Neonatal Seizures

• Seizures are often associated with significant illnesses, and at times, they necessitate specific therapy.
• Seizures can disrupt cardiorespiratory function and interfere with nutrition, potentially leading to adverse long-term effects on cerebral development.
• Neonatal seizures are the most common overt manifestation of neurological dysfunction in newborns, making them a frequent neurological emergency.
• A key point to remember is that a seizure in a newborn is not a standalone diagnosis; it is always secondary to an underlying factor.

Definition

• A neonate refers to a newborn baby, specifically within the first four weeks after birth.
• The neonatal period is confined to the first 28 days for term infants.
• A seizure is characterized by paroxysmal behavior resulting from the hyper synchronous discharge of a group of neurons.
• It presents as a stereotypic, paroxysmal spell involving altered neurologic function, including behavior, motor activity, and/or autonomic function.

• Neonatal seizures occur in up to 1.4% of term babies and 20% of preterm babies.
• The overall incidence is approximately 1-3 per 1000 live births for term babies and 10-15 per 1000 live births for preterm babies.
• Most neonatal seizures tend to happen within the first 1-2 weeks of life.
• The incidence of seizures is higher in the neonatal period compared to any other age group.

Neonates often exhibit unusual presentations of seizures due to:

• Immature central nervous system that cannot sustain a synchronized, well-orchestrated generalized seizure.
• Lack of myelination and incomplete formation of dendrites and synapses in the brain.

I. Clinical Seizure:

• Subtle
• Tonic
• Clonic
• Myoclonic

II. Electroencephalographic Seizure:

• Epileptic
• Non-epileptic

Clinical Classification

Subtle Seizure:

• Most frequent neonatal seizures
• Accounts for about 50% of seizures seen in the newborn
• More common in preterm than in term babies
• Eye deviation (term)
• Blinking, fixed stare (preterm)
• Repetitive mouth and tongue movements
• Apnea
• Pedaling and tonic posturing of limbs

Tonic Seizure:

• Primarily in preterm babies
• May be focal or generalized
• Sustained extension of the upper and lower limbs (mimics decerebrate posturing)
• Sustained flexion of upper with extension of lower limbs (mimics decorticate posturing)
• Signals severe intracranial hemorrhage (ICH) in preterm infants

Clonic Seizure:

• Primarily in term babies
• Focal or multifocal
• Clonic limb movements (synchronous or asynchronous, localized or often with no anatomic order of progression)
• Consciousness may be preserved
• Signals focal cerebral injury

Myoclonic Seizure:

• Rare, usually affecting a specific group of muscles
• Focal, multifocal, or generalized
• Lightning-like jerks of extremities (upper > lower)

1. PERINATAL PROBLEMS:
   • Perinatal asphyxia
     • Commonest cause of seizures, especially in the first 72 hours of life
   • Intracranial haemorrhage
     • Intraventricular haemorrhage
     • Mainly affects the lateral ventricle
     • Primarily a problem of preterm babies <34 weeks
   • Subarachnoid haemorrhage
     • Occur in term babies
   • Subgleal haemorrhage
   • CNS trauma from birth trauma
     • May lead to skull fracture or cerebral contusion
2. METABOLIC:
   • Hypoglycemia
   • Hypocalcemia
   • Hyponatremia
   • Hypernatremia
   • Hypomagnesemia
   • Pyridoxine deficiency
     • Common in babies with mothers on INH
   • Pyridoxine-dependent state
   • Inborn errors of metabolism
3. INFECTIONS:
   • Sepsis
   • Meningitis
   • Encephalitis
   • Congenital infections (TORCHES)
4. CNS ANOMALY:
   • Cerebral dysgenesis
   • Neurocutaneous syndromes
     • Tuberous sclerosis
     • Incontinentia Pigmenti
     • Sturge Weber
5. DRUGS:
   • Drug withdrawal
   • Mothers on illicit drugs (e.g., heroin, cocaine)
6. OTHERS:
   • Benign familial neonatal seizure
     • Rare autosomal dominant inherited form of seizure
     • Exact pathophysiology is unknown
     • Manifests within the first 7 days of life as tonic clonic seizure
     • Infants are otherwise normal between attacks and develop without incident
     • Attacks normally spontaneously cease within the first 15 weeks of life
     • Increased lifetime susceptibility to seizures
   • Polycythemia

Jitteriness is a phenomenon characterized by the following features:

• Not accompanied by abnormal eye movements
• May be spontaneous or stimulus-sensitive
• Similar to clonic seizures but with fine and very rapid movements
• Can be stopped by passive flexion or repositioning of the affected body part
• Normal EEG findings

Evaluation

The aim of the evaluation is to identify the underlying cause of the seizure. The following aspects should be considered:

History:

• Ask about the seizure – how it started, frequency, and any interventions
• Pregnancy history is important
• Search for history that supports TORCH infections
• Consider history of fetal distress, preeclampsia, or maternal infections
• Delivery history:
  • Type of delivery and antecedent events
  • Apgar scores can offer guidance
  • Low Apgar score without the need for resuscitation and subsequent neonatal intensive care is unlikely to be associated with neonatal seizures
• Postnatal history:
• Neonatal seizures in infants without uneventful antenatal history and delivery may result from postnatal causes
• Tremulousness may be secondary to drug withdrawal or hypocalcemia
• Temperature and blood pressure instability may suggest infection

During the evaluation of neonatal seizures, a thorough physical examination is essential. Consider the following aspects:

• In neurocutaneous syndromes, check for cutaneous manifestations
• For meningitis:
  • Check the anterior fontanelle
  • Assess for fever
• Polycythaemia may present with a plethoric appearance of the baby

During the evaluation of neonatal seizures, a range of investigations is important to determine the underlying cause. Consider the following tests:

• Complete blood count, including differential and platelet count
• Urinalysis
• Blood glucose measurement
• Measurement of blood urea nitrogen (BUN), calcium (Ca), phosphorus (P), magnesium (Mg), and electrolytes
• Blood oxygen and acid-base analysis
• Blood, cerebrospinal fluid (CSF), and other bacterial cultures
• CSF analysis
• ELECTROENCEPHALOGRAPHY (EEG) is essential in the diagnosis and management of neonatal seizures.
• Cranial ultrasound (USS) – for detecting intraventricular hemorrhage (IVH)
• Skull X-ray – to assess birth trauma
• NEUROIMAGING: Imaging the brain is essential in determining the etiology of neonatal seizures.
  • CT scan is effective for determining the presence of hemorrhage and calcification (e.g., congenital infection, cortical dysplasia).
• Clinical Suspicion of Specific Disease: In cases where specific diseases are suspected, consider additional tests such as:
  • Serum immunoglobulins, TORCH antibody titers, and viral cultures
  • Blood and urine metabolic studies (bilirubin, ammonia, lactate, reducing substance)
  • Blood and urine toxic screen
  • Blood and urine amino and organic acid screen

1. Neonatal seizures require urgent treatment to prevent brain injury.
   • Give anticonvulsant medication only after adequate ventilation and perfusion have been established and the blood glucose concentration has been measured. Seizures with hypoglycemia or hypoxia are detrimental to the brain!
   • Abort seizure with paraldehyde
   • Use phenobarbitone or sodium phenytoin
2. Ensure adequate ventilation and perfusion.
3. Correct metabolic disturbances.
   • Hypoglycemia: (10% glucose in water) 2ml/kg IV (0.2 g/kg) as bolus. Follow with continuous infusion at up to 8 mg/kg/min IV
   • Hypocalcemia: (calcium gluconate 10%) 100mg/kg IV over 1 to 3 minutes (Note: Monitor cardiac rhythm for bradycardia). Follow with maintenance of 500 mg/kg/24 hrs IV or PO
   • Hypomagnesemia: (magnesium sulfate) 25-250 mg/kg/dose IV/IM

The outcome following neonatal seizures depends primarily on the underlying cause.

The presence of both clinical and electrographic seizures in the newborn often indicates some degree of brain injury and may alter the prognosis of the underlying disease.

• Cerebral palsy
• Hydrocephalus
• Epilepsy
• Spasticity
• Feeding difficulties