Secondary headaches are classified by the cause of the underlying disease process that is causing the headache. There are hundreds of secondary headache diagnoses and this article is not an exhaustive discussion of secondary headache disorders. Maintaining a high level of virulence and having a structured approach to evaluating all patients with headache is the key to timely diagnosis of secondary headache disorders. Diagnostic testing is indicated based on the suspected disorder and management is determined by treatment of the underlying disease causing the headache.
Key points
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Secondary headaches are classified by the cause of the underlying disease process that is causing the headache.
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Maintaining a high level of vigilance and having a structured approach to evaluating all patients with headache is the key to timely diagnosis of secondary headache disorders.
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Diagnostic testing is indicated based on the suspected disorder and management is determined by treatment of the underlying disease causing the headache.
The number of disorders associated with the symptom of headache is as impressive as it is complex. Timely identification and diagnosis of secondary headaches often poses a significant challenge to clinicians. No single test or imaging study can conclusively diagnose all headache disorders. The most effective tool a clinician has to evaluate a patient with headache is a good history. Effective communication between a health care professional and patient is the essential key to successful diagnosis.
The consequences of missing a serious secondary headache can be severe. However, a serious disorder as a cause of headache is uncommon, especially in the outpatient setting. In medical settings such as emergency departments, referral centers, or urgent care facilities, the frequency of secondary headaches is higher, but, even in these settings, secondary headaches are less common than primary headache disorders. Although this fact is comforting, it is often the familiarity with headache that is the reason a secondary disorder is sometimes overlooked. Therefore, it is essential that health care professionals maintain a high level of vigilance when evaluating a patient with headache, especially in patients with long-standing primary headache disorders. A secondary headache is likely to mimic a preexisting primary headache. It has been estimated that approximately 90% of patients with a secondary headache also have a primary headache disorder and a normal examination. Therefore, establishing a systematic approach to evaluating the patient with a complaint of headache is the best insurance against missing a disorder associated with serious secondary headaches.
Primary versus secondary headache
The first step in evaluating a patient with the complaint of headache is to differentiate primary from secondary headache. Primary headaches are syndromes in which headache is the disease process. They are classified according to symptoms. The most common primary headache disorders are migraine, tension-type headache, and cluster headache. Less common primary headaches include other trigeminal autonomic cephalalgias; primary stabbing headache; headaches associated with cough, exertion, or sexual activity; new-onset persistent daily headache; and primary thunderclap headaches. The common primary headaches are, by definition, recurrent and thus have generally been experienced by the patient on multiple occasions. The less common primary headaches are also usually recurrent (with the general exception of primary thunderclap headache), but these often require diagnostic work-up to exclude disorders. Only after repeated episodes of the same headache can the diagnosis of primary headache be firmly established.
Secondary headaches are classified by their causes. In secondary headaches, headache is a symptom of an underlying pathologic process. In general, secondary headaches are unfamiliar or new to the patient. The clinical caveat in this classification is that whenever a clinician is evaluating a new or different headache, there should be a high index of suspicion for a disorder. For diseases known to cause headache, the disorder often occurs in close temporal proximity to the onset of headache.
Central to understanding the distinction between primary and secondary headaches is that symptoms alone are inadequate criteria for differentiating primary and secondary headaches. The brain has limited mechanisms to express pain. The symptoms included in diagnostic criteria of primary headache disorders are also frequently present in secondary headache disorders, and a patient can experience a secondary headache with the same symptoms as any primary headache disorder. More often, it is the context in which a headache occurs that allows timely differentiation between primary and secondary headaches. The key element is for the clinician to accurately ascertain whether the evaluation is of a new or different type of headache, or whether it is an evaluation of an already established pattern of headache that is consistent and stable over time.
Consider the following case study: EM is a 42-year-old woman with a history of migraine of 30 years or more. Over the past 5 years, the migraines have occurred between 2 and 4 times per month. She has experienced a good sustained abortive response to oral sumatriptan for many years. She uses propranolol long acting 80 mg as migraine prophylaxis and to control hypertension. At an office visit 6 months ago, her migraine was well controlled and no changes were made in her treatment plan.
She presents stating that over the last 6 weeks her migraines have been getting worse. She reports that she has some type of headache almost every day and the migraines are worsening in intensity. The headaches are associated with nausea and sensory hypersensitivity, but the intensity of these symptoms varies from day to day and at times it is worse than in the past. She is perplexed about why her migraines are getting worse because she is not under increased stress and there is no change in her menstrual cycle. She noted that during her last menstrual period the migraine was only mild, which was unusual for her. She reports that sumatriptan is less effective and no longer aborts her migraine, although generally it still provides relief. Her sleep is disrupted by the headache and frequently she is nauseated in the morning. Her mood is stable and there have been no other changes in her health or medication usage. Her examination is normal.
Should this history sound alarm bells for the evaluating health care professional? Although the history alone does not diagnose a specific disorder, it does provide reasons for a high index of suspicion to evaluate this patient further. Most significant in this history is that the patient is communicating a change in her headache pattern that is distinct from her established primary headache disorder. Thus further evaluation of a headache in evolution is warranted. Although this change in headache pattern may be a progression of her migraine, there is little support in her history for this rapid transformation into a new headache pattern. In addition, her long-recognized response to sumatriptan has changed and she specifically noted that during menses this headache was different than her usual migraine. This patient should be evaluated for a secondary headache disorder.
The boundaries that define primary and secondary headaches are often indistinct and require a clinician to take time and care in interpreting a patient’s history and to sift astutely through the hundreds of patients presenting with primary headache in order not to overlook the rare patient with a serious disorder. Again, the most valuable tool for accomplishing proper diagnosis is effective communication with the patient.
Primary versus secondary headache
The first step in evaluating a patient with the complaint of headache is to differentiate primary from secondary headache. Primary headaches are syndromes in which headache is the disease process. They are classified according to symptoms. The most common primary headache disorders are migraine, tension-type headache, and cluster headache. Less common primary headaches include other trigeminal autonomic cephalalgias; primary stabbing headache; headaches associated with cough, exertion, or sexual activity; new-onset persistent daily headache; and primary thunderclap headaches. The common primary headaches are, by definition, recurrent and thus have generally been experienced by the patient on multiple occasions. The less common primary headaches are also usually recurrent (with the general exception of primary thunderclap headache), but these often require diagnostic work-up to exclude disorders. Only after repeated episodes of the same headache can the diagnosis of primary headache be firmly established.
Secondary headaches are classified by their causes. In secondary headaches, headache is a symptom of an underlying pathologic process. In general, secondary headaches are unfamiliar or new to the patient. The clinical caveat in this classification is that whenever a clinician is evaluating a new or different headache, there should be a high index of suspicion for a disorder. For diseases known to cause headache, the disorder often occurs in close temporal proximity to the onset of headache.
Central to understanding the distinction between primary and secondary headaches is that symptoms alone are inadequate criteria for differentiating primary and secondary headaches. The brain has limited mechanisms to express pain. The symptoms included in diagnostic criteria of primary headache disorders are also frequently present in secondary headache disorders, and a patient can experience a secondary headache with the same symptoms as any primary headache disorder. More often, it is the context in which a headache occurs that allows timely differentiation between primary and secondary headaches. The key element is for the clinician to accurately ascertain whether the evaluation is of a new or different type of headache, or whether it is an evaluation of an already established pattern of headache that is consistent and stable over time.
Consider the following case study: EM is a 42-year-old woman with a history of migraine of 30 years or more. Over the past 5 years, the migraines have occurred between 2 and 4 times per month. She has experienced a good sustained abortive response to oral sumatriptan for many years. She uses propranolol long acting 80 mg as migraine prophylaxis and to control hypertension. At an office visit 6 months ago, her migraine was well controlled and no changes were made in her treatment plan.
She presents stating that over the last 6 weeks her migraines have been getting worse. She reports that she has some type of headache almost every day and the migraines are worsening in intensity. The headaches are associated with nausea and sensory hypersensitivity, but the intensity of these symptoms varies from day to day and at times it is worse than in the past. She is perplexed about why her migraines are getting worse because she is not under increased stress and there is no change in her menstrual cycle. She noted that during her last menstrual period the migraine was only mild, which was unusual for her. She reports that sumatriptan is less effective and no longer aborts her migraine, although generally it still provides relief. Her sleep is disrupted by the headache and frequently she is nauseated in the morning. Her mood is stable and there have been no other changes in her health or medication usage. Her examination is normal.
Should this history sound alarm bells for the evaluating health care professional? Although the history alone does not diagnose a specific disorder, it does provide reasons for a high index of suspicion to evaluate this patient further. Most significant in this history is that the patient is communicating a change in her headache pattern that is distinct from her established primary headache disorder. Thus further evaluation of a headache in evolution is warranted. Although this change in headache pattern may be a progression of her migraine, there is little support in her history for this rapid transformation into a new headache pattern. In addition, her long-recognized response to sumatriptan has changed and she specifically noted that during menses this headache was different than her usual migraine. This patient should be evaluated for a secondary headache disorder.
The boundaries that define primary and secondary headaches are often indistinct and require a clinician to take time and care in interpreting a patient’s history and to sift astutely through the hundreds of patients presenting with primary headache in order not to overlook the rare patient with a serious disorder. Again, the most valuable tool for accomplishing proper diagnosis is effective communication with the patient.
Taking a headache history
Making a headache diagnosis is often considered an exercise in quizzing a patient with a checklist of headache characteristics and associated symptoms. Some questions are common to any textbook discussion of headache history, such as: where is the headache located? What is its intensity? What is the quality of the pain? What are the specific symptoms associated with the headache? What are the exacerbating and alleviating factors for the headache? However, primary and secondary headaches share symptom expression and thus symptoms alone are of limited value in defining secondary headache disorders.
A more effective strategy to obtain a good history is to let patients tell their stories by asking open-ended questions and considering the patient interview as a collaborative exercise between 2 experts: the clinician by virtue of education and medical experience, the patient by virtue of insightful understanding of the personal history. Detailed questioning can be used by the clinician to elaborate specific aspects of the patient’s history. In this way the headache history is put into a context that permits better differentiation and alignment of headache diagnoses and potential causes.
Key features to communicate and discuss can be summarized in the mnemonic of the 5 Ps: pattern, phenotype, patient, pharmacology, and precipitants or provoking factors.
The 5 Ps
Pattern
Understanding the temporal pattern of headache is one of the most important elements of taking a headache history. The headache pattern reflects how the headaches have evolved over time and provides useful insight into important and sometimes subtle changes in an underlying headache pattern. A pattern that cannot be defined or is of recent onset is suspicious for a disorder, whereas a well-established stable pattern of headache indicates primary headaches. Querying about the pattern of headaches is also useful in detecting important changes such as chronification of migraine secondary to medication overuse. If changes in the pattern of a patient’s headaches are not readily explained, or whenever the evaluation is of a new or recent headache, diagnostic evaluation for secondary headaches should be undertaken.
Phenotype
The phenotype of the headache refers to the characteristics and symptoms that are associated with the headache. Phenotypes may have recognizable diagnostic patterns such as migraine, tension-type headache, cluster headache, or other primary headaches, but headache with a recognizable primary headache phenotype does not ensure diagnostic exclusion of secondary headache. Different headache disorders can produce headache phenotypes mimicking any of the primary headache disorders. However, changes in a patient’s headache phenotypes are an important means of differentiating primary and secondary headache. For example, it is reasonable to consider secondary headaches if a patient has been experiencing migraine with aura for years and suddenly develops tension-type headache without aura. A change in headache phenotype should be considered a red flag or warning sign. The presentation of a new headache phenotype should alert the clinician to a disorder, because accurate diagnosis of primary headache can only be made after repeated episodes of the same headache phenotype over time. Although not every red flag is the basis for exhaustive testing, it is the basis for additional diagnostic vigilance.
Patient Factors
Evaluation of patient factors is often overlooked as a critical aspect in evaluating a patient with headache. Critical patient factors include (1) age and general health; (2) baseline function before the onset of this headache; (3) return of the nervous system to its normal physiologic baseline function between each headache episode; (4) changes in normal physical, neurologic, or psychosocial function since the advent of this specific headache.
In addition, inquiry into the state of a patient’s general health allows the clinician to probe for underlying diseases that may relate to secondary headache disorders. Questions relevant from this perspective concern (1) recent travel, both domestic and abroad; (2) recent trauma; (3) other medical diagnoses that may have a bearing on the headaches; (4) a family history to determine the risk of secondary headaches; (5) significant psychopathology; (6) reproductive status.
Pharmacology
An accurate accounting of recent pharmacologic interventions is a critical step in evaluating all patients with headache. Medications can cause headache, alter headache-related symptoms, or change important physiologic parameters such as cognitive function, body temperature, or blood pressure. It is essential to obtain a listing of prescription as well as nonprescription medications and to understand how and why specific mediations are being used (or not used). In addition, consider the possibility of recreational drug use and weigh the value of a drug screen.
Precipitating/Provoking Factors
The role of precipitating or provoking factors for secondary headaches includes evaluating risks associated with underlying disease such as infection, hypertension, pregnancy, coronary heart disease, or human immunodeficiency virus (HIV). Also, specific triggers are important to consider, such as trauma, exertion, sexual activity, or activities associated with a Valsalva maneuver. However, as headache frequency increases it is more difficult to assign specific triggers because at some point virtually any change seems to provoke the next headache. In addition, medications or food substances such as monosodium glutamate or tyramine, especially in the context of a monoamine oxidase inhibitor, may relate to the cause of a new secondary headache.
By incorporating the 5 Ps as a routine part of the history-taking process, a clinician can obtain a comprehensive understanding of both the headache and the patient experiencing the headache. From this vantage point, suspicion of a secondary disorder can be better ascertained and appropriate diagnostic testing initiated.
Physical Examination
Headache is a neurologic symptom, but numerous neurologic and non-neurologic diseases can cause secondary headache disorders. It is therefore essential to conduct both a thorough physical and neurologic examination. Components include vital signs with particular attention to blood pressure, weight change, and temperature. Examination of the mental status can often be made through the process of history taking. It is useful to examine nasal and oral cavities and perform a funduscopic examination. Examination of the thyroid, lungs, heart, and abdomen, as well as checking for lymphadenopathy, is also useful. While performing screening dermatologic and rheumatological examinations, look for inflammatory disease, rashes, signs of trauma or physical abuse, or evidence of intravenous drug use. In many instances, the history provides information indicating where to focus specific attention during the physical examination.
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