see also:

• meningitis
• the child with headache
• subarachnoid haemorrhage (SAH)
• migraine
• acute unilateral headache
• cervicogenic headache
• a diagnostic approach to the adult with acute headache
• AFTB lectures - headache

• patients with headache as a prime feature are a worrying group of patients as there are a number of potentially life threatening or morbid conditions that, although uncommon, are easily missed:
  • meningitis
  • subarachnoid haemorrhage - classically, a thunderclap onset in occipital region
  • raised intracranial pressure (ICP) such as due to:
    • subdural haematoma 
      • may be chronic in the elderly after a forgotten fall; decreased mental state usually more significant than headache;
      • have a low index of suspicion in any elderly patient after a fall, especially if they are on anticoagulants such as aspirin or warfarin.
    • extradural haematoma - usually a history of trauma with LOC
    • brain tumour - frontal/vertex headache if above tentorioum; occipital headache if subtentorial; pain on wakening; worse on Valsalva;
    • intracerebral abscess (rare)
    • venous thrombosis (rare)
      • consider in pregnancy, pueperium, tamoxifen¹⁾
  • toxic metabolic headaches:
    • fever > 38.8degC
    • influenza typically presents with severe headaches and then cough
    • hypoxia or hypercapnia are potent cerebral vasodilators
    • carbon monoxide poisoning
    • acute anaemia due to blood loss
  • internal carotid artery dissection
  • vertebral artery dissection - especially after chiropractic manipulation of the neck
  • hypertensive headaches
    • a throbbing occipital headache, usually do not occur unless diastolic > 130mmHg
  • acute glaucoma:
    • orbital pain with N/V and cornea may be oedematous with pupil mid-position, decreased acuity & raised i/ocular pressure.
  • temporal arteritis
    • mainly women aged > 50yrs; this requires starting on prednisolone 60-80mg/d ASAP to prevent optic neuritis and bilateral blindness.
    • untreated, if blindness occurs in one eye, blindness will occur in the other eye within 1-20 days in 75%.
    • maintenance dose of prednisolone usually recommended for a year or more with periodic ESR to assess progress.
• the majority of patients have headaches due to less worrying conditions such as:
  • tension headache
  • cervicogenic headache
    • see non-traumatic upper neck pain
    • occurs in up to 4% of the population, and perhaps a quarter of those who have had neck trauma
    • up to 70% are due to issues with the C2-3 zygapophyseal joint (innervated by C2 and C3 which can give referred pain to occiput, fronto-temporal and perioribital regions), with the atlanto-axial joint (innervated by C1 and pain is referred to occiput) being the 2nd most common aetiologic focus
    • suggestive features include palpably painful upper cervical joints and restricted range of neck extension
    • lesions cannot be detected on either CT and MRI but these may be done to exclude other pathology
    • many patients also have tension headaches and migraine headaches
  • migraine
  • post-concussion headache
  • analgesic abuse headaches
  • post-ictal headache
  • cluster headaches:
    • mainly young adult males, recurrent, peak pain 10-15min after onset and lasts 45-60min, unilateral, excruciating, non-throbbing and usually retro-orbital with ipsilateral nasal stuffiness and lacrimation. Often nocturnal; 
    • 10min of oxygen at 5-8L/min may abort attacks in 70%
    • instillation of 4% lignocaine into ipsilateral nostril is useful
    • consider verapamil
  • sinusitis
    • BUT be aware that ~20% of patients having CT brain for headache or mild CHI will have a CT report of “chronic sinusitis” - this finding without acute URTI should probably NOT warrant Rx and is probably NOT the cause of an acute headache ²⁾
  • coital headache
    • usually severe, sudden onset headache associated with orgasm and last a few hours
    • be aware that SAH should still be excluded as SAH can occur during coitus
  • post-LP headaches:
    • usually starts within 48hrs (but not within 1hr) of lumbar puncture or epidural procedures although may be delayed for up to 14 days.
    • bi-cranial, pulsatile, worse in upright position and on movement, median duration is 5 days with early onset usually more severe and longer lasting.
    • see post LP headaches (PLPH)
    • Rx options - simple pain, analgesia and analgesics, methylxanthines such as caffeine, and if severe, an epidural blood patch.
    • Post-lumbar pucture headache. Shah & Thomas. Hospital Physician June 2007 (pdf)
  • high altitude - eg. non-acclimated climbers at altitudes greater than 3000-3600m
  • drug-induced
    • vasodilators such as GTN
    • even inhaled Rx for asthma such as LABA with steroids can cause headaches and nasopharyngitis
  • benign intracranial hypertension (pseudotumour cerebri) 
    • usually, young, obese female with amenorrhoea or irregular cycles or on tetracyclines; 
    • papilloedema present; CT shows slit-like ventricles and no mass effect;
  • trigeminal neuralgia - usually age > 50yrs; brief, excruciating attacks of facial pain;
  • obstructive sleep apnoea headaches - usually morning headaches
  • post-dialysis headaches may be due to:
    • electrolyte and fluid shifts:
      • large shifts in water and electrolytes during dialysis can induce headaches. This includes changes in levels of sodium, magnesium, and calcium.
    • sudden alterations in blood pressure, either intradialytic hypertension or hypotension, are significant contributors.
      • patients with higher pre-dialysis blood pressure values are more likely to experience headaches
    • caffeine withdrawal:
      • dialysis can remove caffeine from the bloodstream, leading to withdrawal symptoms, including headaches, especially in habitual caffeine consumers.
    • dialysate composition:
      • the composition of the dialysate, such as high levels of calcium or magnesium, can contribute to headaches. Acetate dialysate has also been implicated.
    • toxins in Dialysate:
      • contaminants like fluoride or chloramine in the dialysate can cause headaches
    • serotonin levels and cerebral vasoconstriction:
      • acute yet transient alterations in serotonin levels and cerebral vasoconstriction during dialysis can trigger headaches
    • renin-angiotensin-aldosterone system activation:
      • sudden drops in blood pressure can activate the renin-angiotensin system, causing vasoconstriction and contributing to headaches
    • other factors:
      • factors such as hypoxia, anaemia, and disturbances in parathyroid hormone levels have also been associated with dialysis-related headaches
• other rare causes
  • persistent CSF leak due to a fistula resulting in low CSF pressures can cause chronic throbbing headaches

• the patient with strongly suspected bacterial meningitis:
  • urgent IV antibiotic Rx 
  • +/- IV fluid/inotrope support if evidence of septic shock - purpura, poor capillary refill or hypotension.
  • investigations such as CT and LP as time allows
• the patient with decreased mental state:
  • assessment of A,B,C's +/- airway support (eg. intubation if GCS < 8)
  • FBE, U&E, RBG, dextrostix, +/- blood cultures if high fever, +/- ABG's.
  • rapid assessment for localising neurology (eg. stroke, SAH) 
  • rapid assessment for possible sepsis with early IV antibiotics/antivirals administered if clinically indicated.
  • early CT scan once stabilised, and if normal, then LP may be indicated, although this can usually be delayed.
  • differential diagnosis includes:
    • intracranial event:
      • stroke, SAH, meningitis, encephalitis (eg HSV), brain tumour
      • intracranial thrombosis,  
      • traumatic brain injury - concussion, subdural or extradural haemorrhage
    • general conditions:
      • hypertensive encephalopathy
      • drug overdose
      • metabolic conditions - hypoglycaemia, DKA, hyperosmolar coma, hyponatraemia, hypoxia, hypercapnia
• the patient with neurologic symptoms:
  • although hemiplegic migraine may be the cause, one needs to exclude a stroke, space occupying lesion or aneurysm
  • early CT brain 
  • do not use ergotamine or sumatriptan as these vasoconstrict and may exacerbate ischaemia

• see below for indications for brain CT scan.

• thunderclap headaches are those with rapid time to peak headache intensity (seconds to five minutes)
• these patients need to have subarachnoid haemorrhage (SAH) excluded - preferably with a CT brain within 6 hours of onset
• other serious causes which usually have focal neurology include:
  • intracerebral haemorrhage
  • carotid or vertebral artery dissection
• other less serious causes include:
  • orgasm headaches
  • primary exercise headache (esp. in hot weather or at high altitude - need to consider altitude sickness or high altitude cerebral oedema in such cases)
  • primary thunderclap headache
  • trigeminal-autonomic cephalgias
  • hypnic headache - a rare recurrent headache that awakes one from sleep usually between 1-3am

• this is unlikely to be migraine
• FBE, ESR, U&E, RBG, check BP
  • if ESR high, consider temporal arteritis, meningitis, sinusitis, other infection (eg. pneumonia)
• consider CT brain

• send bloods for FBE, RBG (+/- blood cultures if high fever)
• before embarking on CT brain and lumbar puncture (LP) (assuming there is true neck stiffness not just soreness):
  • consider CXR to exclude pneumonia as a cause
  • consider painful Cx lymphadenopathy as cause of neck pains - could it be infectious mononucleosis?

• the longer the duration of headache without change in its severity or character, the more benign it is likely to be.
• increasing frequency, severity, especially if nocturnal and/or associated with vomiting, the more one should consider an intracranial tumour with rising intracranial pressure as a cause - do not do LP on these patients - do a CT brain (although this does not exclude raised ICP) and look for CLINICAL signs of raised intracranial pressure and consult with seniors.

• patients with PH migraine who present with their typical features of migraine and no red flags for other conditions should be moved to a quiet room with low level of lighting and treated for migraine depending on severity of attack, medications already used and contraindications
• see Mx of acute migraine

• 1st line: paracetamol +/- codeine, rest, Rx cause
• 2nd line: non-steroidal anti-inflammatory drugs (NSAIDs)
• 3rd line: aspirin with oral maxolon +/- codeine
• 4th line: iv maxolon 20mg + antihistamine appears to be better than parenteral ketorolac and probably safer
• AVOID opiates and opioids

• these headaches respond well to indomethacin but not as well to other non-steroidal anti-inflammatory drugs (NSAIDs)
• paroxysmal and continuous hemicranias
• valsalva-induced headache
• primary stabbing headache or ice-pick headache
• a select group of trigeminal-autonomic cephalgias
• hypnic headache

• raises possibilities of infections:
  • meningo-encephalitis including viral vector borne
  • malaria
  • dengue fever
  • influenza, COVID-19 coronavirus (2019-nCoV / SARS-CoV-2)
  • other infections
• ask about possible trauma whilst on holiday, especially in context of alcohol intake
  • delayed presentation of chronic subdural haemorrhage

• see also indications for head CT scan for non-“headache” patients
  • eg. head injury in the adult patient
• sudden onset headache (esp. occipital) suggestive of sub-arachnoid haemorrhage:
  • CT ASAP, then if normal, may require lumbar puncture (LP) if CT done more than 6hrs after onset.
• headache with acute unexplained impaired mental state or new neurology
• possible meningitis:
  • eg. meningism, fever, headache
  • empirical antibiotics, then CT ASAP & if normal, usually requires LP
• head trauma with reasonable risk of intracranial haemorrhage such as:
  • patient on anticoagulants
  • ongoing vomiting
  • decreased mental state
  • penetrating injury or possible fracture base of skull
  • see under head injury in the adult patient for more details
• “migraine” patient with red flag features that may warrant a CT scan (EEG is seldom helpful):
  • aura symptoms always at same side of body (should alternate)
  • aura symptoms with acute onset without spread or with either very brief (<5min) or prolonged (>60min) duration
  • brainstem aura
  • acute change in migraine characteristics
  • acute, substantial increase in attack frequency
    • NB. ask about substance misuse
  • first or worst “migraine”
  • onset above age 50yrs
  • aura without headache
  • high fever
  • 2nd or 3rd TM pregnancy (risk of venous dural thrombosis)
  • immunosuppression
  • abnormal neurologic examination:
    • ie. new focal deficit such as “hemiplegic migraine”, altered mental status, or altered cognitive function
    • increases probability of abnormal CT by 3x and a PPV of 39%
    • CT should be performed ASAP.
• new onset seizures with headache
• HIV / AIDS patients with new type of headache
• age > 60 yrs with acute or recent onset unexplained headache
• long standing headaches without past CT scan to exclude pathology, particularly if new features such as vomiting that may indicate rising intracranial pressure or complication of an intracerebral tumour.