Headache disorders are listed as the third-highest cause of disability worldwide in the 2013 Global Burden of Disease Study.^1,2 It is reported that up to 20% of all women have a primary headache disorder, up to 60% of women reported suffering from headache within the past year, and up to 80% have experienced headache at least once in their life.^3–5

There are nearly 100 different classifiable types of headache. Fortunately, 90% of headaches in pregnancy are benign migraine or tension headaches.^6,7 Other benign primary headaches are cluster headache and analgesic overuse headache. These headaches do not have significantly adverse outcomes in pregnancy, save for some rare reports of increased risk of preeclampsia and low birth weight in those with migraine headaches.

However, secondary and pathological headaches also manifest themselves in pregnant women more frequently than in nonpregnant adults.⁸ These include preeclampsia and eclampsia, cerebral hemorrhagic or thrombotic vascular event, raised intracranial pressure through brain tumor or other intracranial hypertension conditions, and intracranial infections. It is imperative that the clinician differentiates between benign headache and serious headache by appropriately identifying concerning history and physical exam findings that would result in more specialized workups such as laboratory studies, imaging studies, and neurological consultation.

See Table 28-1.

Pregnancy’s physiologic changes, hormonal factors, and hypercoagulability increase the risk of dangerous intracranial conditions such as preeclampsia and eclampsia, cerebral vascular events (thrombotic or hemorrhagic), increased intracranial pressure (tumor or intracranial hypertension), arteriovenous malformations (AVMs), and postdural puncture headache. Although most headaches in pregnancy are benign primary headaches, particularly in women with a history of headache prior to pregnancy, a new-onset severe headache during pregnancy is a secondary and potentially life-threatening event more than half the time.⁹ Among pregnant women presenting to acute care with headache and receiving neurologic consultation, 35% had secondary headache disorders. Secondary headaches were positively associated with lack of headache history, elevated blood pressure, seizures, and fever, while negatively associated with the presence of psychiatric comorbidity or phonophobia.⁸

PREECLAMPSIA, ECLAMPSIA, AND HYPERTENSIVE HEADACHES

Preeclampsia is a syndrome that includes an elevated blood pressure and proteinuria or thrombocytopenia, renal insufficiency, impaired liver function, pulmonary edema, or cerebral or visual symptoms. Eclampsia is when seizure occurs in preeclampsia. Preeclampsia’s first clue may be a new or different headache. It may be the only reason that brings a pregnant woman to seek medical care. If left untreated, preeclampsia can lead to eclamptic seizure and more serious end-organ damage in the mother and to poor fetal outcomes.

Out of 76 pregnant women with new onset of headache during gestation, 33% had headache attributable to arterial hypertension, which includes headache due to pheochromocytoma, hypertensive crisis, hypertensive encephalopathy, preeclampsia and eclampsia, and autonomic dysreflexia.⁶ See Chapter 31, on hypertension in pregnancy, for details on diagnosis and management.

Posterior reversible encephalopathy syndrome (PRES) is a serious condition associated with preeclampsia, with classic features of headache, elevated blood pressure, mental status change, visual disturbances, and epileptic seizure. Neuroimaging shows bilateral, symmetric, and parietooccipital patterns of subcortical vasogenic edema.^10,11 PRES is a diagnosis of exclusion. Treatment includes rapid blood pressure reduction and removal of triggers, while watching for concerning signs that warrant admission to the intensive care unit (ICU) for close monitoring.

POSTDURAL PUNCTURE HEADACHES

Postdural puncture headache is a common complication in the postpartum period, caused by the unintended puncture of the dura during administration of epidural analgesia. Leakage of cerebrospinal fluid (CSF) drops CSF pressure, which in turn stretches the meninges and causes the headache. A severe, throbbing fronto-occipital headache often starts 24 to 48 hours after puncture, radiates to the neck and shoulders, worsens with head movement or sitting up, and improves with lying down. It can be associated with some neurological symptoms, such as photophobia, nausea and vomiting, tinnitus, diplopia, hearing loss, vertigo, and cranial VI palsy. Treatment involves hydration and an epidural blood patch often performed by an anesthesiologist at least 24 hours after the initial epidural placement to ensure a maximal success rate.¹²

PRIMARY INTRACRANIAL HYPERTENSION

Primary intracranial hypertension or idiopathic intracranial hypertension (IIH) is commonly seen in obese women of childbearing age. Its first clue is headache with the hallmark papilledema. It may start with transient visual changes, pulsatile tinnitus, and diplopia. Visual deficits worsen over time into permanent visual loss, particularly in severely obese African Americans with recent weight gain.^11,13 Further workup reveals normal magnetic resonance imaging (MRI) and magnetic resonance venography (MRV), excluding a space-occupying lesion or venous sinus thrombosis, and normal CSF analysis other than an elevated opening pressure >25 cm H₂O.

Often, lumbar puncture (LP) is both diagnostic and therapeutic, as most symptoms resolve with rare recurrence after the initial LP, suggesting that serial LPs may not be indicated. Acetazolamide, along with a low-sodium, weight-reduction diet, has been effective in treating IIH with mild visual loss in a multicentered, randomized, controlled trial.¹⁴

REVERSIBLE CEREBRAL VASOCONSTRICTION SYNDROME (RCVS)

Reversible cerebral vasoconstriction syndrome (RCVS) presents as a recurrent, sudden-onset, severe headache suffered over 1 to 3 weeks during the postpartum period, often associated with some migraine features such as photophobia, blurred vision, confusion, nausea, and vomiting. It is similar to a subarachnoid hemorrhage headache, but without hemorrhage shown via imaging. RCVS is diagnosed by cerebral angiography, showing diffuse arterial beading that resolves upon repeat imaging 1 to 3 months later. Treatment currently involves calcium channel blockers, high dose corticosteroids, and magnesium sulphate.¹⁵

CEREBRAL VENOUS THROMBOSIS

Cerebral venous thrombosis (CVT) is an uncommon but catastrophic event whose prevalence increases in pregnancy (particularly from the third trimester to 4 weeks postpartum), Caesarean section (C-section), systemic infection, vomiting, and anemia. The incidence is 11.6/100,000 deliveries in the United States,¹⁶ and it commonly affects the sagittal sinus and cortical veins. An acute to subacute (hours to weeks), persistent, localized, moderate to severe headache may be the first presenting symptom of CVT. It is usually followed by neurological findings such as papilledema, mental status change, seizures, and focal neurological deficits, including cranial nerve palsies such as diplopia. Rare cases of psychosis have also been reported.

CVT cannot be detected by a plain, noncontrast computed tomography (CT), which is often used in the initial workup of focal neurological deficit. Instead, a high index of suspicion is needed as CVT is diagnosed with T2-weighted MRI and MRV. Treatment includes anticoagulation with low-molecular-weight heparin (LMWH) or unfractionated heparin for 6 months. Endovascular therapy may be indicated if neurological deterioration or coma persists despite LMWH treatment. Referral to hematology for a coagulopathy workup is advised, along with counseling about the risk of recurrent thrombotic events in the future.¹⁶

Vital signs should be reviewed, particularly blood pressure (preeclampsia) and systemic inflammatory response (SIR) markers such as temperature, heart rate, and respiratory rate, for signs of meningitis, which can be of concern.