Headache
Peter J. Goadsby
Headache is a remarkably common problem in neurology and even in general medicine and, by definition, has a substantial pain component. Books are devoted to the topic, and interested readers are directed to recent editions for more detail on the subjects covered here.1,2,3,4,5 The headache disorders are classified by the International Classification of Headache Disorders,6 now in its third edition, as being either primary, where the headache syndrome is itself the problem, or secondary, where the headache syndrome is driven by other pathologic processes. This chapter is designed to cover the primary headaches with a broad view. Facial neuralgias and facial pain syndromes are covered elsewhere in this book. Where a primary headache causes face pain, and most primary headaches can do this, it will be included here for completeness. This chapter covers the broad principles, the generic anatomy, and physiology of head pain and then discusses in turn the currently defined primary headache syndromes. There is much opportunity in headache to make patients significantly better and much research advancement in this very exciting area of medicine.7,8
General Principles
A general system for headache nosology is outlined in Table 61.1 The clinical challenge remains that although life-threatening headache is relatively uncommon in most societies, it occurs and its detection requires suitable awareness by the doctors of its clinical markers (Table 61.2). Primary headache often confers considerable disability over time and, although not life-threatening, certainly robs patients of a good quality of life.9
PRIMARY HEADACHE SYNDROMES
The primary headaches are a group of remarkable disorders in which headache and associated features are seen in the absence of any exogenous cause. First, the general anatomy and physiology will be described as it applies to most of the syndromes. Then, the primary headache syndromes will be addressed in turn.
ANATOMY AND PHYSIOLOGY
The most common disabling primary headaches, migraine and cluster headache, have been studied extensively in recent times, and they are now relatively well understood insofar as neurologic disorders that involve the brain are concerned. The word disabling is emphasized as the writer takes the view that there are not sufficient clear data that tension-type headache provides a substantial and disabling community problem.10 In experimental animals, the detailed anatomy of the connections of the pain-producing dura mater and intracranial extracerebral vessels has built on the classical human observations of Wolff11 and Feindel et al.12,13 It is these structures, and not the brain itself, that primarily generate, or are perceived to generate, head pain.
TABLE 61.1 Common Causes of Headache | ||||||||||||||||||||||||||||||||
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The key structures involved are7
The large intracranial vessels and dura mater
The peripheral terminals of the trigeminal nerve that innervate these structures
The central terminals and second-order neurons of the caudal trigeminal nucleus and dorsal horns of C1 and C2 (trigeminocervical complex)
Higher center processing in the thalamus, ventroposteromedial and posterior thalamus, and cortex
Modulatory centers in the diencephalon and brainstem, such as periaqueductal gray matter, locus coeruleus, and parts of the hypothalamus
The innervation of the large intracranial vessels and dura mater by the trigeminal nerve is known as the trigeminovascular system. The cranial parasympathetic autonomic innervation provides the basis for symptoms such as lacrimation and nasal stuffiness, which are prominent in the trigeminal autonomic cephalalgias,14,15 although they may also be seen in migraine.16 It is clear from human functional imaging studies that vascular changes in migraine and cluster headache are driven by these neural vasodilator systems so that these headaches should be regarded as neurovascular.17 The concept of a primary vascular headache should be abandoned because it neither explains the pathogenesis of what are complex central nervous system disorders, nor does it necessarily predict treatment outcomes.18 The term vascular headache has no place in modern medical practice when referring to primary headache.
Migraine is an episodic syndrome of headache with sensory sensitivity, such as to light, sound, and head movement, probably due to dysfunction of aminergic brainstem/diencephalic sensory control systems (Fig. 61.1). The first of the migraine genes has been identified for familial hemiplegic migraine and includes mutations in the CACNA1A gene for the CaV 2.1 (α1A)
subunit of the neuronal P/Q voltage-gated calcium channel,19 the Na/K ATP pump α2 subunit gene ATP1A220 and the voltagegated sodium channel SCN1A.21 These findings and the clinical features of migraine suggest it might be part of the spectrum of diseases known as channelopathies, or now ionopathies: disorders involving dysfunction of ion channel fluxes.22 Functional neuroimaging has suggested that brainstem regions, in migraine (Fig. 61.2), and the posterior hypothalamic region, in cluster headache (Fig. 61.3), are good candidates for specific involvement in primary headache.17
subunit of the neuronal P/Q voltage-gated calcium channel,19 the Na/K ATP pump α2 subunit gene ATP1A220 and the voltagegated sodium channel SCN1A.21 These findings and the clinical features of migraine suggest it might be part of the spectrum of diseases known as channelopathies, or now ionopathies: disorders involving dysfunction of ion channel fluxes.22 Functional neuroimaging has suggested that brainstem regions, in migraine (Fig. 61.2), and the posterior hypothalamic region, in cluster headache (Fig. 61.3), are good candidates for specific involvement in primary headache.17
TABLE 61.2 Warning Signs in Head Pain | |
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 FIGURE 61.1 Pathophysiology of migraine. Diagram of some structures involved in the transmission of trigeminovascular nociceptive input and the modulation of that input that form the basis of a model of the pathophysiology of migraine.7 Afferents from dural-vascular structures innervated predominantly by branches of the first (ophthalmic division) of the trigeminal nerve whose cell bodies are found in the trigeminal ganglion (Vg) project to second-order neurons in the trigeminocervical complex (TCC). The TCC extends from trigeminal nucleus caudalis to the caudal portion of the dorsal horn of the C2 spinal cord. Input from cervical structures, such as joints or muscle, project through cell bodies in the upper cervical dorsal root ganglia (DRG) to the TCC. TCC neurons project to ventrobasal thalamus (thalamus) and then to cortex. Sensory modulation can occur by descending influences onto the TCC that largely respect the midline (dashed line), such as those from hypothalamus, midbrain periaqueductal gray (PAG), pontine locus coeruleus (LC), and nucleus raphe magnus (NRM). These influences are cartooned as being direct, but both direct and indirect projections are recognized. In addition, sensory modulation can occur from at least LC, PAG, and hypothalamic projects to thalamus nuclei as ascending systems again that largely respect the midline. |
 FIGURE 61.2 Activations identified on positron emission tomography in migraine. Consistently, there is dorsolateral pons activation in episodic migraine without aura, triggered by nitroglycerin144 (A) or spontaneously studied145 (B), and in chronic migraine146 (C). Moreover, there is lateralization to the right (D) and left (E) in this structure that parallels the unilateral presentation of the pain.147 |
SECONDARY HEADACHE
It is imperative to establish in the patient presenting with any form of head pain whether there is an important secondary
headache. Perhaps, the most crucial clinical feature to elicit is the length of the history. Patients with a short history require prompt attention and may require prompt investigation and management. Patients with a longer history generally require time and patience rather than alacrity. There are some important general features, including associated fever or sudden onset of pain (see Table 61.2). Patients with a history of recent-onset headache or neurologic signs need a positive diagnosis of a benign disorder or require brain imaging with computed tomography (CT) or magnetic resonance imaging (MRI). Patients with a history of recurrent headache over a period of 1 year or more, fulfilling International Headache Society (IHS) criteria for migraine (Table 61.3) and with a normal physical examination, have positive brain imaging findings in only about 1/1,000 images.25 In general, it should be noted that brain tumor is a rare cause of headache and rarely a cause of isolated long-term histories of headache. A notable exception to the general rules about secondary headache is pituitary tumor, which can trigger underlying primary headache biologies and should always be considered, especially in the differential diagnosis of trigeminal autonomic cephalalgias (see the following text; Levy et al.26).
headache. Perhaps, the most crucial clinical feature to elicit is the length of the history. Patients with a short history require prompt attention and may require prompt investigation and management. Patients with a longer history generally require time and patience rather than alacrity. There are some important general features, including associated fever or sudden onset of pain (see Table 61.2). Patients with a history of recent-onset headache or neurologic signs need a positive diagnosis of a benign disorder or require brain imaging with computed tomography (CT) or magnetic resonance imaging (MRI). Patients with a history of recurrent headache over a period of 1 year or more, fulfilling International Headache Society (IHS) criteria for migraine (Table 61.3) and with a normal physical examination, have positive brain imaging findings in only about 1/1,000 images.25 In general, it should be noted that brain tumor is a rare cause of headache and rarely a cause of isolated long-term histories of headache. A notable exception to the general rules about secondary headache is pituitary tumor, which can trigger underlying primary headache biologies and should always be considered, especially in the differential diagnosis of trigeminal autonomic cephalalgias (see the following text; Levy et al.26).
 FIGURE 61.3 Activations on positron emission tomography in the posterior hypothalamic gray matter in patients with acute cluster headache (A). The activation demonstrated is lateralized to the side of the pain.23 When comparing the brains of patients with cluster headache with a control population using an automatic anatomical technique known as voxel-based morphometry (VBM) that employs high-resolution T1 weighted magnetic resonance imaging, a similar region is demonstrated (B) and has increased gray matter.24 |
The management of secondary headache is generally self-evident: treatment of the underlying condition, such as an infection or mass lesion. One notable exception is the condition of persistent posttraumatic headache. This is an important problem that may be seen after central nervous system infection; trauma, both blunt and surgical; intracranial bleeds; and other precipitants, using the term trauma in its broader context to mean a biologic insult. The prevalence of the problem in returning service personnel has served to draw attention to the condition.27,28 It can certainly often be both prolonged and disabling.
MIGRAINE
Clinical Features
Migraine is an episodic brain disorder that affects about 12% to 15% of the population29 and can be highly disabling.9 It has been estimated to be the most costly neurologic disorder in the European Community at more than &U20AC;27 billion per year,30 and its cost to the US economy was a staggering $19.6 billion per year more than a decade ago.31 Migraine presents with headache generally accompanied by features, such as sensitivity to light, sound, or movement, and often with nausea, or less often vomiting (see Table 61.3). None of the features is compulsory and indeed, given that the migraine aura, visual disturbances with flashing lights or zigzag lines moving across the fields or other neurologic symptoms, is reported in only about 25% of patients, a high index of suspicion is required to diagnose migraine. In a controlled study of patients presenting to primary care physicians with a main complaint of headache over the previous 3 months, migraine was the diagnosis on more than 90% of occasions10; thus, a high index of suspicion is important. A headache diary can often be helpful in making the diagnosis, although in reality, usually the diary helps more in assessing disability or recording how often patients use acute attack treatments. Phenotyping remains an essentially clinical art mixing experience and an understanding of the problems likely to present: Good headache histories are taken not given. In differentiating the two main primary headache syndromes seen in clinical practice, migraine at its simplest is headache with associated features, and tension-type headache is headache that is featureless; furthermore, most disabling headache presentations in primary care are probably migrainous in biology. By features, here is meant throbbing pain; sensitivity to sensory stimuli: visual, auditory, olfactory; or to head movement itself.
TABLE 61.3 Simplified Diagnostic Criteria for Migraine | ||||||||
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Frequent Migraine
If headache with associated features describes migraine attacks, then headachy describes the migraine sufferer over his or her lifetime. It is important to realize that the word migraine can both describe the attacks using standard criteria (see Table 61.3) and describe the disorder itself, which is more than just the attacks. The migraine sufferer inherits a tendency to have headache that is amplified at various times by their interaction with their environment, the much-discussed triggers. The brain of the migraineur seems more sensitive to sensory stimuli and to change, and this tendency is notably amplified in females during their menstrual cycle. Migraine sufferers may have headache when they oversleep, when tired, when they skip meals, when they overexert, when stressed, or when they relax from a stressor. They are less tolerant to change, and part of successful management is to advise them to maintain regularity in their lives in the knowledge of this fluctuating biology. It is this biology that marks migraine and in clinical practice must override the phenotype of individual headaches. Chronic migraine is the largest part of the group of headaches known collectively as chronic daily headache, a term best not often employed because almost invariably, a more specific diagnosis can be made.
 FIGURE 61.4 Migraine Disability Assessment Score Questionnaire. This survey was developed by Richard B. Lipton, MD, Professor of Neurology, Albert Einstein College of Medicine, New York, NY, and Walter F. Stewart, MPH, PhD, Associate Professor of Epidemiology, Johns Hopkins University, Baltimore, MD. Reprinted from Stewart, WF, Lipton RB, Downson, AJ et al. Development and testing of the Migraine Disability Assessment (MIDAS) Questionnaire to assess headache-related disability. Neurology 2001;56(S1) with permission. |
Chronic migraine currently requires some 15 days a month of headache of which 8 are clearly migrainous and with a predating history of migraine.6 After making a diagnosis, the second step in the clinical process is to be sure that the disease burden has been captured, how much headache does the patient have and more important, what can the patient not do; what is his or her degree of disability? One can ask the patient directly to get a flavor for this, keep a diary or get a quick but accurate estimate using the Migraine Disability Assessment Scale (MIDAS), which is well validated and very easy to use in practice (Fig. 61.4).
Principles of Management of Migraine
After diagnosis, the management of migraine begins with an explanation of some aspects of the disorder to the patient.
Migraine is an inherited tendency to have headache; this is caused by the patient’s genes; therefore, it cannot be cured, but
Migraine can be modified and controlled by lifestyle adjustment and the use of medicines;
Migraine is not life-threatening nor associated with serious illness with the exception of females who smoke and use estrogenic oral contraceptives but migraine can make life a misery; and
Migraine management takes time and cooperation when, for example, a headache diary has to be collected or inquiry made concerning the disability.
Nonpharmacologic Management of Migraine
This approach aims to help the migrainous patient identify things making the problem worse and encouraging them to modify these. Patients need to know that the brain sensitivity to triggers in migraine varies. Patient associations are often very helpful in supporting migraineurs to identify triggers. The knowledge that there is variability will remove considerable frustration on the patient’s part and will ring true to most as they have had the experience. The crucial lifestyle advice is to explain to the patient that migraine is a state of brain sensitivity to change. This implies that the migraine sufferer needs to regulate their lives: healthy diet, regular exercise, regular sleep patterns, avoiding excess caffeine and alcohol, and, as far as practical, modifying or minimizing changes in stress. The balanced life with less highs and lows will benefit most migraine sufferers.
Preventive Treatments of Migraine
The patient needs to understand they have an inherited, noncurable but manageable problem. To start a preventive, they need to have sufficient disability to wish to take a medicine to reduce the effects of the disease on their life. The basis of considering preventive treatment from a medical viewpoint is a combination of acute attack frequency and attack tractability that is conferring an unacceptable degree of disability. Patients with attacks unresponsive to abortive medications are easily considered for prevention, whereas patients with simply treated
attacks may be less obvious candidates. Another important consideration is disease progress. If a patient diary shows a clear trend of an increasing frequency of attacks, it is better to initiate a preventive than wait for the problem to worsen.
attacks may be less obvious candidates. Another important consideration is disease progress. If a patient diary shows a clear trend of an increasing frequency of attacks, it is better to initiate a preventive than wait for the problem to worsen.
TABLE 61.4 Preventive Treatments in Migrainea | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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A simple rule for frequency might be that for one to two headaches a month, there is usually no need to start a preventive; for three to four, it may be needed but not necessarily; and for five or more per month, prevention should definitely be considered. Options available for treatment are covered in detail in Table 61.4 and vary by country. One problem with preventives is that they have fallen into use for migraine from other indications and often bring unwanted or intolerable side effects. It is not clear how preventives work, although it seems likely that they modify the brain sensitivity that underlies migraine. Another key clinical point is that generally, each drug should be started at a low dose and gradually increased to a reasonable maximum if there is going to be a clinical effect.
New advances: The development of migraine-specific preventives is on us as monoclonal antibodies to the calcitonin gene-related peptide (CGRP) pathway are nearing the clinic; effective and well tolerated, a new era is beginning.32 There are four monoclonal antibodies effective in both episodic and chronic migraine: three to CGRP, eptinezumab,33,34 fremanezumab,35,36 and galcanezumab,37,38 and one to the receptor, erenumab.39,40 Neuromodulation or neurostimulation approaches are promising as patients and physicians seek nonpharmaceutical approaches to treatment41; the best established of these being single-pulse transcranial magnetic stimulation (sTMS).42,43
Acute Attack Therapies of Migraine
Acute attack treatments for migraine can be usefully divided into disease-nonspecific treatments, analgesics and nonsteroidal anti-inflammatory drugs (NSAIDs), disease-specific treatments, ergot-related compounds, and triptans (Table 61.5). It is important to be aware that most acute attack medications seem to have
a propensity to aggravate headache frequency and can induce a state of refractory daily, near-daily, or medication overuse headache. As evidence is gathered, this seems to occur in patients with migraine, either a previous clear history or a family or personal history of headacheyness.44 Codeine-containing analgesics are particularly troublesome when available in over-the-counter (OTC) preparations. One should advise patients with migraine to avoid taking acute attack medicines on more than 2 days a week. A proportion of patients who stop taking regular analgesics will have substantial improvement in their headache with a reduction in frequency; however, for some, it will not make any difference. It is crucial to emphasize to the patient that standard preventive medications often simply do not work in the presence of regular analgesic use.
a propensity to aggravate headache frequency and can induce a state of refractory daily, near-daily, or medication overuse headache. As evidence is gathered, this seems to occur in patients with migraine, either a previous clear history or a family or personal history of headacheyness.44 Codeine-containing analgesics are particularly troublesome when available in over-the-counter (OTC) preparations. One should advise patients with migraine to avoid taking acute attack medicines on more than 2 days a week. A proportion of patients who stop taking regular analgesics will have substantial improvement in their headache with a reduction in frequency; however, for some, it will not make any difference. It is crucial to emphasize to the patient that standard preventive medications often simply do not work in the presence of regular analgesic use.
TABLE 61.5 Acute Migraine Treatments | ||||||||
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Treatment strategies: Given the array of options to control an acute attack of migraine, how does one start? The simplest approach to treatment has been described as stepped care. In this model, all patients are treated, assuming no contraindications, with the simplest treatment, such as aspirin 900 mg or paracetamol (acetaminophen) 1,000 mg with an antiemetic. Aspirin is an effective strategy, has been proven so in double-blind controlled clinical trials, and is best used in its most soluble formulations. The alternative would be a strategy known as stratified care, by which the physician determines, or stratifies, treatment at the start based on likelihood of response to levels of care. An intermediate option may be described as stratified care by attack. The latter is what many headache authorities suggest and what patients often do when they have the options.45 Patients use simpler options for their less severe attacks relying on more potent options when their attacks or circumstances demand them.
Nonspecific acute migraine attack treatments: Simple drugs, such as aspirin and paracetamol (acetaminophen), are cheap and can be effective. Dosages should be adequate and the addition of domperidone (10 mg orally) or ondansetron (4 mg) or aprepitant (80 mg) can be very helpful. NSAIDs can very useful when tolerated. Their success is often limited by inappropriate dosing, and adequate doses of naproxen (500 to 1,000 mg orally or rectally, with an antiemetic), ibuprofen (400 to 800 mg orally),46 or tolfenamic acid (200 mg orally)47 can be extremely effective.
Specific acute migraine attack treatments: When simple analgesic measures fail or more aggressive treatment is required, the specific antimigraine treatments are required (Table 61.6). Although ergotamine remains a useful treatment, it can no longer be considered the treatment of choice in acute migraine.48 There are particular situations in which ergotamine is very helpful, but its use must be carefully controlled as ergotamine overuse produces dreadful headache in addition to a host of vascular problems. The triptans, serotonin 5-HT1B/1D receptor agonists, have revolutionized the life of many patients with migraine and are clearly the most powerful option available to stop a migraine attack. They can be rationally applied by considering their pharmacologic, physicochemical, and pharmacokinetic features49 as well as the formulations that are available.45 Recent data suggests that combining a triptan with an NSAID can improve efficacy and reduce headache recurrence.50
TABLE 61.6 Stratification of Acute Specific Migraine Treatments | |||||||||||||||||||||||||||||||||||||||
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New advances: There are exciting new developments in acute therapy of migraine that are on the horizon. Neuromodulation approaches with supraorbital stimulation,51 noninvasive vagus nerve stimulation (nVNS),52 and transcranial magnetic stimulation53 each have controlled trials and an interesting physiologic basis.54,55 They offer patients a nonpharmaceutical option. What has been sought almost since the launch of the triptans is effective acute antimigraine treatments without vasoconstrictor effects.8 The development of lasmiditan, a serotonin 5-HT1F receptor agonist, or ditan, that is without vasoconstrictor effects,56 yet works in clinic in phase II57 and now in two phase III studies,58 is an important development. Similarly, the development of small molecule CGRP receptor antagonists, or gepants, notably now rimegepant59 and ubrogepant,60 which are both effective in treating acute migraine, and come from a clearly safe class of treatments,61 again offers the real promise of an important advance for patients.
Medication Overuse
An important clinical issue, which is probably a consequence of the interplay between migrainous biology and acute attack treatment, is what is described as medication overuse.
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