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Traumatic porencephalic cyst of the brain.

BACKGROUND
A porencephalic cyst is a cavity within the cerebral hemisphere, filled with cerebrospinal fluid, that communicates directly with the ventricular system. It is a rare condition probably caused by vascular occlusion resulting from an insult during fetal development or an injury occurring later in life. Porencephaly is often associated with various ophthalmic and neurologic signs, including visual-field defects, abnormal pupillary responses, optic nerve hypoplasia, decreased vision, nystagmus, strabismus, hemi-inattention, seizures, and mental deficiencies.


CASE REPORTS
Two cases are presented of patients in whom porencephalic cysts developed as a result of traumatic head injuries. Both had demonstrable visual-field defects, with diagnosis of porencephaly verified by computed tomography scans of the head.


CONCLUSIONS
Visual-field defects resulting from porencephalic cysts can mimic those observed with strokes or brain tumors. A thorough case history and complete neurologic workup can assist with differential diagnosis. The clinical features of porencephaly, different theories of brain recovery after trauma, and treatment options are discussed.