Chronic Daily Headache

• Objective: To review the classification, diagnosis, and management of chronic daily headache (CDH). • Methods: Qualititative assessment of the literature. • Results: Many patients present to their physicians with frequent or even daily head pain. Careful evaluation of these patients is essential to rule out a number of possible secondary causes of persistent headache, such as trauma, vascular causes, altered intracranial pressure, and neoplastic and infectious processes. Proposed subdivisions of primary CDH include chronic migraine, chronic tension-type headache, new daily persistent headache, and hemicrania continua. All of these may be exacerbated by frequent use of analgesics (analgesic rebound), and all imply a duration of more than 4 hours and a frequency of greater than 15 days per month. A number of medications are available for use in the treatment of CDH, but no controlled double-blind studies have examined pharmacotherapy for CDH. • Conclusion: CDH is a common and frustrating condition. Successful treatment hinges on correct diagnosis. Fortunately, for most causes of CDH treatment is usually at least partially effective. Many patients present to their physicians with frequent or even daily head pain [1]. In these patients, headache pain is often not severe every day, and generally migraine aura symptoms or accompaniments such as nausea are lacking or infrequent. Nonetheless, these patients often find the recurrent head pain maddening. What to call this headache type is the question. In recent years the term “chronic daily headache” (CDH) has been used by most authors to describe headaches of more than several hours’ duration not due to an underlying “secondary” cause occurring on the majority of days. Estimates of CDH prevalence vary, but several population-based studies suggest that 4% to 5% of all people have CDH [2–4]. In 1988, when the International Headache Society (IHS) produced its groundbreaking “classification and diagnostic criteria for headache disorders, cranial neuralgias, and facial pain,” CDH was not well described [5]. As a result, this diagnostic category was not even listed. The closest the IHS classification came to describing CDH was the term “chronic tension-type headache,” which was simply intended to refer to a very frequent form of tension-type headache. Unfortunately, it did not describe very well the patients who had migrainous features, who were in analgesic rebound, who had new onset of frequent headache (with no features of tension-type headache), or other groups of patients, such as those with postconcussive daily headaches. The revised classification soon to be published by the IHS Classification Committee will include a new category, “chronic migraine,” but it is unlikely that there will be a broad attempt to sort out CDH completely. It has become clear that the category of CDH includes some important subcategories. Stephen Silberstein and colleagues have proposed a classification scheme for primary From Dartmouth Medical School, Hanover, NH. INSTRUCTIONS The following article, “Chronic Daily Headache: Classification, Diagnosis, and Management,” is a continuing medical education (CME) article. To earn credit, read the article and complete the CME evaluation form on page 616. OBJECTIVES After participating in the continuing education activity, primary care physicians should be able to: 1. Understand the definition and classification of chronic daily headache (CDH) 2. Identify primary and secondary causes of CDH 3. Understand the relationship between of analgesic rebound and CDH 4. Know pharmacologic and nonpharmacologic options for treatment of CDH CDH that includes chronic migraine, chronic tension-type headache, new daily persistent headache, and hemicrania continua (Table 1). All of these may be exacerbated by frequent use of analgesics (analgesic rebound), and all imply a duration of more than 4 hours and a frequency of greater than 15 days per month. Chronic migraine is thought by many to originate from intermittent migraine, with the increase in frequency perhaps resulting from a natural progression of the disease. Many have termed this “transformed migraine” or “evolved migraine” [6] to imply that the problem began with intermittent migraine. This certainly seems to be true in some cases but not all [7]. In some patients, frequent analgesic use is such a key contributing factor that discontinuing analgesics reduces headache frequency back to the level of intermittent migraine. Chronic tension-type headache tends to be diagnosed in patients with a history of episodic tension-type headache and who have no migraine features such as nausea or auras. Location is generally diffuse. Here, too, analgesic rebound can play a major role, converting intermittent tension-type headaches to the chronic form. Both episodic and chronic forms do not seem to be linked to a muscular etiology (as was thought in the past) and, like migraine, may have a genetic basis [8]. New daily persistent headache (NDPH) was first described by Vanast in 1986 and refers to the relatively acute onset of headache that persists on a frequent basis [9]. Some patients can clearly date the onset of these headaches to a viral or other infectious disease. Chronic tension-type headaches are very similar morphologically to NDPH (absence of migrainous features and diffuse location). Previous tensiontype headache theoretically excludes NDPH, but this is problematic because of the high prevalence of intermittent tension-type headache, which in some patients might be coincidental. Chronic posttraumatic headaches are also similar to NDPH. Hemicrania continua is a relatively rare condition that consists of persistent unilateral head pain varying in intensity that is unresponsive to virtually all known migraine, cluster, and tension-type headache treatment except for indomethacin. In the “remitting form,” head pain can disappear for prolonged periods of time, reminiscent of the timing pattern of cluster headache [10]. Cluster headache, paroxysmal hemicrania, SUNCT (short-lasting, unilateral neuralgiform pain with conjunctival injection and tearing), cranial neuralgias, and stabbing headaches can also occur daily or nearly daily. These are all very distinctive and almost never lead to pain beyond 4 hours’ duration. The exception is the patient with cluster headaches who describes exacerbations of periorbital pain with autonomic features (ptosis, lacrimmation, congestion) but with underlying persistent aching pain between exacerbations of severe pain. This article presents 2 cases that illustrate important issues in evaluation, classification, and treatment of patients with CDH, with emphasis on the evidence (where available) supporting diagnostic and therapeutic decision making. CASE ONE Initial Presentation A 36-year-old woman presents with complaints of “increasing headaches” that are becoming harder to treat successfully.