Headache

GENERAL PRINCIPLES

Classification

• Primary headache syndromes include migraines with or without aura, the hemicranias and indomethacin-responsive headaches, tension headaches, chronic daily headaches, and cluster headaches.

• Secondary headaches have specific etiologies, and symptomatic features vary depending on the underlying pathology (e.g., SAH, tumor, hypertension, posterior reversible encephalopathy syndrome, reversible cerebral vasoconstriction syndrome (RCVS), analgesic overuse, iatrogenic).

• Migraine without aura: At least five attacks that last 4-72 hours. Symptoms should include at least two of the following: unilateral location, pulsating or throbbing, moderate to severe in intensity, aggravated by activity, and at least one of these associated features: nausea/vomiting, photophobia, and/or phonophobia.

• Migraine with aura: Same as above, except at least two attacks with an associated aura that lasts from 4 minutes to 1 hour (longer than 60 minutes is a red flag). The aura should have a gradual onset, should be fully reversible, and can occur before, with, or after headache onset.

• Cluster headache: Unilateral orbital or temporal pain with lacrimation, conjunctival injection, nasal congestion, rhinorrhea, facial swelling, miosis, ptosis, and eyelid edema.

• Rebound headache (medication overuse headache) occurs in the setting of chronic use of analgesics or narcotics.

• Trigeminal neuralgia presents as episodic sharp stabbing pain that is unilateral. Rule out MS or an alternative etiology with MRI.

• Temporal arteritis presents as a dull unilateral headache with a thick tortuous artery over temporal region. The disease is almost exclusively limited to individuals older than 60 years with jaw claudication, low-grade fever, and an elevated ESR and CRP.

Etiology

Secondary headache etiologies include:

• Subdural hematoma (SDH), intracerebral hemorrhage, SAH, AVM, brain abscess, meningitis,

encephalitis, vasculitis, obstructive hydrocephalus, and cerebral ischemia or infarction.

• Idiopathic intracranial hypertension (commonly known as pseudotumor cerebri) presents with headache, papilledema, diplopia, and elevated CSF pressure (at least gt;20 cm H₂O in relaxed lateral decubitus position). CVST should be ruled out in all patients presenting with suspected idiopathic intracranial hypertension.

• Extracranial causes include giant cell arteritis, sinusitis, glaucoma, optic neuritis, dental disease (including temporomandibular joint syndrome), and disorders of the cervical spine (i.e., “cervicogenic” headache).

• Systemic causes include fever, viremia, hypoxia, carbon monoxide poisoning, hypercapnia, systemic hypertension, allergy, anemia, caffeine withdrawal, and vasoactive or toxic chemicals (e.g., nitrites).

• Depression is a common cause of long-standing, treatment-resistant headaches. Specific inquiry about vegetative signs of depression and exclusion of other causes help support this diagnosis.

DIAGNOSIS

Clinical Presentation

HISTORY

• The sudden onset of severe headache (“the worst headache of my life,” also known as a “thunderclap headache”) or a severe persistent headache that reaches maximal intensity within a few seconds/minutes warrants immediate investigation for possible SAH.

• Other headache syndromes that can present with a thunderclap headache include RCVS, posterior cerebral artery infarcts, CVST, arterial dissections, CNS vasculitis, pituitary apoplexy, intracerebral hemorrhage, and some of the indomethacin-responsive headache syndromes.

• History should focus on:

î Age at onset

î Frequency, intensity, and duration of attacks

î Triggers, associations (menstrual cycle), associated symptoms (e.g., photophobia, phonophobia, nausea, vomiting), and alleviating factors

î Location and quality of pain (e.g., sharp, dull)

î Number of headaches per month, including number of disabling headaches

î Family history of migraines

î Sleep and diet hygiene (caffeine intake)

î Use of pain medications, including over-the-counter medications.

PHYSICAL EXAMINATION

• On general examination, check BP and pulse, listen for possible bruits, palpate head and neck muscles, and check temporal arteries.

• If neck stiffness and meningismus (resistance to passive neck flexion) are present on examination, then consider meningitis.

• If papilledema is observed on examination, then consider an intracranial mass, meningitis, CVST, or idiopathic intracranial hypertension.

Diagnostic Testing

IMAGING

Neuroimaging is generally not indicated for known primary headache syndromes but may be required to exclude secondary etiologies (listed earlier) in cases that have not been previously diagnosed or in patients presenting with new headaches, especially those who present with atypical features or abnormal examination findings.

DIAGNOSTIC PROCEDURES

LP is indicated in a patient with severe headache with suspicion of SAH even if the head CT scan is negative. However, head CT is over 99% sensitive for detecting SAH if obtained within 6 hours of headache onset.

TREATMENT

• Acute treatment of migraine, the most common primary headache syndrome, is directed at aborting the headache. This is easier at onset and often very difficult when the attack is well established. Accordingly, the threshold for treating at the first sign of a headache should be low. Patients have often used nonprescription analgesics (acetylsalicylic acid [ASA], acetaminophen, NSAIDs) and oral prescription medications (butalbital with aspirin or acetaminophen), which are the first-line treatments and are most effective early in the course of an attack. Emergent treatments include serotonin agonists and other parenteral medications.

• Scheduled IV NSAIDs (e.g., ketorolac) in combination with antiemetics (typically prochlorperazine) and IV fluids are an effective first-line regimen in many cases.

• Antidopaminergic therapies including haloperidol and droperidol are also effective first-line therapies. A baseline ECG should be obtained to evaluate for a prolonged QTc.

• Triptans (serotonin receptor 5HT_ib and 5HT_id agonists) are effective abortive medications available in multiple formulations and may be effective even in a protracted attack. Triptans should not be used in patients with coronary artery disease, cerebrovascular disease, uncontrolled hypertension, hemiplegic migraine, or vertebrobasilar migraine.

• Dihydroergotamine is a potent venoconstrictor with minimal peripheral arterial constriction. Cardiac precautions and a baseline ECG are indicated in all patients. This medication is contraindicated when there is a history of angina, myocardial infarction, or peripheral vascular disease. Alternative therapies should also be considered in elderly patients.

• Ergotamine is a vasoconstrictive agent effective for aborting migraine headaches, particularly if administered during the prodromal phase. Ergotamine should be taken at symptom onset in the maximum dose tolerated by the patient; nausea often limits the dose. Rectal preparations are better absorbed than oral agents. This medication is also contraindicated in patients with a history of angina, myocardial infarction, or peripheral vascular disease.

• Additional abortive therapies with less evidence supporting their use include IV valproic acid, IV/PO methylprednisolone, IM ziprasidone, and IV magnesium.

• Chronic daily headaches should not be treated with narcotic analgesics so as to prevent addiction, rebound headaches, and tachyphylaxis.

• Treatment of secondary headaches is directed at the primary etiology, such as surgical treatment of cerebral aneurysm causing SAH, evacuation of SDH, calcium channel blockers in RCVS, or shunting in obstructive hydrocephalus.

• Prophylactic medications should be considered if a patient has at least three disabling migraines per month.

î It is important to review a patient's use of all medications and comorbidities because they may influence choice of medication and offer additional factors contributing to the headache syndrome.

î Alternative (nonprescription) therapies for migraine prophylaxis include butterbur, riboflavin, magnesium, and acupuncture.

î Botulinum toxin (onabotulinum toxin A) and anticalcitonin gene-related peptide therapies are approved for migraine prophylaxis in adult patients with chronic migraine (defined as #8805;15 headache days per month for gt;3 months).

Lifestyle Modifications

• Patients should keep a headache diary to identify possible triggers.

• Patients should reduce alcohol, caffeine, and other triggers that may increase risk of migraines.

Referral

Neurosurgical consultation is indicated for managing SAH, SDH, vascular malformations, tumors, and other space-occupying lesions resulting in mass effect. Neurologic consultation is indicated if a patient is not well controlled on a first-line prophylactic agent with appropriate use of an abortive therapy.