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This is an overview of the diagnosis of headaches presenting to the Emergency Department (ED). When patients come to the ED, it is imperative that the doctors try to differentiate between primary and secondary headache disorders. The primary headache disorders include migraine headache with and without aura, cluster headache, and tension-type headache. It is unlikely that the patients will come to the ED with tension-type headache; however, they frequently can come with moderate-to-severe migraine or cluster headaches. Migraine is diagnosed by various accepted criteria. [Figure 1] These are available online from the International Headache Society as part of the International Classification of Headache Disorders (ICHD), published in Cephalalgia in 2004. In essence, the patient with migraine headache has a history of at least five headaches, which are usually unilateral (one-sided), lasting 4 to 72 hours. They must have two out of four characteristics: 1) one-sided, 2) pulsating, 3) moderate or severe in intensity, and 4) aggravated by physical activity or movement. Patients can also have nausea or vomiting, and light or sound sensitivity. These are important base characteristics of the primary migraine attack. Remember however, the headache cannot be attributable to another disorder.

Figure 1 (From the International Classification of Headache Disorders, ICHD II, 2004)

As noted, tension-type headache patients usually do not come to the ED; for cluster headache patients, on the other hand, this is quite a different story. True cluster headache is rare and far more severe than migraine. Patients get severe periorbital pain associated with drooping of the eyelid, called ptosis, and a small pupil or a Horner’s syndrome. These headaches can last up to 15 to 180 minutes and occur with regularity. Unlike migraine, cluster headache [Figure 2] can be more predominant in males, although there is an increasing prevalence of this disorder in women. It has a built-in clock for recurrence, in other words it occurs annually or at the same times each year. The other thing about cluster headache is that the patient is agitated and restless in contradistinction to the migraine patient who likes to go to a dark room and lie down. Like migraine, primary cluster headache cannot be attributable to another disorder. It is important to recognize that cluster headache is one of the TACs, or trigeminal autonomic cephalalgias. The TACs are primary headache disorders which can be mimicked by secondary lesions; in other words, serious diseases within the brain that look like cluster headache but have some atypical features. Also it should be recognized that the patients with migraine headache can have mimics. The anatomical pathways through which migraine pain is produced involve the trigeminal nucleus in the brainstem to the thalamus and sensory cortex. These are the same pathways through which pain of secondary headache disorders can be transmitted. Thus a brain tumor can present with a “tension-type headache” or “migraine headache” and not the usual headache tumor story that one hears from medical school lectures, such as early morning headache, nausea and projectile vomiting. This is so important to recognize since patients with any atypical features need to be investigated.

Figure 2 (From the International Classification of Headache Disorders, ICHD II, 2004)

In the ED, patients more likely will present with a severe migraine headache if it is of primary origin; it could be the worst migraine headache they have ever had on a past history of migraine, or it could be the very first migraine headache. If it is a very first migraine headache, and since they have not had five attacks to make the diagnosis, then it is possible there could be a secondary cause. If the patient actually has a thunderclap component to the headache, then there must be a concern about an intracranial aneurysm or a bleed within the brain producing a subarachnoid hemorrhage. This is probably the most important life-threatening secondary headache not to miss, and it is the intensity and sudden onset, sometimes associated with loss of consciousness that are the clues to the diagnosis, as well as being the worst headache they have ever had in their life.

Migraine headache can present in other ways as well, including status migrainosus where the patient has continuous headaches for several days with nausea, vomiting and dehydration. These patients look sick and in fact are very sick, mimicking any number of systemic and organic diseases. In this particular situation, it is necessary to ensure there are no other secondary causes for the “migraine headache.” Once again, by the time the patient comes to the ED, it is important to determine whether they have anything that will suggest that there are atypical features. Atypical features might include many symptoms, signs and methodologies. To look for signs of worrisome headache, the SNOOP mnemonic is helpful. [Figure 3] The S stands for systemic symptoms or secondary headache risk factors. Systemic symptoms include fever and weight loss. Secondary risk factors include prior disease like cancer or HIV. The N stands for neurological symptoms or abnormal signs. The O stands for a sudden abrupt or split-second onset. The next O stands for the older patient with new onset and progressive headache especially in middle-age over 50, and the P stands for previous headache history or headache progression, which is a first or different headache than in the past in terms of frequency, severity or clinical features.

Figure 3 (From Ambassadors Course, American Headache Society, 2006)

Migraine without aura is defined by the headache characteristics, while migraine with aura is more defined by the presence of neurological symptoms. Most patients with aura have visual symptoms or zigzag lines that usually occur in the periphery of their vision, are about 20 minutes in duration, and mostly precede the headache and/or occur during headache. The aura symptoms frequently settle down as the headache begins. On the other hand, if the patient has focal neurological symptoms such as vision impairment, difficulty with speech, weakness or numbness in an extremity that persists beyond the headache, then one has to be seriously concerned about a secondary cause. Also, if the patient has physical symptoms or signs of a neurological deficit suggesting focality within the brain, then the persistence of these signs beyond the headache phase would be a clear indication of an ‘atypical headache’ and therefore require further investigation.

For example, two of the most important differential diagnoses of patients with migraine headache are transient ischemic attack (TIA), and a seizure disorder. In simple terms, a migraine headache has a progressive onset over minutes. It does not occur quickly in most cases; although, in children it can come on faster than in adults. The symptoms such as numbness of the face, arm or leg occur in succession, usually over several minutes, and the patient can have loss of vision, scotomata, or they can have positive colored or uncolored zigzag lines. The anatomical territory is cortical in the brain and the duration of each aura symptom lasts ≥5 and ≤60 minutes, with at least one aura symptom developing gradually over ≥5 minutes and/or different aura symptoms occur in succession over ≥5 minutes. This is in contrast to a TIA, a warning of stroke, which comes on suddenly. It does not progress over the anatomic parts of the body. In other words, the patient could be ‘numb’ completely on one side of the body. Different symptoms can also occur with TIA such as loss of vision in one eye or amaurosis, and the difficulty with feeling in an arm and leg does not march from one part of the brain to the other – the types of symptoms they get are negative phenomena or loss of function. The anatomical territory of the symptoms suggests the blood supply of one blood vessel, such as middle cerebral artery. Further, the duration of the TIA is minutes rather than longer as in the migraine. Rarely, a seizure disorder can mimic a migraine attack and that can be difficult to separate out on occasion, although the neurological symptoms of a seizure occurs over a few minutes, they are sudden in onset and the patients have positive colored phenomena in their vision.

Any of the above neurological or headache features make it unlikely the headache is due to a primary headache disorder, and serious causes of headache have to be sought in the ED. By far the most serious secondary headaches would be subarachnoid hemorrhage (SAH) and other vascular abnormalities. SAH presents with a sudden and severe, sometimes thunderclap, headache occurring over seconds. This can occur in patients who have had migraine before, but frequently the headache is different. The patient may have a stiff neck and there may be a transient loss of consciousness. If any of these presentations occurs, then it is prudent and important to do a CT scan of the head to see if there is any blood in the subarachnoid space, the ventricles, in front of the midbrain, or in the brain parenchyma. If no blood is seen, then it is important to move on to a lumbar puncture to see if there is blood in the cerebrospinal fluid (CSF). More accurate diagnosis of the cause of the bleeding will require further investigation and neuroimaging.

Another presentation to the ED is of patients with pain in their anterior neck and a Horner’s syndrome with headache around the eye or front of the head. This could be migrainous headache with autonomic signs or even a cluster-like headache. However, it could be a carotid dissection. Importantly in dissection cases, the physical findings of the Horner’s syndrome tend to persist more so than primary headache disorders. Neuroimaging, including MRI scan to look at the blood vessels including the carotid arteries at the base of the skull, can frequently make this diagnosis. It should be noted that patients with migraine can also have dissection.

Cerebral vein thrombosis (CVT), where there is clotting of the venous sinuses within the brain, ie, the superior sagittal sinus through the deep, straight sinus, or lateral sinus, can be another vascular disorder presenting with headache, including thunderclap headache, in the ED. CVT can also present with a non-specific headache. In that instance, it is important to do appropriate imaging including magnetic resonance imaging (MRI) and possibly MRV (magnetic resonance venography). In that way, the diagnosis can be made.

Hypertension rarely causes headache unless there is a very severe hypertension with a high diastolic blood pressure. In that instance, the patients have severe headache associated with paroxysmal or elevated severe high blood pressure and a tendency of diaphoresis (sweating), which can rarely also be secondary to a pheochromocytoma. Also, patients who have ischemic stroke or transient ischemic attack can present with headache prior to developing the major neurological symptoms but, as noted above, the persistence and presence of neurological signs and symptoms tend to not indicate a primary headache diagnosis. A CT scanning and diffusion-weighted MRI can show the presence of ischemic stroke of new onset and also the presence of blood due to an intracerebral hematoma, which is far less common than cerebral infarction. Finally, in the vascular group, patients who have had minor head injury, older patients, sometimes patients who have alcoholism and fall, develop subdural hematoma which can produce headache.

Elder patients in the ED may present with visual symptoms and headache, but they also complain of tiredness and fatigue. They may have pain in their shoulders (polymyalgia rheumatica) or pain in the tongue on talking or chewing (tongue claudication) their food. These patients look sick and they are sick. They may be found to have anemia, an elevated sedimentation rate, or C-reactive protein (CRP). The diagnosis of temporal arteritis should be considered, and it is imperative to treat the patient with steroid medication until such time that the diagnosis can be confirmed by temporal artery biopsy.

Primary and secondary brain tumors do not necessarily present with signs of increased intracranial pressure and can present looking like primary headache disorders, so it is important to rule these out by doing imaging, not only of the head but of the lungs as well, if a metastatic disease, such as lung cancer, is suspected clinically.

Meningitis and encephalitis present with neck pain, fever, and headache in the early stages, which may mimic a primary headache, but ultimately they worsen and the patient needs neuroimaging and CSF examination to determine whether there is any infection. Sinus infections frequently turn out to be migraine headaches, but on rare occasions patients can actually have true sinus disease and infection requiring appropriate neuroimaging and ENT consultation.

Intracranial pressure disorders can present with headache. Patients can present with low pressure headache where there is a leak of spinal fluid either as a result of the procedure, such as lumbar puncture, or they could have a spontaneous leak somewhere in the thoracocervical region of the spine. These patients present with headache, which is worse when they stand up and better as they lie down, and the headache is worse as the day goes on, if they remain in the upright position. In these cases, there are very specific neuroimaging findings on MRI scan for this disorder which need to be reviewed carefully by a neurologist or neuroradiologist. Any patient with positional headache requires that a secondary headache diagnosis be considered. Other patients can present with severe headache and papilledema, or swelling of the optic discs, and they also can present with what looks like a primary headache. Scanning may show no lesion whatsoever and, therefore, the diagnosis of idiopathic intracranial hypertension is entertained. This is another complex disorder requiring consultation with a neurologist and further neuroimaging and studies to be done.

Importantly, metabolic disorders such as hypothyroidism, difficulty with hypercapnia (elevated CO2), drug intoxications, and many medication side effects can present in the ED with headache as well. The goal of assessment, of course, is to do a good history and physical and to judge the type of investigation based on that outcome of the clinical assessment at the bedside – in the ED, if in doubt check it out! Always consider doing some testing in the ED as the context is important as well. In an office, the chances of seeing a serious headache in a patient with a long history of stable recurrent severe headache, which most likely represents migraine, is exceedingly low but never zero. In an ED, however, the patients come because of severe symptomatology and need your help. Sometimes that help is treating primary headache disorders, but other patients harbor sinister secondary causes of headache.

So the final analysis, the bottom line for assessing the patient in ED is an approach and workup consisting of a thorough history taking, in tandem with comprehensive general and neurological examinations. One formulates the differential diagnosis biased toward serious etiologies and uses appropriate testing tools to help with that diagnostic formulation to determine the actual diagnosis so the headache can be treated or a secondary headache disorder sought. If in doubt, repeat the history or get it from another person. Always take time with patients in the ED and no matter what you do, if the patient is discharged, remember to follow-up with the patient in the outpatient clinic or send them back to the primary care physician and allow that person to follow-up with them directly. There is no question that mistakes can be made in assessing patients in the ED, including the fact that the patient indicates they have had a severe headache before. Do not be reluctant to use consultations, when appropriate, and neuroimaging and blood work, as well as other testings, if necessary. With an open mind and the knowledge presented here, you should be able to handle the majority of patients presenting to the ED who have secondary headache disorders.

General References

Purdy RA. Clinical evaluation of a patient presenting with headache. Med Clin North Am. 2001;85(4):847-863.
Purdy RA, Kirby S. Headaches and brain tumors. Neurol Clin. 2004;22(1):39-53.

Schoenen J, Sándor P. Headache with focal neurological signs or symptoms: A complicated differential diagnosis. Lancet Neurol. 2004;3(4):237-245.

Goadsby PJ, Lipton RB. A review of paroxysmal hemicranias, SUNCT syndrome and other short-lasting headaches with autonomic feature, including new cases. Brain. 1997;120(Pt 1):193-209.

Headache Classification Subcommittee of the International Headache Society. The International Classification of Headache Disorders: 2nd edition. Cephalalgia. 2004;24 Suppl 1:9-160.