Chapter 29 – Convulsions and Epilepsy




Abstract




Types of Seizures





Chapter 29 Convulsions and Epilepsy



Ingrid Watt-Coote




Key Facts


Definition Epilepsy is a neurological condition characterised by recurrent epileptic seizures unprovoked by any immediately identifiable cause. An epileptic seizure is the clinical manifestation of an abnormal and excessive discharge of a set of neurons in the brain [1].


Incidence Approximately 40–70 new cases per 100 000 individuals per year in high-income countries and 100–190 per 100 000 per year in low-income countries.


Prevalence Varies between 3 and 40 per 1000 individuals worldwide. Epilepsy affects 0.5%–1% of pregnant women; 3.5% of epileptic women will have a seizure in labour [2] and 1%–2% of epileptics will develop status epilepticus.



Types of Seizures



Focal Seizures




  • Focal indicates that the seizures originate primarily within networks limited to one cerebral hemisphere [3].



  • Tonic seizures: The person’s muscles suddenly become stiff. If they are standing they often fall backwards and may injure the back of their head [3].



  • Tonic–clonic seizures: During a tonic–clonic seizure the person becomes stiff, usually falls to the ground and shakes or makes jerking movements (convulses). Their breathing can be affected and the person may grow pale or blue, particularly around the mouth. They may also bite their tongue [3].



  • Atonic seizures: In an atonic seizure (sometimes called a ‘drop attack’) the person’s muscles suddenly relax, and they become floppy. If they are standing they often fall forwards and may injure their face or head [3].



Generalised


Generalised epileptic seizures originate within, and rapidly engage, bilaterally distributed networks [3]. The person becomes unconscious and afterwards will not remember what happened during the seizure.




  • Myoclonic seizures: Involve the jerking of a limb or part of a limb, and often happen shortly after waking up from sleep.



  • Clonic seizures: During the seizure the person usually falls to the ground and shakes or makes jerking movements (convulses).



  • These include simple and complex. Such seizures can present as a twitching of one limb or part of a limb, an unusual smell or taste, a strange feeling such as a ‘rising’ sensation in the stomach or ‘pins and needles’ in parts of the body or a sudden intense feeling of fear or joy. Sometimes patients can start wandering around or behaving strangely and they may not know what they are doing. They may pick objects up for no reason, fiddle with their clothes or make chewing movements with their mouth.



Absence Seizures




  • During an absence seizure a person becomes unconscious for a short amount of time, usually a few seconds [3].



  • They may look blank and not respond to what is happening around them.



Key Implications




  • Maternal: Increase of seizure frequency in 10%–30% during pregnancy; deterioration of disease in those with poorly controlled epilepsy before pregnancy; modest increase in preeclampsia and caesarean section [4]; premature labour (especially if woman is a smoker) [5]; placental abruption; trauma; indirect cause of maternal death; sudden unexpected death in epilepsy.



  • Fetal: Increased risk of congenital abnormalities due to antiepileptic drugs (higher with polytherapy); risk of epilepsy in child; risk of fetal hypoxia if prolonged convulsive seizures or status epilepticus develop; possible neurocognitive effects [4].



Key Pointers



Risk Factors for Seizures in Pregnancy/Labour




  • Decreased compliance to take medication due to concern about teratogenicity



  • Decreased drug absorption because of nausea and vomiting



  • Decreased drug levels due to increased volume of distribution in pregnancy, increased drug metabolism and renal elimination



  • Impaired sleep/rest, hyperventilation



Key Diagnostic Signs


Epilepsy is, in most cases, diagnosed before pregnancy; however, it may occasionally present for the first time during pregnancy. Seizure that occurred in pregnancy/labour needs to be differentiated from syncope.


The following questions could be used to help differentiation [1].


Questions used that, if positive, support a diagnosis of epileptic seizure:




  • At times do you wake up with a cut tongue after your spells?



  • At times do you have a sense of déjà vu or jamais vu before your spells?



  • Has anyone ever noted that you are unresponsive, have unusual posturing or have jerking limbs during your spells or have no memory of your spells afterwards?



  • Has anyone noticed that you are confused after a spell?



  • At times is emotional stress associated with losing consciousness?



  • Has anyone noticed your head turning during a spell?


Questions used that, if positive, support a diagnosis of syncope:




  • Have you ever had light-headed spells?



  • At times do you sweat before your spells?



  • Is prolonged sitting or standing associated with your spells?


Differential diagnosis for convulsions in pregnancy should include the following:




  • Eclampsia




    • Associated with proteinuria, raised blood pressure




  • Epilepsy




    • Usually previous history




  • Cerebral venous thrombosis




    • Associated with headache, vomiting, photophobia, focal neurological signs




  • Thrombotic thrombocytopenic purpura




    • Associated with headache, drowsiness, fever, renal impairment with haemolytic anaemia; hypertension is not common.




  • Stroke (ischaemic/haemorrhagic)




    • Associated with headache and raised blood pressure, often secondary to preeclampsia or ruptured arteriovenous malformations




  • Encephalitis/meningitis




    • Associated with headache, neck stiffness signs or psychiatric features, meningism, focal central nervous system signs




  • Cerebral tumours




    • Might be preceded by symptoms associated with space-occupying lesion in the head




  • Cerebral trauma




    • Signs of trauma, history from friends, relatives, witnesses




  • Drug withdrawal




    • History from friends and relatives




  • Toxicity




    • Epidural, overdose of tricyclic antidepressants




  • Metabolic disturbances (hypoglycaemia, hypocalcaemia, hyponatraemia)




    • Associated with tremor, hunger prior to attack, paraesthesia, carpo-pedal spasm




  • Postdural puncture




    • Preceded by postdural headache that is relieved by lying down, associated neck stiffness, tinnitus, visual symptoms




  • Amniotic fluid embolism




    • Presence of predisposing factors (age, induction of labour, hyperstimulation, uterine trauma), respiratory distress, cyanosis, shock with further vaginal bleeding




  • Cardiogenic (Stokes–Adams attacks, arrhythmias)




    • Associated with palpitation, chest pain or shortness of breath, during the attack pallor and pulse is slow or absent




  • Infection




    • Neurocysticercosis (history of eating uncooked pork or drinking contaminated water)



    • Cerebral malaria (living or visiting endemic area, recent high fever with rigors, sometimes jaundice)



    • Tetanus (recent ‘unclean’ delivery, unsafe abortion, trismus, arched back, board-like abdomen)



    • Septicaemia (high fever, abdominal pain, purulent discharge, very ill patient with delirium, signs of septic shock)




Evaluation of a Pregnant Woman Who Has Had a Seizure




  • Obtain as much history as possible from the patient and witnesses.



  • Try to establish associated symptoms (headache, visual disturbances, epigastric pain, neck stiffness, tinnitus, palpitation, shortness of breath, chest pain).



  • Send blood for full blood count (FBC), urea and electrolytes (U&E), liver function tests (LFTs), urea, Ca2+, PO43−, glucose, international normalised ratio (INR)/partial thromboplastin time (PTT), blood film, serum and urine toxic screen, thrombophilia screen



  • Imaging: CT, MRI or magnetic resonance angiography (MRA) (if seizure occurs for the first time in pregnancy)



  • ECG, 24-hour ECG, EEG



Key Actions



Immediate Management of Short-Lasting Self-Limiting Convulsions in Pregnancy



During the Seizure



  • Summon senior staff, call for help, but try not to leave the patient on her own. You would need the most senior obstetricians, anaesthetist, midwife, other nursing and ancillary staff. Specify that it is a maternal seizure.



  • Note the time the seizure starts – note the exact time when seizure was witnessed to have started. Allocate one of the staff to record the events and watch the time. Also ask to inform you if seizure lasts more than 4–5 minutes. Most tonic–clonic seizures last less than 2 minutes [6].



  • Prevent injury. Most of the seizures are self-limiting. Do not try to restrict the convulsions. Move the patient only if she is in a dangerous place, for example, on the edge of a staircase. Preferably try to ease the patient down onto the floor if she was sitting down before. Try to put padding on the side rails of the bed and move objects away if they might hurt the patient.



  • Semi-prone position if possible. Place wedge under right hip or place the patient in a left lateral position. After the convulsion subsides put patient in recovery position.



  • Secure airway and administer high-flow oxygen. Do not try to open the mouth and introduce anything solid in the mouth during the fit. After the convulsive movements subside check the airway is not obstructed.



  • Check urine for proteins.



  • Check blood pressure, pulse, oxygen saturation, temperature and respiratory rate.

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May 9, 2021 | Posted by in OBSTETRICS | Comments Off on Chapter 29 – Convulsions and Epilepsy
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