Description

A subdural hematoma (SDH) is a collection of blood between the outer pial and inner dural meningeal layers. The bleeding is usually venous in origin, although either cortical arteries or bridging veins may be torn.

Epidemiology

• Heterogeneous causes; occur in all age groups
• Incidence in infants <1 year old estimated at 20 to 25/100,000

Risk Factors

• In infants and young children, SDHs are frequently the result of abusive head trauma.
• In older children, SDHs are often the result of motor vehicle collisions.
• Neonatal SDHs occur with spontaneous deliveries but may be more frequent following deliveries with forceps or vacuum extraction. SDHs related to birth usually resolve.
• Abusive head trauma
  • Risk factors for abusive head trauma include disability or prematurity of the child, unstable family situations, parents of young age, and low socioeconomic status.
  • One study found that fathers were the most frequent perpetrators, followed by boyfriends, female babysitters, and mothers, in descending order of frequency.
• Accidental trauma

General Prevention

• Parents should be counseled about appropriate methods to channel frustration and anger toward infants and children. Shaking an infant when the parent is angry is never appropriate.
• Bicycle helmets, car seats, and seat belts are all valuable in preventing head injuries in children.

Pathophysiology

• SDHs may be acute or chronic:
  • Arterial SDHs grow quickly, whereas venous SDHs may accumulate slowly, remaining undetected for weeks or months.
  • Acute SDHs contain blood, whereas chronic SDHs contain proteinaceous exudate and blood-breakdown products.
  • Rebleeding may be the underlying cause of many chronic SDHs.
• Significant force is usually required for SDH unless there are predisposing circumstances; SDH is only rarely due to trivial or minor trauma. However, SDH can occur with relatively minor trauma in individuals with bleeding disorders, children on chronic dialysis, and those with enlarged extracerebral spaces, arachnoid cysts, or cortical atrophy.
• SDHs in abusive head trauma may be due to the striking of the infant’s head against a surface (such as a mattress):
  • The sudden deceleration associated with the impact may tear bridging veins traveling in the subdural space.
• The term shaking-impact syndrome may be more accurate than shaken baby syndrome.

Etiology

• See “Risk Factors.”
• SDHs can also occur after ventricular shunting and extracorporeal membrane oxygenation (ECMO).

Commonly Associated Conditions

• Some metabolic disorders, such as glutaric aciduria type I and Menkes disease, can be associated with both acute and chronic SDHs.
• Victims of motor vehicle collisions with SDH may have other intracranial injuries such as diffuse axonal injury.
• Traumatic SDHs are often associated with cerebral contusions. Other associated injuries include skull fractures, diffuse axonal injury, and penetrating injuries.