Treatment of hydrocephalus with functionally isolated ventricles

Rapid therapeutic drainage of one lateral ventricle may lead to ipsilateral slit ventricle, and the resultant functional obstruction of cerebrospinal fluid flow through the foramen of Monro may cause dilatation of the contralateral ventricle. Drainage of the lateral ventricle with a low-pressure shunt led to functionally isolated contralateral ventriculomegaly in this report. The patient's condition was complicated by a Candida albicans shunt infection. Following effective treatment of the infection by chemotherapy and removal of the shunt system, the patient was treated by bridging two lateral ventricles with ventricular catheters connected to an Ommaya reservoir. An occipital ventricular catheter was then inserted and connected to a programmable valve to drain the bridged lateral ventricles. Modern centers, caring for patients with infantile hydrocephalus, should have endoscopic facilities available but in cases with extensive ventricular adhesions and in asymmetric hydrocephalus where endoscopic septostomy between the ventricles is impossible our described technique may be used.

The use of waterjet dissection in endoscopic neurosurgery

✓Waterjet dissection enables vessel preservation and a reduction in intraoperative blood loss. Because even minimal bleeding should be avoided during neuroendoscopy, the waterjet device may be a particularly valuable tool in such procedures. The authors used this instrument in experimental endoscopic procedures in 20 cadaveric porcine brains and clinically in four patients with obstructive hydrocephalus. A precise and accurate septostomy was achieved in all of the pig brains. In two patients the hydrocephalus was due to intraventricular hemorrhage, in one a posterior fossa tumor, and in one a cystic craniopharyngioma. In all patients the surgical view was kept clear with waterjet irrigation and suction. Using a pressure setting of 10 bars, the waterjet device successfully perforated the cyst wall of the craniopharyngioma in one patient and the floor of the third ventricle in three patients. The use of the waterjet device in selected endoscopic procedures appears safe, and may help reduce intraoperative bleeding. However, further studies are needed to confirm the utility of the waterjet tool in endoscopy.

Two-stage treatment of a tectal ganglioglioma: Endoscopic third ventriculostomy followed by surgical resection

Tumours of the quadrigeminal plate in adults are usually benign. Nevertheless, obstructive hydrocephalus due to compression of the Sylvian aqueduct is an almost invariable early finding. Whether or not direct excision is undertaken, temporary or permanent treatment of the hydrocephalus is warranted. Endoscopic third ventriculostomy is an alternative to insertion of a shunt and provides both acute and long-term relief of hydrocephalus-related symptoms. We chose a two-stage approach for treating a tectal ganglioglioma in an adult: endoscopic third ventriculostomy followed by surgical excision. The advantages and disadvantages of each therapeutic strategy are discussed.

Neurofiberscopic biopsy of tumors of the pineal region and posterior third ventricle: indications, technique, complications, and results

OBJECTIVE

Evaluation of results of the neurofiberscopic biopsy of tumors of the pineal region and posterior third ventricle.

METHODS

From 2001 to 2004, 23 patients (mean age, 30.6 yr) with tumors located in the pineal region or posterior third ventricle underwent neurofiberscopic biopsy with simultaneous third ventriculostomy. The procedure was indicated for verification of the histological diagnosis of the neoplasm, which was planned to be treated by radiotherapy and/or chemotherapy without open surgery (eight patients), establishment of the pathological diagnosis for further choice of the most appropriate treatment strategy (11 patients), differentiation of the recurrent neoplasm and radiation necrosis (two patients), and decompression of the large tumor-associated cyst (two patients). In six previously shunted patients, substitution of the ventriculoperitoneal shunt on the third ventricle stoma was performed.

RESULTS

There was no postoperative mortality or permanent morbidity. In all cases, the obtained tissue sample was sufficient for pathological diagnosis. Transient postoperative complications included fever (15 patients), nausea and vomiting (three patients), and diplopia (one patient). On the long-term follow-up, delayed third ventricular stoma failure caused by tumor regrowth and scar formation was found in one patient, and dissemination of the malignant glioma through the subarachnoid space was found in another patient.

CONCLUSION

Neurofiberscopic biopsy represents a useful method for sampling of tumors of the pineal region and posterior third ventricle, which can be effectively used in both previously shunted and shunt-free patients.

Study of tryptophan metabolism via serotonin in cerebrospinal fluid of patients with noncommunicating hydrocephalus using a new endoscopic technique

By a recent minimally invasive neuroendoscopic technique, the cerebral ventricles have been reached in a quick, reliable, and harmless way, making possible the study of cerebrospinal fluid (CSF) of the lateral ventricles and, above all, the CSF adjacent to the walls of the third ventricle. Tryptophan, 5-hydroxytryptophan, serotonin (5-HT), and 5-hydroxyindoleacetic acid (5-HIAA) were measured in CSF by HPLC equipment. Twenty-six patients affected with noncommunicating hydrocephalus were enrolled in the study and, as controls, 28 subjects not suffering from any neurological disease. The concentrations of tryptophan were higher in right ventricular CSF than in lumbar CSF (P < 0.01). 5-HT was detectable in the CSF of the right ventricle of hydrocephalic patients. 5-HIAA was higher in right ventricular CSF than in cisternal and lumbar CSF (P < 0.01), both in controls and in hydrocephalic patients. However, there was a higher concentration of 5-HIAA in right ventricular (P < 0.05) and cisternal (P < 0.01) CSF in hydrocephalic patients in comparison with controls. In the CSF samples withdrawn during neuroendoscopy, 5-HT presented the highest concentrations in the pineal recess. The highest amounts of 5-HIAA were found in the choroid plexus, third and right ventricles, pituitary recess, and aqueduct, and the lowest in pineal recess, subarachnoid space, infundibulum, and interpeduncolar cistern. These results provide new insight into the fate of tryptophan and its metabolites via serotonin in the CSF and suggest the feasibility of the new neuroendoscopic technique for brain metabolic studies.

Analysis of dynamic autoregulation assessed by the cuff deflation method

INTRODUCTION

Dynamic testing of cerebral pressure autoregulation is more practical than static testing for critically ill patients. The process of cuff deflation is innocuous in the normal subject, but the systemic and cerebral effects of cuff deflation in severely head-injured patients have not been studied. The purposes of this study were to examine the physiological effects of cuff deflation and to study their impact on the calculation of autoregulatory index (ARI).

METHOD

In 24 severely head-injured patients, 388 thigh cuff deflations were analyzed. The physiological parameters were recorded before, during, and after a transient decrease in blood pressure. Autoregulation was graded by generating an ARI value from 0 to 9.

RESULTS

Mean arterial blood pressure (MAP) dropped rapidly during the first 2-3 seconds, but the nadir MAP was not reached until 8 +/- 7 seconds after the cuff deflation. MAP decreased by an average value of 19 +/- 5 mmHg. Initially the tracings for MAP and cerebral perfusion pressure (CPP) were nearly identical, but after 30 seconds, variable increases in intracranial pressure caused some differences between the MAP and CPP curves. The difference between the ARI values calculated twice using MAP as well as CPP was zero for 70% of left-sided studies and 73% for right-sided studies and less than or equal to 1 for 93% of left- and 95% of right-sided cuff deflations.

CONCLUSION

Transient and relatively minor perturbations were detected in systemic physiology induced by dynamic testing of cerebral pressure autoregulation. Furthermore, this study confirms that the early changes in MAP and CPP after cuff deflation are nearly identical. MAP can substitute for CPP in the calculation of ARI even in the severely brain-injured patient.

Neuroendoscopic Management of Symptomatic Septum Pellucidum Cysts

OBJECTIVE:

Ten rare cases of symptomatic septum pellucidum cysts in patients who underwent endoscopic fenestration are described. The approaches and techniques used in the management of these cysts and the endoscopic surgical indications are discussed.

CLINICAL PRESENTATION:

In the past 5 years, 10 patients (age range, 3–60 yr) with symptomatic septum pellucidum cysts underwent neuroendoscopic fenestration. The most common symptom was intermittent headache (seven patients) accompanied by dizziness, vomiting, and epileptic seizures. Two patients presented with epileptic seizures. One patient presented with abnormally increased head circumference. Magnetic resonance imaging scans of 10 patients showed septum pellucidum cysts, two with hydrocephalus, and two with pituitary microadenoma.

INTERVENTION:

All 10 patients underwent endoscopic fenestration with a rigid endoscope via a frontal approach. Eight cases were performed freehand. Two cases were assisted by a frameless neuronavigation system. Postoperatively, the mass effect of the cysts and the symptoms resolved immediately, and computed tomographic or magnetic resonance imaging scans showed significant decrease in the cyst size and no recurrence during follow-up. Ventricular sizes in the two patients with hydrocephalus were normal.

CONCLUSION:

Neuroendoscopic pellucidotomy could be an effective, safe, and convenient therapeutic method for symptomatic septum pellucidum cysts. This approach might provide communication between the cyst and the ventricular system, thus avoiding shunting or craniotomy. We consider that it is appropriate to use the rigid endoscope via the frontal approach. It is helpful to fill the ventricles with lactated Ringer's solution and leave an external drain after surgery.

Robotic Virtual Endoscopy: Development of a Multidirectional Rigid Endoscope

INTRODUCTION

The use of neuroendoscopy has increased in the past 20 years. Despite an increase in the number of indications for use, novel adjuncts and modifications to existing endoscopes remain all but nonexistent. We introduce a robotic virtual endoscope with applications for neurosurgery that could serve as a novel step in the evolution of future endoscopic technologies.

METHODS

Over the past 8 years, we have worked on the construction of a prototype endoscope with three degrees of freedom that was designed to allow for enhanced safety while maximizing the benefits of virtual field rendition and robotic control. We have developed a prototype to examine a cerebral ventricular model in vitro that functions via either a direct video- or computer-based interface.

RESULTS

Assessment of viewing angulation with robotic feedback has verified the accuracy of the prototype. Models support the ability of the endoscope to localize regions identified via a software interface.

CONCLUSION

The endoscope is a rigid virtual robotic endoscope that provides complete visual coverage of a three-dimensional space by controlling an adjustable viewing direction with three degrees of freedom.

Transparent endoscopic sheath and rigid-rod endoscope used in endoscopic third ventriculostomy for hydrocephalus in the presence of deformed ventricular anatomy

OBJECT

Endoscopic third ventriculostomy (ETV) has been widely performed for the treatment of noncommunicating hydrocephalus. In cases of hydrocephalus in conjunction with deformed and complex ventricular anatomy, it is preferable to use a rigid-rod endoscope for ETV, because the excellent visibility provided by this instrument yields a smooth and correct orientation in the ventricle. The authors report on ETV procedures in which they used a transparent endoscopic sheath that has a common channel in which a rigid-rod endoscope and an instrument can be inserted.

METHODS

In 15 cases of noncommunicating hydrocephalus, a transparent endoscopic sheath and a rigid endoscope were used for ETV. In 11 of the 15 patients, the diameter of the foramen of Monro and the width of the third ventricle were greater than 5 mm, and thus a transparent endoscopic sheath and a rigid endoscope could be smoothly introduced through the foramen of Monro and an ETV successfully performed. Four patients had congenital or acquired narrowing of the foramen of Monro and an anatomically deformed ventricular system. In three of the patients, opening of the narrowed foramen and an ETV were successfully performed using the transparent endoscopic sheath under direct visualization through the rigid-rod endoscope.

CONCLUSIONS

A transparent endoscopic sheath increases safety by offering a corridor to the third ventricle. It also provides excellent visibility without troublesome bleeding from tissues surrounding the foramen of Monro during endoscopic procedures in which a rigid endoscope is used.

The International Infant Hydrocephalus Study: concept and rational

INTRODUCTION

During the recent meetings of the International Study Group on Neuroendoscopy and the International Society for Pediatric Neurosurgery, the consensus view emerged that there is a need to assess the value and efficacy of neuroendoscopic procedures against shunting in a scientific manner, to resolve long-lasting debates on the subject.

MATERIAL AND METHODS

A prospective randomized, controlled trial of endoscopic third ventriculostomy vs shunting in children presenting under the age of 2 years with pure aqueduct stenosis is been proposed and organized (the International Infant Hydrocephalus Study, IIHS). The participating surgeons must adhere to the philosophy of randomization and be suitably experienced in endoscopic techniques in infants. The primary outcome of the trial will be the overall health-related quality of life of these children at 5 years of age. Hence, the study is focusing on the effect of surgery on neurodevelopment, rather than the less important issue of shunt or stoma survival, that has been debated extensively with no conclusion so far. Intention-to-treat analysis will be performed according to the first surgery. Secondary outcomes such as complication and reoperation rate, total hospitalization time and cost, need for repeat imaging, and others will be analyzed as well.

RESULTS

Pure aqueduct stenosis is relatively rare, making recruitment problematic, but has been chosen to avoid other confounding factors that could influence outcome. More than 25 centers worldwide have committed already to patient recruitment to the study. It is anticipated that recruitment will last for 2 years, aiming for 91 patients per arm. The study has started recruiting patients already in some countries.

CONCLUSION

It is hoped that the trial will not only provide answers to unsettled debates on the value of neuroendoscopy but also create a network of collaborating pediatric neurosurgeons for future initiatives.

Recording CSF pressure with a transducer-tipped wire in an animal model of Chiari I

In dogs, a wire with a pressure-sensitive transducer was inserted percutaneously into the subarachnoid space and manipulated under fluoroscopic monitoring in the posterior fossa or upper cervical spinal canal. Pressure recordings from the wire showed fluctuations in pressure corresponding to the cardiac cycle. When a balloon was distended in the foramen magnum, maximum and minimum pressures increased. Continuous monitoring of CSF pressure remote from the site of cannulation was feasible with a wire-based pressure transducer.

Neuroendoscopic Appearance of an Intraventricular Cavernous Angioma Blocking the Foramen of Monro-Case Report-

A 47-year-old woman presented with unilateral ventricular enlargement detected by magnetic resonance imaging during a medical checkup. Neuroendoscopic exploration identified a multilocular lesion in which dark red fluid formed a niveau near the right side of the foramen of Monro. The diagnosis was intraventricular cavernous angioma. Restricted flow of cerebrospinal fluid at the foramen of Monro was observed. Xanthochromia, which seemed to be due to previous bleeding, was observed at the fornix. When the neuroendoscope touched the angioma, the wall collapsed and bled. Endoscopic removal of the angioma was abandoned, and craniotomy and resection of the angioma were performed. No new neurological anomalies were observed after surgery. Preoperative diagnosis of intraventricular cavernous angioma is difficult based on neuroimaging. Neuroendoscopy is effective for diagnosis and the decision-making process regarding treatment.

Endoscopic third ventriculostomy in the treatment of hydrocephalus in pediatric patients

Advances in surgical instrumentation and technique have lead to an extensive use of endoscopic third ventriculostomy in the management of pediatric hydrocephalus. The aim of this work was to point out the leading aspects related to this technique. After a review of the history, which is now almost one century last, the analysis of the endoscopic ventricular anatomy is aimed to detail normal findings and possible anatomic variations which might influence the correct conclusion of the procedure. The overview of modern endoscopic instrumentation helps to understand the technical improvements that have contributed to significantly reduce the operative invasiveness. Indications are analysed from a pathogenetic standpoint with the intent to better understand the results reported in the literature. A further part of the paper is dedicated to the neuroradiological and clinical means of outcome evaluation, which are still a matter of debate. Finally a review of transient and permanent surgical complications is performed looking at their occurrence in different hydrocephalus etiologies.

Neuroendoscopy: past, present, and future

Neuroendoscopy began with a desire to visualize the ventricles and deeper structures of the brain. Unfortunately, the technology available to early neuroendoscopists was not sufficient in most cases for these purposes. The unique perspective that neuroendoscopy offered was not fully realized until key technological advances made reliable and accurate visualization of the brain and ventricles possible. After this technology was incorporated into the device, neuroendoscopic procedures were rediscovered by neurosurgeons. Endoscopic third ventriculostomy and other related procedures are now commonly used to treat a wide array of neurosurgically managed conditions. A seemingly limitless number of neurosurgical applications await the endoscope. In the future, endoscopy is expected to become routine in modern neurosurgical practice and training.

Endoscopic navigation of the fourth ventricle

Transaqueductal navigation of the fourth ventricle has long been considered dangerous and of no clinical relevance. After the refinement of the endoscopic technique and supported by the extensive experience gained at the authors' institution since 1994, endoscopic exploration of the fourth ventricle has been performed by the same surgeon in 54 patients. In all cases reviewed, endoscopic navigation of the fourth ventricle was successfully performed with no related neurological deficit. This preliminary experience shows the feasibility of transaqueductal navigation of the fourth ventricle, which is made possible by the use of small, flexible endoscopes in expert hands.

Hollow mandrin facilitates external ventricular drainage placement

BACKGROUND

Placement of ventricular catheters is a routine procedure in neurosurgery. Ventricle puncture is done using a flexible ventricular catheter stabilised by a solid steel mandrin in order to improve stability during brain penetration. A correct catheter placement is confirmed after removing the solid steel mandrin by observation of cerebrospinal fluid (CSF) flow out of the flexible catheter. Incorrect placement makes further punctures necessary. The newly developed device allows CSF flow observation during the puncture procedure and in addition precise intracranial pressure (ICP) measurement.

METHOD

The developed mandrin is hollow with a blunt tip. On one side 4-5 small holes with a diameter of 0.8 mm are drilled corresponding exactly with the holes in the ventricular catheter, allowing CSF to pass into the hollow mandrin as soon as the ventricle is reached. By connecting a small translucent tube at the distal portion of the hollow mandrin ICP can be measured without loss of CSF. The system has been used in 15 patients with subarachnoid haemorrhage (SAH) or intraventricular haemeorrhage (IVH) and subsequent hydrocephalus.

FINDINGS

The new system improved the external ventricular drainage implantation procedure. In all 15 patients catheter placement was correct. ICP measurement was easy to perform immediately at ventricle puncture. In 4 patients at puncture no spontaneous CSF flow was observed, therefore by connecting a syringe and gentle aspiration of CSF correct placement was confirmed in this unexpected low pressure hydrocephalus. Otherwise by using the conventional technique further punctures would have been necessary.

CONCLUSIONS

Advantages of the new technique are less puncture procedures with a lower risk of damage to neural structures and reduced risk of intracranial haemorrhages. Implantation of the ventricular catheter to far into the brain can be monitored and this complication can be overcome. Using the connected pressure monitoring tube an exact measurement of the opening intracranial pressure can be obtained performed without losing CSF.

Neurofiberscope-guided management of slit-ventricle syndrome due to shunt placement

OBJECT

The purpose of this study was to evaluate an original neurofiberscope-guided strategy for the management of slit-ventricle syndrome that occurs after shunt placement.

METHODS

Between 1995 and 2003 15 patients with slit-ventricle syndrome (mean age 14.2 years) underwent endoscopic third ventriculostomy (ETV) and shunt removal. During the initial surgical procedure a neurofiberscope with a small outer diameter was inserted along the shunt tube into the collapsed ventricle for endoscopically controlled removal of the ventricular catheter and evaluation of brain compliance. If the latter was sufficiently preserved, primary ETV and shunt removal were performed (four cases). If brain compliance seemed to be significantly reduced, endoscopically controlled replacement of the ventricular catheter and implantation of the Codman-Hakim programmable valve shunt device were performed (11 cases). In these patients, delayed ETV and shunt removal were performed later (mean period of 16.3 months). No medical or surgical complications occurred in any case. Follow up ranged from 6 to 84 months (mean 31.1 months; median 22 months). All patients became shunt independent and 13 became symptom free. Overall, the size of the ventricles returned to normal in five cases, became slightly dilated in nine, and moderately dilated in one.

CONCLUSIONS

Neurofiberscope-guided treatment of slit-ventricle syndrome involving shunt removal and ETV appears to be beneficial; all patients in this series were symptom free and shunt independent at the end of follow up.

Bacterial meningitis caused by the use of ventricular or lumbar cerebrospinal fluid catheters

Object. In the present study the authors compared the incidence and risk factors for external drainage—related bacterial meningitis (ED-BM) by using ventricular and lumbar catheters.

Methods. A cohort of 230 consecutive patients with ED was evaluated. Cerebrospinal fluid samples were obtained daily for microbiological culture, and ED-BM was defined based on culture results in combination with clinical symptoms. The incidence of ED-BM was 7% in lumbar and 15% in ventricular drains. Independent risk factors included site leakage, drain blockage, and most importantly duration of ED. Despite a higher infection rate, ventricular catheters did not have a significant higher risk of infection after correcting for duration of drainage.

Conclusions. Analysis of data in the present study showed that the incidence of ED-associated death is low (0.45%) in patients who do not receive continuous antibiotic prophylaxis during ED.

Endoscopic third ventriculostomy for chronic hydrocephalus after tuberculous meningitis

BACKGROUND

Cerebrospinal fluid diversion procedures are indicated in patients with hydrocephalus after tuberculous meningitis (TBM). We present 2 patients with hydrocephalus after TBM who were successfully treated with endoscopic third ventriculostomy (ETV).

METHODS

Two patients had been diagnosed with hydrocephalus after TBM and had undergone ventriculoperitoneal shunt surgery for the same. They presented with multiple episodes of shunt dysfunction. Endoscopic third ventriculostomy was performed (twice for one patient), and the patients were evaluated clinically and radiologically after the procedure.

RESULTS

On long-term clinical follow-up (3 and 2 years, respectively), both patients were asymptomatic after the ETV. The first patient was radiologically evaluated 7 months after the procedure and the second patient 2 years after the procedure. The first patient showed a decrease in ventricular size. The second patient did not show any significant change in the ventricular size.

CONCLUSION

Endoscopic third ventriculostomy can be considered as a safe and long-lasting solution for hydrocephalus after chronic TBM.

Risk of Infection with Prolonged Ventricular Catheterization

OBJECTIVE:

The relationship between extended ventricular catheterization and infection remains controversial. Although studies have substantiated an increasing infection rate with prolonged catheterization, there has been less agreement on whether this trend continues beyond 10 days. Our study reviews the daily infection rate of 595 patients, 213 of whom underwent more than 10 days of catheterization.

METHODS:

All patients who underwent ventricular monitoring in the neurological intensive care unit from 1995 to 2003 at the University of Michigan Health System were reviewed retrospectively. Infection was defined as a positive cerebrospinal fluid culture. Life-table analysis was used to calculate daily hazard (infection) rates. Patient age, sex, diagnosis, catheter exchanges, location of patient during catheter insertion, and cerebrospinal fluid leak were evaluated as risk factors for infection.

RESULTS:

The average patient age was 51.3 years, and 51.3% were male. Duration of catheterization averaged 8.6 days. The overall infection rate was 8.6%. Daily infection rates increased from the onset of catheter insertion but reached a plateau after Day 4, with subsequent rates ranging predominantly between 1 and 2%, even with extended catheterization beyond 10 days. Only ventricular catheters that had been placed at other institutions significantly affected the infection rate.

CONCLUSION:

A relationship between duration of catheterization and infection seems to be present. However, this relationship is not linear. There is an extremely low daily infection rate that rises over the initial 4 days but then remains relatively constant even with prolonged catheter use. Clinical decisions to continue ventricular catheterization should reflect this low daily risk of infection, which does not seem to increase with extended catheter use.

A simplified endoscopic third ventriculostomy under local anesthesia

The aim of this study is the analysis of our experience with awake endoscopic third ventriculostomy (ETVS) in hydrocephalic patients. From September 1994 to December 2001, 24 neuroendoscopic procedures were performed under local anesthesia. Local infiltration was administered using a bupivacaine and lidocaine mixture. Analgesics were titrated to the effect. A free-hand technique with a flexible endoscope was adopted in 24 patients with primitive and secondary (neoplastic) hydrocephalus. ETVS was performed successfully in all cases. No procedure needed to be discontinued due to seizures, bleeding or agitation. Dural incision/coagulation and Fogarty dilatation proved to be the most painful maneuvers requiring, sometimes, supplemental analgesic administration. No intraoperative complications were observed; however, two asymptomatic trajectory hematomas were incidentally discovered two and three days after the operation, respectively. Awake ETVS is a valuable alternative procedure that can be adopted in adult cooperative patients, provided that the procedure is done in an essential and fast way with the free-hand technique, by means of a flexible endoscope, and with the assistance of an anesthesiologist.

Neuroendoscopic basket dilation technique for the fenestration of the ventricular wall or intracranial cysts--technical note

A basket dilation technique has been developed for fenestration of ventricular or cystic walls, using a basket type widely used in the urological field to collect renal or ureteric stones. This technique allows deep-seated structures to be visualized directly through the expanded basket during dilation and the thinnest part of ventricular wall to easily be pierced, cut, and dilated. Fine control can be exerted over expansion pressure through the hand piece directly connected to the basket tip. In addition, the basket can be rotated to cut the floating tissue that must be removed around the stoma. This basket dilation technique is safer than the balloon inflation technique currently used because it allows visualization of deep-seated structures that cannot be seen through the balloon, and should therefore prove useful in third ventriculostomy, plasty of the sylvian aqueduct, and fenestration of intracranial cystic lesions.

Robot-assisted navigated endoscopic ventriculostomy: implementation of a new technology and first clinical results

BACKGROUND

Important landmarks in the evolution of advanced neurosurgical techniques during the past decades include microneurosurgery, neuro-endoscopy and its minimally invasive nature, as well as neuronavigation and advanced intra-operative imaging. With conventional neuroendoscopic techniques, e.g. free-hand endoscopy or the use of mechanical or pneumatic holding devices, a definitive and controlled movement of the endoscope within the brain does depend on the experience and manual skill of the individual neurosurgeon. Therefore, the development of robotic systems to assist surgeons in performing complex neurosurgical procedures is a growing field of interest.

METHOD

With the precision robot "Evolution 1" (U.R.S. Universal Robot Systems, Schwerin, Germany) a new neurosurgical tool has just become available for the precise steering of instruments within the cranium. After preclinical anatomical as well as precision studies the system was used for robot-assisted navigated endoscopic third ventriculostomies in six patients with hydrocephalus related to aqueductal stenosis.

FINDINGS

All robot-assisted navigated endoscopic procedures were successfully completed. The time for the registration procedure and setup of the robot decreased from 60 min. for the first procedure down to 30 min. The time for the surgical part of the neuro-endoscopic procedure itself ranged from 17 to 35 min. During all procedures no system-related complications occurred.

INTERPRETATION

The use of robotic technology for neuro-endoscopic third ventriculostomies is a major step towards the controlled movement of the neuro-endoscope within the cranium. The start up procedure and calibration of the robot is still time consuming, but the real operation time is comparable to free hand neuro-endoscopy. The steering of the endoscope is facilitated and the precision of the endoscopic movements is noteworthy.

A Newly Designed Disposable Introducer Sheath for a Ventricular Fiberscope

We have developed a disposable plastic introducer sheath for use with a flexible endoscope during intraventricular procedures. The sheath is composed of a thin polypropylene tube passing through the center of a plastic stopper. The tube serves as a sheath through which the fiberscope is introduced into the ventricle. The stopper seats in the burr hole and prevents downward and lateral movement of the tube. The sheath can be placed safely in the ventricle with a drainage catheter used as an introducing guide. We used this sheath system in 10 patients and found it very useful. Manipulation of the fiberscope was not hindered, copious irrigation was allowed, and the sheath remained stable on the skull. This new introducer sheath may contribute to the increased use of a flexible endoscope in neuroendoscopic procedures.