The incidence of extradural clots following exploratory craniotomy in cases of focal epilepsy in which no increased intracranial pressure exists and no organic lesion is found is high, even if before closure of the osteoplastic bone flap the utmost caution is exercised in controlling all the small bleeding points. The suturing of the dura to the galea or periosteum has been consistently practiced in neurosurgical clinics, and it has been invaluable in controlling bleeding from under edges of the bone. Bleeding may occur several hours after the closure and an extradural clot may develop even though the oozing from the inner surface of the bone flap has been thoroughly stopped with bone wax and electrocoagulation and a considerable portion of the bone has been stripped from its muscular attachments.
By making several small openings with a drill through the osteoplastic bone flap, the dura can be sutured firmly against the