Epilepsy

G40.9

• Description
• Diagnostic criteria
• General and supportive measures
• Medicine treatment
• Referral

DESCRIPTION

Epilepsy is a disease of the brain characterised by any of the following conditions

• At least two unprovoked (or reflex) seizures occurring > 24 h apart.
• One unprovoked (or reflex) seizure and a probability of further seizures similar to the general recurrence risk (at least 60%) after two unprovoked seizures, occurring over the next 10 years.
• Diagnosis of an epilepsy syndrome.

An epileptic seizure is defined as transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain.

Generalised epileptic seizures originate within, and rapidly engage, bilaterally distributed networks in the cortical and subcortical structures.

Focal epileptic seizures: originate within networks limited to one hemisphere. These may be discretely localized or more widely distributed.

Besides the classification according to types there are also specific seizure syndromes with specific treatment

1. Absence epilepsy of childhood.
2. Benign focal epilepsy of childhood.
3. Epileptic spasms (West syndrome).
4. Lennox-Gastaut syndrome.
5. Severe myoclonic epilepsy of infancy (Dravet syndrome).
6. Genetic epilepsy with febrile seizures plus (GEFS+).

Epileptic syndromes include:

Absence Epilepsy of Childhood

• Short spells of sudden onset of motor arrest and impairment of consciousness lasting between 5 and 30 seconds.
• Little or no associated automatic movements.
• No post-ictal effect.
• Onset from 5-7 years old until puberty.

Benign focal epilepsy of childhood

• Sleep related events of hemifacial clonic spasm.
• Inability to speak but retained awareness.
• Peak onset at ± 6–10 years.
• Usually resolves by late adolescence.

Epileptic spasms (West syndrome)

• An infantile onset encephalopathy with epileptic spasms associated with hypsarrhythmia on the EEG and developmental regression.
• Frequent age of onset 3-6 months old.
• It is a neurological emergency. Do not delay diagnosis, treatment and referral. Early intervention reduces subsequent neuro-disability.
• Clinically, the child appears to stare, gives a sudden flexion of the trunk and head, with the limbs in extension or flexion but held in this tonic spasm for a few seconds.
• Events occur in clusters and are most common when the infant is going to sleep or rousing.
• The episodes are distressing to the infant and he/she will often appear red in the face and may cry out.
• Events are often confused with colic.

Lennox-Gastaut syndrome (LGS)

• Combinations of GTCS, atypical absences, myoclonic seizures, tonic seizures, atonic drop attacks and occasionally complex partial seizures.
• May occur spontaneously but usually structural.
• Onset between 2–3 years of age.
• Behavioural problems and neuroregression occurs.

Severe Myoclonic Epilepsy of Infancy (SMEI) - Dravet Syndrome

• A severe form of myoclonic epilepsy with onset in children < 1 year of age with recurrent clusters of febrile convulsions, severe neuroregression and other non-febrile seizures by 2–3 years.

Genetic epilepsy with febrile seizures plus (GEFS+)

• Children with febrile convulsions that persist beyond 6 years.
• These children have epilepsy triggered by fever and may warrant antiepileptic drug intervention.
• There is often a family history of febrile convulsions.

Note:
West syndrome, Severe Myoclonic Epilepsy of Infancy and Lennox-Gastaut syndrome are regarded as epileptic encephalopathies and are associated with neuroregression and behavioural problems.

DIAGNOSTIC CRITERIA

A child may be diagnosed:

• with a specific anatomical or systemic cause for the seizure type (see table of possible causes);
• as having an epileptic syndrome, i.e. a specific seizure type associated with a characteristic EEG, natural history, response to anticonvulsant therapy and prognosis;
• with cryptogenic epilepsy.

Investigations:

• MRI of the brain is the preferred investigation for recurrent seizures in children. If not available, a CT scan of the brain is indicated.
• EEG: is indicated for recurrent or syndromic seizures where a diagnosis cannot be made on clinical grounds alone. Delay an EEG for at least one week after the convulsive episode.
• If atypical, a 12 lead ECG should be considered in diagnostic uncertainty – it is important to consider prolonged QT interval syndromes.

GENERAL AND SUPPORTIVE MEASURES

• Minimise the impact of the epilepsy by obtaining complete seizure control to maximise the child’s full potential.
• Educate the patient and caregiver about epilepsy and associated complications and comorbidities, i.e. learning difficulties and ADHD.

MEDICINE TREATMENT

Acute:

Manage as per seizures/status epilepticus, see Seizures , and: Status epilepticus (convulsive) .

Maintenance therapy

• Monotherapy is preferred but combination therapy may be necessary.
• Combination therapy should be specialist initiated.
  Caution: potential drug-drug interactions.
• As a general rule, start with small doses and titrate slowly upwards.
• Aim for low to mid-therapeutic dose range and accept the lowest dose at which seizures are controlled.
• If seizures continue, titrate to high therapeutic doses, if there are no unacceptable side-effects.
• Measuring drug levels is rarely indicated unless there is concern about toxicity or adherence and in polytherapy.

Maintenance medicine treatment choices for different types of epileptic seizures.

• Valproate, oral, 5 mg/kg/dose (starting dose), 8–12 hourly.
  • Increase by 5 mg/kg weekly to 15–20 mg/kg/day given 8–12 hourly over 4 weeks.
  • Maximum total daily dose: 40 mg/kg/day.
  • Exclude liver dysfunction prior to initiating therapy (at least ALT), in children under 2 years or if clinical suspicion of liver dysfunction or metabolic disease
  • Monitor at least clinically for hepatotoxicity.
• Carbamazepine, oral, 5 mg/kg/day (starting dose), 8-12 hourly.
  • Increase slowly by 0.2 mg/kg at 2 weekly intervals to 5–10 mg/kg/dose 8–12 hourly.
  • Usual maintenance total daily dose: 10–20 mg/kg/day.
  • Maximum total daily dose: 20 mg/kg/day.
  • Dosage intervals: syrup 8 hourly, tablets 12 hourly.
  • Exacerbates myoclonic seizures and absence seizures.
• Lamotrigine, oral, 0.2 mg/kg/dose starting daily dose. (Specialist initiated.)
  • Increase slowly at 2 weekly intervals to 1–5 mg/kg/dose 12–24 hourly.
  • Rapid escalation associated with side adverse effect of skin rash.
  • Maximum total daily dose when given with valproate: 5 mg/kg/day.
  • Lamotrigine is given as add-on therapy for different seizure types and in drug-resistant paediatric epileptic syndromes, such as Lennox-Gastaut syndrome.
  • Double the maximum dose of lamotrigine when using carbamazepine or phenobarbitone and,
  • Lamotrigine must be given at a reduced dosage, of no more than half the above recommended dose in patients using valproate,
• Phenobarbitone, oral, 3–5 mg/kg/dose as single dose at night.
  • May be used in children under six months of age.
  • Is not recommended as maintenance therapy for children older than 2 years due to undesirable side effects such as sedation, behaviour disturbances, hyperkinesia and dependence, except in situations where there is poor adherence to other drugs.
  • Exacerbates absence seizures.

REFERRAL

• Suspected but undiagnosed secondary cause for seizures.
• Focal seizures for neuro-imaging (MRI preferred), if facilities or expertise not available.
• All seizures other than typical febrile convulsions in children < 2 years.
• Seizures that are not controlled within 2 months on one agent with minimal side effects.
• Neuroregression.
• Mixed seizure types in one patient.
• All myoclonic seizures and epileptic spasms at presentation.
• If need to add a second medicine.