Supratentorial volumn and pressure increasing factors

1) Swelling gyrus and basal ganglia caused by IAE

2) Intermittent chronic occlusion of the aqueduct resulting in gradual increase in ventricular pressure

3) Edema caused by vascular compression of the central herniation

Infratentorial volumn and pressure decreasing factors

Decreased volumn of the posterior fossa cystic space of PCH created the space and negative pressure gradient

Other

Idiopathic