Chapter 18 - Headaches

Causes of head pain

Intracranial disease can produce pain in only a limited number of ways. With rare exception, stimulation or destruction of the brain itself does not produce pain. The following intracranial structures are pain-sensitive:

  1. Meningeal arteries
  2. Proximal portions of the cerebral arteries
  3. Dura at the base of the brain
  4. Venous sinuses
  5. Cranial nerves 5, 7, 9, and 10, and cervical nerves 1, 2, and 3

Distortion or traction

Increased intracranial pressure, when it does not result in traction on pain-sensitive structures, does not cause headache. You may raise your own intracranial pressure to abnormally high values transiently by the Valsalva maneuver; this does not cause pain. Conversely, an intracranial mass that distorts the dura or the arteries at the base of the brain causes headache even if the intracranial pressure is normal.

Drainage of spinal fluid with the patient in erect posture causes headache, presumably secondary to traction on the venous sinuses when the brain sinks toward the tentorium as it loses CSF flotation. This is thought to be the mechanism of headache following lumbar puncture, which is relieved when the person lies down. A more general term for this headache is "low pressure headache" because it can also result from any cause of CSF leakage.

Distensions of a vessel

Distension of extracranial and occasionally intracranial arteries is thought to be the cause of pain in migraine. Increased flow through collateral circulation may produce the headache that sometimes accompanies large-vessel occlusion. This appears to activate the trigeminal nerve terminals in the vessel wall.

Inflammation

Inflammation in the subarachnoid space, whether caused by infection, hemorrhage, or chemical irritation, results in headache. Some inflammation may be intrinsic to the blood vessel walls. This may occur with autoimmune diseases (see giant cell arteritis, below), or may accompany activation of certain nerves in the blood vessel wall. A leading theory of migraine pain is inflammation around blood vessels due to release of pro-inflammatory neurotransmitters from nerve terminals in the blood vessels around the brain.

Referral of pain

Referred pain refers to the phenomenon of feeling pain in a region that is not actually the source of the pain. This occurs because pain from many sources converge on single "wide dynamic range" pain transmission neurons. Therefore, when the pain signal is relayed, its location requires interpretation. In the case of pain from the head and upper neck region, there is a high degree of convergence on neurons of the spinal nucleus of the trigeminal nerve (which extends several segments down in the neck region). In general, lesions above the tentorium produce pain that is referred to the trigeminal distribution (the forehead or behind the eye), because the dura in this region is supplied by the trigeminal nerve. Lesions in the posterior fossa most often produce pain in the ear and the back of the head (this part of the dura is supplied by cranial nerves 9 and 10 and the upper three cervical roots). When the first cervical segment has a dorsal root (as in about 50% of individuals) it may, in addition to receiving afferents from the posterior fossa, which refer pain to the occiput and ear, refer pain to the orbit. This probably relates to the termination of orbital (ophthalmic division) pain nerve fibers in the lowest part of the spinal nucleus of the trigeminal nerve, which also receive termination of the upper cervical pain afferent nerve fibers. Irritation of cranial nerves 7, 9, and 10 may be referred to the ear, because the ear has cutaneous supply from each of these nerves as well as cranial nerve 5.

Although the location of pain may at times be misleading, in general, pain lateralization accurately predicts the side of the lesion.

Classification of Headaches

Table 18-1 presents a clinically useful classification of headaches. The clinical evaluation of the person who has headaches should be designed to define an underlying cause for headache when possible (categories A and B) and thereby rule out disease that might endanger the patient. When this is not possible, the evaluation should suggest a classification of the headache based on the characteristic symptoms (categories C and D).

Dangerous headaches

These represent a small minority of headaches. Fortunately, with a little thought, it is quite easy to rule out most of these conditions on the basis of the history and examination alone. Most of these conditions are discussed elsewhere in this book. The following comments apply to the patient whose chief complaint is headache (i.e., the patient is not comatose or hemiplegic, etc.). This does not imply that isolated headache is the typical presentation for these conditions, but the person who has a hemiparesis or seizure or coma from a tumor or intracranial hemorrhage does not present a problem in the differential diagnosis of headache.

Meningeal irritation.

These include subarachnoid hemorrhage and meningitis. Most of these cases present with meningismus (severe neck stiffness particularly with neck flexion, i.e., nuchal rigidity), although this sign can be lost with deepening coma.

Subarachnoid hemorrhage

Arterial bleeding in the subarachnoid space from a ruptured aneurysm is almost invariably accompanied by the sudden (instantaneous) onset of severe pain and, frequently, vomiting. The pain persists and the patient usually looks very ill or uncomfortable. Nuchal rigidity is often (but not always) found. The remainder of the neurologic examination can be normal. The history of sudden onset of a severe headache that persists, therefore, indicates subarachnoid hemorrhage until proved otherwise. CT scan and (if the scan is negative) lumbar puncture are indicated in the absence of neurologic signs other than those of meningeal irritation.

Meningitis

This diagnosis should not prove difficult because the patient looks ill, and fever and nuchal rigidity are usually present. Remember that in the elderly or debilitated person and in the young child, nuchal rigidity may not be present (see Chapter 11 ). Lumbar puncture is diagnostic.

Intracranial mass lesions

This category contains neoplasms, intracerebral hemorrhage, subdural or epidural hemorrhage, abscess, and hydrocephalus.

Neoplasms. Persons often seek medical advice about their headaches because they are afraid they have a brain tumor. Fortunately, although many persons with a brain tumor have headache, the vast majority of patients with headache do not have a brain tumor. The headache of brain tumor is often mild and nonspecific; it may be worse in the morning; and on examination, vigorous head shaking may elicit focal pain. If focal symptoms, seizures, focal neurologic signs, or evidence of increased intracranial pressure are present, a full evaluation must be undertaken. In the absence of any of these findings, brain tumor may practically be dismissed as a diagnosis.

Intracerebral hemorrhage

This is nearly always accompanied by focal neurologic signs or symptoms. Hypertension, trauma or defects in coagulation are the usual antecedents (see Chapter 27).

Subdural or epidural hemorrhage. Epidural and acute subdural hemorrhage occurs in the context of acute head trauma (see Chapter 29). Chronic subdural hematoma may manifest itself weeks or months after an injury, and headache may be the most prominent symptom. This headache must be differentiated from the common postconcussion headache. The latter may persist for weeks or months after an injury and may be accompanied by dizziness or vertigo and mild mental changes. All these symptoms gradually subside. When symptoms increase or when there are lateralizing neurologic findings, subdural hematoma must be suspected.

Abscess (see Chapter 25)

Focal signs or mental changes are often present. There may be evidence of increased intracranial pressure. The history often suggests some source of infection (ear infection, bronchiectasis, etc.) or a reason to be susceptible to infection (cyanotic congenital heart disease, immunosuppressant therapy).

Acute hydrocephalus

This may be caused by obstructing CSF pathways (such as by inflammation, blood or tumor). Acute hydrocephalus is accompanied by evidence of brain dysfunction: confusion, lethargy, ataxia, incontinence, and others. Of course, with rapid or severe elevations of intracranial pressure, the fundi may show evidence of increased intracranial pressure.

"Intracranial hypertension"

"Idiopathic intracranial hypertension" (what has been called "benign intracranial hypertension" or "pseudotumor cerebri" in the past) is a somewhat more insidious cause of headache and increased intracranial pressure. This is believed to result from diminished resorption of cerebrospinal fluid, with pressure buildup. It is most often recognized by a finding of papilledema, but scanning does not reveal an associated mass (there may be small ventricles, but the image is otherwise normal). Rarely, there may be idiopathic intracranial hypertension without papilledema and, in this case, the condition can only be determined by actual CSF pressure measurements.

The prototypical patient is an overweight young woman, possibly with polycystic ovarian disease. This is because high estrogen is believed to predispose to the condition. Exogenous estrogen is also a predisposition, as is excess vitamin A (or some acne medications) or outdated tetracycline. Venous sinus thrombosis (see below) should be considered before labeling the condition as " idiopathic intracranial hypertension".

Although this condition may be termed benign, it can chronically damage the optic nerves, first increasing the physiologic blind spot and later resulting in constriction of the visual fields and even producing retinal hemorrhage. Sometimes serial lumbar punctures are therapeutic as well as diagnostic. Carbonic anhydrase inhibitors may lower pressure a little. Weight loss can also be useful. However, shunting (ventriculoperitoneal or lumboperitoneal) may be necessary in some cases and optic nerve sheath fenestration may prevent damage to the optic nerves.

Vascular headaches

These headaches include giant cell (temporal) arteritis, hypertensive encephalopathy, and vascular malformations.

Giant cell (temporal) arteritis. This is a systemic vasculitis with a predilection for the cranial vessels, which rarely occurs in persons less than 50 years old. The clinical picture may include: (1) polymyalgia rheumatica - malaise, loss of energy, proximal joint pains, and myalgias; (2) nonspecific headaches, sometimes associated with tenderness and swelling over the temporal or occipital arteries; and (3) evidence of arterial insufficiency in the distribution of branches of the cranial vessels. The latter may involve the external carotid circulation, producing the unique symptoms of jaw claudication (painful jaw muscles provoked by chewing) or infarction of the tongue or scalp; or it may involve the internal carotid circulation, producing retinal ischemia and blindness or, less commonly, stroke. Of the main trunks of the major cerebral vessels, the vertebral arteries are more likely to be involved than the carotids, although involvement of the main portions of these vessels is uncommon. When the vertebrals are involved, ischemic infarction in the brainstem, cerebellum and occipital lobes may result.

In giant cell arteritis, the sedimentation rate is usually very high. The disease can be dramatically reversed with steroids. In the person over 50, the ESR should be checked if the history is suggestive of temporal arteritis or polymyalgia rheumatica. If the ESR is high, temporal artery biopsy often confirms the diagnosis, and treatment can be started without delay. Because lesions may skip segments, bilateral biopsy of sufficiently long (one inch) aterial segments should be examined with thorough serial sectioning before discounting the diagnosis. At times, the clinical picture may be sufficiently suggestive so that a trial of therapy is indicated despite normal test results. If the patient is sufficiently symptomatic, a trial of steroids should produce remarkable improvement in symptoms.

There are other conditions that can inflame cerebral blood vessels (such as lupus), however, these are almost invariably accompanied by systemic symptoms.

Hypertensive encephalopathy. Cerebral vasoconstriction occurs in response to systemic hypertension to preserve a constant cerebral blood flow. This process is termed "autoregulation". It is thought that in persons with hypertensive encephalopathy cerebral autoregulation fails and segments of arteries dilate despite severe hypertension. This results in edema and hemorrhage. The diagnosis should be considered in patients with severe hypertension (diastolic pressure more than 120 mm Hg) or in previously normotensive patients who suddenly develop less severe hypertension. Retinal changes (hemorrhages and papilledema) and renal disease are frequent accompaniments. Milder degrees of hypertension are generally not associated with headache. Paroxysmal elevations of blood pressure, such as occur with pheochromocytoma or with tyramine reaction with MAOI (monoamine oxidase inhibitors) can produce headache.

Vascular malformations. Headache from vascular malformations is discussed later in relation to migraine headache since it may result in a headache with features of migraine.

Venous sinus thrombosis. In the case of sinus thrombosis, headache probably results from stretching of the pain sensitive veins that drain into the sinuses, although elevated intracranial pressure may also play a role. In addition to headache, clouding of consciousness and seizures are common and there may be petechial intraparenchymal hemorrhages. Hypercoagulibility and increased osmolarity appear to be the main predisposing factors. High estrogen states can provoke this and dehydration is also a risk factor.

Cervical headaches

Pain from the cervical region (arising from periosteum, ligaments, nerve irritation, or reflex muscle spasm) is usually felt over the neck and occiput, but can be referred around the temples and even into the frontal region. In a person with a history of neck trauma or with symptoms or signs of cervical root or cord compression, cervical imaging with MR or a CT scan must be obtained to rule out a condition that might result in cord compression, such as fracture or dislocation. Cervical spine x-rays with lateral views in flexion and extension are useful to detect excessive mobility of the spine.

Occipital neuralgia. Some individuals may have irritation or entrapment of the greater occipital nerve in its course through tissues between C1 and C2 and then through the cervical musculature. At times this may be traumatic or related to structural abnormalities in the area. The diagnosis may be clear when there is unilateral shooting pain in the occiput provoked by upper neck movement and associated with hypesthesia or paresthesia in the area. Other cases may be bilateral, more constant or more subtle. A trial of occipital nerve block may provide a diagnosis.

Arterial dissection. Dissection of the arteries of the neck can result in an acute neck pain sometimes accompanied by ischemic symptoms. This may be traumatic and usually results in pain over the involved vessel. This occurs due to entry of blood into the wall of the major cervical (carotid or vertebral) artery, usually through a small tear in the intima of the vessel. It may be difficult to diagnose, especially if it was not caused by trauma. However, a completely new type of acute, localized neck pain (often with radiation to the head) that does not improve with rest should be regarded with suspicion.

Metabolic headaches

Headache is often associated with hypoxemia, hypercapnea, and anemia, possibly related to the cerebral vasodilatation that may accompany these conditions. Chronic carbon monoxide exposure may also produce headache.

Glaucoma

Headache may accompany glaucoma, usually the acute, narrow-angle type. Pain is localized in the eye or behind the eye.

Evaluation of dangerous headaches

From the preceding discussion, a physician can be fairly sure of excluding "dangerous" headaches by the following:

  1. There should be no history of serious head or neck injury, of seizures or focal neurologic symptoms, or of infections that may predispose to meningitis or brain abscess.
  2. The patient should be afebrile.
  3. The diastolic blood pressure should not be greater than 120.
  4. The fundi should be normal.
  5. The neck should be supple.
  6. There should be no cranial bruits.
  7. The neurologic examination should be normal; the patient should not be lethargic or confused.
  8. In appropriate cases, complete blood cell count, ESR, cranial imaging or neck x-rays should be obtained and be normal.

The duration of the headache is also significant: headache arising recently in a patient who is not prone to them arouses more suspicions than headache that has been recurrent for years. In addition, the patient's complaints often suggest an alternative diagnosis. Ancillary symptoms that are not classically associated with migraine (nausea, light and sound sensitivity, classic visual symptoms) should be treated with suspicion. A patient with a headache that is always in the same location (most migraines, for example, tend to move around or switch sides from time to time) or one who does not return to normal in between headaches, should also be evaluated carefully. Those patients who have typical migraine only require a good history and physical exam before instituting treatment.

Headaches from extracranial lesions

These are listed in part in Table 18-1. The location of the pain often suggests the site of pathology. Other symptoms may accompany the condition: postnasal drip may accompany sinusitis, and on examination there may be tenderness over the affected sinus. Pain increased by chewing points to dental or temporomandibular joint pathology.

Uveitis or glaucoma should not be missed. Errors of refraction do not commonly cause headache (despite the popular belief to the contrary). The headaches that accompany cervical spine disease may resemble "tension" headaches, in that both produce excessive contraction of neck musculature.

Specific headache syndromes

Migraine

A migraine attack may consist of an aura and a headache, or either alone. In the absence of the aura, it may be difficult to diagnose the migraine with certainty. Research criteria for the diagnosis of migraine are listed in table 18-2. The following are useful diagnostic features (the most helpful are shown by asterisks):

  1. *The headache is episodic; persons can usually tell exactly when a migraine is beginning (and there may be a prodrome). The end of the headache may be less well defined, but it is unusual for a migraine to last more than 3 days (status migrainosus).
  2. Onset is often in childhood or adolescence, although it can arise at any age.
  3. The headache is often unilateral (but may be bilateral).
  4. *The headache can be severe, throbbing (but may be steady), and often accompanied by anorexia, nausea, and sometimes by vomiting, diarrhea, and other symptoms.
  5. The headache lasts from several hours to several days, rarely for a week or more.
  6. Patients often feel like going to bed with the lights out, and sleep may terminate an attack.
  7. There is frequently a family history of migraine.
  8. It can sometimes be relieved by taking ergotamine or triptans early in the course.
  9. Photophobia and an intolerance of loud sounds and strong smells are common complaints during the headache.
  10. There may be a history in childhood of motion sickness or cyclic vomiting (episodic vomiting without other accompanying symptoms or signs).

Physiologically, the headache of migraine is accompanied by vasodilatation of the extracranial arteries, and compression of the carotid or temporal artery on the side of the headache may relieve the pain. Treatment with vasoconstrictors (chiefly ergotamine) may abort a headache but it would be a mistake to consider this to be primarily a pain due to blood vessel dilation. The pain does appear to result from activation of nerves in the blood vessels that contribute to a sterile inflammatory reaction, both sensitizing and dilating the vessels.

There are many precipitants for migraine that vary somewhat between migraineurs. These include psychological stress, allergies, different food substances (e.g., alcoholic beverages, cheese, chocolate, nitrate-containing foods such as hotdogs, and a number of other substances), the menstrual period, birth control pills, disrupted schedules, lack of sleep, poor eating habits, especially missed meals, strong smells, glare, flickering lights (such as fluorescent lights or CRTs) and many others. Some of these have known mechanisms of action, while the reason fro provocation remains obscure for many of these triggers.

Aura

The aura of a migraine is much more specific than the headache, and a diagnosis of migraine may be made on the basis of the nature of the aura alone. As mentioned, the aura is not always present; in fact, migraine without aura (formerly called "common migraine") is much more common than migraine with aura (formerly called "classic migraine"). Being able to define the aura, however, is important not only in diagnosing migraine but also in differentiating this from more serious conditions (seizures or TIAs).

The aura of migraine is associated with, but probably not caused by intracranial vasoconstriction. The most prominent theory of causation is a slowly spreading wave of initial neuronal excitation, followed by depression that spreads over the cortex. This phenomenon, termed "spreading depression" progresses over the cortex at the rate of about 3mm per minute. This does appear to correlate with the spread of sensory aura symptoms when they can be localized to a specific part of the brain. Rarely, an aura may persist permanently, most often in elderly individuals, and indicates infarction of the brain. The most common symptoms involve visual, somatosensory, and language functions (dysphasia).

The visual aura is variable: scintillating scotomata are characteristic (an enlarging blind spot with a shimmering edge), but negative scotomata, or blurring of the visual field, may also be seen. There may be bright spots (often colored, called "photopsia"), jagged lines ("fortification spectra") or wavy lines (like heat lines). The symptoms are often homonymous (from cortical involvement), but symptoms referable to retinal ischemia (visual loss in one eye only) may also exist. The onset is gradual, and the symptoms usually last from 10 to 60 minutes. they may progress in a characteristic slow march over the visual field or, if tingling, the body.

The somatosensory march of migraine is characteristic and can be differentiated from sensory seizures or from the usual form of TIA by the following:

  1. The onset is gradual.
  2. The march (spread of symptoms) is slow; if it arises in the hand, it may take several minutes to reach the elbow and then the face. This slow spread differentiates it from sensory seizures, which are more rapid. TIAs or strokes usually encompass large somatotopic areas at once (e.g., whole limb or half body).
  3. Symptoms need not be restricted to the distribution of a single blood vessel as they are in TIA, since cortical spreading depression spreads over adjacent areas of sensory cortex rather than along a blood vessel.
  4. It usually clears first in the area that was first involved; that is, if it marched from most involved.
  5. The symptoms are almost always positive (i.e., pins and needles paresthesias) initially. The symptoms of TIAs are usually negative or ablative (i.e., numbness, heaviness).

Aphasia is the third most common feature of the migrainous aura. When all three symptoms appear as part of the same aura, it is characteristic for them to appear successively (e.g., visual, then sensory, then speech) rather than concomitantly (although this can also occur).

The slow march of symptoms appears to correlate with the rate of "cortical spreading depression" (a wave of depolarization which is excitatory on its advanced margin, followed by depolarization inhibition then repolarization). However, despite many lines of evidence, this remains only a theory of what is happening (although it is the best one).

Other symptoms sometimes associated with the aura (but seen much less often) are true motor weakness, emotional changes, micropsia or macropsia, olfactory hallucinations, and symptoms of basilar artery ischemia (diplopia, coma, vertigo). Ophthalmoplegic migraine is a variant that appears clinically quite distinct. Most commonly, the oculomotor nerve is involved; less often, the abducens nerve. Often the oculomotor or abducens paresis lasts for many weeks after the onset at the height of the headache. One possible mechanism is that dilation of the internal carotid artery occurs and compresses either the third or sixth nerve in the cavernous sinus to cause paresis or paralysis. With compression damage, one would expect a prolonged recovery period. These rarer manifestations of headache are often perplexing even to the experienced clinician. Some do not even consider these attacks of headache to be migraine, but instead a cranial neuropathy.

Familial hemiplegic migraine (FHM) is another and dramatic variant. As with ophthalmoplegic migraine, onset early in childhood and a strong family history are common. There are at least three known genetic mutations accounting for the familial variety (on chromosomes 19, 1, and 2 respectively). FHM type 1 involves the CACNA1A gene (P/Q calcium channel), FHM type 2 involves the sodium-potassium ATPase pump ATP1A2), and FHM type 3 involves neuronal voltage-gated sodium channels (SCN1A). Individuals with these abnormalities seem to have a lowered threshold for the initiation of cortical spreading depression. This finding, and the fact that most individuals with migraine have other afflicted family members has led to much speculation about some genetic predilection for many cases of migraine. However, this remains to be proven. In FHM, typically the headache appears first and symptoms and signs of weakness and sensory loss occur later when the headache is most severe. The neurological signs frequently outlast the headache by hours or days and occasionally may be permanent. When the latter is true a CT scan or MRI will usually evidence an area of presumed infarction. Arteriograms carried out during the phase of neurological signs have shown temporary arterial spasm. Hemiplegic migraine may also occur on a sporadic basis.

The migrainous aura usually precedes the headache, but it may accompany it or follow it or occur on its own. The latter is particularly true in elderly persons who have a long history of migraine. These migraine aura symptoms without the headache have been termed a "migraine equivalent," "aura without migraine" or acephalgic migraine. In these individuals, it may be quite difficult to determine that symptoms are due to a migraine mechanism.

Treatment of migraine

There are three basic approaches to treatment of migraine. The first is avoidance of trigger factors. However, this is often not practical and typically does not produce adequate control. The second mechanism is the use of medications during the headache. Some of these are nonspecific analgesics and antiinflammatory medications. Recent years have seen the development of a couple of classes of medications that activate serotonin receptors (ergotamine derivatives and the triptans). These receptors appear to be capable of affecting the trigeminal nerve endings on blood vessels, decreasing the release of inflammatory neuropeptides such as CGRP and substance P, and also constricting blood vessels. The two primary difficulties with the use of short-acting analgesics in migraine treatment are, first of all, that they become less effective once the migraine is well-established and, secondly, that frequent use of short-acting medications results in a gradual decrease in response to these medicines. In some cases this can reach the point that patients develop headache due to discontinuation of the medication, so-called "analgesic rebound headache" or" transformed migraine". This can also occur with regular caffeine use, such that patients may develop headache due to withdrawal from caffeine. With this in mind, however, even patients with occasional severe migraine can be managed with these serotonin agonists (often with the addition of an antiemetic medication). However, frequent migraines may require an alternative approach.

The third way of managing migraine is the use of preventative (prophylactic) medications. There are four classes of medications that have been shown to have preventative capability, and each of these classes have several representatives. Most of these have been shown empirically to be effective, although the specific properties of the drugs that result in prophylaxis are not known. Generally, the medications with prophylactic functions fall into one of the following classes of drugs: beta blockers; calcium channel blockers; heterocyclic antidepressants; or anticonvulsants. It must be emphasized that not all members of each of these classes of drugs have similar (or any) prophylactic potential. However, prophylactic medications should be considered in patients with frequent, severe and incapacitating migraines. Of course, some reassurance of the patient that their headache "is not a tumor" may be a wonderful therapeutic intervention in the migraine sufferer.

The physician should be familiar with the clinical picture of migraine since it is common and can usually be diagnosed with a good history and physical exam. Rarely, arteriovenous malformation (AVM) may cause recurrent unilateral migrainous headaches without bleeding. Some consideration should be given to imaging migraine sufferers with strictly unilateral headaches. It is reassuring for the patient with migraine to have had some headaches on the other side or to have the headache ipsilateral to the aura, because this would not be likely with a structural lesion.

Cluster headaches

Cluster headaches are uncommon but very severe headaches. They are associated with a variety of autonomic signs and symptoms. This headache syndrome is characterized as follows (research criteria are found in table 18-2):

  1. The headache is brief (15 minutes to 3 hours).
  2. It usually occurs once or twice daily (or more), often at the same time and often at night.
  3. The headache is very severe; persons with the headache are usually agitated and prefer to pace the floor as opposed to the patient with migraine who prefers to remain very still.
  4. It is often accompanied by lacrimation and nasal congestion on the same side as the headache. An ipsilateral Horner's syndrome may be present during the headache, and miosis may persist after the headache.
  5. The headaches occur in clusters; they may occur daily for several weeks or months and then disappear entirely for months or years, only to recur later. Chronic cluster headache is when a cluster episode does not abate.
  6. Men are much more commonly affected than women.

These headaches are clinically distinct from common or classic migraine. There is also a chemical difference: Persons with migraine have an increase in the level of blood serotonin at the onset of their headache and later, a depletion; persons with cluster headache have no change in serotonin levels but have an increase in blood histamine concentration coincident with their headache. In neither instance is the pathogenesis of the headache understood although recent evidence indicates overactivity in the caudal hypothalamus during the attack. Despite these differences, cluster headaches may be helped by certain prophylactic medications effective for migraine prophylaxis (especially calcium channel blockers and some anticonvulsants). Also, the acute attack may be helped by some of the rapidly acting medications used to abort a migraine attack (such as ergot derivatives and parenteral triptans). Interestingly, breathing 100% oxygen can often abort an attack very rapidly, for unclear reasons. Cluster headaches are usually not preceded or accompanied by an aura.

Tension-type headaches

Most people, when under sufficient pressure, get a mild cervical or bifrontal headache which is classified as "tension-type" (research criteria are found in table 18-2). EMG of the frontalis muscle or of the cervical musculature reveals hyperactivity (although increased activity in these muscles is seen in all headache types), and measures directed at relaxing these muscles (benzodiazapines, biofeedback therapy, massage) often relieve the headache. At times tension headaches are quite severe, but generally people are able to continue working with them (unlike many migraines or the usual cluster headache) and rarely are they ill enough to seek a physician's aid. These headaches are rarely pounding, usually don't result in nausea or light/sound sensitivity and usually don't worsen with exertion. The headache may be more prominent when the patient thinks s/he is more relaxed (in the evening or on weekends). Not infrequently, a prolonged tension headache will progress to migraine or the reverse, a migraine may develop the muscle contraction features of tension headache in addition to the typical migraine symptoms. It has been presumed that the stress from one type of headache triggers the other although it must be noted that there are similarities in the treatment and pathophysiology of migraine and tension-type headaches, at least in migraineurs. This has lead some authors to consider these two headache types as the manifestations of a single pathophysiologic entity in different individuals (or at different ages in the same individual). In migraineurs, both migraine and tension-type headaches respond to the same medications described above for migraine although, because they are less intense and disabling, many of the potential side-effects of some of the specific migraine medications would not be warranted. Migraine prophylactic medications often work for tension-type headaches, but would be reserved for the more severe cases. However, since tension-type headaches are more likely to be chronic and more likely to result in very frequent analgesic intake, it must be considered that analgesic rebound headache (see below) may be a common problem in such patients. Daily intake of analgesics for headache run a high risk of developing resistent headaches in the long-run and should be discouraged in favor of lifestyle and risk modification and even prophylactic medications.

Indomethacin-responsive headache syndromes

There is a group of headache syndromes that share the characteristic of being highly responsive to indomethacin (as opposed to resistance to other non-steroidal antiinflammatory medications). These fall into several categories, including: trigeminal-autonomic cephalgias, which result in unilateral headache accompanied by a variety of autonomic symptoms in the head; headaches induced by Valsalva maneuver (lifting, straining, etc); and headaches that have a primary stabbing quality (sometimes called ice-pick headache or jabs and jolts syndrome). Many of these headache syndromes have sharp and localized pain which are often shorter duration than migraine.

A prototypical example of the trigeminal-autonomic cephalgias is SUNCT (short-lasting, unilateral, neuralgiform headache with conjunctival injection and tearing). This usually occurs in middle-age, more commonly in men. The name gives the main features of this headache. The headaches recur frequently, but each one only lasts for seconds to a few minutes. Because of the autonomic symptoms, these headaches may be confused with cluster, but they generally respond to indomethacin. There are other preventative medicines or nerve blocks that may help, as well. Paroxysmal hemicrania has many similar features, although pain is usually longer (2-45 minutes).This is more common in women.

There are some more chronic conditions (hemicrania continua), in which pain waxes and wanes with flare ups several times most days (sometimes provoked by activity). Occasionally, there may be autonomic symptoms as well. The headaches may go away after many months, but can return months or years later.

Many of these syndromes are only finally identified by their dramatic response to indomethacin, justifying a trial in patients who tolerate this medication.

Neuralgias

Neuralgic pain is characteristic; it is very sharp, severe, and brief. There is commonly a "trigger point" - an area of skin or mucosa that, when touched, provokes the pain. There is usually a "refractory period" after the jolt of pain, where the trigger zone may be touched without provoking pain.

Tic douloureux (trigeminal neuralgia) usually occurs in the elderly and usually involves the second and third divisions of the trigeminal nerve. It should not be accompanied by sensory loss. If there is sensory loss, a structural lesion must be suspected. Neuralgic pain must be distinguished from dental pain, particularly malocclusions. When present in the young adult, it may be symptomatic of multiple sclerosis and thought to be secondary to a demyelinating plaque in the spinal tract or root entry zone of the trigeminal nerve.

Treatment with the anticonvulsants such as carbamazepine is often effective. In persons who do not respond to medical treatment, partial transection of the trigeminal sensory root or other trigeminal manipulative procedures may be necessary. In many of these patients there is an abnormal loop of blood vessel surrounding the trigeminal nerve, producing irritation. Surgical decompression of the nerve may provide lasting relief.

Glossopharyngeal neuralgia is much less common. In this condition, neuralgic pain is felt in the throat, ear and neck and may be triggered by swallowing.

Other varieties of headache

There are a couple of other headache types that don't fall neatly into one of the types described in the earlier sections.

"Psychiatric" headaches

A small number of persons complain of intractable, constant, severe, disabling headache for which no cause can be found. As a rule, these persons are severely depressed or have other serious psychopathology. Their headaches may respond to the same medications as common tension headaches, but often they are resistant to all treatment, even narcotic analgesics. This assessment is complicated by the fact that psychological stressors may provoke identifiable headaches (like migraine). Also, patients with intractable headaches have a high incidence of having been abused in childhood. Psychiatric treatment or psychotrophic drugs (such as antidepressants) are sometimes effective.

"Analgesic rebound" headaches (medication overuse headache)

A small but significant population of individuals with debilitating migraine and/or tension headache may become physiologically dependent on daily analgesic therapy and develop bifrontal headaches when they attempt to withdraw the medication, which will only respond by taking more of the habitual analgesic. These have been called analgesic rebound headaches and are often noted on awakening in the morning because no medications have been taken during the night time sleep period, thus allowing an adequate period for withdrawal symptoms to appear. This type of withdrawal headache, typically bifrontal in location, can be seen in individuals with chronic daily use of narcotic analgesics, sedatives such as barbiturates and benzodiazepenes, large amounts of caffeine, or with the frequent use of any short-acting headache medication (including over-the-counter medications). Treatment consists of education and withdrawal of the offending agents. Several weeks may be necessary before all symptoms of withdrawal dissipate and hospitalization is sometimes necessary to medically support the acute phase of withdrawal.

References

Questions

Define the following terms:

subarachnoid hemorrhage, migraine, photophobia, phonophobia, tension-type headache, cluster headache, temporal arteritis, paresthesia, aura.
Subarachnoid hemorrhage is bleeding into the cerebrospinal fluid, usually due to leakage of an aneurysm or vascular malformation.
Migraine is a syndrome characterized by intermittent pounding or throbbing headache, potentially preceded by an aura. It has frequent association with nausea, photophobia, phonophobia and exertional worsening.
Photophobia is light sensitivity.
Phonophobia is sound sensitivity.
Tension-type headache is a recurrent headache with a bilateral, squeezing and pressing sensation that usually does not prevent normal activity and does not significantly worsen with exertion.
Cluster headache is a recurrent, severe headache, which is unilateral and periorbital and often associated with autonomic symptoms of tearing and nasal congestion.
Temporal arteritis is a condition of inflammation of major cranial blood vessels. It can result in blindness or stroke depending on the vessels involved.
Paresthesia is an abnormal sensation that is not due to an external stimulus.
Aura is a warning, prior to the onset of a symptom (this may occur in migraine or seizures.

18-1. What are bad signs/symptoms in the headache patient (and what might it signify)?

Answer 18-1. There are several worrisome signs and symptoms of headache: Sudden onset worst headache of life - subarachnoid hemorrhage; Sudden onset headache with focal neurologic deficit - intracerebral hemorrhge; New or different headache in older patient - giant cell (temporal) arteritis; Headache that awakens from sound sleep - increased intracranial pressure; Escalating headache that is always in the same location - focal lesion such as tumor, abscess or hemorrhage; Headache associated with a focal neurological deficit - focal lesion; Headache with recent head trauma, systemic disease, fever, malignant hpertension; Positional or exertional headache - obstruction of CSF flow

18-2. What does subarachnoid hemorrhage indicate and how can you rule it out?

Answer 18-2. It is usually due to aneurysm or arteriovenous malformation. LP may be the only way to rule this out and angiogram is the definitive test for identification of the specific cause.

18-3. How can you rule out intracerebral hemorrhage?

Answer 18-3. Imaging (particularly CT scan) can identify.

18-4. How can you test for giant cell (temporal) arteritis?

Answer 18-4. Sedimentation rate is almost always high. Biopsy is the only way to diagnose it definitively. It is critical to make the diagnosis because this is treatable with steroids.

18-5. How can you examine for intracranial pressure?

Answer 18-5. Looking for venous pulsations or papilledema in the eye grounds. Otherwise, the only way to determine pressure is by lumbar puncture (which is hazardous unless imaging has showed no intracranial masses).

18-6. What are possible causes of increased intracranial pressure?

Answer 18-6. Mass lesions (tumor, abscess), disruptions of resorption of CSF (meningitis, subarachnoid hemorrhage), sagittal sinus thrombosis or pseudotumor cerebri can all cause increased intracranial pressure.

18-7. What are the symptoms of common migraine?

Answer 18-7. It has no warning. Migraine headache is usually moderate to severe intensity, usually pounding, often unilateral and usually accompanied by nausea, vomiting, light and sound sensitivity. It is worse with exertion, and usually lasts several hours up to a couple of days. The headache may be provoked by food, drink, stress, erratic schedules, lights/glare, smells, part of menstrual cycle, etc.

18-8. How do you recognize classic migraine?

Answer 18-8. Classic migraine has warning before headache begins (aura). This aura is usually visual or paresthesia, although it may result in actual loss of function on some occasions (numbness, weakness, aphasia, etc). The aura often includes positive phenomena (lights, bright spots, lines, tingling/prickling) rather than simple loss of function.

18-9. How do you recognize tension-type headache?

Answer 18-9. These headaches are usually pressing or squeezing pain of mild to moderate intensity, with few associated symptoms and no warning. The headaches are not worsened by exertion.

18-10. How do you recognize cluster headache?

Answer 18-10. Cluster headaches are severe, unilateral pain starting in the orbit area, often occurring on a regular and predictable schedule that may awaken the patient from sound sleep. Usually the eye is red and teary, and nose is congested on that side. Horner's syndrome may be present on that side. Patients are agitated and are often awakened from a sound sleep. Headaches are short, usually lasting less than 90 minutes but they may occur in clusters lasting weeks to months and then go away.

18-11. What is analgesic rebound headache?

Answer 18-11. Regular intake of certain analgesics can increase frequency and decrease responsiveness of headaches.

18-12.What medical conditions can produce headaches?

Answer 18-12. Many medical conditions can produce headache, consider the possibility of problems with the temporomandibular joint, sinusitis or occipital neuralgia (greater occipital nerve). Systemic illness (such as the flu) can produce headache as can diseases such as: malignant hypertension, various infections in and around the brain, meningeal inflammation (infectious and non-infectous), inflammatory vasculitis, arterial dissection, thyroid and parathyroid disease, cardiac disease, pulmonary disease, renal disorders, sleep disorders. Also many medicines can trigger headaches.
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