Delayed Intraventricular Pneumocephalus Following Shunting for Normal-Pressure Hydrocephalus

Pneumocephalus is usually seen in trauma or cranial surgery. It is rarely reported as a delayed complication of ventriculoperitoneal shunt placement for hydrocephalus secondary to trauma, tumor, or aqueduct stenosis. We describe a case of intraventricular pneumocephalus manifesting 10 months after placement of a shunt for normal-pressure hydrocephalus.

A pressure-regulated ventriculoperitoneal shunt was implanted in an 81-year-old patient after diagnosis of normal-pressure hydrocephalus. He showed postoperative clinical improvement. Routine computed tomography performed 2 months after the procedure showed no abnormalities. He presented 10 months after shunting with a subacute deterioration of gait. Imaging revealed major intraventricular pneumocephalus and a left-sided temporal porencephalic cyst with a small, bony defect in the left petrous bone. A middle fossa approach was performed, and the temporal defect was covered with fascia of the temporal muscle. This resulted in a gradual resolution of pneumocephalus.

Pneumocephalus after shunting for NPH is rare and described as a complication only during the first 2 postoperative months. This case is unique, as the pneumocephalus developed 10 months after shunting. The combination of an occult, possibly congenital, skull base defect and the insertion of a shunt resulted in delayed intraventricular and intraparenchymal pneumocephalus.