Febrile Seizures

DISCUSSION POINTS (NCBI – Febrile seizures)

It is confirmed that Lucy has had complex febrile seizures (with concerns of meningitis) since she has had focal symptoms and the symptoms at presentation to ED. Hence a detailed history and examination with investigations is needed for the child. Incidence of meningitis in children presenting with febrile seizures is around 2-5%.

History includes:

• details of the diarrhea and vomiting and any other associated symptoms
• relationship of the fever to the seizures
• seizure semiology (focal followed by generalised)
• duration of the post-ictal drowsiness
• any pre-treatment with antibiotics
• past medical history (any previous similar episodes)
• developmental milestones (abnormal in this case )
• immunisation status, known allergies, any recent travel or exposure (mainly meningitis in this case) 
• family history of seizures (paternal aunt has had febrile seizures as a child)

Examination includes:

• head to toe examination – including vital signs and skin examination for non-blanching rashes and presence of any neurocutaneous stigmata (port wine stain, cafe-au-lait spots etc)
• hydration status of the child (consider electrolyte imbalance as one of the probable causes of the seizures)
• detailed neurological examination – for any signs of meningism and any focal/lateralizing signs 

Investigations includes:
NICE – Meningitis and meningococcal septicemia in under 16s + NCBI – Febrile seizures + ALIEM – LP after febrile seizures

• Capillary blood gas – check the acid base status, blood glucose and electrolytes
• Full blood count
• CRP
• Renal function tests – including electrolytes (sodium, potassium, chloride, calcium, magnesium and phosphorus)
• Stool cultures – to determine the cause for D&V
• Blood cultures
• Lumbar puncture – It is not indicated for all cases of simple or complex febrile seizures.

Indications for LP in simple febrile seizures are:

• There are signs or symptoms of meningitis after the seizure
• If the child is not fully immunized or immunization status is unknown  (H. influenza type b or S. pneumonaie)
• If the patient has been pretreated with antibiotics, because this may mask signs and symptoms of meningitis

LP to be performed in children with complex febrile seizures who appear unwell and show signs and symptoms of meningitis or encephalitis (prolonged post ictal phase, irritability, excessive drowsiness, neck rigidity, positive Kernig’s and Brudzinski’s sign, focal neurological deficits)

CSF examination should include white blood cell count and examination, total protein and glucose concentrations, Gram stain and microbiological culture.

Contraindications for LP are:

• signs suggesting raised intracranial pressure
  • reduced or fluctuating level of consciousness (Glasgow Coma Scale score less than 9 or a drop of 3 or more)
  • relative bradycardia and hypertension
  • focal neurological signs
  • abnormal posture or posturing
  • unequal, dilated or poorly responsive pupils
  • papilloedema
  • abnormal ‘doll’s eye’ movements
• shock
• extensive or spreading purpura
• after convulsions until stabilised
• coagulation abnormalities
  • coagulation results (if obtained) outside the normal range
  • platelet count below 100 x 109/litre
  • receiving anticoagulant therapy
• local superficial infection at the lumbar puncture site
• respiratory insufficiency (lumbar puncture is considered to have a high risk of precipitating respiratory failure in the presence of respiratory insufficiency
• Neuroimaging – CT scan to be performed in children  with a reduced or fluctuating level of consciousness (GCS < 9 or a drop of 3 or more), with focal neurological signs to detect alternative intracranial pathology. (cerebral abscess, tubercular meningitis, traumatic injuries), with suspected structural defects of the brain or with abnormally large heads. 
• Raised intracranial pressure to be determined clinically rather than by CT scan. However, if radiological evidence of raised intracranial pressure is seen, do not perform lumbar puncture.
• EEG – Children with complex febrile seizures (and no other risk factors) have a 5-6 fold increased risk of developing epilepsy. In this case, an EEG may be used as a means of establishing prognosis for development of epilepsy.
• If performed should be at least 48 hrs after the complex febrile seizures to avoid confusing post-ictal electrical activities with abnormal electrical activities.

Treatment:

IV hydration – based on percentage of dehydration and the calculated water deficit

Ceftriaxone – IV or IM

IV aciclovir

Management of active seizures in the ED:

• Airway assessment and management  – confirm and protect the airway. Start the child on high flow oxygen via the non-rebreather mask. 
• Monitor the duration of the seizures 
• Protect the child from injury during the seizures 
• Termination of  prolonged seizures (longer than 5-10 mins) – with appropriate rescue medications (IV / IM / buccal diazepam,midazolam or lorazepam)
• Post-termination of seizures – assess airway, breathing, circulation and disability – if still drowsy (after post-ictal period) and GCS is low and  – you need to intubate

Recurrence and risks of epilepsy in complex febrile seizures:

There is a 30% chance of recurrence. Risk factors for recurrence are: onset before 18 months of age, shorter duration of fever (< 1hr) before onset of seizures, lower temperature threshold (around 38⁰), going to child care, multiple seizures in one illness and family history of febrile seizures.

The risk of developing epilepsy is between 5-15% in case of complex febrile seizures, multiple or prolonged febrile seizures, family history of epilepsy, presence of neurodevelopmental abnormality, shorter duration of fever (<1 hour) before the seizure, an onset of febrile seizures before the age of 1 year or after the age of 3 years and epileptiform discharges on EEG. The risk increases up to 50% in presence of more than one risk factor.

This is a case of febrile status epilepticus probably secondary to herpes encephalitis.(h/o fever, irritability and presence of cold sores)

Treatment plan for status epilepticus:
(NICE – protocol for convulsive status epilepticus)

Step 1: (0 mins)

• Assess and maintain airway, breathing and circulation + high-flow O2 by non-rebreather mask
• Prevent injuries during the seizures
• IV access + blood glucose levels

Step 2: (5 mins)

• Administer – midazolam (0.5mg/kg buccally stat) or Lorazepam (0.1mg/kg IV stat)
• Midazolam may be given by parents, carers or ambulance crew in non-hospital setting

Step 3: (15 mins)

• Administer lorazepam (0.1 mg/kg IV stat)

Step 4: (25 mins)

• administer phenytoin (20 mg/kg IV infusion over 20 minutes) or paraldehyde ( 0.8 ml/kg of mixture PR)
• if already on phenytoin, administer phenobarbital (20 mg/kg IV infusion over 5 mins)
• inform the intensive care team and the anesthetic team with the probability of needing to continue to the next step if the seizures do not cease.

Step 5: (45 mins)

• Rapid sequence induction of anaesthesia using thiopental sodium (4 mg/kg IV stat followed by IV infusion)
• the child needs to be transferred to Paediatric intensive unit

Investigations includes:
NICE – Meningitis and meningococcal septicemia in under 16s + NCBI – Febrile seizures + BMJ – Neonatal and childhood herpes encephalitis

• Capillary blood gas – check acid-base status, blood glucose and electrolytes
• Full blood count
• CRP
• Renal function tests – including electrolytes (sodium, potassium, chloride, calcium, magnesium and phosphorus)
• Blood cultures
• Lumbar puncture – indicated in this case. 

Children produce around 0.35mL/kg/ hr of CSF. Hence upto 0.2mL/kg CSF can be taken for investigations.

CSF examination includes measuring the opening pressures using a manometer,  white blood cell count and examination, total protein and glucose concentrations, bacterial screen (Gram stain and microbiological culture and sensitivity) and  viral screen (PCR for herpes simplex virus (HSV-1 and HSV-2), VZV, enterovirus, parechovirus, EBV, HHV6 and mumps)

• Neuroimaging – CT scan with contrast  (to look for any space occupying lesions / other causes of raised ICP) + MRI (diagnostic of encephalitis) 
• EEG – not indicated in this case unless there is diagnostic uncertainty even after lumbar puncture and MRI

Treatment
BMJ – Neonatal and childhood herpes encephalitis

• IV hydration
• IV aciclovir – for 21 days . Dosages as follows:
  • birth to 3 months of age – 20 mg/kg TDS
  • 3 months to 12 yrs of age – 500 mg/m2 TDS
  • more than 12 yrs of age – 10 mg/kg TDS
• broad spectrum IV antibiotics

Recurrence of the seizures and treatment of recurrence:
NCBI- Febrile seizures

There is a 30% chance of recurrence. Risk factors for recurrence are: onset before 18 months of age, shorter duration of fever (< 1hr) before onset of seizures, lower temperature threshold (around 38⁰), going to child care, multiple seizures in one illness and family history of febrile seizures.

Rescue benzodiazepines may be considered for children presenting with multiple or prolonged seizures, those with high risk of recurrence or who have poor access to medical care. Intermittent therapy with oral or rectal diazepam or nasal  or buccal midazolam at the onset of a febrile illness may be considered. There is no evidence to show continuous antiepileptic treatment to prevent recurrence.

Recurrence of herpes encephalitis and treatment:
BMJ – Neonatal and childhood encephalitis

Reactivation of herpes simplex virus may occur at later stage of life manifesting with dermatological or neurological symptoms.

Prophylaxis with oral aciclovir (for neonates) and oral valaciclovir (for older children) is recommended for up to 3 months (for immunocompetent children) and up to 12 months (for immunocompromised children).