Stroke may occur during pregnancy and delivery and may be caused by intracranial haemorrhage or thrombosis. The incidence varies but is thought to be between 11 and 26 per 100,000 deliveries.
Problems and special considerations
Stroke presenting during pregnancy or peripartum
Pregnancy and labour increase the risk of stroke. This risk will be further increased if there is associated obesity, smoking or hypertensive disease of pregnancy.
Intracerebral haemorrhage may occur at any stage during the pregnancy; the risk is increased in the third trimester and is highest during the intra- and postpartum periods. The most common problem is subarachnoid haemorrhage (SAH), which presents as an acute onset of severe headache, often with associated neck stiffness, photophobia and vomiting. There may be neurological deficits or loss of consciousness. SAH is often associated with an underlying berry aneurysm or arteriovenous malformation, and is also a cause of death associated with pre-eclampsia. Haemorrhagic stroke was identified as one of the most common causes of death in women with hypertensive disease of pregnancy. Intracranial haemorrhage may also be a consequence of reversible cerebral vasoconstriction syndrome or may be caused by venous bleeding associated with cerebral venous thrombosis.
Ischaemic stroke usually occurs in the territory of the middle cerebral arteries and can be associated with an underlying structural cardiac or vascular cause. Pregnancy predisposes to cerebral thrombosis, including cortical vein thrombosis. More than three-quarters of all pregnancy-associated cases of cerebral venous thrombosis occur postpartum. Other predisposing factors include dehydration and other hypercoagulable states (e.g. thrombophilias). Although cortical vein thrombosis is rare, it is important to the obstetric anaesthetist in the differential diagnosis of postdural puncture headache. The patient may present with focal neurological signs, seizures or other signs of raised intracranial pressure.
Sudden collapse carries the risk of airway obstruction and hypoxaemia, aspiration of gastric contents, aortocaval compression and fetal compromise. As for many acute medical emergencies in the maternity suite, staff may be unfamiliar with basic resuscitative measures unless these are regularly practised.
Previous history of stroke
The most common presentation in the childbearing age group is a previous history of SAH. Some of these women will have made a complete recovery and others will have a neurological deficit of which the anaesthetist should be aware. They may be frightened by the thought of a needle in their back after a bad experience with lumbar puncture. There may be an exaggerated hyperkalaemic response to suxamethonium 10 days to 6-7 months after stroke. Women with a previous cerebral thrombosis may be taking heparin or aspirin.
Management options
Prevention
The risk of SAH is one reason for ensuring adequate blood pressure control in preeclampsia, particularly in the peripartum period and in parturients who receive general anaesthesia. The intense sympathetic stimulation associated with tracheal intubation may precipitate a sharp rise in systemic blood pressure and intracranial pressure, and appropriate modification of the anaesthetic technique is required to attenuate this pressor response.
Simple preventive measures for intracranial venous thrombosis include avoidance of dehydration and prompt treatment of infection, especially in women with a recognised risk factor such as thrombophilia.
Diagnosis
Diagnosis of stroke is by computerised tomography or magnetic resonance imaging of the brain; if the diagnosis is suspected, it is wise to involve the neurologists early. The use of lumbar puncture has largely been superseded by imaging techniques for the diagnosis of SAH, partly because of the risk of coning.
Therapy
In pregnant women who suffer a stroke with loss of consciousness, basic resuscitation must be performed, with particular attention to uterine displacement and avoidance of aspiration. There is a significant risk of rebleeding following SAH, so assessment by neurosurgeons with a view to surgical treatment is essential. The indication for surgical intervention should not be altered by the fact that the woman is pregnant, and the procedure should generally be managed as for non-pregnant patients.
In addition to supportive treatment, thrombolysis should be considered in women with acute ischaemic strokes. Cerebral venous thrombosis in pregnancy requires systemic anticoagulation for the remainder of the gestation and for the initial postpartum period.
Management of delivery depends on the clinical condition of the patient, who may still have a significant neurological deficit. If the patient is well recovered, a stress-free vaginal delivery with epidural analgesia is the management of choice, taking care to avoid significant fluctuations in blood pressure and exercising caution in the presence of anticoagulation. The indications for caesarean section should only be obstetric. However, if the patient is confused or has a problem with cognitive function, the wisest course of action may be delivery by caesarean section under general anaesthesia, which should be carefully managed to minimise the hypertensive response to tracheal intubation. Each patient will need to be considered individually in consultation with the obstetrician and neurosurgeons, and other disciplines where appropriate. Combined caesarean section and neurosurgery has been performed.
The management of women with previous SAH depends on whether the underlying pathology has been surgically treated. If so, the woman can be regarded as relatively normal. The risk of a further bleed is increased if there is hypertension, and in particular if there are sudden surges in blood pressure. The control of blood pressure and the avoidance of stress during labour or delivery are therefore important. Generally, regional analgesia should be recommended for labour. If a caesarean section is required, regional anaesthesia is appropriate. This should, however, be preceded by a detailed discussion with the woman, ideally in the antenatal period, when a clearly documented plan for the management of analgesia and anaesthesia should be made. If general anaesthesia is necessary, strict pharmacological control of blood pressure is required, and alternatives to suxamethonium should be used if within the period of risk.
Rarely, stroke (usually subdural or subarachnoid haemorrhage) has followed spinal anaesthesia or accidental dural puncture.
Key points
• Control of blood pressure in hypertension is important in pregnancy, whether or not it is pregnancy-related.
• Headaches are not always caused by dural puncture.
• Pregnancy is not a contraindication to neurosurgery.
• Regional analgesia or anaesthesia is usually indicated unless there is significant neurological impairment.
Further reading
Edlow JA, Caplan LR, O’Brien K, Tibbles CD. Diagnosis of acute neurological emergencies in pregnant and post-partum women. Lancet Neurol 2013; 12: 175-85.
Frontera JA, Ahmed W. Neurocritical care complications of pregnancy and puerperum. J Crit Care 2014; 29: 1069-81.
Scott CA, Bewley S, Rudd A, et al. Incidence, risk factors, management, and outcomes of stroke in pregnancy. Obstet Gynecol 2012; 120: 318-24.
Shainker SA, Edlow JA, O’Brien K. Cerebrovascular emergencies in pregnancy. Best Pract Res Clin Obstet Gynaecol 2015; 29: 721-31.