7.3 Neonatal Seizures & Intraventricular Hemorrhage (IVH)

Neonatal Seizures & Intraventricular Hemorrhage (IVH)

Neonatal Seizures

Neonatal seizures represent abnormal, paroxysmal electrical discharge within the newborn brain. They are a clinical manifestation of an underlying neurological insult rather than a disease in themselves. Common etiologies include hypoxic-ischemic encephalopathy (HIE), focal ischemic stroke, intracranial hemorrhage, meningitis, electrolyte disturbances (hypoglycemia, hypocalcemia), or genetic/metabolic disorders.

Classification of Seizure Types

Neonatal seizures differ from older child seizures because the newborn brain is immature, lacking myelination and dendritic branching needed to propagate generalized tonic-clonic activity.

• Subtle Seizures: The most common type in both term and preterm infants. They present as subtle behavioral or autonomic deviations. Ocular signs include sustained horizontal eye deviation, staring, or repetitive blinking/fluttering. Oral-facial movements include lip smacking, sucking, chewing, or tongue thrusting. Motor movements include 'swimming' or 'rowing' of the arms, and 'pedaling' or 'cycling' of the legs. Autonomic fluctuations may present as sudden apnea, bradycardia, or spikes in blood pressure.
• Clonic Seizures: Rhythmic, repetitive jerking of a limb or muscle group, typically at a rate of 1 to 3 times per second. They can be focal (involving one limb or one side of the body) or multifocal (migrating from one muscle group to another). These movements cannot be suppressed by holding or repositioning the limb.
• Tonic Seizures: Sustained, non-rhythmic posturing or stiffening of a limb, neck, or trunk. They can be focal (sustained posturing of a single limb) or generalized (bilateral stiffening, decerebrate posturing).
• Myoclonic Seizures: Rapid, single or multiple non-rhythmic jerking of a limb or muscle group, typically affecting flexor muscle groups. They are often associated with severe, diffuse encephalopathy.

Seizure vs. Jitteriness

Distinguishing neonatal seizures from benign jitteriness is a critical clinical skill.

Diagnosis

Continuous video electroencephalography (vEEG) is the gold standard for diagnosis. Bedside amplitude-integrated EEG (aEEG) is widely used for continuous screening. Notably, many neonatal seizures are subclinical (electrographic-only), showing abnormal electrical discharges without clinical motor manifestations. This electroclinical dissociation is common after the administration of anticonvulsants.

Pharmacological Treatment

• Phenobarbital: The first-line drug of choice. It acts as a gamma-aminobutyric acid (GABA-A) receptor agonist, enhancing inhibitory neurotransmission.
  • Loading Dose: 20 mg/kg IV administered slowly over 10 to 20 minutes. If seizures persist, additional doses of 5-10 mg/kg can be given up to a maximum cumulative dose of 40 mg/kg.
  • Maintenance Dose: 3 to 5 mg/kg/day IV or PO, divided once or twice daily, typically started 12 to 24 hours after the loading dose.
  • Nursing Considerations: High risk for respiratory depression, apnea, and systemic hypotension. Resuscitation equipment must be at the bedside. Monitor therapeutic drug levels (target range is 15 to 40 mcg/mL).
• Second-Line Agents: If phenobarbital fails, second-line agents include Levetiracetam (Keppra) (20-50 mg/kg load), which has a lower risk of respiratory depression and sedation, or Fosphenytoin (15-20 mg PE/kg load, requiring continuous EKG monitoring during infusion due to arrhythmia risk).
• Refractory Seizures: If seizures are resistant to standard therapies, a trial of pyridoxine (vitamin B6, 50-100 mg IV) is administered to rule out pyridoxine-dependent epilepsy.

Intraventricular Hemorrhage (IVH)

Intraventricular Hemorrhage (IVH) is a major complication of prematurity, primarily affecting infants born at or before 32 weeks' gestation or with a birth weight <1500 g.

Pathophysiology

The primary site of bleeding is the germinal matrix, a highly cellular, richly vascularized structure located in the subependymal region of the lateral ventricles. The blood vessels in this region are highly fragile, consisting of a single layer of endothelial cells lacking structural support (collagen, elastin, basement membrane). In addition, premature infants have impaired cerebral autoregulation ('pressure-passive' circulation), where cerebral blood flow fluctuates directly with changes in systemic blood pressure. Surges in systemic blood pressure, venous congestion, or rapid changes in osmolarity can easily rupture these fragile capillaries. Most hemorrhages (approx. 90%) occur within the first 72 hours of life.

IVH Grading Criteria

IVH is graded from I to IV using the Papile or Volpe classification based on cranial ultrasound findings:

• Grade I (Subependymal Hemorrhage): Bleeding is confined to the germinal matrix only, without extending into the lateral ventricles.
• Grade II (IVH without Ventricular Dilation): Blood enters the lateral ventricles, filling between 10% and 50% of the ventricular volume, but the ventricles remain normal in size.
• Grade III (IVH with Ventricular Dilation): Blood fills more than 50% of the lateral ventricles, causing active dilation (distension) of the ventricles. This carries a high risk of post-hemorrhagic hydrocephalus.
• Grade IV (Parenchymal Involvement): Hemorrhage extends into the surrounding cerebral parenchyma (white matter). This is typically caused by venous obstruction of the medullary veins, leading to a periventricular hemorrhagic infarction (PVHI). It carries a high risk of long-term motor deficits (spastic diplegia or hemiplegia) and cognitive impairment.

Clinical Presentation

• Catastrophic Deterioration: Rapid onset over minutes. Signs include a bulging fontanelle, hypotonia, stupor/coma, decerebrate posturing, non-reactive pupils, apnea, bradycardia, shock, metabolic acidosis, glucose instability, and a sudden drop in hematocrit.
• Silent (Subclinical) Presentation: Gradual or asymptomatic presentation. Often detected only during routine screening head ultrasound.

HUS Screening Protocol

Screening head ultrasound (HUS) is routinely performed on all infants born at or before 32 weeks' gestation. The first scan is typically performed between 7 and 10 days of life to detect the peak incidence of IVH, or earlier if the infant exhibits acute clinical deterioration.

IVH Prevention Bundle (Nursing Care Priorities)

Because there is no treatment to reverse IVH, clinical care focuses on prevention through a standardized neuroprotective bundle during the first 72 hours of life:

1. Antenatal Corticosteroids: Administered to mothers at risk of preterm delivery. This accelerates the structural maturation of the germinal matrix blood vessels, significantly reducing the incidence of IVH.
2. Delayed Cord Clamping (30-60 seconds): Stabilizes neonatal blood pressure, reduces systemic hypotension, and minimizes the need for early volume expansion or inotropic support.
3. Midline Head Positioning: Keep the infant's head in a neutral midline alignment, with the head of the bed elevated 15 to 30 degrees for the first 72 hours. Avoid lateral neck rotation or neck flexion, which compress the jugular veins, impede cerebral venous drainage, and cause cerebral venous congestion.
4. Avoid Rapid Volume Expansion: Administer normal saline boluses, blood products, or medications slowly (over 20-30 minutes) to prevent sudden surges in arterial blood pressure and cerebral blood flow.
5. Minimize Pain and Handling: Cluster nursing care, handle the infant gently, and provide adequate sedation/analgesia for painful procedures. Avoid routine, aggressive endotracheal suctioning without sedation. Avoid lifting the legs above the head during diaper changes, as this increases abdominal pressure and venous congestion.
6. Avoid Hyperosmolar Infusions: Infuse hyperosmolar medications (such as sodium bicarbonate) slowly and only when diluted 1:1 with sterile water to prevent rapid shifts in intravascular volume.