Febrile seizures. Olivier Dulac. Hôpital Necker-Enfants Malades, Université Paris V, INSERM U663

Transcription

1 Febrile seizures Olivier Dulac Hôpital Necker-Enfants Malades, Université Paris V, INSERM U663

2 Definition Seizures precipitated by fever that is not due to an intracranial infection or other definable CNS cause They result from Fever Immature brain Genetic predisposition

3 Incidence The most common type of seizures in the pediatric age group They affect 2 to 5% of children aging three months to five years 2 to 10% develop subsequent unprovoked seizures About one-third of all children with a first febrile seizure will experience recurrent

4 Clinical manifestations Febrile seizures are Tonic / clonic Hypotonic (syncope?) Uni- or bilateral Not as myoclonus, spasms, or non convulsive Distinguish: Simple Febrile : generalized, <15 minutes, single Complex seizures: partial, >15 minutes, repeated

5 Risk Unilateral seizures may be followed by a Todd hemiplegia lasting a few hours, rarely several days The incidence of Todd hemiplegia is probably in the range of 0.4% of all cases of FS If lasting hours, seizure may be first stage of HH (hemiconvulsion hemiplegic) syndrome

6 MRI in HH syndrome

7 Diffusion vs T1 and FLAIR HH syndrome

8 Hippocampal Atrophy : A mild form of HHE syndrome?

9 A possible mechanism for HH syndrome? Viral infection? triggering factor Cytokines Cell Epileptic Death activity + Network reorganization Callosal maturation permits bilateral involvement

10 Pathways between mesial temporal and neocortical structures 1) infant 2) adolescent Neocortical dysplasia Hippocampal atrophy

11 Temporal lobe epilepsy : A model to distinguish semantic andepisodic memories Semantic abilities learning Child Adolescent Episodic memory years

12 Investigations in FS Lumbar punction for children under 12 months with first seizure, to exclude: Bacterial meinigitis Herpetic encephalitis Seizures affect one side of the face On 2 nd /3 rd day of fever CSF, MRI not reliable begin with Aciclovir Blood glucose (hypoglycaemia), calcium + Viral investigations

13 Infectious aetiology Viruses are responsible for precipitating illness in 90% of cases Herpes virus 6 (Roseola Infantum) and 7 may be responsible for triggering febrile seizures Rotavirus infection have been also associated with encephalopathic manifestations Bacterial infections less commonly cause FS The incidence of febrile seizures with shigellosis is about 19.7% Fever resulting from immunization can provoke febrile seizures. Prognosis seems favorable in most cases. Mainly with pertussis (wdpt not dtap) and measles vaccines.

14 Risk of recurrence Early age at onset (< 12 months) Family history of febrile seizures or epilepsy Epilepsy or febrile seizures in a first degree relative Short duration between 2 fits < 3 months Relatively low fever at time of first seizure Brief duration between fever onset and initial seizure

15 Family history febrile seizures in a first degree relative Developmental delay or neurological problems. Age of onset <18 months Level of temperature at first seizure Duration of illness before seizure Attendance at day care Predicting a first febrile seizure Predicting recurrence after a first febrile seizure (possible)

16 Genetic factors FS occur with increase frequency among family members of patients with FS Most studies suggest a dominant mode of inheritance with reduced penetrance and variable expression Six loci of FS susceptibility : 8q 13-q21 (FEB1), 19 q (FEB2), 2q23-q24 (FEB3), 5q14-q15 (FEB4), 6q22-q24, 18q11

17 Risk of epilepsy following FS Non febrile seizures following febrile convulsions occur in 2% - 7% of patients Risk for generalized epilepsy is increased by: Positive family history of non febrile seizures Large number of brief generalized febrile seizures Risk for partial epilepsy: Prolonged lateralized febrile seizures. Early age at onset of febrile seizures and persisting neurologic dysfunction MRI studies have shown frequent evidence of hippocampal atrophy and mesial temporal sclerosis in patients with intractable temporal lobe epilepsy and history of prolonged febrile seizures

18 Epilepsy syndromes following febrile seizures Absence epilepsy in 15% -25% of children with history of FS The incidence of FS in patients with Benign Rolandic epilepsy ranges from 9% to 20% which clearly is in excess of its incidence in the general population. Myoclonic absences Juvenile myoclonic epilepsy Have been observed to follow FCs

19 Febrile seizures + FS usually with multiple recurrences, that recur after the age of 6 years, and often associated with non febrile generalized seizures (Scheffer and Berkovic 1997). Dominant transmission termed as GEFS+ to. Missense mutations in the pore-forming subunit sodium channel subunit (SCN1B, SCN1A, and SCN2A) defect in the gamma 2 subunit of GABA receptor

20 Dravet syndrome At the severe end of the GEFS + spectrum is Severe Myoclonic Epilepsy of infancy (SMEI, Dravet syndrome): Onset in the 1st year of life Unilateral (alternating sides) and generalized Clonic With mild fever Myoclonus and SW occurring after age 3 years Families in which both Dravet syndrome and GEFS+ presented in different individuals have been reported

21 Treatment of FS Three main issues are especially important for the treatment: febrile seizures are extremely upsetting for the parents the recurrence rate is 30-40% the febrile status occurs unpredictably and is potentially damaging to the CNS

22 Acute management Control of the ongoing seizure Treatment of the fever preferably with external cooling and paracetamol Treatment of the underlying illness

23 Management of continuing seizure Placement in the recovery semi-prone lateral position Adequate airway should be maintained Benzodiazepines, usually diazepam is the first choice: rectally in solution at seizure onset 0.5mg/kg/dose or intravenously 0.3 mg/kg/dose or midazolam buccally Seizures are controlled more quickly with intravenous diazepam than with intranasal midazolam, although midazolam is as safe as diazepam

24 Prophylaxis of recurrence Two types of prophylactic treatment : Intermittent prophylaxis given at the first sign of a febrile illness (0.3 mg/kg/dose Diazepam t.d.s) Continuous prophylaxis by administering daily anticonvulsant drugs

25 Continuous prophylaxis Children with high risk for recurrence are good candidates (complex FS or onset before 1 year of life) Usually maintained for 1 year : a vast majority of recurrences take place within 1 year of the first seizure severe seizures occur mainly in younger infants Phenobarbitone (3 mg/kg/d) blood level of around 15 µg Sodium valproate reduces recurrences by about two-thirds

26 Side effects of continuous prophylaxis Acute poisoning in the child or siblings Abrupt discontinuation provoking seizures The interactions with other medications The interference with calcium-phosphorus metabolism Phenobarbital side effect on behavior and I.Q

27 Conclusions Differencial diagnosis: bacterial meningitis, viral encephalitis Distinguish simple/complicated FS Risk factors: HH syndrome, Dravet syndrome, mesial temporal lobe epilepsy Treatment restricted to complicated/early onset FS Intermittent (benzodiazepine) And/or continuous (valproate)

28 Stiripentol in Dravet syndrome Double blind, multicentric Placebo Stiripentol % Responders Seizure frequency Seizure cessation Placebo Stiripentol p 5% 71% < /mths 6.5/mths <

29 Treatment of Dravet syndrome Avoid carbamazepine, phenobarbital, phenytoin, vigabatrin and lamotrigine Valproate after the first seizure (complex, first year of life) Preventive treatment of seizures in case of fever, with diazepam Clobazam and Stiripentol are added after the first prolonged seizure or repeat seizures