Subdural hematomas may produce macrocephaly during the neonatal period. Progressive increases in head circumference may be noted during the third week of life. Subdural hematomas present with irritability or hyperalertness, or with signs of focal cerebral disturbances such as seizures, hemiparesis, or gaze preference. The causes of subdural hematomas are trauma and coagulation disorders. Subdural hematoma is diagnosed by CT of the brain. More about... 53, 250

Patients with benign enlargement of the subarachnoid space are usually not born macrocephalic; however, some patients with this condition may have excessive head growth during the neonatal period. The presence of bilateral enlarged frontal subarachnoid spaces (>5.7 mm), widening of the Sylvian fissure (>7.6 mm) and other sulci, and normal or minimally enlarged ventricles establishes the diagnosis. The anterior fontanelle is large and soft to palpation. Family members, most often the father, may also have a large head.