Diagnostic and therapeutic stereotactic cerebral endoscopy

Novel application of computer-assisted cisternal endoscopy for the biopsy of pineal region tumors: cadaveric study

BACKGROUND

Long-standing debate continues about the management and biopsy of pineal tumors because of their complex microsurgical anatomy and deep location. Inspired by the concept of biopsy under direct visualization in the absence of hydrocephalus, we explored the effectiveness of neuroendoscope outside of its traditional territory using a new minimally invasive technique, computer-assisted cisternal endoscopy (CACE), for the biopsy of pineal tumors.

METHOD

Five cadaver heads were dissected to expose the pineal region through the posterior fossa. In the other 5 heads, a rigid endoscope-wand combination was introduced in the supracerebellar space lateral to the arachnoid of the superior cerebellar cistern in midline. Endoscopic exposure of the pineal gland was correlated with the real-time image of the localizing wand. After the wand was removed, arachnoid was further dissected from the deep veins and the pineal gland, and a four-quadrant biopsy was obtained.

FINDINGS

The combination of technologies of frameless guided stereotaxy and neuroendoscopy enhanced our ability to navigate the ventriculoscope in narrow spaces (e.g., posterior fossa cisterns). Compared with transventricular and conventional stereotactic trajectories, application of CACE in supracerebellar infratentorial trajectory offered the shortest route to the pineal region, anatomical orientation, no violation of eloquent neurovascular structures, and adequate visibility to deep veins and arteries.

CONCLUSIONS

CACE may be used to approach pineal lesions outside the cerebral ventricular system for biopsy or debulking. Continuous computer updates on the endoscope position allows its safe navigation in narrow spaces (e.g., cerebrospinal fluid cistern). Its success will await future surgical trials.

Complete Microsurgical Resection of Colloid Cysts with a Dual-port Endoscopic Technique

Objective:

A dual-port endoscopic approach, used for the surgical management of colloid cysts, was developed with the following goals: 1) a direct, unobstructed, high-illumination endoscopic view of the attachment point of the colloid cyst to the tela choroidea, and 2) a gross total resection of the colloid cyst capsule using microsurgical techniques.

Methods:

Eleven symptomatic, hydrocephalic, colloid cyst patients who underwent operation with a unilateral, precoronal-frontopolar dual-port endoscopic technique were retrospectively assessed. Preoperative magnetic resonance imaging scans were analyzed, comparing the lateral precoronal to the frontopolar approach, to determine the degree of angulation that would be required to directly view the roof of the third ventricle. Clinical outcome and radiographical follow-up were assessed.

Results:

The frontopolar approach achieved an approach angle to the roof of the third ventricle of only 15 ± 4 degrees compared with 56 ± 6 degrees (P< 0.0001) for the precoronal approach. The view obtained from the frontopolar endoscope allowed excellent visualization of the cyst attachment point. Microsurgical dissection techniques, using many standard microsurgical instruments introduced through the second port, were satisfactorily accomplished. Complete resections were obtained in 10 out of 11 dual-port patients. Worsening of memory deficits occurred in one patient. There was no cyst recurrence with a mean follow-up period of 26 ± 27 months.

Conclusion:

The dual-port endoscopic technique described is an alternative to classic microsurgical craniotomy approaches. The technique allows excellent visualization of the colloid cyst attachment and permits microdissection techniques.

History of neurosciences at the School of Medical Sciences, Universiti Sains Malaysia

Universiti Sains Malaysia is the only institution in Malaysia which incorporates all fields of the neurosciences under one roof. The integration of basic and clinical neurosciences has made it possible for this institution to become an excellent academic and research centre. This article describes the history, academic contributions and scientific progress of neurosciences at Universiti Sains Malaysia.

Intracranial navigation using a novel device for endoscope fixation and targeting: technical innovation

Intracranial endoscopy involves point-to-point navigation: first, in the introduction of the endoscope into a cerebrospinal fluid-containing space and, second, in the identification of a target structure. We report testing and preliminary clinical use of a device for the direct cranial fixation and point-to-point neuronavigation of a rigid ventricular endoscope. An 18-month-old female child presented with rapidly progressive macrocephaly, developmental delay and left hemiparesis. Neuroimaging revealed a large suprasellar cyst and obstructive hydrocephalus. We adapted a ball-stem device with an endoscopic working channel for direct cranial fixation over a burr hole. This device was successfully used in conjunction with MR-based neuronavigation to fenestrate the cyst. Seven months after the operation her developmental delay, macrocephaly and hemiparesis resolved. This device may be particularly effective in cases of small ventricles, ambiguous intra-ventricular landmarks, and in children too young for head-holder immobilization.

Image-guided endoscopy: description of technique and potential applications

Object

Neuroendoscopic approaches to lesions of the central nervous system and spine are limited by the loss of stereoscopic vision and high-fidelity image quality inherent in the operating microscope. Image-guided endoscopy (IGE) and image-guided surgery (IGS) have the potential to overcome these limitations. The goal of this study was to evaluate IGE for its potential applications in neurosurgery.

Methods.

To determine the feasibility of IGE, a rigid endoscope was tracked using an IGS system that provided navigational data for the endoscope tip and trajectory as well as a computer-generated, three-dimensional, virtual representation of the image provided by the endoscope.

The IGE procedure was successfully completed in 14 patients (nine with pituitary adenomas, one with a temporal cavernous malformation, and four with unruptured aneurysms). No complications could be attributed to the procedure. Compared with direct microscopy performed using anatomical landmarks, registration of the endoscope, and virtual image were highly accurate.

Conclusions

This procedure offers many potential advantages for central nervous system and spinal endoscopy. Advances in IGE may enable its application to regions outside the central nervous system as well.

Value of Cushing reflex as warning sign for brain ischaemia during neuroendoscopy † †This work was performed at the Department of Anaesthesia, Ghent University Hospital, Ghent, Belgium

BACKGROUND

During an endoscopic neurosurgical procedure a sudden increase in intracranial pressure may occur at any time. We present a prospective study of haemodynamic changes during such procedures.

METHODS

Physiological data were recorded during the whole operative procedure in 17 consecutive patients who underwent an endoscopic neurosurgical procedure under general anaesthesia. Monitoring included invasive blood pressure, intracranial pressure, electrocardiogram, end-expired carbon dioxide, pulse oximetry and heart rate. Pressure and ECG waveforms were recorded at 100 Hz and evaluated in a subsequent offline analysis.

RESULTS

In almost every case, the occurrence of hypertension and tachycardia was clearly the result of an increase in intracranial pressure. Also, a Cushing reflex developed in almost every case where the cerebral perfusion pressure dropped below 15 mm Hg. The occurrence of bradycardia was not systematically associated with a low cerebral perfusion pressure.

CONCLUSION

In this study, we describe the haemodynamic effects of increased intracranial pressure during endoscopic neurosurgical procedures and their respective sequence of events at high temporal resolution. Although most clinicians rely on the occurrence of bradycardia to diagnose intracranial hypertension during endoscopic neurosurgical procedures, we show that a simultaneous onset of hypertension and tachycardia is a better indicator of impaired brain perfusion. Waiting for a persistent bradycardia to alert the surgeon during endoscopic neurosurgical procedures could allow severe bradycardia or even asystole to develop.

Anesthesia for minimally invasive neurosurgery

Neurosurgerical techniques utilizing minimally invasive approaches will continue to emerge. For some of these future possibilities, anesthesia may not be required. Other types of neurosurgery, whether performed by humans or a machine, will require entry through the cranium and an absolute lack of movement. Anesthesia will keep pace with these innovations by accurately controlling the delivery of anesthetic to achieve optimal conditions. This control will allow for a safer, more comfortable surgical procedure while decreasing blood loss and morbidity associated with neurosurgery.

A new method of ultrasonic guidance of neuroendoscopic procedures. Technical note

The authors present a newly designed device for ultrasonic guidance of neuroendoscopic procedures. It consists of a puncture adapter that attaches to a rigid endoscope having an outer diameter of 6 mm and is mounted on a small, bayonet-shaped ultrasound probe. This adapter directs the movement of the endoscope precisely within the ultrasonic field of view. The targeted region is identified by transdural insonation via an enlarged single burr-hole approach, and the endoscope is tracked in real time throughout its approach to the target. The procedure has been performed in 10 patients: endoscopic ventriculocystostomy in four cases; removal of a colloid cyst of the third ventricle in two cases; and intraventricular tumor biopsy, intraventricular tumor resection, third ventriculostomy, and removal of an intraventricular hematoma in one case each. The endoscope was depicted on ultrasonograms as a hyperechoic line without disturbing echoes and, consequently, the target (cyst, ventricle, or tumor) was safely identified in all but one case, in which intraventricular air hid a colloid cyst in the foramen of Monro. The method presented by the authors proved to be very effective in the guidance and control of neuroendoscopic procedures. Combining this method with image guidance is recommended to define the entry point of the endoscope precisely.

Virtual image navigation: a new method to control intraoperative bleeding in neuroendoscopic surgery. Technical note

In this neuroendoscopic study the authors tested the newly developed "red-out module" of their visual navigation system that enables the neurosurgeon to achieve hemostasis if total visualization is lost due to hemorrhage ("red out") within the visual field. An optical position measurement system connected to the endoscope guarantees that digitized endoscopic images are coupled with the accurate endoscopic position. Computerized images are simultaneously stored with their respective position data, and this creates a virtual anatomical landscape. The system was tested in in vivo bleeding conditions in a rat model. Artificial endoscopic cavities were created in the inguinal, pelvic, and jugular regions in rats to imitate the conditions of the human ventricular system. Two experimental settings were tested: Technique I, in which a computer landmark has been previously determined at the point where the vessel will be lesioned; and Technique II, in which a landmark has been previously set in the surrounding area of the vessel. Immediately after hemorrhage obscures the visual field (red out), the computer automatically displays the virtual images on a separate monitor. The previously set landmarks and the graphic overlay of the coagulation fiber enable the surgeon to navigate within the operative field based on the virtual images and to perform coagulation at the site of the lesion. A total of 175 vessels were coagulated: 43 arteries and 132 veins. In using Technique I, 130 (90.9%) of 143 vessels and in using Technique II, 26 (81.2%) of 32 arteries were successfully coagulated. The authors' data revealed that virtual image guidance has the potential to be a helpful tool in neuroendoscopy.

Neurosurgical management of patients with central nervous system malignancies

OBJECTIVES

To provide an introduction to and description of the neurosurgical technologies used for the diagnosis and treatment of central nervous system (CNS) malignancies.

DATA SOURCES

Published articles, books, and other reference materials.

CONCLUSIONS

Recent advances in the development of assessment tools and surgical techniques have improved the outcome and quality of life for patients with brain and spinal cord tumors. Further improvements in intraoperative instrumentation and postoperative adjuvant therapy are expected to increase the safety and effectiveness of treatments for CNS malignancies.

IMPLICATIONS FOR NURSING PRACTICE

Preoperative education for the patient with a CNS malignancy is a special challenge to nurses. Management of these aggressive tumors requires multiple treatment modalities and continued vigilance to detect and palliate recurrent tumors.

Computer-assisted endoscopy for neurosurgical procedures: technical note

OBJECTIVE

As neuroendoscopy technology evolves, the ventriculoscope is playing a greater role in the diagnosis and treatment of disorders affecting the ventricular system. However, even with direct visualization, correctly orienting and safely navigating an endoscope may be difficult with abnormal anatomy, in small ventricles, or when searching for small periventricular lesions identified on neuroimaging studies. The ability to define the location of the endoscope during such procedures enhances its effectiveness and safety.

INSTRUMENTATION

We report the successful adaptation of an image-guided stereotactic wand to a rigid neuroendoscope. With computer-assisted neuroendoscopy (CANE), the tip position and orientation of a rigid ventriculoscope were visualized in real-time on neuroimaging studies that were obtained before surgery. Because computer guidance may also be used with the neuroendoscope obturator during ventricular access, uncertainty in accessing small ventricles is minimized.

RESULTS

Eleven patients were operated on at The Cleveland Clinic Foundation using the CANE system. All patients except one were improved after surgery. Early experience suggests that CANE is useful for certain endoscopic procedures by aiding in trajectory planning, ventricular navigation, and localizing certain pathological conditions.

CONCLUSION

Even with direct visualization, ventriculoscopy in abnormal anatomy may be difficult. Although the CANE system may not always be necessary in neuroendoscopy, correlation of the endoscope tip location, with an intraoperative magnetic resonance image via continuous computer updates, may enhance the safety, as well as the efficiency, of neuroendoscopy in the future.

Neuroendoscopic management of pineal region tumours

The management of pineal tumours remains controversial. During 1994 we treated four consecutive adults (16-44 yrs) harbouring a pineal tumour with a neuroendoscopic procedure. All of them presented with hydrocephalus. Pre-operative workup included cranial computerized tomography (CT), craniospinal magnetic resonance imaging (MRI) and serum levels of biological tumour markers. The endoscopic procedure consisted of a third ventriculostomy followed by biopsy with a flexible, steerable neuroendoscope. Histological diagnosis was achieved in three patients who no longer required a shunt device. Recorded complications were: bleeding during ventriculostomy that prevented us from obtaining a good sample for biopsy, short-term memory loss that cleared over a two-week period, and transient increase of pre-operative hemiparesis. Complications and morbidity are emphasized so as to be avoided with further technical experience. Neuroendoscopy affords a minimally invasive way of reaching three objectives by one-step surgery in the management of pineal region lesions: 1) CSF sample for analysis of tumour markers. 2) Treatment of hydrocephalus by third ventriculostomy. 3) Several biopsy specimens can be obtained identifying tumours which will require further open surgery or adjuvant radiation and/or chemotherapy.

Neuroanatomical details under endoscopical view--relevant for radiosurgery?

Both, neuroendoscopy and radiosurgery, are upcoming techniques in neurosurgery and become nowadays more and more important. In planning radiosurgical interventions it is very important to have both, the information about the morphology of the pathology itself, and also a clear understanding from the surrounding structures. Neuroendoscopic techniques gives the possibility to demonstrate well known structures without prior dissection. This paper focuses on these anatomical informations which might be relevant in planning further radiosurgical interventions especially in cases of the vascularization of the cranial nerves and the arachnoid membranes, these structures appears much more complex than described in "common" neuroanatomical textbooks. Endoscopic techniques also better demonstrate the real in vivo relationships and gives so a better understanding for interpreting "planning" MRI and CT scans. We therefore consider that neuroanatomical studies under a neuroendoscopical view are very important and could be very helpful in planning radiosurgical intervensitons.

Minimally invasive endoscopic neurosurgery--a survey

In 1989 we introduced "endoscopic stereotaxy" as a new operative procedure into neurosurgery. This technique was first scheduled to optimize stereotactic biopsy. In its further development it proved to be effective for other indications. We choose the term "Minimal Invasive (Endoscopic) Neurosurgery (MIEN)" for these interventions. Minimal invasive endoscopic techniques are applied preferably for diagnostic and therapeutic interventions on preformed or pathological cavities of the central nervous system. The indications are, endoscopic-stereotactic biopsy of space-occupying lesions, ventriculoscopy and endoscopic ventriculostomy in diagnosis and treatment of hydrocephalus, endoscopic evacuation of cystic space occupying lesions, endoscopic evacuation of intracerebral haematoma, endoscopic evacuation of septated chronic subdural haematoma, endoscopic evacuation of subacute or chronic brain abscesses, endocavitary syringostomy. Our results with minimal invasive endoscopic interventions for different indications are encouraging when compared to conventional microsurgical techniques. We have performed more than 300 minimal invasive endoscopic interventions. The mortality rate was below 1%, the operative morbidity was below 2%.

Lasers in neurosurgery

Lasers have been used in neurosurgery for the past 25 years, undergoing modifications to suit the specific needs of this medical discipline. The present report reviews the current use of lasers in neurosurgical practice and examines the pros and cons of lasers in specific neurosurgical applications. In spite of their advantages, laser use is still not widespread in neurosurgery. One reason is the continued lack of complete control over real-time laser interactions with neural tissue. A greater acceptance and use of lasers by neurosurgeons will depend upon automated control over defined specific parameters for laser applications based upon the type of tissue, the desired effect on tissue, and application to the clinical situation without loss of precision and a lot of expense. This will require the integration of newer lasers, computers, robotics, stereotaxy, and concepts of minimally invasive surgery into the routine management of neurosurgical problems.