Headache Disorders

Principles

Migraine is a common, chronic, sometimes incapacitating neurovascular disease characterized by recurrent attacks of severe headache, autonomic nervous system dysfunction, and, in some patients, an aura causing visual, sensory, motor, or other neurologic symptoms. It is a primary headache disorder with a genetic basis.

Migraine is a common disorder; attacks typically begin in the second decade of life and peak in prevalence in the fourth decade, affecting about 1 of 4 women and 1 of 12 men. There is no gender difference in the prevalence of migraine in children. After menopause, the prevalence of migraine among women decreases.

Historically, migraine headaches were considered to be vascular in origin. However, this hypothesis is no longer tenable as alterations in cerebral blood flow do not correlate with the various phases of the headache attack or vascular territories and do not explain features of an acute migraine, such as premonitory mood disturbances, nausea, and osmophobia (aversion to odors). Rather, vascular changes are now thought to be an epiphenomenon to what is a primary neurologic event. Abnormal trigeminal nerve and thalamic activity, possibly triggered by a sterile neuropeptide-induced inflammatory process, leads to activity and sensitization of higher order neurons in the brainstem and thalamus. Descending modulation is likely to be compromised as well. It is not yet known what initiates the pathophysiologic process that leads to a migraine attack. Migraine is commonly thought of in two major categories: (1) migraine without aura, which accounts for approximately 75% of all cases ( Box 89.2 ); and (2) migraine with aura, which has specific reversible neurologic symptoms that precede the actual headache ( Box 89.3 ). Cortical spreading depression, a neuroelectrical event characterized by a slow wave of depolarization, is the mechanism behind the symptom of migraine aura.

Clinical Features

Migraine is by definition a chronic and recurrent disease. The headache, characteristically, is unilateral, pulsating in quality, moderate to severe in intensity, and exacerbated by routine activities. The side of the headache can vary with individual attacks, and the headache may be bilateral in 40% of patients. The onset usually is gradual, and the attacks typically last 4 to 72 hours. Headache frequency is variable; those patients with more than 15 headache days per month are considered to have chronic migraine. Associated symptoms and signs include nausea, vomiting, anorexia, photophobia, phonophobia, osmophobia, blurred vision, lightheadedness, vertigo, muscle tenderness, and nasal congestion. Many patients have dramatic light and sound sensitivity and seek a dark, and quiet room. Some patients experience premonitory cognitive impairment during the days leading up to the acute attack producing forgetfulness, irritability, and depression.

The migraine aura consists of focal neurologic symptoms that usually precede the headache, though patients may experience aura without headache. By definition, the aura is fully reversible and typically lasts 10 to 20 minutes, although it may continue for as long as 1 hour. The most common aura is visual; features may include scintillating scotoma (bright rim around an area of visual loss), teichopsia (subjective visual image perceived with eyes open or closed), fortification spectra (zigzagged lines that slowly drift across the visual field), photopsias (poorly formed brief flashes or sparks of light), and blurred vision. Less common auras include somatosensory phenomena, such as tingling or numbness, motor disturbances, and cognitive or language disorders.

Retinal migraine is a rare syndrome consisting of recurrent attacks of monocular visual dysfunction, including positive features (such as scintillations) or negative features (such as blindness). As with aura, these symptoms are completely reversible.

Hemiplegic migraine is characterized by a motor aura consisting of hemiparesis or hemiplegia. The progression of the motor deficit is gradual and, in most cases, is accompanied by a visual, sensory, or speech disturbance. The neurologic symptoms last up to 60 minutes, followed by headache. Rarely, the motor deficit is persistent, resulting from a true stroke. A familial version of hemiplegic migraine is associated with genetic channelopathies.

Migraine with brainstem aura presents with an aura referable to the brainstem. Common neurologic findings include dysarthria, tinnitus, vertigo, diplopia, and altered level of consciousness.

Status migrainosus is a severe unremitting migraine headache that persists unabated for more than 72 hours.

Many factors can trigger migraine headaches in predisposed persons. Common precipitants include sleep deprivation, stress, hunger, hormonal changes, including menstruation, and use of certain drugs, including oral contraceptives and nitroglycerin. In addition, some patients report specific food sensitivities to chocolate, caffeine, and foods rich in tyramine, monosodium glutamate, and nitrates. Alcohol, specifically red or port wine, has also been implicated. In others, certain sensory stimuli, such as a strong glare or strong odors, loud noises, and weather changes, can trigger an attack.

Differential Diagnoses

Among patients without stereotypical recurrent headaches, migraine may be difficult to distinguish from secondary causes of headache, see Chapter 16 and Table 16.1. Headaches with an acute onset may have a cerebrovascular etiology. Headaches that have lingered for longer than several weeks may be due to an intracranial mass lesion or other causes of high cerebrospinal fluid (CSF) pressure. Headaches that occur in the setting of upper respiratory infections may be due to sinus inflammation. Medication overuse headache, which is a disorder characterized by worsening headache frequency in the setting of increased use of analgesic or migraine abortive medication, may coexist with migraine.

Diagnostic Testing

Neuroimaging is not necessary for patients with typical recurrent migraine headaches. Neuroimaging should be considered for older or immunocompromised patients with new-onset headaches, headaches associated with unexplained neurologic abnormalities, and new headaches with an abrupt onset. (Please see Chapter 16 for the diagnostic algorithm.) Such patients have a higher likelihood of having a secondary cause of headache, such as an intracranial bleed or space-occupying lesion. Among patients with an acute migraine headache, laboratory testing should be limited to a pregnancy test for those who are to be treated with medications that may be teratogenic and electrolytes for those patients with marked nausea, anorexia, or vomiting sufficient to require intravenous (IV) fluid hydration.

Management

The pharmacologic treatment of migraine is divided into abortive therapies, which attempt to limit the intensity and duration of a given episode, and preventive therapies, which are intended to decrease the frequency and intensity of attacks. The goals of abortive therapy include rapid pain relief, minimization of headache recurrence and medication side effects, and restoration of the patient’s ability to function.

There are several approaches to treatment of the acute headache episode, depending on the severity of the attack ( Table 89.1 ). The choice of agents depends on the patient’s previous response to specific therapies, the existence of comorbid conditions, and the presence or absence of nausea or vomiting. Gastric stasis is common during acute migraine attacks and may limit the effectiveness of oral agents.

For mild to moderate attacks, simple analgesics such as acetaminophen or nonsteroidal antiinflammatory drugs (NSAIDs), such as ibuprofen or naproxen, are often effective. In the presence of nausea or vomiting, administration of intravenous metoclopramide 20 to 30 minutes before the oral analgesic enhances the absorption and effectiveness of these medications. Appropriate doses for these and other oral medications are listed in Table 89.1 .

For moderate to severe attacks, three classes of medications are recommended as initial parenteral therapy: the antiemetic dopamine antagonists, such as metoclopramide and prochlorperazine; migraine-specific agents, such as the triptans and dihydroergotamine (DHE); and parenteral nonsteroidal medications, such as ketorolac.

Dopamine antagonists, such as the neuroleptic prochlorperazine, and the antiemetic metoclopramide, are highly effective as monotherapy for acute migraine attacks. Because of their efficacy, safety, tolerability, and few contraindications, we recommend either of these agents as first-line therapy for acute migraine. Metoclopramide is a less potent antinauseant, and is less likely to induce drowsiness and sleep, which can be factored into the choice of agents, depending on the patient’s circumstances. For this class of medication, the mechanism of action is not known, but migraine pathogenesis likely involves dopaminergic pathways. The most common side effects after parenteral administration include sedation and extrapyramidal symptoms, most notably akathisia, which can be treated with diphenhydramine, 25 to 50 mg IV, or midazolam, 2 mg IV.

Sumatriptan, the first-approved medication of the triptan class, a class of selective 5-HT (1B/1D) receptor agonists, is the most frequently used triptan in the ED, and is available for oral (50 to 100 mg) and subcutaneous (6 mg) administration; the latter is more efficacious but also more likely to cause adverse effects. If the patient has experienced insufficient relief with sumatriptan previously, eletriptan 40 mg orally may be administered. Common side effects of triptans include tingling, flushing, warm or hot sensations, heaviness in the chest, and initial worsening of the underlying headache. Sumatriptan is contraindicated in patients with coronary artery disease and should not be used within hours of administration of an ergotamine-containing medication. Sumatriptan is classified as a category C drug for pregnancy, though there does not seem to be an increase in adverse pregnancy outcomes with its use. A smaller dose of subcutaneous sumatriptan may limit side effects.

DHE is often effective when prochlorperazine or metoclopramide have failed, and is administered intravenously in a dosage of 1 mg over 2 minutes; this can be repeated in 1 hour if pain control has not been achieved. Because DHE can cause nausea and vomiting, patients who have not already received an antiemetic, should be given metoclopramide 10 mg IV or prochlorperazine 10 mg IV at least 15 minutes before administration of DHE. Contraindications to use of DHE include pregnancy, breast-feeding, poorly controlled hypertension, coronary artery disease, and peripheral vascular disease. DHE should not be used if the patient has already taken any drug in the triptan class or if the patient is using macrolides or protease inhibitors.

Alternatively, greater occipital nerve block with bupivacaine 0.5% may be attempted among patients with symptoms refractory to first-line medications ( Fig. 89.1 ).

Calcitonin gene related peptide (CGRP) receptor antagonists and monoclonal antibodies likely will play an increasing role in the management of migraine in the coming years as multiple placebo-controlled studies have demonstrated safety and efficacy. The relative efficacy and safety of these medications vis-à-vis the antidopaminergic antiemetics is still unknown. It is clear that CGRP is released during acute migraine attacks and contributes to migraine symptoms.

Opioid analgesics are nonspecific for migraine pain, and rarely, if ever, are indicated in the treatment of acute migraine. They have not been shown to be more effective than nonsteroidal antiinflammatory agents for treatment of migraine. Opioid requests by patients with “migraine” often represent misunderstanding of effective therapy based on past experience. We recommend that opioids not be used for treatment of migraine. Rare cases may exist where a neurologist who knows the particular patient’s syndrome rationally validates the use of opioids. Opioids should not be administered on the basis of a “doctor’s letter” or other document produced by the patient (see Chapter 151 ).

Status migrainosus can often be treated successfully using the various medications or combinations of the medications discussed in the previous paragraphs.

Recurrence of migraine within 24 hours of ED discharge occurs in two-thirds of patients who initially improve after treatment in the ED, regardless of medication administered or pain intensity at discharge. Patients should be discharged home with oral medication to treat the headache recurrence, such as naproxen 500 mg or sumatriptan 100 mg. Dexamethasone 10 mg IV decreases migraine recurrence after ED discharge and should be administered to all patients without contraindications.

Preventive therapy is indicated for patients who have more than two or three functionally disabling headaches per month. Several classes of medications are used for migraine prevention, including beta-blockers, tricyclic antidepressants, antiepileptic drugs, and botulinum toxin. Patients who meet criteria for preventative therapy and are not on it, and those for whom preventative therapy has failed, should be referred to a primary care physician or neurologist for evaluation.

Disposition

Most patients who present to an ED for treatment of migraine can be treated and discharged after one or several doses of medication and IV fluids if required. Only rarely do patients with migraine require hospitalization. Patients requiring admission often have chronic migraine, with more than 15 days of migraine monthly, or concomitant medication overuse headache . Migraine patients admitted to the hospital receive IV fluids, frequent doses of parenteral migraine medication, and detoxification from medications contributing to the overuse headache.

Principles

Cluster headache is the only headache syndrome that is more common in men than in women. It typically occurs in young to middle-aged adults who smoke, almost always onsetting before the age of 50 years. The headaches tend to occur repeatedly during a defined time interval, hence the term cluster. Several attacks can occur in a single day, and a typical cluster period may last weeks to months. Several precipitating factors have been implicated, most notably the ingestion of alcohol. Stress and climate changes may also play a role in susceptible persons. As with migraine, abnormal activation of the trigeminal nerve contributes to headache nociception. Typically, secondary parasympathetic activation causes ipsilateral lacrimation and rhinorrhea, a characteristic of cluster headache syndrome.

Clinical Features

Cluster headaches occur suddenly with little warning, and multiple episodes can occur within a 24-hour period. Each headache lasts from 15 minutes up to 3 hours, with a mean duration of about two hours. The headache typically begins with a unilateral sharp, stabbing pain in the eye, which may awaken the patient from sleep. The attacks occur exclusively in the territory of the trigeminal nerve. Unlike the patient with migraine, the patient with cluster headache presents agitated and anxious, rocking, rubbing the head, and pacing. The attack subsides rapidly, often leaving the patient exhausted.

Accompanying the headache are ipsilateral autonomic symptoms, such as ptosis, miosis, and forehead or facial sweating. The eye often is injected and tearing, and many patients have unilateral nasal congestion or rhinorrhea.

Differential Diagnoses

Other headache disorders that mimic cluster headache include carotid artery dissection, trigeminal neuralgia, and rare trigeminal autonomic cephalalgias, including paroxysmal hemicranias and short-lasting uniform neuralgiform headache attacks with conjunctival injection and tearing (SUNCT). Carotid artery dissection should be excluded as the diagnosis in patients who present with unilateral face or neck pain and Horner syndrome. With trigeminal neuralgia, the pain peaks within seconds, lasts only a few minutes, and can be provoked by specific trigger points on the face or oral mucosa. The less common trigeminal autonomic cephalalgias are manifested by brief unilateral headaches that recur dozens of times per day, often accompanied by the same unilateral eye and nasal symptoms as cluster.

Diagnostic Testing

Diagnostic testing is not indicated for patients with a well-established history of cluster headache. Cluster headache is a characteristic syndrome with specific onset, distribution, duration, and accompanying symptoms, so in patients younger than 50 years without a prior diagnosis, particularly if they have a previous pattern of similar attacks, the presumptive diagnosis can be made with confidence. Patients with a presentation more consistent with carotid artery dissection, particularly neck pain, Horner syndrome, or unilateral neurologic deficit, should undergo neurovascular imaging

Management

Treatment should focus both on relieving the acute headache and preventing the next headache in the cluster ( Table 89.2 ). Because cluster headache is brief in duration, it may resolve before a patient presents to medical attention. For acute headache relief, high-flow oxygen is first-line therapy. It should be administered at rates of 15 liters/minute or greater through a non-rebreather mask until that headache has remitted completely. High-flow oxygen aborts the headache within 15 minutes in approximately 80% of patients. Subcutaneous sumatriptan, 6 mg, is also an effective therapy for acute cluster headache if the headache fails to resolve after 20 to 25 minutes of high-flow oxygen. Larger doses do not confer additional benefit and may contribute to medication side effects. Antidopaminergic agents and NSAIDs can be used if the patient does not experience relief with oxygen and sumatriptan or if the patient has contraindications to the latter. As with migraine, opioid medications are not indicated for treatment of acute cluster headache, in part because of the evanescent nature of the headache symptoms.

Once the acute attack has been relieved, focus shifts to the ongoing “cluster” of headaches that likely will recur over hours to days. Corticosteroids have long been theorized to help break the cluster, although high-quality evidence is not available. Based on retrospective data, we recommend a 10-day prednisone taper, starting with 60 mg for at least two days. Verapamil, dosed at 120 mg three times a day, may decrease the frequency of attacks by the end of the first week of therapy and should be considered for patients without calcium channel blocker contraindications who are discharged from the ED.

Disposition

Patients with cluster headache usually do not require admission to the hospital. Because these headaches are likely to continue over the following days and weeks, the patient should be referred to a physician with expertise in headache management.

Principles

Tension-type headache is the most common recurrent headache disorder, with one year prevalence of 40% of the population in the United States, but it is an infrequent cause of ED visits. Women are affected slightly more frequently than men, and as with migraine, peak prevalence is in the fourth decade of life. These headaches typically do not cause substantial functional disability, and patients are able to continue with their normal daily activities. Autonomic symptoms, such as nasal congestion, nausea, or vomiting are absent. By definition, episodic tension-type headache lasts as little as 30 minutes and as long as 7 days.

The pathophysiology underlying tension-type headache is not yet clear. There is no consistent evidence that increased muscle activity is present. Physical examination will reveal tender areas of the scalp and neck with both tension and migraine headaches. Despite different epidemiologic profiles, a similar response to many therapeutics suggests that tension and migraine headaches may share pathophysiologic mechanisms.

Clinical Features

Patients typically complain of a tight, bandlike discomfort or pressure around the head that is nonpulsating and dull. They also may experience tightening of the neck muscles. A majority of patients do not seek medical assistance, because the headache usually is mild in intensity and not functionally disabling. On occasion, the discomfort can build up slowly and fluctuate in severity for several days. Unlike in migraine, the headache does not worsen with physical activity, and accompanying symptoms (such as nausea, vomiting, phonophobia, and photophobia) are unusual. Anxiety and depression may coexist with chronic tension headache, which by definition, occurs more than 15 days a month and can be daily and unremitting.

Differential Diagnoses

Tension headache is the least distinct of all of the primary headache disorders, and its diagnosis is based mainly on the absence of features that would suggest another headache diagnosis. The most common disorders mimicking tension headache are migraine, IIH, cervical spondylosis, sinus or eye disease, and intracranial masses. Subtle indolent infections (such as cryptococcal meningitis) should be considered in the immunocompromised.

Diagnostic Testing

Patients who present with a headache similar in quality to previous headaches do not require diagnostic evaluation in the ED. New-onset headache with features of tension-type headache requires evaluation in patients 50 years and older, as well as immunocompromised patients. This evaluation can take place in the outpatient setting, where a scheduled MRI offers more sensitivity for a range of pathologies than a non-contrast CT.

Management

Because the pain of tension-type headache is rarely severe or disabling, the emergency physician should try to understand why the patient with tension-type headache presented to the ED. For a majority of patients with tension headaches, simple analgesics, such as acetaminophen or an NSAID, are adequate for pain control. Opioids are never indicated and consideration of a need for any parenteral treatment, such as metoclopramide, should prompt serious concern that the diagnosis of tension headache is not correct. For chronic outpatient management, acupuncture has shown benefit for some patients. Despite muscle pain and tenderness in many of these patients, spinal manipulation therapy is unlikely to provide a benefit for most patients.

Disposition

Absent comorbidities, patients with tension-type headache do not require admission to the hospital. Chronic tension-type headache is difficult to manage; these patients often have underlying mental health or personal stress issues, and should be referred to clinicians who can evaluate them for these underlying issues and work with them over time.

Principles

SAH refers to extravasated blood in the subarachnoid space. (For discussion of other intracranial hemorrhages, please see Chapter 87 .) Presence of the blood activates meningeal nociceptors, leading to headache and, in about one-third of cases, signs of meningismus. SAH accounts for up to 10% of all strokes and is the most common cause of sudden death from a stroke.

Approximately 80% of patients with nontraumatic SAH have ruptured saccular (berry) aneurysms, which are small (usually <15 mm diameter) aneurysms that usually form at or near the junction of major cerebral vessels, particularly within the circle of Willis. The remainder are in the posterior circulation, particularly the basilar artery and its ramifications. Approximately 25% of people with a berry aneurysm have more than one aneurysm, and most aneurysms do not rupture, but are found incidentally by cerebral imaging or by autopsy. Other etiologies requiring emergent treatment include arteriovenous malformations, cavernous angiomas, mycotic aneurysms, neoplasms, and CNS vasculitis. Perimesencephalic hemorrhage is a benign form of SAH, in which a localized hemorrhage occurs anterior to the midbrain, without extension, and with no vascular abnormalities on cerebral vascular imaging. These hemorrhages resolve spontaneously and do not require intervention. SAH may also be caused secondarily by an intraparenchymal hematoma that dissects its way into the subarachnoid space.

The risk for aneurysmal SAH increases with age; most cases occur between 40 and 60 years old. In children and adolescents, aneurysms are uncommon, and SAH usually is secondary to an arteriovenous malformation. It is estimated that 2% of the general population harbor a berry aneurysm, with the vast majority never rupturing. Risk of rupture appears to be related to the rate of growth of the aneurysm and increases with aneurysmal size. Other risk factors associated with SAH include hypertension, smoking, excessive alcohol consumption, and use of sympathomimetic drugs. Both genetic and familial associations of cerebral aneurysms have been identified, and there is association with several diseases, including autosomal dominant polycystic kidney disease, coarctation of the aorta, Marfan syndrome, and Ehlers-Danlos syndrome type IV.

Less than 1% of patients presenting to the ED with a primary complaint of headache have SAH, but the diagnosis is of great importance because of the morbidity and mortality associated with aneurysmal rupture. One-quarter of patients with SAH die before reaching the hospital. Median mortality in the United States is about one-third with approximately one-third of survivors having functional and cognitive deficits.

Clinical Features

The clinical presentation of SAH is often distinctive. Most patients present with a sudden, cataclysmic thunderclap headache, which often is described as the worst headache of one’s life. The onset of headache may be associated with exertion, the Valsalva maneuver, or sexual intercourse, but the majority occur in the absence of strenuous physical activity. The headache of SAH classically peaks in intensity within seconds to minutes. Headaches that take longer than 60 minutes to peak in intensity are unlikely to be SAH. Associated signs and symptoms include syncope, nausea and vomiting, neck stiffness, photophobia, and seizures. The patient may experience sudden syncope as the initial manifestation, with headache occurring as the patient regains consciousness and increasing thereafter.

Physical findings depend on the extent of the SAH. Up to 20% have focal neurologic abnormalities. Patients may have isolated third or sixth nerve palsy or meningismus. Oculomotor (third) nerve compression secondary to an expanding posterior communicating artery aneurysm causes pupillary dilation. Approximately 50% of patients with a ruptured aneurysm are restless or have a fluctuating or altered level of consciousness. Up to one-third of patients recall an earlier, less severe episode of headache (sentinel headache) days to weeks before the diagnosis of subarachnoid hemorrhage.

The patient’s prognosis is related to neurologic status at hospital admission. The Hunt and Hess scale stratifies patients according to their clinical signs and symptoms at the time of presentation and is predictive of outcome ( Table 89.3 ). Patients who present with a grade 1 or grade 2 hemorrhage tend to have a good prognosis. Patients with grade 4 or 5 hemorrhages tend to do poorly, presenting with an altered mental status, ranging from stupor to deep coma, together with focal neurologic signs and symptoms. Patients with grade 3 hemorrhage present with drowsiness or confusion and are at risk for rapid clinical deterioration.

Differential Diagnoses

Several clinical entities can mimic the abrupt onset headache associated with SAH. These include cervical artery dissection (CAD), cerebral venous thrombosis (CVT), reversible cerebral vasoconstriction syndrome, hemorrhagic or ischemic stroke, and primary headache disorders, including migraine and cluster headaches. CNS infections cause altered mental status and meningismus but can usually be distinguished by the presence of fever and much longer period of onset.

Diagnostic Testing

The Ottawa clinical decision rule can help risk stratify patients with possible SAH. In this rule, high (near 100%) sensitivity is achieved, but with low (less than 20%) specificity. Use of the rule may not improve accuracy compared to clinical gestalt, but a diagnosis of SAH is of sufficient gravity that high use of advanced imaging for diagnosing “positive” patients is justified ( Box 89.4 ).

A non–contrast-enhanced head CT scan should be obtained emergently when SAH is suspected ( Fig. 89.2 ). For acute hemorrhages less than 24 hours old, the sensitivity of third-generation multidetector row CT scanners in identifying hemorrhage is greater than 90%; however, sensitivity decreases to approximately 50% by the end of the first week, as blood is resorbed. The sensitivity of non–contrast-enhanced head CT performed within 6 hours of headache onset approaches 100%. For patients in whom CT has been performed more than 6 hours after headache onset, a normal non-contrast CT should be followed with subsequent diagnostic testing, which may include spinal fluid analysis or cerebrovascular imaging. The choice of whether to perform LP or a subsequent imaging test depends upon patient preference, local availability, and what else is on the differential diagnosis. For example, if the physician is also concerned about meningitis or idiopathic intracranial hypertension, then an LP would be preferred; if the differential diagnosis includes other neurovascular etiologies such as cervical artery dissection or reversible cerebral vasoconstriction syndrome, then imaging is preferred. Options for cerebrovascular imaging include computed tomography angiography (CTA) or magnetic resonance angiography (MRA). The two-stage approach (non-contrast CT first followed by vascular imaging) is as sensitive as non-contrast CT followed by LP.

Interpretation of LP results can be challenging because up to one-third of spinal fluid analyses contain blood or blood degradation products. The presence of xanthochromia may help differentiate a traumatic LP from SAH. This yellowish pigmentation is secondary to the metabolism of hemoglobin to pigmented molecules of oxyhemoglobin and bilirubin, a process that can take up to 12 hours to occur. SAH cannot be ruled out if a substantial number of RBCs persist in tube 4; however, an RBC count of less than 100 in tube 4 indicates that aneurysmal SAH does not need to be pursued further. CSF xanthochromia in association with normal findings on the CT scan is suggestive of SAH. After the diagnosis is established, angiography should be performed to study the vascular anatomy and to identify the source of hemorrhage.

A normal non–contrast-enhanced head CT scan followed by a normal spinal fluid analysis definitively rules out SAH and does not need to be followed with angiography, even in patients at high risk of disease. However, this strategy does not rule out other causes of thunderclap headache that may be in the differential diagnosis, such as cervical artery dissection, cerebral venous sinus thrombosis, and reversible cerebral vasoconstrictor syndrome.

Up to 90% of patients with SAH have cardiac arrhythmias or electrocardiographic abnormalities suggestive of acute cardiac ischemia, which may lead to an erroneous primary cardiac diagnosis, especially when syncope has occurred. Typical electrocardiographic findings include ST-T wave changes, U waves, and QT prolongation.

Management

The management of SAH is aimed at treating acute medical and neurologic complications, preventing recurrent hemorrhage, and forestalling the ischemic complications of vasospasm. Because of an altered level of consciousness, patients with SAH of grade 3 or higher are at risk for respiratory depression and hypercapnia, which can lead to further increases in intracranial pressure (ICP); therefore, early endotracheal intubation should be considered in these patients, using a technique consistent with that used for patients with elevated intracranial pressure (see Chapter 1 ). Blood pressure should be closely monitored because of the risk of continued bleeding or recurrent hemorrhage. The typical treatment goal is a systolic blood pressure below 160 mm Hg or a mean arterial pressure (MAP) below 130 mm Hg. To achieve this, the physician should use intravenous nicardipine or labetalol. Care is required to maintain MAP above 95 mm Hg, though, because iatrogenic hypotension may cause more harm than elevated blood pressure. Nimodipine, a calcium channel blocker, should be started soon after a diagnosis of aneurysmal SAH is made to lessen the likelihood of poor outcome due to vasospasm, even if the patient’s blood pressure is normal. Because nimodipine may cause transient hypotension in some patients, hemodynamic monitoring is required during its administration. The recommended dosage is 60 mg by mouth or nasogastric tube every 4 hours.

Corticosteroids have not been demonstrated to be of benefit. Opioids should be used for persistent headache, though modest doses of short-acting agents should be used to avoid interference with evaluations of neurologic status. Intravenous fentanyl, titrated in 50 microgram aliquots is an appropriate first-line agent. In patients who are nauseated or at risk for vomiting, antiemetics such as metoclopramide 10 mg IV or ondansetron 4 mg IV should be administered. Agitated patients require sedation. Short-acting opioids such as fentanyl 50 micrograms IV may achieve this goal. If not, short-acting benzodiazepines such as midazolam 1 mg IV may be added. All patients should be placed on bed rest in a quiet and dark environment. Clinically evident seizures should be treated with levetiracetam or fosphenytoin. Prophylactic anticonvulsant therapy is of unknown benefit, and we recommend leaving this to the discretion of the admitting consultant or in consultation with the receiving consultant when transfer to another center is planned. For definitive management, endovascular coil embolization is preferable to neurosurgical clipping, but this decision is based on size, location, and morphologic features of the aneurysm, as well as local expertise.

Disposition

Patients with ruptured aneurysms require monitoring of hemodynamics and neurological status in an intensive care setting. Patients requiring transfer to a higher level center for care should be managed in collaboration with the receiving center, including contingency plans for complications (e.g. seizures, decreasing level of consciousness) that might arise in transport.