Endoscope-assisted Brain Surgery: Basic Concept, and Current Technique.

Special Technical Article

Neurosurgery. 42(2):219-224, February 1998.
Perneczky, Axel MD; Fries, Georg MD

RATIONALE: The evolution of neurosurgical techniques indicates the effort to reduce surgery-related traumatization of patients. The reduction of traumatization contributes to better postoperative outcomes. The improvement of diagnostic imaging techniques facilitates not only the precise localization of lesions but also the accurate determination of topographical relations of specific lesions to individual anatomic variations of intracranial structures. This precision of diagnostic imaging should be used to perform individual surgical procedures through so-called keyhole approaches. Keyhole craniotomies are afflicted with a reduction of light intensity in the depth of the operating field, and they provide rather narrow viewing angles. Thus, objects located directly opposite the approach entrance are more visible than those in the shadow of the microscope beam. These two deficiencies of keyhole craniotomies can be compensated for by the intraoperative use of rigid rod lens endoscopes, the shaft of which remains easily controllable through the surgical microscope.

CONCEPT: Endoscope-assisted microsurgery, like all routine microsurgical procedures, is performed with both hands; the endoscope is fixed in its desired position via a mechanical arm to the headholder. Because of their superior optical quality and maneuverability, only rigid lens scopes are used for endoscope-assisted brain microsurgery. There are five ways of observing the endoscopic and microscopic images at the same time: 1) observation of the microscopic image through the oculars of the microscope and observation of the endoscopic image on a video screen placed in front of the surgeon, 2) observation of the microscopic image through the oculars of the microscope and display of the endoscopic image on a head-mounted LCD screen, 3) projection of both microscopic and endoscopic images on one screen in a picture-in-picture mode, 4) projection of both microscopic and endoscopic images into specially designed microscope oculars, and 5) transmission of both microscopic and endoscopic images into a head-mounted LCD screen.

DISCUSSION: With the knowledge of almost all individual anatomic and pathoanatomic details of a specific patient, it is possible to target the individual lesion through a keyhole approach using the particular anatomic windows. As the light intensity and the depiction of important anatomic details are improved by the intraoperative use of lens scopes, endoscope-assisted microsurgery during keyhole approaches may provide maximum efficiency to remove the lesion, maximum safety for the patient, and minimum invasiveness.

Endoscope-assisted Brain Surgery: Part 2-Analysis of 380 Procedures.

Clinical Studies

Neurosurgery. 42(2):226-231, February 1998.
Fries, Georg MD; Perneczky, Axel MD

OBJECTIVES: 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.

METHODS: 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.

RESULTS: 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.

CONCLUSION: 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.

Copyright (C) by the Congress of Neurological Surgeons