Porencephaly refers to –
Porencephaly Refers to the presence of cysts or cavities within the brain, that may results from

Developniental defects (True porencephalic cysts).
Acquired lesions of infarction of tissues.        (i.e. Vascular lesions) - AV malformation or infarcts or (Pseudo-porencephalic cysts).

Defects of NeuronalMigration : malformations of cortical development
Lissencephaly        -          Also called agyria
Characterized by absence of cerebral convolutions and poorly formed sylvian fissure giving the appearance of 3-4 months fetal brain.
Schizencephaly       -        Presence of unilateral or bilateral clefts within the cerebral hemisphere due to an Abnormality of morphogenesis
Porencephaly        -          Presence of cysts cavities within the brain that result from developmental defects or acquired lesions including infarction of tissue.
Holoprosencephaly   -     Developmental disorder of brain that results from defective cleavage of prosencephalon.
Foetal alcohal syndrome
Dandy-walker-syndrome
Vascular lesion due to degenerative vessel disease and head injury
Neural tube defects