What are the causes of raised intracranial pressure (ICP) in neonates?

Causes of Raised Intracranial Pressure in Neonates

The main causes of raised intracranial pressure (ICP) in neonates include intracranial hemorrhage, central nervous system abnormalities, cerebral sinovenous thrombosis, hydrocephalus, infections, and systemic conditions affecting cerebral perfusion. 1

Intracranial Hemorrhage

• Intraventricular hemorrhage (IVH) is a common cause of increased ICP in neonates, particularly in premature infants 1
• Spontaneous intraparenchymal hemorrhage, though rare in full-term newborns, can cause significant mass effect and elevated ICP 2
• Subdural and subarachnoid hemorrhages may lead to increased ICP, with varying pathophysiology 3
• Hemorrhagic infarction complicates cerebral sinovenous thrombosis in approximately 40% of cases, more frequently in neonates (72%) than in older children (48%) 4

Vascular Anomalies

• Arteriovenous malformations (AVMs) can cause hemorrhage and subsequent increased ICP 4
• Cavernous malformations carry a substantial risk of hemorrhagic stroke 4
• Venous angiomas and capillary telangiectasias are less commonly associated with ICH and raised ICP 4
• Vein of Galen aneurysmal malformation can cause hydrocephalus through aqueductal compression 4

Cerebral Sinovenous Thrombosis

• Cerebral sinovenous thrombosis has an incidence of 1/200,000 children per year, with neonates accounting for 61% of cases 4
• Risk factors include dehydration, infection, trauma, cancer, and prothrombotic disorders 4
• Can cause elevation in venous pressure, increased intracranial pressure, and venous infarction 4
• The lateral dural venous sinuses (73%) and superior sagittal sinus (35%) are most commonly affected 4

Infections

• Meningitis can cause elevated ICP in neonates 4, 5
• Central nervous system infections may lead to increased ICP through various mechanisms including cerebral edema, hydrocephalus, or cerebral venous thrombosis 1
• HIV infection has been associated with acquired complete AV block and potential ICP elevation 4

Hydrocephalus

• Post-hemorrhagic ventricular dilatation (PHVD) following IVH 1
• Congenital malformations affecting CSF circulation 1
• Hydrocephalus associated with intracranial hemorrhage has worse outcomes 1

Systemic Conditions

• Hypothermia can cause sinus bradycardia and potentially affect cerebral perfusion 4
• Hypopituitarism may lead to altered cerebral blood flow regulation 4
• Obstructive jaundice can affect brain function and potentially ICP 4
• Hypovolemia and dehydration can affect cerebral perfusion and venous drainage 1

Clinical Signs of Raised ICP in Neonates

• Progressive splaying of sagittal suture width (most reliable indicator) 1
• Bulging or tense fontanelle 1, 5
• Increasing orbitofrontal head circumference 1
• Apnea, bradycardia, lethargy, and decreased activity (though nonspecific) 1
• Altered consciousness level 1
• Abnormal eye movements 1
• Seizures, which may be subtle or subclinical in up to 25% of cases 1

Diagnostic Approach

• Cranial ultrasonography is the preferred initial imaging modality for diagnosing ICP in neonates 1
• Key ultrasonographic measurements include:
  • Levene ventricular index (horizontal measurement from midline falx to lateral aspect of anterior horn) 1
  • Anterior horn width (AHW) > 6 mm is generally considered abnormal 1
  • Thalamooccipital dimension > 26 mm and third ventricle width > 3 mm may indicate post-hemorrhagic ventricular dilatation 1
• MRI of the head and orbits is recommended for comprehensive evaluation when clinically stable 1, 4
• CT venography (CTV) or MR venography (MRV) should be performed when cerebral venous sinus thrombosis is suspected 4, 6

Management Considerations

• Position with head elevated at 20-30° to improve venous drainage 1
• Osmotic diuretics: Mannitol (0.5-1 g/kg IV) administered over 5-10 minutes can effectively lower ICP 1, 7
• Maintain adequate cerebral perfusion pressure (CPP) ≥ 60 mmHg while managing ICP 1
• Surgical evacuation of intraparenchymal hematoma may be necessary with significant mass effect or signs of elevated ICP 4, 2
• Ventricular drainage and shunting for progressive hydrocephalus caused by IVH 4
• Continuous monitoring of ICP via subdural catheter allows for immediate treatment initiation 8

Pitfalls and Caveats

• Relying solely on clinical signs may be unreliable in neonates 1
• Different pressure gradients may exist in and around hematomas versus distant areas 1
• Age-dependent normal values should be considered when interpreting ICP measurements 1
• Avoid rapid correction of PCO₂ in patients with metabolic acidosis and compensatory hyperventilation 1
• Indiscriminate use of sedatives may mask neurological deterioration 1