What are the causes of neonatal subarachnoid hemorrhage?

Causes of Neonatal Subarachnoid Hemorrhage

Neonatal subarachnoid hemorrhage (SAH) is most commonly caused by birth trauma and hypoxic-ischemic injury, with arteriovenous malformations, coagulopathies, and cerebral infarction representing other significant etiologies. 1

Primary Causes

Birth Trauma

• Traumatic delivery is a leading cause of neonatal SAH 1, 2
• Associated with:
  • Vacuum-assisted delivery 3
  • Forceps-assisted delivery 3
  • Difficult vaginal deliveries 2
• Often presents with seizures on the first day of life 2
• May show evidence of overlying soft-tissue swelling on imaging 3

Hypoxic-Ischemic Injury

• Severe hypoxic-ischemic encephalopathy is a major cause of diffuse SAH 2
• Associated maternal risk factors include:
  • Chorioamnionitis
  • Premature rupture of membranes
  • Preeclampsia
  • Placental insufficiency 1

Vascular Abnormalities

Arteriovenous Malformations (AVMs)

• Account for a significant percentage of hemorrhagic strokes in children 1
• More likely to be giant (>25mm) or fusiform in children compared to adults 1

Other Vascular Abnormalities

• Arteriovenous fistulas
• Cavernous malformations
• Aneurysms (though less common in neonates than older children) 1

Hematologic Disorders

Coagulopathies

• Congenital or acquired coagulation disorders 1
• Thrombocytopenia (accounts for approximately 6% of hemorrhagic strokes in children) 1
• Vitamin K deficiency (particularly in infants whose mothers took warfarin, phenytoin, or barbiturates during pregnancy) 4

Other Causes

Cerebral Venous Thrombosis

• Can lead to venous infarction with hemorrhagic transformation 1
• Incidence of 0.3 per 100,000 children per year, with neonates comprising 43% of cases 1

Focal Cerebral Infarction

• Can be associated with focal subarachnoid hemorrhage 2

Brain Tumors

• Account for approximately 15% of hemorrhagic strokes in children 1

Idiopathic

• Some cases occur without identifiable risk factors 2, 3
• May be related to local trauma with contusion or venous compression/occlusion 3

Anatomical Distribution

• Temporal lobe hemorrhages are common, particularly adjacent to the pterion 3
• Other locations include parietal lobe, frontal lobe, and areas near sutures 3
• Often associated with overlying soft-tissue swelling 3

Clinical Implications

• SAH in term neonates frequently presents with seizures (69%) or apnea (23%) 5
• Post-hemorrhagic hydrocephalus develops in approximately 19% of survivors, sometimes with delayed onset 5
• Among survivors, about 52% may be neurologically normal at follow-up 5
• Outcomes appear similar regardless of whether the etiology is hypoxic-ischemic or traumatic 5

Understanding these causes is crucial for proper diagnosis, management, and prognostication in neonates with subarachnoid hemorrhage.