Clipping of an aneurysm 20 years after encasement with methyl methacrylate. Case report.

A variety of agents have been used to coat aneurysms as an alternative to clipping. These agents were employed more frequently prior to the routine use of the operating microscope and the presently available variety of aneurysm clips. One such coating agent is methyl methacrylate. This report describes a patient with an anterior communicating aneurysm that rebled 20 years after being encased in methyl methacrylate. At operation, the pulsating aneurysm had eroded the adjacent layer of methyl methacrylate, creating a small intervening space. This space allowed removal under the microscope (with a high-speed air drill and a diamond bit) of the methyl methacrylate from the anterior cerebral arteries and aneurysm, exposing it for definitive clip placement. The feasibility of clipping encased aneurysms is discussed.