We evaluated the effectiveness of assist-systems such as endoscopy, navigation, and motor evoked potential (MEP) monitoring in terms of improving the safety and accuracy of surgery for cerebrovascular diseases.
Since January 2000, the following devices have been used at our institution to assist in surgical procedures: an endoscope (diameter, 2.7 or 4.0 mm; tip angle, 30° or 70°) in 69 surgical procedures to treat cerebral aneurysms, a navigation system (Stealth Station) in 22 operations for cerebral aneurysms and arteriovenous or cavernous malformations, and MEP monitoring (bipolar or mono-polar electrical stimulation of the motor cortex and EMG recording of the face, trunk and upper extremity contralateral to the stimulated side) in 11 operations for cerebral aneurysms or arteriovenous malformations.
Endoscopy allowed visualization of the anatomical relationship between the aneurysm neck and the parent or perforated artery before clipping, and the location of the clip tip, occlusion of the perforated artery, or stenosis of the parent artery could be evaluated after clipping. Postoperative MR and/or CT images revealed an asymptomatic infarction of perforated artery in 4 patients. Navigation allowed prediction of the sites of aneurysms, cavernous malformations, or of the feeding arteries of arteriovenous malformations. This resulted in accurate approaches to these structures, although a brain shift in some patients was recognized by ultrasound imaging linked to the navigation system. Although MEP monitoring should have predicted postoperative motor function, MEP findings after clipping the neck of aneurysms or obliterating the arteriovenous malformation of a feeding artery were normal in all of the analyzed patients. Postoperative convulsive seizures developed in patients as a result of 20 mA of bipolar electrical stimulation.
Endoscopy, navigation, and MEP monitoring are considered helpful for safe and accurate surgical treatment of cerebrovascular diseases, although the disadvantages of these systems should also be considered.
