A subdural effusion is a collection of fluid trapped between the surface of the brain and the outer lining of the brain (the dura matter). If this fluid becomes infected, the condition is called a subdural empyema.

A subdural effusion is a rare complication of bacterial meningitis. Subdural effusion is more common in infants and in persons who have meningitis caused by Haemophilus influenzae.

• Bulging fontanelles in babies
• Increased head circumference
• Lethargy
• Persistent fever
• Seizures
• Separated sutures in babies
• Vomiting
• Weakness or loss of movement on both sides of the body

The doctor or nurse will examine you. Tests include:

• CT scan of the head
• Head size (circumference) measurements
• MRI scan of the head
• Ultrasound of the head

Surgery to drain the effusion is often necessary. Rarely, a permanent drainage device (shunt) is needed to drain fluid. Antibiotics may need to be given through a vein.

Full recovery from a subdural effusion is expected. If neurological problems continue, they are generally due to the meningitis, not the effusion. Long-term use of antibiotics is usually not necessary.

Complications from surgery include:

• Bleeding
• Brain damage
• Infection

Call your health care provider if:

• Your child has recently been treated for meningitis and symptoms continue
• New symptoms develop

Koshy A, Roos K. Infections of the nervous system: bacterial and fungal. In: Daroff RB, Fenichel GM, Jankovic J, Mazziotta JC, eds. Bradley’s Neurology in Clinical Practice. 6th ed. Philadelphia, Pa: Saunders Elsevier; 2012:chap 53C.

Swartz MN, Nath A. Meningitis: bacterial, viral, and other. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 420.