[Two surgical cases of tectal glioma]

Tectal glioma is rare and difficult to diagnose, and the tumor has been known as the tumor that gives no indication of the need for direct surgery because of its anatomical location. At present, MR imaging is available to detect the tumor and its location. We present two patients who underwent direct surgery. Case 1: A 18-year-old female was admitted with headache and nausea. MRI showed signs of stenosis of the aqueduct and a tumor of the tectal region. The tumor was removed partially. Histological examination of this tumor demonstrated a low grade astrocytoma. After surgery, hydrocephalus improved. Case 2: A 12-year-old boy was admitted with hydrocephalus detected by CT. MRI demonstrated a tumor of the midbrain without confirmation. He underwent a V-P shunt for hydrocephalus, and was discharged without any complaints. After 2 years, he was admitted again with shunt malfunction. After shunt revision, his consciousness recovered. However, Parinaud's sign appeared and patency of the shunt was unstable. MRI revealed a tumor of the tectal region and signs of stenosis of the aqueduct of Sylvius. The tumor was removed directly by the occipital transtentorial approach. The aqueduct was opened and a catheter was inserted from the 3rd to the 4th ventricle. Histological examination revealed a low grade astrocytoma. The patient followed a satisfactory postoperative course except for slight Parinaud's sign, and the V-P shunt was no longer necessary.