Seizures and non-epileptic events

8.3 Seizures and non-epileptic events



Padraic Grattan-Smith




Essentials



1 Seizures are the most common life threatening emergency presentation to EDs requiring immediate management.

2 The diagnosis of a seizure is based on a careful history.

3 There are many paroxysmal events or ‘funny turns’ in children, which can mimic seizures.

4 A bedside dextrostix should be performed on the child who is having a seizure. First-ever seizures should have blood sent for formal glucose, electrolytes, calcium, magnesium and phosphate levels.

5 The acute management of the child having a seizure involves supporting airway and breathing and the graduated use of antiepileptic drugs to terminate the seizure.

6 Parental reassurance and education regarding seizures, BLS and safety issues are an important facet of management in the child presenting with a first convulsion.


Introduction


An epileptic seizure can be defined as a disturbance in neurological function, resulting from uncontrolled excessive neuronal activity in the central nervous system.


The subject of seizures and their differential diagnosis is large. This chapter provides essential information that may be useful in formulating diagnosis and treatment in the emergency department (ED). There is insufficient space for a detailed discussion of the role of the electroencephalogram (EEG) and other investigations.



General comments


There are a number of conditions that must always be considered in children experiencing ‘unusual events’. Hypoglycaemia can cause both partial and generalised seizures. It may also ‘illogically’ produce focal neurological signs. Abnormalities of electrolytes, calcium, magnesium and phosphate can present in a similar fashion. Cardiac arrhythmias associated with prolonged QT interval may cause epileptic seizures that seem to follow the arrhythmia. Sudden loss of consciousness during, or immediately after, intense exercise or associated with strong emotion, raises the possibility of an underlying cardiac cause. A family history of premature unexplained sudden death in a young relative should also raise this possibility.


Some variants of migraine may be difficult to distinguish from seizures. Acute confusional migraine often follows minor head trauma. The episodes may last for a number of hours. The child is ‘concussed’, confused and often vomiting. Basilar artery migraine is associated with confusion or loss of consciousness and brainstem symptoms and signs. Neither diagnosis should be made at the first presentation and without further investigation. On the other hand, occipital epilepsy can cause vomiting, visual loss and severe headache. The presence of tonic eye deviation early in the event is a strong clue that this is a seizure rather than migraine.


Pseudoepileptic seizures and Munchausen’s syndrome by proxy always need to be considered in the differential diagnosis of atypical epileptic seizures. However, the diagnosis is often difficult and the ED is usually not an appropriate setting to make a confident diagnosis of either of these conditions.



Classification of seizures


Seizures are conceptually divided into generalised seizures where the onset is from all brain regions simultaneously and partial seizures, where the seizure arises from one area in the brain. In simple partial seizures there is no alteration of consciousness. With complex partial seizures, alteration of consciousness occurs. Partial seizures may spread and become secondarily generalised.


Status epilepticus is said to occur where a seizure lasts more than 30 minutes or there is incomplete recovery between seizures over this time period. In practical terms, any child who arrives in the ED still fitting, should be regarded as a medical emergency. Status epilepticus can occur in both convulsive and non-convulsive forms.



Febrile seizures


Febrile convulsions are not regarded as a form of epilepsy but are discussed because of their frequent presentation to EDs. Typically they occur in children between 6 months and 6 years of age. They are common, affecting around 3% of children. Most children who have febrile convulsions have only one, but 25–30% will have a recurrence. The risk of recurrence is greater in infants less than 12 months, where it may be as high as 50%.


Febrile convulsions most commonly occur in the setting of viral illnesses such as an upper repiratory tract infection, pharyngitis, gastroenteritis, or an exanthem such as roseola infantum. Much less commonly, pneumonia or a urinary tract infection may be the underlying cause. Febrile seizures typically occur relatively early in the course of an infectious illness and sometimes the convulsion is the first sign that the child is unwell.


Most febrile seizures are generalised and brief, lasting less than a few minutes. The child returns to normal after a short (usually less than 30 minutes) postictal period. The seizures may be clonic, tonic–clonic or atonic where the child may simply seem to stop breathing. Examination should confirm the presence of a fever, identify the source of the fever, and exclude signs of central nervous system (CNS) infection or of a focal neurological process. Most children with an uncomplicated febrile seizure who have completely recovered and have a clear source of infection require no blood tests or other investigations.


Prolonged (lasting >10 minutes) and complicated (focal, multiple) febrile seizures can occur. Underlying meningitis/encephalitis must always be considered in the child who fails to return to normal, has multiple or prolonged seizures or has residual neurological signs. The threshold to perform a cerbrospinal fluid (CSF) examination is lower when the child is less than 12 months of age or has been on antibiotics, which may mask the usual signs of meningism. However, lumbar puncture can be dangerous in the child with focal signs such as a hemiparesis or if there has been a rapid deterioration in conscious level or an abnormality of respiratory rhythm. Consultation with senior colleagues is advised if there is doubt about the safety to perform a lumbar puncture.


Children with seizures are seen in the ED in two broad settings:


The child who is seen after an event. Was this a seizure?

The child who is still fitting.


The child seen after the event



History


The diagnosis of seizures is based almost entirely on the history.


The parents or any witnesses of the event should be taken through the episode systematically. An exact description of what took place is crucial in making a correct diagnosis. What was the child doing when it started? What was the very first sign of a problem, and what followed? If abnormal movements were present, did they principally involve one side of the body? How long did the event last? What was the child like afterwards? How long before the child was back to normal? Was there any faecal or urinary incontinence or tongue biting? Was there any apnoea or colour change?


Witnessing a sudden loss of consciousness in a child is an extremely upsetting event for any observer, particularly the parents. Many parents report that they thought their child had ‘stopped breathing’ and commenced various resuscitation techniques. There are obvious limitations to the history, but it remains the single piece of information most likely to provide a diagnosis. It is also worth talking to the verbal child about what happened. Even young children can sometimes give very helpful accounts if spoken to soon after the event.


It is important to establish whether there may have been provocative factors, such as sleep deprivation, a febrile illness, head trauma or potential exposure to epileptogenic medications. A past history of similar events should be sought. It is also important to ask about a family history of seizures or unusual turns and to review the child’s developmental milestones.



Examination


The physical examination is often normal, but it must be carefully performed, looking for fever, evidence of intercurrent illness and abnormal neurological signs. Other important diagnostic clues include a Todd’s paralysis, skin lesions of tuberous sclerosis or morphological features of a chromosomal disorder or other underlying neurological abnormality associated with a seizure disorder. The finding of lateral tongue trauma or incontinence supports a suspicion of seizure when the diagnosis is unclear. The febrile child needs to have an underlying meningitis or encephalitis excluded.


In infants, the sudden onset of frequent seizures and failure to regain consciousness is a common presentation of child abuse and a careful retinal examination must be performed, looking for retinal haemorrhages.



Differential diagnosis


Tonic–clonic seizures, myoclonic seizures and clonic seizures, in general, can occur at any age. They are well described in standard textbooks and will not be discussed here except to discourage the tendency to loosely label any event with loss of consciousness as a ‘tonic–clonic’ seizure.


Although there is overlap, it is helpful to approach the problem in terms of age of presentation. For neonatal seizures refer to Chapter 2.6.



Infancy



Seizure types



Infantile spasms

Typically take the form of ‘salaam’ seizures. There is characteristic sudden flexion of the arms, head and trunk in a brief spasm. Asymmetrical or extensor spasms can occur. The characteristic feature of established infantile spasms is that the episodes occur in runs (clusters) which can continue for 10 minutes or more. In the early phases, the spasms may be mild and relatively infrequent, making diagnosis difficult.

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Sep 7, 2016 | Posted by in EMERGENCY MEDICINE | Comments Off on Seizures and non-epileptic events

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