Development and Clinical Usefulness of a New Neuroendoscope System for CT-guided Stereotactic Brain Surgery

Since computed tomography (CT)-guided stereotactic surgery is essentially blind surgery, it always involves the risk of injuring viable brain tissue and vessels, and it is difficult to obtain a sufficient amount of biopsy specimen from cystic or necrotic lesions. Moreover, the direct observation of the lesion would provide extremely valuable information. The authors have therefore developed a new subminiature rigid endoscope and an ultrasonic aspirator for use in stereotactic surgery, as well as a new micro manipulative system to attach the equipment to the stereotactic frame so that they can be accurately inserted into the optimum position from any direction. The new neuroendoscope includes a graded refractive index glass rod only 1.0 mm in diameter (Selfoc®, Nippon Sheet Glass Co., Osaka), which provides a focal depth from 1 mm to infinity, as well as an extremely bright and wide visual field with an angle of 70°. Furthermore, because the outer probe and endoscopic sheath share the outer rigid metal tube 4.5 mm in outer diameter, a large internal channel of 2.1 mm in diameter allows the introduction of various microinstruments such as an ultrasonic aspirator probe, laser probe, and biopsy forceps. When a miniaturized video camera is attached, the surgical procedures can be controlled using the video monitor and photographed. The new probe for the ultrasonic aspirator has been developed in various types suitable for fragmentation and aspiration of hematomas and brain tumors, so under endoscopic control even the harder coagulants and tumors can be removed. During removal of an intracerebral hematoma, intraoperative bleeding was prevented by the observation of microvessels in the wall of the hematoma cavity, which cannot be detected by CT or ultrasonography alone, and a cystic lesion of the thalamus was biopsied by inspecting the cystic inner cavity under the endoscope. Neuroendoscopic surgery is less invasive, safer and more accurate for the treatment of small, deep-seated tumors, hemangiomas, arteriovenous malformations, and other lesions.