In the general medical outpatient setting, the most common year-round reason for medical consultation is pain, including headache. Unfortunately, the level of training in the diagnosis and management of such problems has yet to be optimally addressed by most clinical programs, at least to a reasonable degree considering the shortage of specialists in the area and the frequency of such problems. This is particularly true for headache. As a result, many clinicians on the “front lines” fall short of being able to provide adequate care to many patients whose headaches are not as clear-cut as teaching sources commonly suggest. For example, about 40% of migraine headaches are misdiagnosed by family practitioners and only half of those who might benefit from preventative therapy are provided it [1]. This problem can extend to the rehabilitation setting, where significant cross-training is required to care for injured or disease-compromised patients, a number of whom have pre-existing conditions including primary headaches.

As is the case within general medical clinics and inpatient wards, co-morbidity in the rehabilitation setting can be viewed as complicating the focus of care, or it can be seen as part of the overall clinical picture and treated as such. Consultation with another service is an option when co-morbid headaches are difficult to manage; however, the rehabilitation clinician should be able to construct a reasonable differential diagnosis of headache and should be able to attempt several approaches to care before seeking help from others. It can be a serious mistake to discount an exacerbation of pre-existing headache or, even worse, new occurrence of headache when the picture is less clear and the risk of making an incorrect diagnosis potentially dangerous. Secondary headaches must be ruled in or out. When the situation is under control, with or without the help of other professionals, the clinical focus can then shift back to the prescribed rehabilitation program.

The primary headaches include the following: tension-type headache; migraine with and without aura; migraine variants; cluster headaches and other trigeminal autonomic cephalalgias; primary or idiopathic stabbing headache; cough, exertional, and sexual activity-related headaches; primary thunderclap headache; nummular; new persistent daily headache.

Philosophically speaking , there are essentially two forms of headache, two types of patients, and two types of treating clinicians. These will be discussed over the next few paragraphs. Whether primary or secondary in designation, the two main types of headache are those that are easily treatable versus others that are relatively intractable. Approximately 80–90% of headaches are primary [2]. They are the result of a confluence of predisposing genetic, environmental, psychosocial, and sensory mis-processing factors. Primary headaches are not secondary to another condition. They are essentially idiopathic and the pain is generally recurrent-acute, but may be chronic in nature. Secondary headaches are by contrast symptomatic of injury or other clinical disorders. They are covered elsewhere in this book.

While easily treatable, headaches of any type are inconvenient if painful, and they are generally not life affecting. However, the relatively refractory headaches require considerable resources to manage them. The skills and costs often lie beyond the patient’s geographical location or financial resources. It is this type that frustrates patients, families, and clinicians alike.

At some point, out-of-control headaches of any type can change a relatively highly functioning patient, which is the first of the two kinds of patients, to the second kind, whose family, vocational, and psychosocial lives have been severely disrupted by pain and suffering. Such suffering can render them psychosocially dysfunctional, which is a significant therapeutic problem in and of itself that can complicate the picture. Note that this dysfunction is usually created by refractory headaches and the frustration involved and not the other way around. This is so in the majority of cases. To determine otherwise mandates the involvement of a highly trained mental health professional to assess more thoroughly a potential co-morbid psychiatric disorder. It must be a professional who is knowledgeable about the evaluation and management of chronic pain and suffering; otherwise, such an evaluation and intervention is likely to prove less accurate and potentially damaging.

An interdisciplinary and/or multimodal approach to care is best advised before such complications develop. Prevention of escalation should be at the front of every clinician’s assessment. Too often, early signs of co-morbidity are ignored or go unnoticed and at some point, it may be too late to do much about it. Fortunately, a single clinician well versed in a number of approaches to the diagnosis and management of headache can achieve much. Not every problem needs to be solved immediately yet early clarification can help others to provide effective management after the patient is discharged from the rehabilitation program.

A common problem is poor communication or misunderstanding between clinician and patient. Their goals may differ. Clinicians tend to focus on what they feel are the key medical or surgical issues (“at least we can cut it out or block the pain with medication”), whereas patients worry more about how they might be affected as a person or how their condition might interfere with their role as a family member or provider (“what if I can’t work again or properly take care of my newborn child, while experiencing recurrent pain like this?”). Communication is of utmost importance to minimize anxiety yet, in order to communicate effectively, there must be an interpersonal connection. If the clinician is both a healer and an empathetic human being, such qualities are likely to foster connection with the patient. Caring is always possible, whereas cure is not. This is akin to the difference between the biopsychosocial versus the biomedical approach to the treatment of pain.

Contrary to a popular saying, pain does kill. Suicide is not uncommon, especially by those who feel alone in their suffering. This is a perception that is derived from feeling that their pain is neither sufficiently validated nor appropriately managed. Suicide is also more likely to occur when hopelessness and helplessness result in what psychologists refer to as a change in the locus of control [3]. This factor can be ascertained on interview. Essentially, it describes a patient’s attitude regarding his or her ability to self-modulate pain when given the tools to do so. This is the best-case scenario; the worst-case scenario occurs when there is no locus of control, constituting a loss of hope or a medical surrender. The middle ground, or third type, is when patients feel reliant upon the “magical” powers of others to cure them. Mental health specialists trained in pain management can be very helpful here. They can empower patients to help themselves. They should be introduced as pain specialists with a psychological background, the goal of their involvement being to enable patients to cope more effectively. Even a single consultation or a few clinical sessions in either a group or individual setting can be useful. It is vital that the patient not mistake the message or referral to mean that “the pain is all in your mind”. That is every bit as important to them as knowing that there is no tumor present responsible for the pain. Pain is always real when experienced. The cause is relevant only in terms of how it is best handled and that cause may at times be hard to determine.

Very broadly speaking, clinicians themselves may also be of two types. Many are disease or medically focused, whereby interventions are largely predicated upon an understanding of the disease process per se. Essentially, if unwittingly so, treating the patient becomes somewhat incidental. Their biomedical perspective to care is predominantly pharmaceutical, interventional, or surgically based. Other, more empathetic and “people-oriented” practitioners with a biopsychosocial perspective see patients as persons afflicted with life-affecting conditions, providing them with an opportunity to try different approaches and to devise a plan of care based upon a patient’s personality, their family dynamics, socioeconomic and cultural influences, as well as their medical condition. In either case, treatments might include those lying outside allopathic or “western” medicine; although, it is increasingly common to find practitioners combining them in an integrative or collaborative manner. Not all approaches need be tried within the rehabilitation setting; however, a few are easily initiated there.

Clinicians and nursing staff can provide patients with contact information for post rehabilitation care. It is always a good idea to foster realistic expectations, an example of which is that in the long run, most primary headaches are generally managed rather than cured; hopefully, this will diminish the problem by 50–75% and ongoing care will likely be required after discharge. At some point, patients may even “grow out of them”. In a tiny minority, some headaches have an onset well into the seventh decade [4].

It may be helpful to think of the primary headaches, especially migraine, as aberrantly amplified and prolonged normal physiological processes that result in head pain. Pain is the most focused-upon symptom, but it is not always present or even necessary for the diagnosis; “acephalgic migraine” and migraine variants are the best examples of this. The notion of sensory hypersensitivity is not very different from the basic concepts used to explain neuropathic pain or the hypersensitivity to stimuli seen in fibromyalgia, all being aberrant responses to normal stimuli caused by dysfunctional central nervous system processing, which might involve wind-up and centralization of pain [5]. This may explain the therapeutic overlap of certain agents commonly employed in pain and headache management. The treatments may help to re-set the nervous system’s processing of sensory input.

Unfortunately, where headaches are concerned and especially the primary headaches, pain generators are still imperfectly understood. Such missing information is not merely academic given the fact that treatment strategies vary considerably depending on the headache subtype, pathophysiology involved, and the clinical presentation. They all help to more accurately define the type of headache. However, detailed assessment in making the most accurate diagnosis as possible is not always easy. Clinical acumen and experience, along with a broad knowledge of diagnostic and therapeutic interventions are invaluable given the lack of evidence-based methods and objective testing that might otherwise be applied. Headache medicine, for all its advances in pathophysiology over the past half-century, is still not unlike the field of psychiatry. To a great extent, the diagnosis is determined via a signs and symptoms approach, sometimes necessitating a diagnosis of exclusion, a case in point being that of migraine.

Despite the significant overlap between the fields of pain and headache medicine, the details of management may differ in important ways. For example, medication overuse can lead to chronicity of headache , with different time periods of overuse being needed for different classes of medication [6]. This is not really a concept thought to affect other forms of pain; although, there are emerging percepts that contradict such a position. Some workers believe that pain medication can, over time, negatively affect a patient’s perception of pain and/or decrease their pain thresholds.

Importantly, many of the compounds used to abort, prevent, or to minimize the frequency or recurrence of several primary headaches cannot be used to make the diagnosis, even when successful. This is so because such compounds might work well on several disorders, not all of which need be headache. Epilepsy, hypertension, facial pain, stroke, anxiety, insomnia and depression, and others might all respond to a narrow range of medication. Such conditions can also result in the emergence of a new headache disorder or exacerbation of an already present one. Furthermore, several types of headache may respond to the same treatment. Triptans, for example, may alleviate headache associated with stroke, but leave the patient dangerously untreated for a life-threatening condition if a full workup is deferred. Triptans may also alleviate tension-type appearing background headache present between acute exacerbations of migraine, something seen in both chronic-from-the-start migraine, as well as the etiologically different form of migraine transformed from episodic to chronic by overuse of any abortive medication, the latter being a condition that can usually be reversed by detoxification and carefully implemented prophylaxis. However, triptans will fail to alleviate tension-type headache when migraine is not present. This brings up the point that the lesser pain experienced between peaks of migraine intensity appears similar to, but not quite the same, as tension-type headache. While there has been much debate about these two similar types of headache lying in a continuum, at this point in time, most workers in the field believe that they are disparate; although, there may be a subset of people for whom such a continuum exists. Therefore, the art of thorough history taking is crucial as is the physical examination. Both help to define the initial or presumptive differential diagnosis so that appropriate imaging studies and tests might be most efficiently obtained. A good history does not preclude the physical examination or testing, but rather directs them. The diagnosis is usually reached via a combination of all three.

Primary headaches tend to begin most often as recurrent-acute head pain with associated signs and symptoms. Some types involve the autonomic nervous system ; whereas, others are chronic from the start. New Persistent Daily Headache is the classic example of this. Autonomic nervous system-related signs and symptoms are nearly always present in the trigeminal autonomic cephalalgias and, to a far lesser degree, migraine. While many primary headaches are episodic in origin, most can become chronic over time and most commonly via overuse of abortive medication; although, chronicity can manifest from the start or can be created by other mechanisms, such as stress-induced vacillation between more than one form of headache [7]. Once again, a case in point is chronic migraine . Determining how and when it became chronic can drastically alter the treatment plan. Importantly, chronic migraine cannot be diagnosed in the presence of medication overuse [7]. Chronic migraine , which includes headache for more than 15 days a month, may be very similar in presentation to transformed migraine; the latter being an older term most commonly associated with medication overuse, but potentially inclusive of other mechanisms. Other mechanisms include frequent triggers by one or more co-existing headache disorders.

Despite their similarity in presentation, the approach to treatment of certain headaches that have become chronic is different. Medication over-use headache, which was previously known as rebound headache , is an umbrella term covering many forms of once-episodic headaches that include, but are not restricted to, migraine. It is not difficult to treat if one understands what likely caused the persistence or intractability. Additionally, good clinical skills and an encouraging bedside manner help substantially. This is described further in its own subsection.

Regardless of the cause of chronicity, headache subtypes can occur alone or together. The importance is that the differentiation between co-existent headaches helps the clinician to elucidate potential endpoints, treatment goals, or the best timing and sequencing of them. The only way to obtain this information is through a very detailed history, which includes asking questions from several angles since many patients experience headache as a continuous uni-dimensional type of pain, until they are taught to separate signs and symptoms. This is not unlike learning to listen to an orchestra perform. With up to 106 musicians performing on the stage alone or together, it becomes far more interesting to the listener when individual instruments, melodies, and musical counterpoints, etc., can be discerned, whilst never losing track of the whole score. This requires education beyond medical school and residency training. A similar analogy can be made using team sports, whereby an understanding of the role various players have on and off the ball enhances understanding of the game. If multiple headaches are diagnosed, given that several treatments may cover several forms of headache, fewer compounds might then be needed as a component of care.

The reason for near black and white classification of headaches by the International Headache Society (IHS) is mostly to improve the sensitivity and specificity of research protocols. This is to assure that the same form of headache is more likely to be consistently diagnosed, which makes it easier to judge the efficacy of treatments for them, whether new or in comparison to one another.

In non-research clinics, headaches are often of a mixed type of etiology, and the pathophysiology remains even more controversial. There is also far greater overlap and mixing of terminology in the clinical, as compared to the research setting. An example would be “cluster-migraine ”, for which there is no IHS diagnosis. However, the two separate types of headache, cluster headache and migraine, can co-exist. Interestingly, when this happens, a treatment often helpful for one, but not the other, may work well for both. Oxygen, via a non-re-breathable face mask, may thereby alleviate a migraine headache, just as preventative medications that are typically useful for only one might help with the other. In other words, it is important not to get too caught up in the research setting’s “rules”; it is important to maintain the flexibility of mind that facilitates creativity, as well as a healthy level of skepticism, whereby mechanisms of action or causation are concerned. Rarely do the data for such things remain static, and to achieve this flexibility of mind, keeping up on the literature is important.

For the most part, while there are few specific bedside neurological examination techniques or “high-tech” tests available outside of the research setting to diagnose primary headaches, some procedures can help to clarify the differential diagnosis and/or prognosis. Tests are necessary at times to rule in or out other possibilities that might mimic certain headaches and facial pain. They can also help to predict a successful treatment of an already confirmed diagnosis or can help to justify a different, longer lasting, if sometimes more expensive approach to alleviation of pain, such as by neuromodulation (i.e., peripheral nerve stimulation). Three successive and successful diagnostic and therapeutic greater occipital nerve injections, if only of temporary help, might justify the use of a peripheral nerve stimulator, a modality that has the potential for effectively aborting cervicogenic as well as cluster headaches. For further details, please see chapter on peripheral nerve stimulation.

Other interventional techniques may also be of value. Diagnostic and/or therapeutic applications of anesthetic agents placed into the intra-nasal region (lidocaine, procaine, or rarely cocaine), or peri-cranial muscle injections of Botox A, etc., are commonly used to alleviate specific pains in the short or the long term, respectively. Some injections are purely diagnostic, some therapeutic, and others both.

Imaging studies may also be useful. For example, tumors may “mimic” migraine, as can seizures. Tumors can cause epilepsy as well as stroke, both of which can lead to intense headache. Therefore, objective tests may be required to narrow the differential diagnosis. Trigeminal neuralgia must be differentiated from painful trigeminal neuropathy, the latter of which includes negative symptoms, such as loss of facial sensation, with positive symptoms of trigeminal neuralgia, such as spontaneous lancinating, stabbing, and aching facial pain. These symptoms are sometimes the result of a tumor in the cavernous sinus.

Facial pain alone is often due to irritation of the root of the fifth cranial nerve by an abutting pulsating artery that injures the nerve, while that same pain, which is sometimes experienced bilaterally, can be produced by a multiple sclerotic plaques adjacent to the nerve root. A head MRI and MRA with contrast can help to rule in or to rule out a mass-producing headache. In the second case, pressure-induced peripheral cranial nerve pain should be considered. Because radiologic technology and diagnostic protocols undergo such rapid change, it is best to check with a neuroradiologist for the most appropriate imaging study based upon the signs and symptoms and differential diagnosis. An EEG might also prove useful if post-ictal seizure-related headaches are suspected. For the most part, at least where the primary headaches are concerned, the neurological examination is generally normal and head MR imaging is unrevealing.

Knowledge of pathophysiologic terminology can be important for authorization of procedures, depending on the health insurance companies’ policies. Additionally, this will facilitate a means of communication between clinicians from different generations. While occipital neuralgia is a more recent and accurate term for what was once referred to as “occipital neuritis”, even today there are cases where only one or the other term will qualify for a peripheral nerve stimulator, despite them being the same disorder. For example, it was not long ago that “sick headache” was still accepted by Medicare as a pseudonym for migraine. Outdated terminology is abundant in clinical medicine, mostly outside of the research setting; yet; such terminology is still important to know.

It is also important to understand that the language used in most respected textbooks and papers can rapidly become accepted as “gospel” by the medical community. Through time, and by convention, this language becomes the dominant descriptors or hypothesized causes of pain for a given diagnosis. These then become recognized as “fact”, even when at a later time the information is known by many to be incorrect. Misnomers and misinformation can persist for years and can even appear in the latest revisions of a textbook. For example, as will be mentioned below, “vascular headache” is an inaccurate and well-outdated term [8], which was replaced in recent years by the concept of neurovascular pain; yet, it is still commonly used. Failure to stay abreast of such things can be clinically limiting, contributing to misdiagnosis as well as mismanagement given that optimum therapy depends upon accurate understanding of the mechanisms of dysfunction.

Even simple pain descriptors can be problematic. For example, “stabbing” pain does not equate with cluster headache, as might be taught in medical school. It is seen in other trigeminal autonomic cephalalgias as well. That group of headaches now includes paroxysmal hemicrania , and the stabbing symptom is a defining pain in another primary headache disorder, idiopathic stabbing headache . Even migraine may include stabbing pain and autonomic dysfunction ; yet, it is in a category of its own. Boundaries between syndromes are not always sharp. Throbbing, pulsating pain may be a frequent manifestation of migraine, but are also prominent features of caffeine withdrawal headache and acute sinusitis . Even the unilaterality of migraine is merely a most common scenario. In fact, just as lateralized partial seizures can secondarily spread, so too can migraine phenomena, as often as 40% of the time [9]. It may typically begin on one side and then become bilateral, especially during sleep. It may then awaken one with pain on both sides, even if generally felt as most intense on the side of origin. Nausea and vomiting are prominent features of most migraine attacks, 80–95% and 50% respectively; yet, in a very small minority (perhaps 3–5%), they are both absent. Clinically, they may not be a necessary feature of migraine, even though they are considered so for research purposes. There is room for greater flexibility in the clinic. While cervicogenic headaches are typically described as unilateral, Nicolai Bogduk has stated wryly that on occasion they can be “bilaterally unilateral”. As can be seen by these examples, nosology is not always clear-cut, so it is best to minimize rigidity of thinking regarding diagnostic criteria by being as open as possible to frequent changes within the classification systems.

Primary headaches can be induced or exacerbated directly or indirectly by ongoing medical or surgical issues that may or may not be painful, which include internally disrupted cervical disks from C4-C5 and up, cervical facetogenic pain, reactive myofascial pain, restless legs syndrome (RLS), periodic limb movements of sleep (PLMS) , as well as obstructive sleep apnea . Injury or pain from other conditions, the treatments for those problems, exercise or lack thereof, dietary factors, sexual activity or exertion, and irregular sleep patterns can all make headache worse in terms of frequency and intensity. If sleep apnea is present, headaches, anxiety, or depression may be extremely difficult to control. Additionally, with non-restorative sleep due to other interferences with sleep architecture, including alcohol, or movement disorders such as RLS, PLMS, or alpha-wave intrusion of sleep as seen in fibromyalgia, headaches may become very hard to manage. Even a number of commonly used antidepressants such as TCAs, SSRIs (but usually not SNRIs) might exacerbate the movement disorder, even though they may be appropriately prescribed for other signs and symptoms. If a TCA causes sedation but exacerbates RLS/PLMS , then it is of no help. Each patient is different. It is always important to keep the bigger picture in mind. Conversely, dopaminergic compounds used to treat sleep-disrupting disorders, such as RLS and PLMS, may result in hallucinations or compulsions. These often manifest in psychosocially disruptive behavior and the emergence of addictions, the ramifications of which can be serious both legally and socially, and can negatively affect headache frequency clinically. Knowledge of pharmacology and drug–drug or drug–disease interactions is of paramount importance whenever clinical outcomes are concerned.

Stress is most commonly cited as a trigger for headaches, but that is itself a complex topic. Stress can be both a cause and a result of headache. A migraine headache may follow stress, such as after completion of a demanding project. Stress can negatively affect eating schedules and the type of food consumed, can increase alcohol consumption, can decrease time and energy available for exercise, and can disrupt sleep patterns. All of these can, even without stress as a factor, trigger certain headaches. All can induce migraine. In the laboratory setting, nitrates, such as in nitroglycerin paste, are more reliable in inducing headache, at least in migraineurs, than are the more commonly cited triggers of alcohol, stress, chocolate, or nuts. However, stress plays a minimal role in the onset of cluster headache, and relaxation training is fairly worthless in its prevention. Alcohol, in contrast, is a clear and avoidable trigger. As aforementioned, one type of headache can trigger another, bouncing back and forth. Hence, failure to recognize a person’s different headache subtypes, triggers, and the lifestyle factors that impact them can lead to relatively ineffectual results in terms of management.

Where migraine is concerned, during an attack, oral medication absorption is diminished in some patients and the head pain can rapidly escalate to a point where it becomes very difficult to alleviate. This phenomenon mandates early treatment , usually within the first 20 min. However, if done so too frequently, it can lead to medication overuse headache . Thus premature or excessive treatment can prove counter-productive. Treatment recommendations require thoughtful and careful observation, as well as patient and family education. It is important to remember that each individual is different. A really helpful question is, “when you develop the migraine pain on one side or the other, do you lay your head down on a soft pillow, gently applying pressure to that side, or does that make it worse?” If the answer is “worse”, then such rapidly escalating one-sided allodynia, which is defined as pain from a non-painful stimulus, requires aggressive and early abolition. Otherwise, it may last miserably for 72 h and may prove relatively refractory to treatment. If the person lies down with the painful side touching a pillow with gentle pressure providing some relief, then there is a more leeway in trying distraction, relaxation, or other methods to avert a full-blown, long-lasting migraine headache. Even a visit to the Emergency Department (ED) with bright lights, loss of rest, forced movement, noise can be highly stressful and can significantly worsen a migraine attack. After all, most migraineurs wish only to lie down in a quiet, dark place in order to sleep it off.

Sometimes, distraction can avert a migraine headache or a tension-type headache, the latter of which can sometimes turn into a migraine if co-existent. Again, care in advising patients based upon their own profile, history of pain, alleviation, plus back-up strategies are necessary for optimal results. If medication overuse has turned episodic headaches into the chronic type, preventative medication will usually fail until detoxification has been in place for 1–3 months [10]. Because of this little known fact, previously tried and failed preventatives might thus be reconsidered at a later date, post detoxification. Patients should have at least a couple of safe abortive medication options to use at home or at work in case one fails. Conversely, failure to bring some headaches quickly under control can negatively impact the time needed for headache relief. Subsequently, this can perpetuate suffering or can require an otherwise preventable visit to the ED. Too many such episodes while in the rehabilitation setting will impede therapeutic success, will increase the cost of care, and will prolong the time needed for healing and recuperation. It becomes a balancing act, as medicine so often does. The trick is to avoid it becoming a circus.

One of the most common reasons for failure to help those with chronic pain and intractable headache is misuse of medication by clinicians, let alone patients. As a headache and pain specialist for both adults and children, it is not unusual to receive a referral for care that contains a list of up to 30 medications that have been tried and “failed”. Generally, failure is due to a lack of understanding about how to apply pharmacologic knowledge differently than might be the case in other areas of medicine, with the exception of general pain management and epilepsy. It simply is not taught in medical school or in most residency programs, and those gaining such experience in fellowships or by trial and error are small in number. The following are some general principles to keep in mind with patients suffering primary headaches, either episodic or chronic in presentation: