INTRODUCTION
Primary headache disorders are highly prevalent conditions affecting tens of millions of U.S. citizens and hundreds of millions of individuals worldwide. The lifetime prevalence of common headache disorders can be more than 78%, with migraine prevalence greater than 20% in adult females. The economic and quality-of-life burden of migraine alone is substantial, with
the most disabled half of migraine sufferers accounting for more than 90% of migrainerelated work loss. Barriers to successful care include failure to diagnose properly, underestimation by both the professional and public domains of the morbidity of these conditions, and denied access to appropriate treatment.
PRIMARY AND SECONDARY HEADACHES
Primary headaches include those in which intrinsic dysfunction of the nervous system, often genetic in origin, predisposes to increased vulnerability to headache attacks. Examples include cluster headache and migraine. Secondary headaches are those in which the headache is secondary to an organic or physiologic process, intracranially or extracranially.
Table 8.1 is a short overview version of the International Headache Society’s (IHS) classification of primary headaches.
Table 8.2 lists some of the more frequently occurring categories of illnesses that produce secondary headaches.
MIGRAINE
▪SPECIAL CLINICAL POINT: Migraine is a complex neurophysiologic disorder characterized by episodic and progressive forms of head pain in association with numerous neurologic and nonneurologic (autonomic, psychophysiologic) accompaniments. These can precede, accompany, or follow the headache itself.
Migraine is classified into three major subtypes:
Migraine with aura—characterized by heralding neurologic events lasting 30 minutes to 1 hour and preceding the head pain attacks (only 15-20% of migraine attacks). A migraine aura should last longer than 5 minutes and less than 60 minutes. If an aura is consistently less than 5 minutes in duration, then a “secondary aura” should be suspected (arteriovenous malformation, epileptic aura). If an aura lasts longer than 60 minutes in duration, it is termed a “prolonged aura,” and an underlying coagulopathy or other cerebral pathology should be ruled out.
Migraine without aura—in which attacks of migraine and accompaniments occur without clear-cut preheadache neurologic symptomatology. This is the most common form of migraine (80% to 85%). A
prodrome is a period of time, up to 24 hours or so, prior to the aura or headache phase in which mental or physiologic events herald the next phases of migraine. The prodrome may consist of subtle or less than subtle phenomena, such as excessive yawning, food cravings, and mental changes, such as excitability, anxiety, elation, or even depression. Many
have misinterpreted the prodrome as a “trigger” phenomenon for the headache, but in actuality the prodrome represents the earliest phases of the ensuing attack.
Chronic or transformed migraine— frequently a progressive form of migraine in which intermittent attacks occur at increasing frequency, eventually reaching 15 or more days per month. By definition, chronic migraine occurs on a backdrop of episodic migraine without aura, often accompanied by comorbid neuropsychiatric phenomena. Chronic migraine frequently is associated with medication overuse and “rebound.”
▪ SPECIAL CLINICAL POINT: Comorbid conditions associated with migraine, particularly chronic migraine, include depression, anxiety and panic disorders, bipolar disorder, obsessive-compulsive disorder, character disorders, and perhaps fibromyalgia.
Migraine—Clinical Symptoms
Between 80% and 90% of patients with migraine have a family history. In childhood, there is a ratio of 1:1, males to females, but in adulthood a 3:1 female-to-male gender ratio occurs. This is primarily thought to result from the adverse influence on the headache mechanism by estrogen. At older ages, the gender ratio again declines to almost 1:1, further suggesting that estrogen is likely to be influential. Each attack generally lasts between 4 and 72 hours and can be accompanied by a wide range of autonomic and cognitive symptoms. In complex cases, particularly in chronic migraine, a likely association with several neuropsychiatric comorbid disorders, including depression, panic/anxiety syndromes, sleep disturbance, obsessive-compulsive disorder, and others, occurs. Predisposed individuals are particularly vulnerable to provocation (triggering) by certain extrinsic and intrinsic events, including hormonal fluctuation, weather changes, certain foods, delayed meals and fasting, extra sleeping time, stress, and others.
Pathophysiology of Migraine
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SPECIAL CLINICAL POINT: Migraine is a brain disorder that renders the brain “hypersensitive” and overresponsive to a variety of internal and external stimuli. Trigeminal/cervical connections and cervical activation may be important phenomena in the clinical manifestations, pathogenesis, and treatment. The key features of current pathophysiologic understanding are identified in Table 8.3.
TENSION-TYPE HEADACHE
This controversial disorder is classified into both episodic and chronic forms. Episodic forms have certain features that overlap with migraine without aura, although there is a general absence of throbbing pain and autonomic accompaniments. Chronic tension-type headache overlaps in clinical features with chronic migraine. Both forms of tension-type headache may be present in patients who have otherwise typical migraine headaches. Some authorities believe that these disorders are variant forms of migraine.
MEDICATION OVERUSE HEADACHE (FORMERLY CALLED REBOUND HEADACHE)
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SPECIAL CLINICAL POINT: Medication overuse headache (MOH), formerly referred to as rebound headache, is a self-sustaining headache condition characterized by persisting and recurring headache (usually migraine forms) against a background of chronic, regular use of centrally acting analgesics, ergotamine tartrate, or triptans. The descriptive features of this condition are noted in Table 8.4. Table 8.5 reflects the current IHS criteria for MOH.Among the most important clinical concerns is that MOH can be a progressive disorder, perhaps prompting the conversion of intermittent headache to daily headache, and ultimately has toxic and perhaps fatal implications because of the compulsive and often physiologically dependent features that reflect this medication/headache cycle. Also, MOH imposes a refractoriness to otherwise appropriate treatment, thereby forcing the discontinuation of these drugs before more appropriate medication treatment will be effective. The authors of this chapter believe that there are certain behavioral underpinnings to the development of MOH in some, but not all, patients. Addressing these, if present, is essential in order
to remedy the acute problem and maintain prevention in the long run.
MOH, medication overuse headache.
CLUSTER HEADACHE AND ITS VARIANTS
Cluster headache is a relatively rare disorder that affects more men than women in a ratio of 3:1. Current concepts of pathophysiology suggest disturbances within the hypothalamus with relevant involvement of autonomic systems and alterations in melatonin function. Melatonin “fine-tunes” endogenous cerebral rhythms and homeostasis.
The clinical features of cluster headache include the presence of headache cycles or bouts (clusters) lasting weeks to months and occurring one or more times per year or less. During these periods, repetitive attacks of short- lasting headache occur daily. Individual attacks of headache last 1 to 3 hours (averaging 45 minutes). The attacks are associated with focal orbital or temporal pain, which is always unilateral, is of extremely severe intensity, and is accompanied by lacrimation, nasal drainage, pupillary changes, and conjunctival injection. Attacks of headache commonly occur during sleeping times or napping and can be provoked by ingestion of alcohol or nitroglycerin. It is interesting that a high likelihood of blue or hazel-colored eyes; ruddy, rugged, lionized facial features; and a long history of smoking and excessive alcohol intake characterize the majority of men with cluster headache.
Table 8.6 lists the clinical distinctions between cluster headache and migraine.
Cluster headache may occur in its episodic form (bouts or cycles of recurring headaches followed by a period of no headache [remission], lasting weeks to years) or in a chronic form without an interim period, with headache attacks daily for years without interruption. Treatment differences may exist.
In addition to cluster headache, several shortlasting headache entities are recognized and currently are classified with cluster headache in a category referred to as the
trigeminal autonomic cephalgias. These disorders are characterized primarily by the presence of short-lasting headaches of variable duration—seconds (short-lasting unilateral neuralgiform headaches with conjunctival injection and tearing [SUNCT]) to 3 hours (cluster headache). The attacks are associated with autonomic features.
Table 8.7 lists the current members of the trigeminal autonomic cephalgia group.
