited range of motion in the neck. If a nerve block in the neck relieves the headache, that would confirm that the pain originates in the neck, but nerve blocks are not routinely done and are not required for diagnosis.
Is manipulation effective for CGH?
There is controversy over whether spinal manipulation is an effective treatment for CGH. A 2005 systematic review concluded that “A greater number of well-designed, randomized, controlled trials are required to confirm or refute the effectiveness of spinal manipulation.”
The results of 6 RCTs suggested that SM is effective for treating CGH compared to physical therapy, light massage, drug therapy, or no intervention. Three RCTs showed no differences in pain, headache duration and frequency compared to placebo manipulation, physical therapy, massage, or wait list controls. Most trials had major methodological flaws.
…the evidence that SM is effective for CGH is not conclusive. Further rigorous research in this area is needed. Until conclusive data are available, SM cannot be regarded as an evidence-based approach in the treatment of CGH.
Comparison of manipulation and mobilization
Cochrane reviews in 2010 and 2015 compared manipulation and mobilization for neck pain and found that the evidence was poor quality; they concluded that manipulation offered no clear advantage over mobilization.
A new study published in February 2016 in the journal BMC Musculoskeletal Disorders is the first to compare the effectiveness of high velocity low amplitude (HVLA) cervical and thoracic manipulation to mobilization and exercise for CGH. It found that manipulation was more effective than mobilization. How convincing is that study?
The study was a multicenter randomized trial with 110 carefully selected subjects, with 6-8 treatments over a four-week period and a follow-up evaluation at 3 months. The treatments were performed by physical therapists with an average of 10 years’ experience and with special additional training to ensure standardization of treatments. The patients were randomized into two groups.
The manipulation group got manipulations with the patient supine (lying face up). The right and left C1-2 articulations and bilateral T1-2 articulations were manipulated on at least one of the 6–8 treatment sessions. On other treatment sessions, therapists either repeated the C1-2 and/or T1-2 manipulations or targeted other spinal articulations (i.e., C0-1, C2-3, C3-7, T2-9, ribs 1–9) using manipulation. The selection of the spinal segments to target was left to the discretion of the treating therapist and it was based on the combination of patient reports and manual examination. For both the upper cervical and upper thoracic manipulations, if no popping or cracking sound was heard on the first attempt, the therapist repositioned the patient and performed a second manipulation.
The mobilization/exercise group got mobilization in the prone (lying face down) position targeting C1-C2 and T1-2 on at least one session. On other treatment sessions, therapists either repeated the C1-2 and/or T1-2 mobilizations or targeted other spinal articulations (i.e., C0-1, C2/3, C3-7, T2-9, ribs 1–9) using mobilization. The selection of the spinal segments to target was left to the discretion of the treating therapist. Staged craniocervical flexion exercises were performed with the subject supine.
All subjects improved over the course of the study. The manipulation group had greater improvements in headache intensity, disability, headache frequency, headache duration, and medication intake than those who got mobilization combined with exercises. They estimated a number needed to treat (NNT) of four patients treated with manipulation for one additional patient to achieve clinically important pain reduction at 3 months follow-up. No patients had either of the two major potential adverse events that they specifically asked about, but ‘We did not collect any data on the occurrence of “minor” adverse events (transient neurological symptoms, increased stiffness, radiating pain, fatigue or other).’
- How many subjects would have improved with no treatment or with other treatments like massage?
- How can we know which treatments worked when so many different articulations were treated and individual patients were treated differently?
- How do these treatments compare to what the average patient with CGH would get from visiting the average chiropractor or physical therapist?
- Why did they not collect data on minor adverse events? I would think radiating pain and transient neurological symptoms would be very worrisome.
- Might these subjects have been biased by previous experience with manipulation or mobilization? Were they biased by hearing the popping or cracking sound?
- Did the supine vs. prone position make a difference? Would it have been as effective and possibly safer to do manipulations with the patient seated?
- Could therapist preference have biased the results?
- Could the authors’ competing interests have influenced the results in some way? Four of them are instructors who provide postgraduate training in manipulation and mobilization.
- If these treatments work, what is the mechanism?
- Why were they intent on producing a popping or cracking sound? Is it of any benefit or might it possibly increase the incidence of adverse effects?
- Do the benefits of treatment justify the small risk of stroke or death from neck manipulation? The authors cited the Cassidy study as evidence that patients receiving spinal manipulations were no more likely to have a stroke than patients treated by a medical physician. That is not at all what that study showed. It provided no data on whether patients got manipulation. And it showed that if you are under the age of 45 and visit a chiropractor, there is a strong association between that visit and a stroke in the next 24 hours. See Mark Crislip’s evaluation of the Cassidy study.
Conclusion: Still not enough to justify cervical manipulation
In my opinion, considering the evidence from previous studies, the possible risk of stroke, and the unanswered questions, this one study is not enough to justify adopting manipulation for CGH. Samuel Homola, a science-based chiropractor, advises against neck manipulation for cervicogenic headache in a post following this one and explains why.