Headache and Other Craniofacial Pain

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Chapter 69 Headache and Other Craniofacial Pain

Headache is one of humanity’s most common afflictions. Estimates are that one person in three experiences severe headaches at some stage of life. Most people with a mild recurrent or isolated headache do not consult a physician, and therefore the true prevalence is unknown. The lifetime prevalence for any type of headache as estimated from population-based studies is more than 90% for men and 95% for women.

A survey of a sample of 20,000 households estimated 27.9 million migraine patients in the United States. More than 90% of patients report an impaired ability to function during migraine attacks, and 53% report severe disability requiring bed rest. Approximately 31% of patients with migraine missed at least 1 day from work or school in the preceding 3 months due to migraine (Lipton et al., 2001). Indirect costs of migraine related to decreased productivity and lost days of work have been calculated to be $13 billion per year; estimates are that the equivalent of 112 million bedridden days per year are due to migraine (Hu et al., 1999). The World Health Organization declared migraine to be among the most disabling medical conditions experienced worldwide.

Pain Transmission and Modulation as Related to Headache

Headache arises from activation of pain-sensitive intracranial structures. In the 1930s, Ray and Wolfe identified which intracranial components were pain sensitive and mapped the pattern of pain referral based on studies in which various intracranial structures were stimulated during intracranial surgery performed during local anesthesia. Intracranial pain-sensitive structures include the arteries of the circle of Willis and the first few centimeters of their medium-sized branches, meningeal (dural) arteries, large veins and dural venous sinuses, and portions of the dura near blood vessels. Pain-sensitive structures external to the skull cavity include the external carotid artery and its branches, scalp and neck muscles, skin and cutaneous nerves, cervical nerves and nerve roots, mucosa of sinuses, and teeth. Cranial nerves (CN) V, VII, IX, and X carry pain from these structures.

Trauma, inflammation, traction, compression, malignant infiltration, and other disturbances of pain-sensitive structures lead to headache. Superficial structures tend to refer pain locally, whereas deeper-seated lesions may refer pain imprecisely. A purulent maxillary sinus, for example, causes pain over the involved sinus, whereas within the cranial vault, nociceptive signals reach the central nervous system (CNS) largely by way of the first division of the trigeminal nerve (CN V), so an occipital lobe tumor may refer pain to the frontal head region. Infratentorial lesions tend to refer pain posteriorly because innervation of this compartment is by the second and third cervical nerve roots, which also supply the back of the head. However, posterior lesions or cervical spine pathological conditions may also produce frontal headache, because the caudal portion of the trigeminal nucleus extends down as far as the dorsal horn at the C3 level. Impulses arriving from C2-C3 converge on neurons within the trigeminal nucleus and may refer pain to the somatic distribution of CN V.

Afferent pain impulses into the trigeminal nucleus are modulated by descending facilitatory and inhibitory input from brainstem structures including the periaqueductal gray matter, rostral ventromedial medulla, locus ceruleus, and dorsal raphe nuclei. Opioids diminish pain perception by activating the inhibitory systems, whereas fear, anxiety, and overuse of analgesics may activate the facilitatory systems, thereby aggravating pain.

Classification

In 1988, the Headache Classification Committee of the International Headache Society introduced a detailed classification of headaches. The classification, revised in 2004, contains 14 main headache types (Box 69.1), and each headache type is further subclassified (Headache Classification Committee, 2004). Careful definition of migraine subtypes and other primary headache disorders is expected to rid future research and clinical publications of the confusing and often poorly defined terminology of earlier work. The 2004 classification has undergone a few revisions since its publication, and further refinement over the next few years is expected.

Headache Attributed to Nonvascular, Noninfectious Intracranial Disorders

Intracranial lesions that occupy space, or “mass lesions,” produce head pain by traction on or compression of pain-sensitive structures. The nature, location, and temporal profile of headache produced by an intracranial mass depend on many factors including lesion location, rate of growth, effect on cerebrospinal fluid (CSF) pathways, and any associated cerebral edema. The intracranial mass lesion may be neoplastic, inflammatory, or cystic. Mass lesions can result in either localized or generalized head pain.

Tumors

Approximately 50% of patients with brain tumors report headaches; in one-third to one-half of these patients, headache is the primary complaint. In a prospective study of over 200 patients with intracranial tumors, 47.6% had headache at the time of presentation (Valentinis et al., 2009). Generalized headache is usual, but in approximately a third of patients, it overlies the tumor and is referred to the scalp near the lesion. Rapidly growing tumors are more likely to produce headache than indolent lesions, but slowly enlarging lesions can eventually produce pain by compromising the ventricular system or exerting direct pressure on a pain-sensitive structure. When the CSF circulation is partially obstructed, headache often becomes generalized and worse in the occipitonuchal area. This type of headache, which is a manifestation of raised intracranial pressure (ICP), is often worse on awakening, aggravated by coughing and straining, and often associated with nausea and vomiting. A prospective study showed that only 5.1% of patients presented with this pattern of headache; in most cases, the headache pattern was nonspecific (Valentinis et al., 2009). In children particularly, the vomiting may be precipitate and without nausea (projectile vomiting).

Large parenchymal tumors and small tumors that interfere with the CSF pathways can be associated with periodic increases in ICP. Monitoring reveals periods of increased pressure (plateau waves of Lundberg), the beginning of which may be associated with increasing headache severity and the peak of which may be associated with vomiting, decreased consciousness, or a change in respiration.

Supratentorial masses generally produce frontal or temporal head pain because of the trigeminal nerve supply to the anterior and middle cranial fossae. The superior surface of the tentorium cerebelli is supplied by the meningeal branches of the first division of the trigeminal cranial nerve, so an occipital lesion can cause pain referred to the fronto-orbital region. A posterior fossa mass generally causes occipitonuchal pain, because the meningeal nerve supply is largely through the upper cervical nerves which also supply the occipital and cervical dermatomes. CNs VII, IX, and X also provide sensory innervation of the posterior fossa, and therefore pain referral can be more widespread. Posterior fossa tumors result in headache earlier than their supratentorial counterparts, because the greater likelihood of compromise of the ventricular system leads to rapidly developing hydrocephalus and raised ICP (Edmeads, 1997).

Pituitary tumors and tumors near the optic chiasm commonly cause a frontotemporal headache, but they may cause referred pain near the vertex. However, patients with tumors of the sellar and parasellar regions do not often present with headache as the initial symptom, because the visual and endocrine symptoms are typically noted first (Edmeads, 1997).

Tumors growing in the ventricular system are rare, but they can manifest dramatically. The classic presentation of a colloid cyst of the third ventricle is a sudden headache of great severity, rapidly accompanied by nausea and vomiting and sometimes by loss of consciousness. Intraventricular meningiomas, choroid plexus papillomas, and other intraventricular tumors can present in this manner if they suddenly obstruct the ventricular outflow pathways. A positional change may precipitate such an event; similarly, adoption of a different posture may rapidly relieve the headache and other symptoms. Colloid cysts of the third ventricle generally lead to slowly enlarging hydrocephalus that may result in a generalized rather constant headache, superimposed on which there may be episodes of catastrophic increases in headache. Obstruction of egress of CSF from the ventricular system rapidly leads to increased ICP, which can exceed the capillary perfusion pressure of the brain and lead to loss of consciousness due to cerebral ischemia. Headaches that have a rapid onset and are associated with loss of consciousness, amaurosis, or vomiting are serious and should lead the examiner to seek a secondary cause.

Headache (especially in the occipital region) precipitated by sudden Valsalva maneuvers (e.g., coughing, sneezing, lifting) or exertion may be due to a posterior fossa lesion such as a cerebellar tumor or Chiari malformation. In many patients with cough or exertional headache, however, no underlying lesion is found.

Infiltrating tumors such as gliomas can reach considerable size without causing pain, because they may not deform or stretch the pain-sensitive vessels and nerves. Such lesions are more likely to present as focal neurological deficits or with seizures rather than headache. Sudden worsening of the neurological state due to hemorrhage into the tumor mass may present with sudden headache. The headache may initially appear in the part of the skull overlying the tumor and then become generalized if ICP rises. Infarction of a tumor can cause edema and swelling that result in a similar dramatic onset of head pain and neurological deficit.

Tumors that are intracranial but extraparenchymal (e.g., meningioma, acoustic neuroma, pinealoma, craniopharyngioma) can all produce headaches, but as with parenchymal lesions, there are no specific headache patterns. Headaches can be near the lesion, referred to a more distant site in the cranium, or generalized when ICP increases. Meningiomas and meningeal sarcomas can invade the skull and even cause a mass externally by direct tumor spread or by overlying hyperostosis. Such tumors are often associated with localized head pain. Meningeal carcinomatosis (carcinomatous meningitis) produces a headache in most subjects, but the associated cranial nerve involvement and other neurological symptoms are generally more striking.

The headache associated with other intracranial mass lesions such as cerebral abscess and intracranial granuloma is no more specific than that due to a cerebral neoplasm.

Features that should serve as warnings that a patient’s headaches may not be of benign origin and raise the possibility of an intracranial mass lesion are (Purdy, 2001): subacute and progressive; new onset in adults; change in pattern; associated with nausea or vomiting; nocturnal or upon awakening in the morning; precipitated or worsened by changes in posture or Valsalva maneuver; associated with confusion, seizures, weakness, and/or abnormal neurological examination.

Obstruction of the Cerebrospinal Fluid Pathways

Lesions that prevent free egress of CSF from the ventricular system result in obstructive hydrocephalus. If this occurs before closure of the cranial sutures, enlargement of the skull occurs, usually without producing headache. Ventricular obstruction after closure of the sutures leads to raised ICP and often to headache. The pain is often worse on awakening, occipital in distribution, and associated with neck stiffness. Vomiting, blurred vision, and transitory obscuration of vision due to papilledema may follow, as well as failing vision due to optic atrophy.

Rapidly developing obstruction due to a posterior fossa mass lesion or a ball-valve tumor, such as a third ventricular colloid cyst, can lead to a rapidly increasing headache followed by vomiting, impaired consciousness, and increasing neurological deterioration. Slowly developing hydrocephalus may result in massively dilated ventricles and may be associated with little or no headache.

Congenital obstruction of the foramina of Luschka and Magendie (the Dandy-Walker syndrome) can lead to ballooning of the fourth ventricle and deformity of the cerebellum. Minor degrees of this malformation can remain asymptomatic until later in life and then manifest with obstructive hydrocephalus and headache. Similarly, the Chiari malformation in its various forms can obstruct the free circulation of CSF and lead to hydrocephalus and headache (Taylor and Larkins, 2002). This malformation can result in an occipital-suboccipital headache worsened or even initiated by a Valsalva maneuver during lifting, straining, or coughing. Thus, the Chiari malformation is one of the causes of an exertional or Valsalva maneuver–induced headache.

In communicating hydrocephalus, free communication exists between the ventricular system and the subarachnoid space, but CSF circulation or absorption is impaired. Obstruction in the basal cisterns or at the arachnoid granulations may follow subarachnoid hemorrhage and meningitis. Venous sinus occlusion can impair absorption of CSF. Headache may be a prominent symptom of both obstructive and communicating hydrocephalus, except in the case of normal-pressure hydrocephalus, which is generally painless (see Chapter 59).

Low–Cerebrospinal Fluid Pressure Headache

The headache of lowered CSF pressure characteristically develops with the patient in the upright position and is rapidly relieved by recumbency. It most commonly occurs after a lumbar puncture. Loss of CSF volume due to the removal of CSF for diagnostic purposes and to leakage through the hole in the arachnoid and dural layers results in headache. The brain normally floats in the intracranial CSF, loss of which allows the brain to sink and thereby exert traction on structures such as bridging veins and sensory nerves. Recumbency removes the effect of gravity, and the traction headache is relieved. The headache that occurs after a spinal tap usually resolves in a few days if the patient remains in bed with good hydration, but occasionally it is prolonged. Relief can usually be obtained by the application of a blood patch, in which 10 to 20 mL of the patient’s own blood is injected into the epidural space close to the site of the original lumbar puncture. Compression of the thecal space for the first 3 hours and a presumed elevation of subarachnoid pressure presumably explains the rapid resolution of the headache. However, compression of the thecal sac is not sustained; maintenance of the therapeutic effect is likely due to the presence of the clot eliminating the CSF leak. The injection of blood is associated with a small risk for cauda equina compression or subarachnoid hemorrhage, but this is unlikely if the blood volume is small and injected gently.

An identical low–CSF pressure headache can occur when a tear develops in the spinal theca. This is usually in the midthoracic region and may result from lifting or coughing or, at times, occurs spontaneously. It can also occur with a crush injury to the chest or abdomen and in patients with overdraining CSF shunts. When it occurs, in the absence of a significant history of trauma, it may not be considered as a cause of daily headache. A history of a headache rapidly responding to recumbency suggests a tear. However, in some patients whose headaches are long standing, a persistent headache may be noted and the postural feature of the headache may become less prominent. Nausea or emesis, neck pain, dizziness, horizontal diplopia, changes in hearing, photophobia, upper-limb paresthesias, vision blurring, and dysgeusia may also occur, particularly when the headache first develops. As additional cases have been reported in the literature, the clinical picture of CSF leaks has been found to take many forms (Mokri, 2004).

When a CSF leak is possible, the initial diagnostic test is MRI with gadolinium. MRI has become an invaluable diagnostic tool in this syndrome, with the cardinal features being diffuse pachymeningeal thickening with gadolinium enhancement, subdural collections of fluid, and evidence of brain descent (Figs. 69.1 to 69.3). This evidence includes cerebellar tonsillar descent (resembling a Chiari type I malformation); reduction in size or effacement of the prepontine, perichiasmatic, and subarachnoid cisterns; inferior displacement of the optic chiasm; and descent of the iter (the opening of the aqueduct of Sylvius as seen on a midsagittal MRI scan).

If the clinical and MRI findings are typical, determination of the CSF opening pressure may not be necessary. Measurement of the opening pressure is warranted in patients with normal MRI studies. However, in only 50% of patients is the CSF pressure less than 40 mm H2O. Because the opening pressure may be normal, the term CSF volume depletion best identifies the core of the problem in this disorder (Mokri, 2004). These patients may have a variable pleocytosis with up to 50 or more mononuclear cells/mm and a mild to modest increase in CSF protein (Mokri, 2004).

In patients with the typical clinical and radiographic features of low–CSF pressure headache, treatment may be conservative with bed rest and hydration for 1 to 2 weeks. If this is either impractical or ineffective, options include empirical treatment with a blood patch or further studies to identify the site of the CSF leak. In patients with spontaneous leaks, the leak is often at the level of the thoracic spine or cervicothoracic junction. Myelography with CT of the spine is more sensitive than radioisotope cisternography or MRI of the spine at localization of the source of the leak, but the latter procedures may serve as guides for obtaining multiple CT images at the appropriate levels. MR myelography may also be helpful in some patients to reveal a leak that is not demonstrable on conventional MRI sequences (Katramados et al., 2006). Most leaks are stopped with either conservative therapy or blood patches. Although an epidural blood patch is effective in the majority of patients, most require more than one blood patch, and some require as many as four to six blood patches (Mokri, 2004). For resistant leaks, surgical repair of the dural tear may be necessary. Even after a protracted duration, surgical repair of the causative dural tear can be quite effective (Mokri, 2004).

A similar syndrome of headache due to low pressure occurs uncommonly when the CSF is leaking through the cribriform plate, petrous bones, or any basal skull defect. CSF rhinorrhea and especially CSF otorrhea may not be obvious to the patient, whose complaint may be postoperative or posttraumatic headache. Leakage of CSF from the skull can occur spontaneously when ICP is raised or a tumor erodes through the base of the skull. This occurs most often around the cribriform plate region, where the bone is especially thin. The CSF leak can be identified by radioisotope cisternography. Placing numbered cotton pledgets in the nose next to the ostia of the sinuses detects leakage of CSF through the nasal sinuses. Contamination of the pledgets by radioactivity enables the sinus through which the fluid is leaking to be identified. CSF otorrhea is not easy to identify if the fluid is draining down the eustachian tube when the eardrum is intact. Scanning with a gamma camera after instillation of a radioactive tracer by lumbar puncture may allow the leak to be identified. Treatment is usually surgical repair of the bony and meningeal defect.

Transient Syndrome of Headache with Neurological Deficits and Cerebrospinal Fluid Lymphocytosis

Although originally termed migrainous syndrome with CSF pleocytosis, several later reports used various terms including headache with neurological deficits and CSF lymphocytosis (Berg and Williams, 1995) and pseudomigraine with temporary neurological symptoms and lymphocytic pleocytosis (Gomez-Aranda et al., 1997). This self-limited syndrome consists of one to several episodes of variable neurological deficits accompanied by moderate to severe headache and sometimes fever. Each episode lasts hours, with total duration of the syndrome being from 1 to 70 days. CSF abnormalities have included a lymphocytic pleocytosis varying from 10 to more than 700 cells/mm, elevation of CSF protein, and in some patients, elevated opening pressure. MRI and CT are normal in the vast majority of reported cases. A single patient had MRI evidence of gray-matter swelling in addition to right temporal and occipital sulci CSF enhancement and hypoperfusion. Similar findings have been reported in hemiplegic migraine (Yilmaz et al., 2009). Another patient was found to have global hemisphere hypoperfusion on MRI perfusion imaging (Vallet et al., 2010). Results of microbiological studies are usually negative. A single patient was reported to have evidence of recent human herpesvirus-6 infection, but its pathogenic role in the syndrome is unclear (Emond et al., 2009). Accordingly, the cause of the syndrome is unclear, although an immune response to a viral infection is speculated. No treatment alters the self-limited course of this disorder. In contrast to this syndrome, episodes of Mollaret meningitis (see Chapters 53B and 73) are separated by months to years and are typically not accompanied by focal neurological symptoms.

Headache Attributed to Head or Neck Trauma

Posttraumatic Headache

Since head and neck trauma frequently occur together, take care not to overlook cervical spine injuries or instability. Cervical spine radiographs with odontoid views are important, especially when patients present with an altered level of consciousness or when other factors prevent a more thorough neurological evaluation. In some cases, such as in the presence of focal neurological abnormalities, CT or MRI may be necessary for additional evaluation of cervical spine pathology.

Headaches, dizziness, difficulty concentrating, irritability, decreased libido, and fatigue are common complaints after head injury (Keidel and Ramadan, 2005). Many studies suggest that milder injuries are more frequently associated with posttraumatic headache then more severe injuries (Packard, 2005). This counterintuitive observation may result from the fact that seriously injured patients may have other symptoms of such severity that headache may be overshadowed by their other complaints; however, there is no definitive evidence as of yet to support this assumption. In civilian populations, the phenotypical appearance of headache attributed to traumatic brain injuries is most consistent with tension-type headache. In military populations, however, posttraumatic headache more commonly meets criteria for migraine. The underlying mechanisms behind this discrepancy are unclear. The variable latencies between injury and the onset of headache observed in combat veterans suggests the need to revise the diagnostic criteria for posttraumatic headaches; the currently accepted window of 7 days may not adequately capture the number of true cases (Vargas, 2009). Brain imaging rarely reveals abnormalities in the absence of an abnormal neurological examination, although unexpected subdural hematomas are occasionally found. MRI examination tends to be more sensitive for the detection of small occult extracerebral hematomas, cortical contusions, and indeterminate changes in the cerebral parenchyma. Treatment of posttraumatic syndrome and posttraumatic headache is difficult. Encouragement, patience, and a sympathetic attitude on the part of the physician are essential. Undoubtedly, a thorough physical examination and evaluation of appropriate imaging studies are important to reassure the patient that more sinister underlying disorders have been ruled out. As successful treatment can be challenging, reasonable expectations should be established. All the treatments useful for tension-type headaches, migraine, occipital neuralgia, and neck sprains may be needed. Physical therapy, biofeedback, and psychotherapy each have a place in treatment. Drug treatment may include analgesics (nonopioid), nonsteroidal antiinflammatory drugs (NSAIDs), and antidepressants. The tricyclic antidepressants and gabapentin can be particularly helpful.

Recovery from posttraumatic syndrome, including the headache, may be significantly delayed. Most patients who continue to have headaches for more than 2 months after the trauma continue to have them for 1 to 2 years (Ramadan and Láinez, 2005). If the history included a period of unconsciousness or if there is a simple skull fracture, a limited period of bed rest followed by a graduated return to full activity should be advised.

Posttraumatic dysautonomic cephalalgia is rare and usually follows a neck injury. Posttraumatic overactivity of the cervical sympathetic system may be the cause. The throbbing unilateral headache, ipsilateral mydriasis, and facial sweating respond to treatment with propranolol.

Headache Attributed to Infection

Inflammation of pain-sensitive structures such as the meninges and intracranial vessels produces the severe headache frequently associated with both meningitis and meningoencephalitis. Headache is the most common symptom in acute bacterial meningitis, occurring in nearly 90% of cases (van de Beek et al., 2004). Acute bacterial meningitis characteristically produces a severe holocephalic headache with neck stiffness and other signs of meningismus, including photophobia and irritability. Pain may be retro-orbital and may worsen with eye movement. The presence of the classic triad of fever, neck stiffness, and altered mental status has a low sensitivity for the diagnosis of meningitis; however, nearly all patients present with at least two of these symptoms and/or headache (van der Beek et al., 2004). Jolt accentuation of headache has a sensitivity of 100% and a specificity of 54% for meningitis diagnosis (Attia et al., 1999).

Chronic meningitis due to fungal or tuberculous infection may lead to headache that may be severe and unrelenting. The headache of intracranial infection is nonspecific but merits consideration, especially in immunocompromised patients. The diagnosis can be confirmed only by examination of the CSF. Further discussion of meningitis can be found in Chapters 53A to 53D.

Sinusitis, mastoiditis, epidural or intraparenchymal abscess formation, and osteomyelitis of the skull can all cause either focal or generalized headache. The diagnosis is usually suspected in the context of other associated symptoms and signs. After craniotomy, increasing pain and swelling in the operative site may be due to osteomyelitis of the bone flap. Plain skull roentgenograms may reveal the typical mottled appearance of the infected bone, necessitating removal of the flap.

Mollaret meningitis is a rare and recurrent aseptic meningitis (see Chapters 53B and 73). The CSF cellular response includes large epithelioid cells (Mollaret cells). The pathogenesis is unknown but may relate to the herpes simplex virus (Jensenius et al., 1998). The condition may recur every few days or every few weeks for months or years. Headache, signs of meningismus, and low-grade fever accompany each attack. Treatment is mainly symptomatic.

Headache Attributed to Cranial or Cervical Vascular Disorders

Aneurysms and Arteriovenous Malformations and Thunderclap Headache

Intracranial aneurysms are rarely responsible for headache unless they rupture or rapidly enlarge. Large aneurysms may produce pain by exerting pressure upon cranial nerves or other pain-sensitive structures. Such pain is most commonly associated with aneurysms of the internal carotid and posterior communicating arteries. Enlargement of an aneurysm may occur shortly before rupture, and the pain is therefore an important clinical sign.

Parenchymal arteriovenous malformations (AVMs) rarely cause pain before rupture. Very large lesions can be associated with ipsilateral or bilateral throbbing cephalalgia, but they rarely cause a migraine-like headache. The presence of a cranial bruit or the classic triad of migraine, seizures, and focal neurological deficits may indicate an AVM. Numerous case reports and retrospective studies suggest migraine may be more prevalent in patients harboring AVMs versus the general population. Among these, the headache frequently occurs ipsilateral to the AVM, highlighting the need for cautious evaluation of patients with side-locked headaches (Monteiro et al., 1993). MR or CT angiography can usually exclude the presence of clinically significant aneurysms and AVMs.

Both aneurysms and AVMs can produce mild subarachnoid hemorrhages that result in sentinel headaches. Such headaches may be abrupt, mild, and short lived. More catastrophic subarachnoid hemorrhages classically present as “the worst headache” the patient has ever had, all the more worrisome when associated with neck stiffness or pain, transient neurological symptoms (e.g., extraocular nerve palsy), or fever. Patients having any suggestion of a sentinel bleeding episode or who describe a recent “thunderclap” headache require emergent examination and CT to detect the presence of subarachnoid blood. If the CT is normal, perform lumbar puncture looking for blood or xanthochromia.

The term thunderclap headache describes a severe headache of instantaneous onset (within seconds) and without warning, like a clap of thunder. Other conditions can also manifest with thunderclap headache: cerebral venous sinus thrombosis, cervicocephalic arterial dissection, pituitary apoplexy, acute hypertensive crisis, spontaneous intracranial hypotension, meningitis, embolic cerebellar infarcts, and reversible cerebral vasoconstriction syndromes (Calabrese et al., 2007; Schwedt et al., 2006). These entities are associated with significant neurological morbidity and not easily seen on the initial CT image, thus underscoring the frequent need for MRI and MRA/magnetic resonance venography (MRV) in this group if results of the initial workup are negative. Finally, for one category of primary thunderclap headache, no underlying cause is established.

Whether an unruptured cerebral aneurysm can cause a thunderclap headache is debated (Schwedt et al., 2006).

Subarachnoid Hemorrhage

Rupture of an intracranial aneurysm or AVM results in a subarachnoid hemorrhage, with or without extension into the brain parenchyma. The headache of a subarachnoid hemorrhage is characteristically explosive in onset and of overwhelming intensity. Subjects who survive may relate that they thought they were hit on the head. The headache rapidly generalizes and may quickly be accompanied by neck and back pain. Loss of consciousness may also occur, but many patients remain alert enough to complain of the excruciating headache. Vomiting often accompanies the headache, which may aggravate the pain. Extension of blood into the ventricles and basal cisterns or distortion of the midline structures can each contribute to the rapid development of hydrocephalus, which frequently worsens the headache.

Suspicion of the diagnosis is easily confirmed by an unenhanced CT scan that reveals blood in the subarachnoid cisterns or within the parenchyma and often early hydrocephalus. When CT unequivocally shows blood in the subarachnoid spaces, it is not necessary or advisable to perform a lumbar puncture, because the resultant reduction of CSF pressure may cause herniation of the brain or may remotely induce further bleeding from the aneurysm. Demonstration of subarachnoid hemorrhage generally indicates the need for cerebral angiography. The timing of this procedure and the subsequent mode of treatment are detailed in Chapter 51C. The headache that occurs after a subarachnoid hemorrhage may be persistent, lasting up to 7 to 10 days. Rarely, a chronic daily headache may persist for months to years.

Movement aggravates the headache of subarachnoid hemorrhage, and photophobia and phonophobia are often associated. Therefore, these patients require a dark, quiet room and comfort measures which minimize straining at stool, vomiting, and coughing.

Cerebral Ischemia

Cerebral infarction, whether embolic or thrombotic, may cause head pain. The location of the pain is a poor predictor of the vascular territory involved. Some studies indicate that cortical infarction is more likely to be associated with headache than deep cerebral hemisphere infarctions. The headache may be either steady or throbbing and is rarely as explosive or as severe as the headache of subarachnoid hemorrhage. Cerebral infarctions and transient ischemic attacks may be associated with transient head pain in up to 40% of patients. Some reports indicate that carotid-distribution ischemia most commonly leads to frontotemporal head pain, whereas vertebrobasilar ischemia tends to lead to occipital headache.

Approximately 10% of patients note the development of a new or different headache in the weeks and months before onset of ischemic stroke.

If a large cerebral or cerebellar infarct produces a significant mass effect as a result of edema, headache may worsen. Obstruction of the ventricular system frequently results in hydrocephalus and further aggravation of the pain. The pain may be pulsatile and may worsen by straining or by the head-low position. As the infarct decreases in size and the phase of hyperemia subsides, headache generally eases. Hemorrhagic transformation of an ischemic infarct may be associated with worsening of headache.

Paroxysmal visual and sensory disturbances commonly associated with migraine aura may mimic symptoms of cerebrovascular disease, occasionally making the differentiation between the two a challenge. The visual aura of migraine is typically a positive phenomenon perceived with the eyes open or closed. Visual disturbances due to ischemic lesions of the visual pathway or retina are usually associated with negative phenomena such as vision loss or a negative scotoma, which are typically unrecognizable in the dark or with the eyes closed; however, emboli to the retinal artery can result in showers of bright flashes, and calcarine ischemia can occasionally produce scintillating scotoma. While visual disturbances associated with stroke and TIA are usually abrupt and fixed, the migrainous aura tends to march across the visual field over the course of a few minutes and is generally followed by headache after a latent interval. The headache associated with stroke and TIA typically has a more variable relationship to the visual disturbances.

Carotid and Vertebral Artery Occlusion and Dissection

Occlusion or dissection of the cervical portion of the carotid artery can result in headache and may be associated with an ipsilateral Horner syndrome. The sympathetic hypofunction may be due to interference with the sympathetic fibers around the internal carotid artery as they ascend from the superior cervical ganglion to the intracranial structures. The combination of headache, ipsilateral Horner syndrome, and contralateral hemiparesis is a common presentation of carotid occlusion or dissection.

Cervicocephalic arterial dissections can result from intrinsic factors that predispose the aneurysm to dissection, including fibromuscular dysplasia, cystic medial necrosis, and association with Marfan syndrome or Ehlers-Danlos syndrome. Extrinsic factors such as trivial trauma may play a pathogenic role when superimposed on structurally abnormal arteries. Severe head and neck trauma may occasionally be the proximate cause of dissection. In most patients, the initial manifestation of internal carotid dissection is pain described as headache, facial pain, or neck pain. The pain associated with carotid dissection is typically ipsilateral but infrequently is present bilaterally. Cerebral or retinal ischemic symptoms are the initial manifestations in a minority of patients. The common clinical syndromes associated with carotid dissection include (1) hemicranial pain plus ipsilateral oculosympathetic palsy, (2) hemicranial pain and delayed focal cerebral ischemic symptoms, or (3) lower cranial nerve palsies, usually with ipsilateral headache or facial pain.

The most common symptoms of vertebral dissection are headache and neck pain. The syndrome seen most often consists of headache with or without neck pain, followed after a delay by focal CNS ischemic symptoms.

MRI or MRA usually confirm the diagnosis of arterial dissection. At the level of involvement, the lumen of the artery typically appears as a dark circle of flow void of smaller caliber than the original vessel, and the intracranial clot appears as a hyperintense and bright crescent or circle (in both T1- and T2-weighted images) surrounding the flow void (Fig. 69.4). Catheter angiography is rarely required (Mokri, 2002). The pain associated with cervicocephalic dissections is of variable duration and may require treatment with potent analgesics. Patients with evidence of distal embolization are usually treated with either antiplatelet agents or anticoagulation.

Giant-Cell Arteritis

Giant-cell arteritis is a vasculitis of elderly persons and is one of the most ominous causes of headache in this population. When unrecognized and untreated, it may lead to permanent blindness. Patients with this disorder most commonly see neurologists for headache of unknown cause.

Clinical Symptoms

The clinical manifestations of giant-cell arteritis result from inflammation of medium and large arteries. Table 69.1 summarizes clinical symptoms in 166 patients examined at the Mayo Clinic between 1981 and 1983. Headache was the most common symptom, experienced by 72% of patients at some time and the initial symptom in 33%. The headache is most often throbbing, and many patients report scalp tenderness. Headache is associated with striking focal tenderness of the affected superficial temporal or, less often, occipital artery. One-third of patients with headache may have no objective signs of superficial temporal artery inflammation.

Table 69.1 Symptoms of Giant-Cell Arteritis in 166 Patients*

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Symptom Patients with Symptom (%) Patients in Whom It Was Initial Symptom (%)
Headache 72 33
Polymyalgia rheumatica 58 25
Malaise, fatigue 56 20
Jaw claudication 40 4
Fever 35 11
Cough 17 8
Neuropathy 14 0
Sore throat, dysphagia 11 2
Amaurosis fugax 10 2
Permanent vision loss 8 3
Claudication of limbs 8 0
Transient ischemic attack/stroke 7 0
Neuro-otological disorder 7 0
Scintillating scotoma 5 0
Tongue claudication 4 0
Depression 3 0.6
Diplopia