Introduction

Cervicogenic headache is a well-known secondary headache. As it is considered a secondary headache, the current clinical understanding devotes musculoskeletal dysfunctions and anatomical lesions in the upper cervical spine as the causative factors. Although the etiology is well-understood and demarcated in the upper cervical spine, one in four individuals with cervicogenic headaches is unresponsive to therapy directed at the underlying dysfunctions. This may be indicative of other factors contributing to the onset or driving cervicogenic headaches. It is hypothesized that cervicogenic headache could be a mechanical disorder mediated by a peripheral nociceptive source or a more complex condition maintained by the peripheral source (the upper cervical spine) and sensitization. The current study wanted to explore whether heterogeneity in pain modulation profiles exists within the cervicogenic headache populations.

Methods

In this retrospective analysis of patient profiles, individuals with cervicogenic headaches were recruited from a headache department and matched to healthy controls. They were between 18 and 55 years of age and were diagnosed by a neurologist according to the International Classification of Headache Disorders-3 (ICHD). They all had a normal cognitive function, objectified with a test score of 30 in the Mini-Mental State Examination. All participants with cervicogenic headaches were asked to complete a four-week headache diary.

Pressure pain sensitivity was examined using a pressure algometer for all included participants. The measurements were obtained cephalic in the suboccipital musculature and extra-cephalic at the erector spinae at L1 and the tibialis anterior muscle. Subsequently, levels of depression, anxiety, and stress were assessed with the Depression Anxiety Stress Scale-21 (DASS-21). The Headache Impact Test (HIT) was filled to quantify quality of life and sleep quality was objectified using the Pittsburgh Sleep Quality Index (PSQI). These measurements were taken together to compose a pain modulation profile which considers a pain profile and a psychosocial lifestyle profile.

To consider the pain pressure threshold abnormal, a cut-off score was determined based on the thresholds of the healthy control group. When the pain-pressure threshold of someone with cervicogenic headache was lower than the lower bound of the 95% confidence interval of the normative threshold, the pain pressure sensitivity was considered decreased and thus altered. This means that pressure leads to pain at a much lower level of pressure than it would normally.

Three pain modulation profiles were considered:

• Pain Profile
• Psychosocial Lifestyle Profile
• Normal Profile

A dominant altered Pain Profile was defined when all pain pressure thresholds (cephalic and extra-cephalic) were altered, 6 in total, but were accompanied by less than 2 altered psychosocial lifestyle factors.

The Psychosocial Lifestyle Profile was considered dominant when less than 6 pain pressure thresholds were altered, but 3 psychosocial lifestyle factors were altered. The psychosocial lifestyle factors were rated altered in case the scores indicated at least moderate depression, anxiety, and stress (as defined by a DASS-21 score of respectively 14, 10, and 19), significant impact on daily life (as shown by a HIT-6 score of more than 56) or poor sleep quality (as defined by a PSQI score of more than 5).

For each factor, the scores were compared against normative values, derived from Mingels et al. (2021). A total of 5 psychosocial factors could therefore be considered (depression, anxiety, stress, headache impact on daily life and sleep quality).

A Normal Pain Profile was defined when no altered pain pressure thresholds and no altered psychosocial lifestyle factors were found. This was when the scores did not exceed the normative values listed above.

Results

A total of 18 participants with confirmed cervicogenic headache and 18 healthy matched controls were included.

Half of the cervicogenic headache participants (n=9) demonstrated an altered dominant Pain Profile since they had 6 altered cephalic and extra-cephalic pain pressure thresholds. Fifteen participants had less than 3 altered psychosocial factors, while three cervicogenic headache patients had more than 3 altered psychosocial factors and were considered to have altered Psychosocial Lifestyle Profiles.

Questions and thoughts

16 out of 18 included headache participants had altered profiles, summing up to a total of 88% of those included with cervicogenic headaches. Sixteen percent of cervicogenic headache patients included in this study were considered to have a dominant altered Psychosocial Lifestyle Profile. Half of the headache patients had a dominant Pain Profile. The findings indicate that the cervicogenic headache population is heterogeneous and that the driving factors of the headache go beyond merely musculoskeletal dysfunctions in the upper cervical spine.

To improve the treatment of cervicogenic headache, it is therefore advised to include an assessment of factors going beyond the mechanical dysfunctions in the musculoskeletal domain. Questioning someone about his psychosocial status could therefore be done by assessing sleep, headache impact on daily activities, stress, anxiety, and depression levels. This seems very important giving the fact that half of the study participants demonstrated signs of central sensitization.

Assessment of central sensitization can be done using quantitative sensory testing, although the use of a pain modulation profile as was done in the current study may be a more easy option to implement in clinical practice.

Importantly, the definition of cervicogenic headache according to the authorities claiming that it develops from an entirely physical nociceptive source can be questioned since this study found individuals with a dominant psychosocial lifestyle profile contributing to their headache.

Talk nerdy to me

The cut-off for an altered psychosocial lifestyle profile was set at 3 out 5 positive variables. Three participants were thus rated as having a Psychosocial Lifestyle dominant pain profile. When looking more closely at the individual data, 9 out of 18 participants had two altered psychosocial factors. It is not exactly known why the authors chose the current cut-off of three variables.

Similarly, an altered dominant Pain Profile was determined to be present when all six pain pressure thresholds were positive. Also here, it was not explained why this cut-off was chosen. Here also, someone with 5 positive out of 6 pain pressure thresholds was categorized as having no altered Pain Profile, but you may see that this may be an all-or-nothing approach which may be a bit radical. I assume that this will certainly be further studied, and the thresholds might still change in the future.

Importantly, the individuals were recruited in a headache unit, but it was not specified whether this was in primary, secondary or tertiary care. Since it was a headache unit where the participants were recruited, I assume it was at least a highly specialized clinic, possibly recruiting people with more severe headache characteristics. Perhaps they were out of treatment in primary/secondary care and the persistence of their headache was impacting their psychosocial domains. It is therefore uncertain whether the psychosocial factors had really contributed to their pain experience or had developed more gradually as their headache remained more chronic.

Take-home messages

An important take-home message from this study is that you could assess your cervicogenic headache patient beyond the musculoskeletal domain, since psychosocial factors may be contributing to the headache characteristics. Assessing the psychosocial domains and pain pressure thresholds lets you create a pain modulation profile from which you can assess the contributing factors. This can guide your management to tailor the interventions accordingly and avoid a one-size-fits-all approach. To note is the exploratory nature of the current study, which might still change in future investigations.

Reference

Mingels S, Granitzer M, Schmid AB, Dankaerts W. Individual endogenous pain modulation profiles within a multidimensional context of people with cervicogenic headache – A retrospective exploratory study. Musculoskelet Sci Pract. 2023 Oct;67:102855. doi: 10.1016/j.msksp.2023.102855. Epub 2023 Sep 2. PMID: 37683308; PMCID: PMC10560891.