Endoscope-assisted brain surgery: part 2--analysis of 380 procedures

Microsurgical techniques and instruments that help to reduce intraoperative retraction of normal intracranial neuronal and vascular structures contribute to improved postoperative results. To achieve sufficient control of the operating field without retraction of neurovascular components, the resection of dura and bone edges is frequently required, which, on the other hand, increases operating time and operation-related trauma. The use of endoscopes may help to reduce retraction and, at the same time, may help to avoid additional dura and bone resection. The aim of this study is to describe the principles on which the technique of endoscope-assisted brain surgery is based, to give an impression of possible indications for endoscope-assisted microsurgical procedures, and, with illustrative cases, to delineate the advantages of endoscopes used as surgical instruments during microsurgical approaches to intracranial lesions.

During a period of 4.5 years, 380 microsurgical procedures were performed as endoscope-assisted microneurosurgical operations. This surgical series was analyzed for time of surgery, usefulness of intraoperative endoscopy, and complication rates. Lens scopes with viewing angles of 0 to 110 degrees and with diameters of 2.0 to 5.0 mm as well as newly designed "viewing dissectors" (curved, rigid fiberscopes) with diameters of 1.0 to 1.5 mm connected to a video unit were used as microsurgical instruments. The positioning of the endoscopes was achieved by retractor arms fixed to the Mayfield headholder. Thus, the surgeon was able to perform customary microsurgical manipulations with both hands under simultaneous endoscopic and microscopic control.

The lesions treated with endoscope-assisted microsurgery comprised 205 tumors, 53 aneurysms, 86 cysts, and 36 neurovascular compression syndromes. Eighty-nine of these lesions were localized in the ventricular system, 242 in the subarachnoid space or intracerebral, and 49 in the sella. Endoscope-assisted microsurgery was advantageous to reduce the size and the operation-related tissue trauma of approaches to lesions within the ventricular system, in the brain tissue as well as in the subarachnoid space at the base of the brain. Using less retraction during tumor removal, the visual control of retrosellar, endosellar, retroclival, and infratentorial structures was improved. Video-endoscope instrumentation was especially helpful during procedures in the posterior cranial fossa and at the craniocervical junction. It allowed for inspection of channels and hidden structures (e.g., the internal auditory meatus, the ventral surface of the brain stem, the ventral aspect of root entry zones of cranial nerves, the content of the foramen magnum, and the upper cervical canal), both without retraction and without resection of dura and bone edges. Endoscope instrumentation during surgery for large or giant aneurysms was useful to dissect perforators on the back side of the aneurysms and to control the completeness of clipping.

Although the results reported herein cannot be compared directly with those of exclusive microsurgical procedures performed during the same period of time, videoendoscope-assisted microsurgery can be recommended as a time-saving, trauma-reducing procedure apt to improve postoperative outcomes.