2. HeadacheHeadache
ClassificationClassification
Three major categories (Primary,Three major categories (Primary,
Secondary, Cranial Neuralgias)Secondary, Cranial Neuralgias)
– Primary HeadachesPrimary Headaches
Tension- typeTension- type
MigraineMigraine
ClusterCluster
– Not life threateningNot life threatening
– Create severe painCreate severe pain
– Reduce quality of lifeReduce quality of life
3. ClassificationClassification
Secondary HeadacheSecondary Headache
– Manifestations of serious underlying possibly lifeManifestations of serious underlying possibly life
threatening illnessthreatening illness
Temporal arteritisTemporal arteritis
Intracranial mass lesionsIntracranial mass lesions
PTCPTC
MeningitisMeningitis
SHSH
Post-concussion headachePost-concussion headache
4. Tension type headachesTension type headaches
Intermittent dullIntermittent dull
pain usually locatedpain usually located
bilaterally in thebilaterally in the
frontal or cervicalfrontal or cervical
regionsregions
5. Tension HeadacheTension Headache
Manifestation isManifestation is
limited to painlimited to pain
– No associatedNo associated
symptomssymptoms
PhotophobiaPhotophobia
HyperacusisHyperacusis
PhonophobiaPhonophobia
NauseaNausea
– Women > MenWomen > Men
6. Tension HeadacheTension Headache
– Attributed toAttributed to
contraction of scalp,contraction of scalp,
neck, face musclesneck, face muscles
Emotional “tension”Emotional “tension”
FatigueFatigue
Cervical spodylosisCervical spodylosis
Bright lightBright light
Loud noisesLoud noises
Emotional factorsEmotional factors
7. Tension HeadacheTension Headache
TreatmentTreatment
– AssuranceAssurance
– Less than twice aLess than twice a
weekweek
Acute therapyAcute therapy
– Onset ofOnset of
headacheheadache
NSAIDSNSAIDS
ASA/caffeineASA/caffeine
8. Tension HeadacheTension Headache
– >2-3 x per week and/or acute therapy is>2-3 x per week and/or acute therapy is
ineffectiveineffective
Preventative therapyPreventative therapy
– Small night time dose TCASmall night time dose TCA
– AntiepilepticsAntiepileptics
Valproate, topiramateValproate, topiramate
– OMMOMM
– MassageMassage
– Warm compressWarm compress
10. MigrainesMigraines
Two subtypesTwo subtypes
– Presence or absence of auraPresence or absence of aura
Migraine with AuraMigraine with Aura
– ““classic migraine”, “migraine with aura”classic migraine”, “migraine with aura”
– 10% of migraine patients10% of migraine patients
– Aura typically precedes the onset of painAura typically precedes the onset of pain
11. MigrainesMigraines
AurasAuras
– Usually appear and evolveUsually appear and evolve
over 4-10 minover 4-10 min
– <1 hour<1 hour
– Disappear with headacheDisappear with headache
onsetonset
Most common areMost common are
– Visual hallucinationsVisual hallucinations
Greying region of visualGreying region of visual
fieldfield
Flashing zig zag linesFlashing zig zag lines
Crescents or brightCrescents or bright
colorscolors
13. MigraineMigraine
Auras continuedAuras continued
– Occasionally consist of languageOccasionally consist of language
impairment (similar to aphasia)impairment (similar to aphasia)
– Sensory misperceptionSensory misperception
– Personality changePersonality change
– In children, “abdominal pain”, nausea,In children, “abdominal pain”, nausea,
vomitingvomiting
14. Migraine without AuraMigraine without Aura
75% of migraine patients75% of migraine patients
4-24 hours4-24 hours
Throbbing, one sidedThrobbing, one sided
– Behind templeBehind temple
– Behind eyeBehind eye
– Around eyeAround eye
– 50% move to other side and50% move to other side and
become generalizedbecome generalized
15. MigraineMigraine
Sensory hypersensitivitySensory hypersensitivity
– PhotophobiaPhotophobia
– PhonophobiaPhonophobia
Tend to seek seclusion in dark quiet roomTend to seek seclusion in dark quiet room
Autonomic dysfunctionAutonomic dysfunction
– Nausea/vomitingNausea/vomiting
– Crave foods, drink large amount of waterCrave foods, drink large amount of water
MoodMood
– Despondent, distraughtDespondent, distraught
16. MigraineMigraine
OnsetOnset
– Women during MenarcheWomen during Menarche
Recurs premenstruallyRecurs premenstrually
– Aggravated by OCPAggravated by OCP
– 70% remiss during pregnancy70% remiss during pregnancy
10% have 110% have 1stst
attack during pregnancyattack during pregnancy
– 70% have 170% have 1stst
degree relative with the disorderdegree relative with the disorder
– Early morningEarly morning
– During REM periodsDuring REM periods
– Can be precipitated “triggers”Can be precipitated “triggers”
Fasting, sleep (too much/too little), menses, stress, headFasting, sleep (too much/too little), menses, stress, head
trauma, alcohol (red wine, brandy), chocolate, MSGtrauma, alcohol (red wine, brandy), chocolate, MSG
Withdrawal from the aboveWithdrawal from the above
17. MigraineMigraine
Psychiatric comorbidityPsychiatric comorbidity
– Anxiety, Panic, Depression, Bipolar d/oAnxiety, Panic, Depression, Bipolar d/o
Therapy for comorbid migraine and depressionTherapy for comorbid migraine and depression
– TCATCA
*SSRIs and Triptans = serotonin syndrome*SSRIs and Triptans = serotonin syndrome
18. MigraineMigraine
SubtypesSubtypes
Childhood migraineChildhood migraine
– < 2 hours< 2 hours
– More severeMore severe
– Less likely unilateralLess likely unilateral
– More susceptible to basilar type andMore susceptible to basilar type and
hemiplegic typehemiplegic type
Basilar: Ataxia, vertigo, dysarthria, diplopia, transientBasilar: Ataxia, vertigo, dysarthria, diplopia, transient
global amnesiaglobal amnesia
Hemiplegic: transient hemiparesis, hemiplegiaHemiplegic: transient hemiparesis, hemiplegia
20. Migraine-Like ConditionsMigraine-Like Conditions
Medication inducedMedication induced
– Anti-anginalAnti-anginal
Nitro, isosorbide, nifedipineNitro, isosorbide, nifedipine
Sex relatedSex related
– ““primary headache associated withprimary headache associated with
sexual activity” “coital cephalgia”sexual activity” “coital cephalgia”
Tx: Propranalol before sexual activityTx: Propranalol before sexual activity
21. Proposed Cause ofProposed Cause of
MigrainesMigraines
““spreading neuronal depression”spreading neuronal depression”
– Impaired metabolism of cerebral neuronsImpaired metabolism of cerebral neurons
spreads as initially increased activity, andspreads as initially increased activity, and
then inhibited neuronal activity fromthen inhibited neuronal activity from
posterior cerebral cortex to anteriorposterior cerebral cortex to anterior
cerebral cortexcerebral cortex
Trigeminal nucleus of Pons triggers release ofTrigeminal nucleus of Pons triggers release of
serotonin, substance P, neurokinin, and otherserotonin, substance P, neurokinin, and other
vasoactive neurotransmiters.vasoactive neurotransmiters.
This incites painfulThis incites painful vasodilationvasodilation andand
perivascularperivascular inflammationinflammation
22. Acute TreatmentAcute Treatment
Headache diary to assess “triggers”Headache diary to assess “triggers”
Occasional mild attacksOccasional mild attacks
– NSAID’sNSAID’s
Opiates not advised unless other medsOpiates not advised unless other meds
are contraindicatedare contraindicated
– Pregnancy, elderlyPregnancy, elderly
23. Acute TreatmentAcute Treatment
TriptansTriptans
– 5HT 1b/1d receptor agonists5HT 1b/1d receptor agonists
Rapidly effective for moderate to severe migraine if takenRapidly effective for moderate to severe migraine if taken
earlyearly
ErgotomineErgotomine
– VasoconstrictorsVasoconstrictors
Also effectiveAlso effective
– Over constriction (digits, coronary arteries)Over constriction (digits, coronary arteries)
– Miscarriage, fetal anomaliesMiscarriage, fetal anomalies
AntiemeticsAntiemetics
HospitilizationHospitilization
– > 3days> 3days
IV fuids, antiemetics, pain controlIV fuids, antiemetics, pain control
24. Preventative TreatmentPreventative Treatment
IndicationsIndications
– > 4 migraines per month> 4 migraines per month
– > 3-4 days of disability per month> 3-4 days of disability per month
– Acute medication losing efficacyAcute medication losing efficacy
– Pts taking excessive medicationsPts taking excessive medications
25. Preventative TreatmentPreventative Treatment
MedicationsMedications
– Beta BlockersBeta Blockers
No history of depressionNo history of depression
– TCASTCAS
Amitriptyline, nortryptilineAmitriptyline, nortryptiline
Prevents, reduces severity and durationPrevents, reduces severity and duration
– Alters REM sleep where migraines beginAlters REM sleep where migraines begin
– Enhance serotoninEnhance serotonin
26. Preventative TreatmentPreventative Treatment
MedicationsMedications
– Calcium Channel BlockersCalcium Channel Blockers
– AED’sAED’s
Topirimate, valproateTopirimate, valproate
– Reduces 5HT neuron firing in dorsal raphe nucleusReduces 5HT neuron firing in dorsal raphe nucleus
– Alters trigeminal GABA a receptors in meningealAlters trigeminal GABA a receptors in meningeal
blood vesselsblood vessels
27. ClusterCluster
HeadachesHeadaches
Occur in groups (clusters)Occur in groups (clusters)
– 45 min to 1.5 hours45 min to 1.5 hours
– 1-8 times daily for period of1-8 times daily for period of
several weeks to monthsseveral weeks to months
DemographicDemographic
– men 6-8x more than womenmen 6-8x more than women
– Little familial tendencyLittle familial tendency
– Develops between ages of 20Develops between ages of 20
-40-40
– > 80% smoke and or drink> 80% smoke and or drink
alcohol excessivelyalcohol excessively
28. Cluster HeadachesCluster Headaches
DescriptionDescription
– Severe, sharp nonSevere, sharp non
throbbing painthrobbing pain
– Bores into one eye andBores into one eye and
adjacent regionadjacent region
– Ipsilateral eye tearingIpsilateral eye tearing
– Conjunctival injectionConjunctival injection
– Nasal congestionNasal congestion
– Partial Horners syndromePartial Horners syndrome
29. Cluster HeadacheCluster Headache
Most have a predictable, cyclicMost have a predictable, cyclic
patternpattern
– ie: Every spring or fallie: Every spring or fall
– Alcohol and REM sleep canAlcohol and REM sleep can
precipitate themprecipitate them
– Cluster free intervals can rangeCluster free intervals can range
months to yearsmonths to years
30. Cluster HeadacheCluster Headache
Cause/TxCause/Tx
– Different but unknown form of cerebrovascularDifferent but unknown form of cerebrovascular
dysfunction than occurs in migraines.dysfunction than occurs in migraines.
– Respond to many of the same medications usedRespond to many of the same medications used
for migrainesfor migraines
– Orally administered acute migraine meds notOrally administered acute migraine meds not
effective (clusters come on too fast, shorteffective (clusters come on too fast, short
duration)duration)
Sumitriptan , dihydroergotomine injectionsSumitriptan , dihydroergotomine injections
Oxygen inhalation 8-10 L/mOxygen inhalation 8-10 L/m
– Chronic tx includes: lithium, steroids, valproicChronic tx includes: lithium, steroids, valproic
acidacid
31. Secondary HeadachesSecondary Headaches
Temporal ArteritisTemporal Arteritis
– Complication when tx is delayedComplication when tx is delayed
Occlusion of opthalmic, ciliary and cerebralOcclusion of opthalmic, ciliary and cerebral
arteriesarteries
– Blindness and strokeBlindness and stroke
Artery biopsy definitive dxArtery biopsy definitive dx
– > ESR in 90% pts> ESR in 90% pts
Tx: high dose steroidsTx: high dose steroids
32. Secondary HeadachesSecondary Headaches
Temporal Arteritis/ Giant Cell ArteritisTemporal Arteritis/ Giant Cell Arteritis
– Temporal, cranial arteries develop overtTemporal, cranial arteries develop overt
inflammationinflammation
– Etiology unknownEtiology unknown
– Histo exam of arteries reveals giant cellsHisto exam of arteries reveals giant cells
– Pts > 55Pts > 55
Predominantly effect elderlyPredominantly effect elderly
Dull continued pain, located in one or both temples,Dull continued pain, located in one or both temples,
jaw pain.jaw pain.
Systemic signs of malaise, fever, weight lossSystemic signs of malaise, fever, weight loss
33. Secondary HeadachesSecondary Headaches
Temporal arteritisTemporal arteritis
– Dangerous complicationsDangerous complications
If untreated occlusion of the opthalmic, ciliaryIf untreated occlusion of the opthalmic, ciliary
and cerebral arteries can lead to blindnessand cerebral arteries can lead to blindness
and strokesand strokes
Temporal artery bx: definitive dxTemporal artery bx: definitive dx
TX: high dose steroidsTX: high dose steroids
34. SecondarySecondary
HeadachesHeadaches
Intracranial Mass LesionIntracranial Mass Lesion
– The 1The 1stst
symptom of brain tumors or chronic subdurals issymptom of brain tumors or chronic subdurals is
headacheheadache
– Brain tumor headache quality is non specificBrain tumor headache quality is non specific
– Usually mimic Tension type headaches as bilateral and dullUsually mimic Tension type headaches as bilateral and dull
– When headache is unilateral 20% of the time the tumor isWhen headache is unilateral 20% of the time the tumor is
on the opposite side of painon the opposite side of pain
35. SecondarySecondary
HeadachesHeadaches
Intracranial Mass LesionIntracranial Mass Lesion
– Subtle cognitive and personality changes maySubtle cognitive and personality changes may
accompany headachesaccompany headaches
– Lateralized signs usually develop within 8 weeksLateralized signs usually develop within 8 weeks
– CT or MRI for all unexplained progressiveCT or MRI for all unexplained progressive
headaches.headaches.
36. Secondary HeadachesSecondary Headaches
Chronic MeningitisChronic Meningitis
– Weeks of dull, continuous headacheWeeks of dull, continuous headache
accompanied by progressive cognitiveaccompanied by progressive cognitive
impairmentimpairment
– Signs of systemic infectious illnessSigns of systemic infectious illness
– Inflammation chokes cranial nervesInflammation chokes cranial nerves
Facial palsyFacial palsy
Hearing impairmentHearing impairment
EO muscle palsyEO muscle palsy
37. Secondary HeadachesSecondary Headaches
Chronic MeningitisChronic Meningitis
– Also impairs CSF reabsorptionAlso impairs CSF reabsorption
HydrocephalusHydrocephalus
– Caused by:Caused by:
Cryptococcus (impairedCryptococcus (impaired
immune function)immune function)
– Long term steroidsLong term steroids
– AIDSAIDS
– ImmunosuppressantsImmunosuppressants
– CT shows hydrocephalusCT shows hydrocephalus
– CSF analysis to confirmCSF analysis to confirm
42. Secondary HeadachesSecondary Headaches
MAOI’s and HemorrhageMAOI’s and Hemorrhage
– Pts on MAOI’s who ingest tyraminePts on MAOI’s who ingest tyramine
containing foods or receive certaincontaining foods or receive certain
medications can experience severemedications can experience severe
hypertension, headache and hemorrhagehypertension, headache and hemorrhage
Aged cheese, pickled foods, chianti, beer,Aged cheese, pickled foods, chianti, beer,
triptans, demerol, L dopa, sinemettriptans, demerol, L dopa, sinemet
amphetamines, carbamazepine, TCA’samphetamines, carbamazepine, TCA’s
43. Secondary HeadachesSecondary Headaches
MAOI’sMAOI’s
– Hypertensive reactions should be treatedHypertensive reactions should be treated
with intravenous phentolamine (alphawith intravenous phentolamine (alpha
adrenergic blocking agent)adrenergic blocking agent)
Substitutes are chlorpromazine andSubstitutes are chlorpromazine and
propranololpropranolol
44. CranialCranial
NeuralgiasNeuralgias
Trigeminal NeuralgiaTrigeminal Neuralgia
– Most common chronic,Most common chronic,
recurring neuralgiarecurring neuralgia
– Dozens of brief, 20-30 secondDozens of brief, 20-30 second
sharp excruciating painsharp excruciating pain
extending along one of theextending along one of the
three divisions of the trigeminalthree divisions of the trigeminal
nerve.nerve.
45. CranialCranial
NeuralgiasNeuralgias
Trigeminal NeuralgiaTrigeminal Neuralgia
– Most commonly affectsMost commonly affects
the V2 division onthe V2 division on
trigeminal nerve.trigeminal nerve.
– Touching the area evokesTouching the area evokes
painpain
– Trigger zones: eating,Trigger zones: eating,
brushing teeth, drinkingbrushing teeth, drinking
cold water evokes “shockcold water evokes “shock
like” painlike” pain
– Usually abates at nightUsually abates at night
46. Cranial NeuralgiasCranial Neuralgias
Cause/TxCause/Tx
– Aberrant superiorAberrant superior
cerebellar artery orcerebellar artery or
other cerebral bloodother cerebral blood
vessel compressing thevessel compressing the
trigeminal nerve root astrigeminal nerve root as
it emerges fro the brainit emerges fro the brain
stemstem
– Tumor at theTumor at the
cerebellopontine anglecerebellopontine angle
may have the samemay have the same
effecteffect
– Multiple SclerosisMultiple Sclerosis
plaque irritatingplaque irritating
trigeminal nerve nucleustrigeminal nerve nucleus
47. Cranial NeuralgiaCranial Neuralgia
Treatment with Gabapentin is first lineTreatment with Gabapentin is first line
If pain persists, carbamazepineIf pain persists, carbamazepine
second linesecond line
Microvascular decompression surgeryMicrovascular decompression surgery
Gamma knife surgery to the root of theGamma knife surgery to the root of the
trigeminal nervetrigeminal nerve
48. Clinical Context…HistoryClinical Context…History
Age of onsetAge of onset
Presence of auraPresence of aura
Frequency/intensityFrequency/intensity
# per month# per month
Time of onsetTime of onset
Quality/radiationQuality/radiation
Associated symptAssociated sympt
Family hx of migraineFamily hx of migraine
State of general healthState of general health
Precipitaing/relievingPrecipitaing/relieving
Effect of activity onEffect of activity on
painpain
Food? alcohol?Food? alcohol?
Caffeine?Caffeine?
Previous tx?Previous tx?
Visual changeVisual change
Trauma?Trauma?
Birth control?Birth control?
menstruationmenstruation
Work/lifestyleWork/lifestyle
49. Danger signsDanger signs
Sudden onsetSudden onset
– Max intensity within a few secondsMax intensity within a few seconds
SAHSAH
– Migraines begin with moderate pain andMigraines begin with moderate pain and
gradual increase over 2 hoursgradual increase over 2 hours
– Cluster may be sudden, but transient andCluster may be sudden, but transient and
assoc with ipsilateral autonomic signsassoc with ipsilateral autonomic signs
(rhinorrhea, tearing)(rhinorrhea, tearing)
50. Danger signsDanger signs
““first” or “worst”first” or “worst”
– Commonly describes ICH or CNS infectionCommonly describes ICH or CNS infection
Worsening patternWorsening pattern
– Mass lesionMass lesion
– Medication overuseMedication overuse
Focal neurological signs (other than aura)Focal neurological signs (other than aura)
– MassMass
– AVMAVM
– Collagen vascular diseaseCollagen vascular disease
51. Danger signsDanger signs
FeverFever
– Intracranial, systemic, local infectionIntracranial, systemic, local infection
May follow SAH 24-48 hoursMay follow SAH 24-48 hours
Rapid onset with strenuous exerciseRapid onset with strenuous exercise
– Carotid artery dissection, ICHCarotid artery dissection, ICH
ANY change in mental status or LOCANY change in mental status or LOC
Neck stiffnessNeck stiffness
PapilledemaPapilledema
52. Danger signsDanger signs
Any new headache in patients <5 orAny new headache in patients <5 or
>50>50
– With CA: metastasisWith CA: metastasis
– Lyme: menigoencephalitisLyme: menigoencephalitis
– HIV: opportunistic infection or tumorHIV: opportunistic infection or tumor
– Pregnancy: cortical vein, venous sinusPregnancy: cortical vein, venous sinus
thrombosis, carotid dissectionthrombosis, carotid dissection
53. Specific SourceSpecific Source
Chronic nasal congestion: sinusitisChronic nasal congestion: sinusitis
Impaired vision “seeing holes” :Impaired vision “seeing holes” :
glaucomaglaucoma
Visual field defects: lesion of opticVisual field defects: lesion of optic
pathway (pituitary mass)pathway (pituitary mass)
Blurring of vision on forward bending,Blurring of vision on forward bending,
HA in early morning, loss ofHA in early morning, loss of
coordination, nausea: Increased ICPcoordination, nausea: Increased ICP
54. Specific SourceSpecific Source
Relieved with recumbency,Relieved with recumbency,
exacerbated by upright postureexacerbated by upright posture
– Low CSF pressureLow CSF pressure
Sudden, severe, unilateral vision lossSudden, severe, unilateral vision loss
– Optic neuritisOptic neuritis
Intermittent with increased BPIntermittent with increased BP
– PheochromocytomaPheochromocytoma
55. QuestionsQuestions
1. Which symptoms accurately1. Which symptoms accurately
differentiate migraine from other formsdifferentiate migraine from other forms
of headache?of headache?
– A. unilateral and throbbingA. unilateral and throbbing
– B. exacerbated by physical activityB. exacerbated by physical activity
– C. respond only to opiatesC. respond only to opiates
– D. disabling, accompanied by nauseaD. disabling, accompanied by nausea
and photophobiaand photophobia
56. Answer #1Answer #1
D. Autonomic symptoms distinguishD. Autonomic symptoms distinguish
migraine from other forms of primarymigraine from other forms of primary
headache. Location is not critical inheadache. Location is not critical in
diagnosis.diagnosis.
57. Question #2Question #2
If a patient with major depression wasIf a patient with major depression was
treated with an SSRI, what would be the risktreated with an SSRI, what would be the risk
of administering a triptan for migraines?of administering a triptan for migraines?
– A. Hypertension, leading to possible hemorrhageA. Hypertension, leading to possible hemorrhage
– B. Delirium, fever and myoclonusB. Delirium, fever and myoclonus
– C. muscle rigidity, rhabdomyolysis, fever andC. muscle rigidity, rhabdomyolysis, fever and
renal failurerenal failure
– D. EPSD. EPS
58. Answer #2Answer #2
B. Serotonin syndromeB. Serotonin syndrome
– C is Neuroleptic Malignant SyndromeC is Neuroleptic Malignant Syndrome
59. Question # 3Question # 3
Which common test yields abnormalWhich common test yields abnormal
results in a patient with chronicresults in a patient with chronic
migraines?migraines?
– A. CTA. CT
– B. MRIB. MRI
– C. EEGC. EEG
– D. ESRD. ESR
– E. none of the aboveE. none of the above
60. Answer # 3Answer # 3
None of the above.None of the above.
– EEG is often abnormal, it is not sufficientEEG is often abnormal, it is not sufficient
or frequent enough to help in diagnosisor frequent enough to help in diagnosis
61. Question 4Question 4
Which of the following headacheWhich of the following headache
varieties is associated with moodvarieties is associated with mood
change?change?
– A. ClusterA. Cluster
– B. Trigeminal NeuralgiaB. Trigeminal Neuralgia
– C. Giant cell arteritisC. Giant cell arteritis
– D. MigraineD. Migraine
– E. idiopathic intracranial hypertensionE. idiopathic intracranial hypertension
63. Question 5Question 5
Which of the following is NOT a reason whyWhich of the following is NOT a reason why
TCA’s work for migraine sufferers withoutTCA’s work for migraine sufferers without
overt depression?overt depression?
– A. improved sleep patternsA. improved sleep patterns
– B. increase serotonin acts as an analgesicB. increase serotonin acts as an analgesic
– C. TCA’s themselves are analgesicC. TCA’s themselves are analgesic
– D. TCA’s stimulate endorphinsD. TCA’s stimulate endorphins
– E. Depression is often co-morbid with migraineE. Depression is often co-morbid with migraine
64. Answer 5Answer 5
D. TCA’s do not stimulate endogenousD. TCA’s do not stimulate endogenous
opiatesopiates
65. Question 6Question 6
Which condition is cyclic or periodicWhich condition is cyclic or periodic
develops predominantly in men, anddevelops predominantly in men, and
responds to lithium?responds to lithium?
– A. migraineA. migraine
– B. clusterB. cluster
– C. Trigeminal neuralgiaC. Trigeminal neuralgia
– D. Giant cell arteritisD. Giant cell arteritis
– E. Tension type headacheE. Tension type headache