Primary headaches: A special case of chronic pain
Headaches by definition are pain in the head (or to use the technical terminology, ‘pain located above the orbitomeatal line’) and hence it seems logical that frequent headaches experienced over a long period should fit into the chronic pain literature. The research literatures on headache and chronic pain, however, are relatively independent, as are the clinical services for these two conditions. Before discussing why this is the case and differences between the management of headache and chronic pain, some qualifiers need to be added to the statement of apparent similarities.
The first qualifier relates to the different types of headache. The classification system of the International Headache Society (IHS) divides headaches into three categories and 14 major types (Headache Classification Committee of the IHS, 2013). However, the most important distinction is between primary headaches (idiopathic), for which headaches are the disorder, and secondary headaches (symptomatic), which are headaches arising as a result of some pathology such as a tumour, infection, or taking too much medication. Psychologists work with primary headaches, and the two most common types are migraine (mainly the subtypes ‘migraine without aura’, and ‘migraine with typical aura’) and tension-type headache. The qualifier is that these headache disorders are defined by a range of symptoms only one of which refers to pain in the head. In fact, it is possible for the diagnosis of migraine to be given in the absence of head pain as a symptom (‘migraine with aura without head pain’).
The second qualifier relates to the term ‘chronic’. In the pain literature, ‘chronic’ refers to pain persisting over a long period, usually defined as three months, but sometimes six or 12 months. A similar definition was used in the headache literature and still is for secondary headaches. However, for primary headaches, ‘chronic’ now means attacks of headaches occurring on more days than not over a period longer than three months.
So why are the literatures on headache and chronic pain relatively distinct? One reason is that medicine proceeds on the basis of starting with a diagnosis driven by the belief that this provides information on mechanisms and hence largely determines management. The biological mechanisms of headache and chronic pain tend to be different. The mechanisms of the different types of headache are still not well understood, and theories of migraine range from neuronal to vascular. Nevertheless, headaches are seen as the domain of the medical speciality of neurology. Chronic pain can arise for many different reasons including where structural damage has occurred (e.g. low back pain) or disease processes (e.g. cancer or arthritis). Hence, chronic pain is typically associated with physiological dysfunction that cannot be remedied, and a range of medical specialists contribute to management from anaesthetists to orthopaedic surgeons as well as pain medicine specialists. There are some signs of the two literatures coming together as the International Association for the Study of Pain has developed a classification of chronic pain for the upcoming International Classification of Diseases 11th Revision (ICD-11) that includes seven categories, one of which is ‘Chronic headache and orofacial pain’ (Treede et al., 2015).
Psychologists approach pain from a psychosocial perspective, so do they assess and treat headache and chronic pain the same way? There would certainly be much in common. For example, pain management strategies, such as relaxation training, cognitive behaviour therapy (CBT), and the use of imagery and attention-diversion strategies are equally applicable to both populations as they are based on targeting the experience of pain. Other aspects of management also transcend the different types of pain, such as a focus on the way individuals have responded to the pain. The goals are often different, however, as the underlying pathology associated with many chronic pain conditions limits the goal to teaching patients how to cope with pain, whereas the absence of underlying pathology in primary headaches enables the more ambitious goal of virtual elimination of headaches.
Conceptualising and assessing primary headaches: The Functional Model of Headaches
A Functional Model of Headaches has been proposed for guiding the assessment and treatment of headaches (Martin, 1993). This model seeks to understand the controlling variables of headaches.
It addresses questions such as:
- Why do headaches occur at one time rather than another;
- Why is the person suffering from headaches at this time in her/his life rather than at other times;
- Why did the headache disorder begin when it did or become significantly worse when it did; and
- Why is the person vulnerable to developing a headache disorder?
To answer these questions, information is collected about the antecedents and consequences of headaches. Antecedent factors are divided into the following categories:
- Immediate antecedents – stimuli that precipitate or aggravate headaches (the triggers);
- Setting antecedents – lifestyle factors that moderate current vulnerability;
- Onset antecedents – events that resulted in headaches developing initially or worsening; and
- Predisposing antecedents – constitutional and personality characteristics that account for individual differences in susceptibility.
Consequences are divided into the immediate consequences of having a headache for the sufferer and their significant others. Hence, this refers to reactions to headaches occurring.
The model also includes the long-term consequences, which refers to the impact of the headache disorder on the sufferer and their significant others. Consequences are included in the model because often vicious cycles occur whereby the reactions to having headaches feedback to the antecedent factors.
Information is collected by interviewing the sufferer and sometimes significant others, and by self-monitoring. Also, a range of questionnaires may provide useful information. For example, the most common trigger of both migraine and tension-type headache is stress. This can be revealed by asking the question, and can be followed up by self-monitoring stress levels and headaches. A setting factor might be ‘low social support’ as this makes people vulnerable to stress, and an onset factor might be starting a new job that was perceived as stressful. A predisposing factor might be susceptibility to stress.
On the consequences side, a common reaction to headaches is elevated stress as sufferers ruminate about what is causing the headache or how they will get through the commitments of the day. This results in a stress-headache-stress vicious cycle. A common long-term response to having a headache disorder is to withdraw from social activities which results in a diminished social network and therefore less social support. This can feedback to the setting factor of inadequate social support resulting in vulnerability to stress.
Stress has been used as an example because it can feature in all the antecedent and consequences categories of the Functional Model, but it would be a gross oversimplification to suggest that headaches are simply a function of stress. Headaches can be triggered by a diverse range of factors including visual disturbance, noise, not eating, dehydration, too little sleep, certain weather conditions, and menstruation in females (Martin & MacLeod, 2009). Nevertheless, headache and migraine fit squarely into the domain of psychologists because they are a function of how people lead their lives – their behaviour, thoughts and feelings.
Treating primary headaches
The most researched methods of psychological/behavioural treatment for primary headaches are: biofeedback training (particularly electromyographic [EMG] feedback and thermal feedback), relaxation training, and cognitive behaviour therapy (CBT). The literature shows that these approaches are quite effective. The United States Headache Consortium, developed evidence-based guidelines for the treatment of migraine and found Grade A evidence (‘multiple well-designed randomised clinical trials, directly relevant to the recommendation, that yield a consistent pattern of findings’) in support of behavioural treatment for migraine (Campbell et al., 2000). Rains, Penzien, McCrory and Gray (2005) summarised the results of meta-analytic reviews for behavioural treatment for migraine (thermal biofeedback, EMG biofeedback, CBT, relaxation training) and concluded that average improvement ranged from 33 per cent to 55 per cent, compared with 5 per cent for no-treatment controls. The results for behavioural treatment of tension-type headache were almost identical as average improvement with treatment ranged from 35 per cent to 55 per cent, compared to two per cent for no treatment. We have evaluated our version of CBT based on our Functional Model of Headaches and found it was associated with the following: (i) average decrease in headaches of 68 per cent post-treatment, and 77 per cent at 12-month follow-up; and (ii) average decrease in medication of 70 per cent post-treatment (Martin, Forsyth, & Reece, 2007).
These results compare favourably with the pharmacological literature. For example, amitriptyline is an established prophylactic medication for both migraine and tension-type headache, and a 27 per cent reduction in headaches has been reported using this medication (Holroyd, Nash, Pingel, Cordingley, & Jerome, 1991). In addition to reducing headaches and medication consumption, behavioural treatments are typically associated with a number of positive changes including decreases in depression and anxiety, increases in self-efficacy, and enhanced quality of life (Martin, 2009). This is in contrast to pharmacological approaches which are associated with contraindications, adverse side effects, and high medication overuse potential (Olesen, Goadsby, Ramadan, Tfelt-Hansen, & Welch, 2006).
The Functional Model of Headaches suggests that a wide range of treatments may benefit headache sufferers beyond the standard ones appearing in the research literature (Martin, 2013). For example, if headaches are triggered by stress and the main source of stress is the setting antecedent of marital dysfunction, then marital therapy should be considered. If the headache sufferer is also suffering from a depressive disorder, then this may require attention before or concurrently with treatment of the headache disorder, as depression is likely to interfere with the headache treatment.
In summary, psychologists have a lot to offer individuals suffering from chronic headaches, and it is unfortunate that more individuals with headaches do not receive treatment from psychologists.
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- Campbell, J. K., Penzien, D. B., & Wall, E. M. (2000). Evidence-based guidelines for migraine headache: Behavioral and physical treatments. Retrieved from http://tools.aan.com/professionals/practice/pdfs/gl0089.pdf.
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- Martin, P. R., Forsyth, M. R., & Reece, J. (2007). Cognitive-behavioral therapy versus temporal pulse amplitude biofeedback training for recurrent headache. Behavior Therapy, 38, 350-363.
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- Treede, R. D., Rief, W., Barke, A., Aziz, Q., Bennett, M. I., Benoliel, R., . . . Wang, S. J. (2015). A classification of chronic pain for ICD-11. Pain, 156(6), 1003-1007.