Absent Septum Pellucidum is a rare condition. The septum pellucidum is a thin, triangular, vertical double membrane separating the anterior horns of the left and right lateral ventricles of the brain. It is usually not seen as a isolated finding. Other symptoms may include learning difficulties, behavioral changes, seizures, and changes in vision. Some time the absence of the septum pellucidum is part of septo-optic dysplasia and the prognosis varies according to the presence and severity of associated symptoms.