Development of a cavum septi pellucidi after Ommaya reservoir placement: report of an unusual complication.

Objective and importance. We present a complication of Ommaya reservoir placement that has not been previously reported. Following injection of a seemingly appropriately placed catheter, the patient developed seizures. Imaging studies showed the development and resolution of a cavum septi pellucidi. This case illustrates that the septum pellucidum is made of two layers and that a potential space exists between these layers. Caution is recommended when injecting a single-hole ventricular catheter if the tip is against the septum pellucidum.