Chauhan AR

Neurological problems in pregnancy though rare, are associated with significant maternal morbidity and mortality, especially cases of stroke and epilepsy. In developed countries, they contribute to approximately 20 % of maternal deaths. Neurological conditions may pre-exist, occur for the first time in pregnancy or may be exacerbated by pregnancy. Neurological manifestations are seen in eclampsia, amniotic fluid embolism and acute fatty liver which are unique to pregnancy, while infective conditions like hepatitis E and falciparum malaria may have increased severity of neurological symptoms in pregnancy. Patients with pre-existing conditions like chronic hypertension or intracranial lesions may deteriorate in pregnancy or puerperium.
The obstetrician is most familiar with eclampsia and its management. Neurological manifestations include cerebral edema, subarachnoid hemorrhage, microinfarctions, hypertensive encephalopathy and changes in the visual cortex. Cerebral imaging, either computerized tomography (CT) scan or magnetic resonance imaging (MRI) reveal cerebral edema or PRES, i.e. posterior reversible (leuko-) encephalopathy syndrome, characterized by bilateral symmetrical cerebral edema of the white matter usually in the parieto - occipital area. Cerebral imaging should be reserved for those cases of eclampsia where the presentation is atypical, prior to 20 weeks of gestation or > 48 hours postpartum, and patients with focal deficits or prolonged coma.
Apart from pregnancy - specific causes, etiology of altered mental state and coma in pregnancy include vascular causes such as infarction, intracerebral bleed, cerebral venous sinus thrombosis and hypertensive encephalopathy, infections like meningitis and cerebral malaria, tumors like meningiomas, tuberculomas and pituitary tumors, metabolic conditions like hypoglycemia, hyponatremia and hepatic encephalopathy, and drugs and toxins.
Neurological conditions in women of child bearing age are numerous but usually categorized in four broad unrelated groups: epilepsy, stroke, multiple sclerosis and headache/ migraine, which are described briefly below.
Epilepsy is the most common; approximately 7 % of epileptic patients conceive, and 0.5 % of all pregnancies are complicated by epilepsy. Even well controlled cases may have at least one convulsion in pregnancy; in a third of cases, there is a worsening of seizure control. This is attributable to a variety of causes, mainly poor control peri- conceptionally, change of medication, non- compliance due to fear of teratogenicity, physiological changes of pregnancy, stress and sleep deprivation. Pregnant women should ideally be managed on only one anti- epileptic drug in the least dose in pregnancy. Solitary convulsion may not cause problems to mother and fetus but status epilepticus or convulsions during labor are associated with high maternal and perinatal mortality. Incidence of congenital malformations is reported to be 4 - 6 %; phenobarbital is probably the least teratogenic anti- epileptic.
Stroke, an acute neurological impairment that may be either ischemic or hemorrhagic, is a rare but serious complication of pregnancy, with a 4 - 5 times increased incidence as compared to non pregnant women. Hypercoagulable state of pregnancy and venous stasis are important physiological risk factors, along with uncontrolled systolic hypertension and eclampsia. Co - morbidities like obesity, diabetes, renal and heart disease and vasculopathies increase the incidence of vascular events. Sudden onset weakness of face or limbs, confusion, difficulty in speech, vision or walking, loss of balance or severe headache may indicate infarction or hemorrhage and warrant neuroimaging to confirm the diagnosis. Stroke should be treated aggressively and fibrinolytic treatment with tissue plasminogen activator should be instituted, ideally within 1 - 3 hours of presentation.
Multiple sclerosis (MS) is a progressive demyelinating disease of the central nervous system characterized by neuro-inflammation and neuro- degeneration; incidence is 3.6 per 100,000 and is more common in Western countries. The disease is usually diagnosed in the 20s and 30s, and has a long course (onset to death is about 38 years). Hence most women will become pregnant prior to worsening of their symptoms. These patients are usually on disease modifying drugs like interferons and synthetic polypeptides like glatiramer acetate, which ideally should be stopped pre- conceptionally. Additionally they may be on  antidepressants and antimuscarinics which also require close monitoring. Though pregnancy may have a favorable effect on MS in first and second trimesters, spasticity and relapse may occur postpartum. Treatments with corticosteroids and intravenous immunoglobulins have been tried.
Neuroimaging in the form of CT scan and MRI form the mainstay in diagnosis. Most practitioners and patients are reluctant to perform these tests in pregnancy, but the risk of fetal exposure with CT scan is < 0.0005 rad; this can be further minimized with abdominal shield. In suspected cases of intracerebral hemorrhage, the benefits far outweigh the risks and timely treatment can be instituted after imaging. In most cases, MRI or MR venogram is preferred as it offers better resolution, however it is time consuming and cumbersome to perform, especially in latter stages of  pregnancy. Women have difficulty remaining supine for any length of time due to aortocaval compression, and experience claustrophobia. Other interventional radiological procedures like digital subtraction angiography (DSA) may be advised to visualize cerebral or spinal vessels in suspected aneurysms or arteriovenous malformations; clinicians should weigh the benefits of complete diagnosis against the potential risk of radiation to the fetus.
Previous issues of the journal have carried reports on some of these conditions in pregnancy, like myasthenia gravis, pituitary macroadenoma and acoustic schwannoma. This issue carries an interesting case of stroke in the third trimester which we hope will be of use to the reader.