Seizures, Neonatal

Description

Diagnostic criteria

General and supportive measures

Medicine treatment

Referral

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ICD-10 code: P90

DESCRIPTION

Neonatal seizures are usually secondary to a serum biochemical disorder or an underlying brain disturbance/injury/malformation. Seizures may be subtle due to the relatively underdeveloped cortex. Seizures persist when limbs are flexed (as opposed to jitteriness).

The most likely causes are:        

• perinatal asphyxia,
• hypocalcaemia,
• birth trauma,
• hypomagnesaemia,
• intracranial haemorrhage,
• hyponatraemia,
• meningitis,
• narcotic or alcohol withdrawal syndrome,
• hypoglycaemia,
• inborn errors of metabolism,
• pyridoxine deficiency, and
• CNS developmental abnormalities.

DIAGNOSTIC CRITERIA

Categories of convulsions

• Subtle seizures:
  • tonic deviation of the eyes,
  • ‘swimming’ movements of the arms,
  • fluttering of the eyelids,
  • ‘cycling’ movements of the legs,
  • sucking and chewing movements,
  • apnoea,
  • vasomotor changes.
• Tonic clonic movements.
• Focal clonic movements.
• Myoclonic movements.
• Tonic movements/posturing.

GENERAL AND SUPPORTIVE MEASURES

• Identify and treat the underlying cause, e.g. meningitis and hypoxic-ischaemic encephalopathy.
• Ensure an open airway and administer oxygen, if necessary.
• Nurse in neutral thermal environment.
• Ensure adequate nutrition and hydration.
• Monitor and maintain within accepted physiological range:
  • respiration,
  • acid-base status,
  • heart rate,
  • electrolytes,
  • blood pressure,
  • minerals,
  • blood gases,
  • blood glucose,
  • SaO₂,
  • haematocrit,
  • body temperature.    

MEDICINE TREATMENT

Seizure Control

Administer anticonvulsants with monitoring of cardiorespiratory function.

Phenobarbitone

• Phenobarbitone, IV.
  • Loading dose: 20 mg/kg administered over 10 minutes.
  • Refractory seizures: Additional 10 mg/kg/dose up to 40 mg/kg.

Maintenance:

• Phenobarbitone, IV or oral
  • 4 mg/kg/day beginning 12–24 hours after the loading dose.

Seizures refractory to phenobarbitone, should be admitted to a high or intensive care unit.

Cardiorespiratory support is usually required in this category of infants.

For seizures refractory to phenobarbitone use:

• Midazolam, IV.
  • Loading dose: 0.05 mg/kg IV over 10 minutes.
  • Followed by a continuous infusion of 0.03-0.3 mg/kg/hour

OR

• Lidocaine (lignocaine)

For term normothermic neonates:

• Lignocaine (lidocaine), IV.
  • Loading dose: 2 mg/kg administered over 10 minutes.
  • Follow with a continuous infusion of:
        6 mg/kg/hour for 6 hours, then,
        4 mg/ kg/hour for 12 hours, then,
        2 mg/kg for 12 hours.
  • If seizures are well controlled, slow taper lignocaine (lidocaine) over 12 hours.

For preterm neonates:

• Midazolam, IV.
  • Loading dose: 0.05 mg/kg IV over 10 minutes.
  • Followed by a continuous infusion of 0.03–0.3 mg/kg/hour.

OR

A safe dose of lidocaine (lignocaine) in preterm neonates has not been established but the following dosing schedule has been used.

• Lidocaine (lignocaine), IV.
  • Loading dose: 2 mg/kg administered over 10 minutes.
  • Follow with a continuous infusion of 3 mg/kg/hour for 3 days.
  • Gradually taper lidocaine (lignocaine) over next 2 days.

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CAUTION
Do not use lidocaine (lignocaine) if phenytoin was given. Do not use lidocaine (lignocaine) for seizures in newborns with congenital heart disease, dysrhythmias, acute heart failure and shock.

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- A safe lidocaine (lignocaine) dosing regimen for term infants undergoing hypothermia treatment for hypoxic ischaemic encephalopathy has not been established. - Clearance of lidocaine (lignocaine) is slower in hypothermic neonates and preterm infants. There is a risk of accumulation. - Start tapering earlier than 3 days if seizures are well controlled. - Continuous monitoring of ECG, heart rate and blood pressure is mandatory if lidocaine (lignocaine) is used. - Dysrhythmias and bradycardia are the main side effects of lidocaine (lignocaine). Life threatening dysrhythmias may indicate lidocaine (lignocaine) toxicity.

Lignocaine (lidocaine) toxicity:

• Lipid emulsion 20%, IV, 1.5 mg/kg administered over 1 minute.
  • Follow with a continuous infusion of 0.25 mL/kg/minute for 30 minutes. (See: Referral section below.)

Pyridoxine deficiency:

• Pyridoxine, IV/IM, 20 mg/kg.

Maintenance anticonvulsant therapy

• Maintenance anticonvulsant therapy is usually considered for neonates with underlying brain damage due to hypoxic-ischaemic encephalopathy, meningitis, intracranial haemorrhage or birth trauma.
• Continue until neonate is seizure-free for 2 weeks, then slowly taper to stop.
• If seizures recur during tapering of anticonvulsant therapy, continue with maintenance therapy.
• Follow-up by medical practitioner or at clinic/hospital after discharge.

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Note:
Patients with head or whole body cooling should have an adjustment of the anticonvulsant doses.

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Hypocalcaemia

Serum total calcium ≤ 1.8 mmol/L, or ionized calcium < 0.7 mmol/L.

• Calcium gluconate 10%, IV, 100–200 mg/kg/dose administered over 10 minutes.
  • Dilute 1:4 with dextrose 5% water.
  • Administer under ECG monitoring over 5 minutes (preferred) or until seizure ceases.  Repeat if necessary.
    (1 mL of 10% calcium gluconate = 100 mg calcium gluconate)

Hypoglycaemia

Serum glucose < 2.6 mmol/L.

• Dextrose, IV as bolus, 250–500 mg/kg.
  • Follow with 6–12 mg/kg/minute or more until blood glucose is within the physiological range. (10% Dextrose = 10g dextrose/100 mL).

Hypomagnesaemia

Serum magnesium < 0.6 mmol/L.

• Magnesium sulphate 50%, IV, 0.25 mL/kg administered slowly over 3 minutes as a single dose.

REFERRAL

• Seizures not responding to adequate therapy.
• Seizures where the underlying cause is unclear.
• Refractory cases for further treatment and aEEG monitoring.
• Lidocaine (lignocaine) toxicity.

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Standard Treatment Guidelines And Essential Medicines List For South Africa, Hospital Level, Paediatrics, 2023 Edition

Chapter  19: Prematurity And Neonatal Conditions,  19.6 Neurological, 19.6.2 Seizures, Neonatal