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Part 2 book “Handbook of obstetric medicine” has contents: Neurological problems, renal disease, liver disease, gastrointestinal disease, skin disease, haematological problems, human immunodeficiency virus and other infectious diseases, tables.
CHAPTER Neurological problems Epilepsy Migraine and headache Multiple sclerosis (MS) Myasthenia gravis (MG) Myotonic dystrophy Idiopathic (benign) intracranial hypertension Stroke Subarachnoid haemorrhage Cerebral vein thrombosis Posterior reversible encephalopathy syndrome (PRES) Reversible cerebral vasoconstriction syndrome Bell’s palsy Entrapment neuropathies Epilepsy Incidence Epilepsy affects about 0.5% of women of childbearing age and is the commonest chronic neurological disorder to complicate pregnancy Clinical features Epilepsy is classified according to the clinical type of seizure or specific electroencephalographic (EEG) features Many types of epilepsy are characterized by more than one type of seizure These may be broadly divided into ■■ ■■ ■■ Primary generalized epilepsy (including tonic–clonic seizures, absences and myoclonic jerks) Partial (focal) seizures with or without loss of consciousness or secondary generalisation (complex partial seizures) Temporal lobe seizures, which are a form of partial seizures Temporal lobe seizures are often associated with an aura, a duration of minute or more and confusion after the event Absences (petit mal) in contrast are normally of short duration (a few seconds), have a rapid onset, rapid recovery and are precipitated by hyperventilation Absences are associated with Hz spike and wave discharge on the EEG The clinical features of tonic–clonic seizures due to primary generalized epilepsy and secondary generalized partial seizures may be similar as there may be no identifiable aura associated with the latter Pointers to a diagnosis of primary generalized epilepsy are myoclonic jerks and photosensitivity 163 Handbook of Obstetric Medicine Pathogenesis Most cases of epilepsy are idiopathic and no underlying cause is found About 30% of these patients have a family history of epilepsy Secondary epilepsy may be encountered in pregnancy in patients who have the following: ■■ ■■ ■■ Previous surgery to the cerebral hemispheres Intracranial mass lesions (meningiomas and arteriovenous malformations [AVMs] enlarge during pregnancy This should always be considered if the first seizure occurs in pregnancy) Antiphospholipid syndrome (see Chapter 8) Other causes of seizures in pregnancy (see also Chapter 16, Table 16.8) include the following: ■■ ■■ ■■ ■■ ■■ ■■ ■■ ■■ ■■ ■■ ■■ ■■ ■■ Eclampsia (see Chapter 1) Cerebral vein thrombosis (CVT) (see Chapter 3) Thrombotic thrombocytopenic purpura (TTP) (see Chapter 14) Stroke (risk is increased in pregnancy and 4% have seizures, see ‘Stroke’) Subarachnoid haemorrhage (SAH) (see ‘Subarachnoid haemorrhage’) Drug and alcohol withdrawal Hypoglycaemia (diabetes, hypoadrenalism, hypopituitarism, liver failure) Hypocalcaemia (magnesium sulphate therapy, hypoparathyroidism) Hyponatraemia (hyperemesis, hypoadrenalism, pre-eclampsia) Infections (tuberculoma, toxoplasmosis) Post-dural puncture Seizures are rare and preceded by typical post-dural puncture headache and other neurological symptoms Seizures occur typically 4–7 days after dural puncture Gestational epilepsy (seizures are confined to pregnancy) Non-epileptic seizure disorder or non-epileptic attack disorder (these patients often have true epilepsy as well) Useful distinguishing features to differentiate these ‘pseudo seizures’ are the following: –– Prolonged/repeated seizures without cyanosis –– Resistance to passive eye-opening –– Down-going plantar reflexes –– Persistence of a positive conjunctival reflex –– Biting the inside of the cheek (as opposed to the tongue) Diagnosis Most women with epilepsy in pregnancy have already been diagnosed, but when a first seizure occurs in pregnancy, the following investigations are appropriate: ■■ ■■ ■■ ■■ Blood pressure, urinalysis, platelet count, clotting screen, blood film Blood glucose, serum calcium, serum sodium, serum urea and creatinine, liver function tests Computerized tomography (CT) or magnetic resonance imaging (MRI) of the brain Although this is not necessarily recommended for the first seizure in the non-pregnant patient, there is no doubt of its value in pregnancy, bearing in mind the above differential diagnoses EEG 164 Neurological problems Pregnancy Effect of pregnancy on epilepsy ■■ ■■ ■■ ■■ ■■ ■■ ■■ ■■ ■■ In most women, pregnancy does not affect the frequency of seizures In a prospective European study, compared to the first trimester, seizure control remained unchanged throughout pregnancy in 64%, 17% had an increase and 16% had a decrease in seizures A woman who has been seizure-free for many years is unlikely to have seizures in pregnancy unless she discontinues her medication or anti-epileptic drug (AED) levels fall substantially Those with poorly controlled epilepsy, especially those whose seizure frequency exceeds once a month, are more likely to deteriorate in pregnancy There is no relation to the seizure type or course of epilepsy during previous pregnancies Women with multiple seizure types are also more likely to experience an increase in seizure frequency in pregnancy The risk of seizures is highest peripartum (see later), and in the prospective EURAP study 3.5% of pregnancies were complicated by intrapartum seizures Epilepsy is a common indirect cause of maternal death in the United Kingdom The maternal death rate due to epilepsy ranges from to 10 per million maternities or about five cases per year in the United Kingdom In many deaths, the cause was aspiration, but epileptic seizures may be fatal in themselves It is not known whether pregnancy increases the risk of sudden unexplained death in epilepsy (SUDEP), estimated at in 500 woman-years outside pregnancy Risk factors for SUDEP include high seizure frequency, increasing numbers of AEDs, low intelligence quotient (IQ) and early-onset epilepsy SUDEP is uncommon in those with good seizure control Possible reasons for deterioration in seizure control during pregnancy include: ■■ ■■ ■■ ■■ ■■ ■■ ■■ Pregnancy itself Poor compliance with anticonvulsant medication (due to fears regarding teratogenesis) One study using hair analysis confirmed that pregnant women commonly stop or reduce AEDs in pregnancy Decreased drug levels related to nausea and vomiting in early pregnancy Decreased drug levels related to increased volume of distribution and increased drug clearance through the liver and kidney Changes in protein binding will tend to increase the free level of drugs, but this is usually outweighed by the first two factors Lack of sleep towards term and during labour Lack of absorption of AEDs from the gastrointestinal tract during labour Hyperventilation during labour Effect of epilepsy on pregnancy ■■ ■■ The fetus is relatively resistant to short episodes of hypoxia, and there is no evidence of adverse effects of single seizures on the fetus Some have documented fetal bradycardia during and after maternal tonic–clonic convulsions, but cerebral damage in the long term is not a feature Large prospective studies show no increased risk of miscarriage or obstetric complications in women with epilepsy unless a seizure results in abdominal trauma 165 Handbook of Obstetric Medicine ■■ ■■ ■■ ■■ ■■ ■■ Status epilepticus is dangerous for both mother and fetus and should be treated vigorously Fortunately, this is rare complicating 1 g/day valproate are at a greater than twofold increased risk of congenital malformations, particularly neural tube defects, compared to those exposed to 600 mg/day or less The EURAP study found a 25% risk of congenital malformations in women taking >1.5 g/day compared with a 6% risk in those taking