Modifications of Crossed-Action Intracranial Clips

DAPTATIONS of crossed-action spring forceps to intracranial vascular surgery began in 1954 with the phosphor-bronze clamps modified by Black and German ~ for temporary clamping. Descending from the forceps (tweezers) of ancient Egypt (circa 3300 BC), and functionally revolutionized by the Charri6re crossed-action principle (1840 AD), prototypes belong to the category called bull-dog forceps2 The stainless steel clips of Schwartz (1955) and Mayfield-Kees (1956) made permanent implantation possible. 4 Each major modification of a cross-legged stainless steel clip to improve it for aneurysmorrhaphy, however, causes changes in the electrochemical or mechanical behavior, or both. ~ Greater inertness softens the metal, weakening the spring so that occasional slippage occurs. A ligature tied through holes in the leg tips, or methylmethacrylate tipping after aneurysmorrhaphy, prevents slippage; both methods create anodes by oxygen deprivation. 1 Radical structural departure from the basic clip formed from one piece of bent metal (to remove the spring loop) requires the addition of a coiled, looped, or leafspring appurtenance. Such springs invariably are less noble electrochemically than the legs, and corrode in eolorimetric tests. ~ In 1964 we reported the addition of half-round legs (curved, angled, and straight) to the Mayfield-Kees clip to facilitate passage through various aneurysmal-arterial interelusions (Figs. 1-4) . If soldered, this modification adds other metals to the stainless steel, causing galvanic action in electrolytic environments. The method now used,* spot welding of identical metals, causes the least chemical Fro. 1. Drawing of straight, curved and rightangle modified Mayfield-Kees intracranial clips. (Courtesy oJ Codman & Shurtleff.)