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Michael R. Gaab and Henry W. S. Schroeder

Object

The purpose of this study was to determine the efficacy of endoscopic treatment in patients with intraventricular tumors.

Methods

A series of 30 patients with endoscopically treated intraventricular lesions is reported. The lesions included seven colloid cysts, six astrocytomas, three subependymomas, two ependymomas, and one each of the following: pineoblastoma, pineocytoma/pineoblastoma (intermediate type), epidermoid cyst, pineal cyst, medulloblastoma, arteriovenous hemangioma, cavernoma, choroid plexus papilloma, pituitary adenoma, craniopharyngioma, melanoma, and germinoma. Total tumor resections, partial resections, biopsies, stent implantations, septostomies, and third ventriculostomies were performed. In two cases (two subependymomas > 2 cm in diameter), piecemeal endoscopic resection was ineffective because of the very firm consistency of the tumors. Therefore the endoscopic procedure was discontinued and the tumors were removed microsurgically. In the remaining cases the procedures were completed as planned. Even in the presence of difficulties such as poor orientation or significant bleeding, there was no need to abandon the endoscopic procedure. A total of 28 strictly endoscopic interventions were performed, in which the average duration was 85 minutes (range 35–170 minutes). All colloid cysts and the epidermoid lesion were completely evacuated and the capsules were widely resected. Total extirpation of solid tumors was achieved in five cases, whereas most astrocytomas were partially resected. The hydrocephalus-related symptoms resolved in all of the 22 patients with cerebrospinal fluid pathway obstruction. There were no endoscopy-related deaths. In two cases, major bleeding occurred and was controlled endoscopically. The authors observed one case of meningitis, one of mutism, two of memory loss attributed to forniceal injury, one of transient trochlear palsy after a biopsy specimen of an aqueductal tumor was obtained, and one of transient confusion after a biopsy specimen of a germinoma was obtained.

Conclusions

In the authors' preliminary experience, the endoscopic approach was found to be safe and effective. In this series, it was possible to achieve relief of noncommunicating hydrocephalus, tumor resections, and even complete tumor removals by using endoscopic techniques. Based on the results, the authors believe that endoscopic techniques should be considered in the treatment of selected intraventricular lesions.

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Henry W. S. Schroeder and Michael R. Gaab

The authors' intention is to reduce the invasiveness of intracranial procedures while avoiding traumatization of brain tissue, to decrease the risk of neurological and mental deficits. Intracranial endoscopy is a minimally invasive technique that provides rapid access to the target via small burr holes without the need for brain retraction. Craniotomy as well as microsurgical brain splitting and dissection can often be avoided. Furthermore, because obstructed cerebrospinal fluid pathways can be physiologically restored, the need for shunt placement is eliminated. The ventricular system and subarachnoid spaces provide ideal conditions for the use of an endoscope. Therefore, a variety of disorders, such as hydrocephalus, small intraventricular lesions, and arachnoid and parenchymal cysts can be effectively treated using endoscopic techniques. With the aid of special instruments, laser fibers, and bipolar diathermy, even highly vascularized lesions such as cavernomas may be treated. Moreover, during standard microsurgical procedures, the endoscopic view may provide valuable additional information ("looking around a corner") about the individual anatomy that is not visible with the microscope. In transsphenoidal pituitary surgery, transseptal dissection can be avoided if an endonasal approach is taken. In the depth of the intrasellar space, the extent of tumor removal can be more accurately controlled, especially in larger tumors with para- and suprasellar growth.

The combined use of endoscopes and computerized neuronavigation systems increases the accuracy of the approach and provides real-time control of the endoscope tip position and approach trajectory. In the future, the indications for neuroendoscopy will certainly expand with improved technical equipment.

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Henry W. S. Schroeder, Christiane Schweim, Klaus H. Schweim and Michael R. Gaab

Object

The purpose of this prospective study was to evaluate aqueductal cerebrospinal fluid (CSF) flow after endoscopic aqueductoplasty. In all patients, preoperative magnetic resonance (MR) imaging revealed hydrocephalus caused by aqueductal stenosis and lack of aqueductal CSF flow.

Methods

In 14 healthy volunteers and in eight patients with aqueductal stenosis who had undergone endoscopic aqueductoplasty, aqueductal CSF flow was investigated using cine cardiac-gated phase-contrast MR imaging. For qualitative evaluation of CSF flow, the authors used an in-plane phase-contrast sequence in the midsagittal plane. The MR images were displayed in a closed-loop cine format. Quantitative through-plane measurements were performed in the axial plane perpendicular to the aqueduct. Evaluation revealed no significant difference in aqueductal CSF flow between healthy volunteers and patients with regard to temporal parameters, CSF peak and mean velocities, mean flow, and stroke volume. All restored aqueducts have remained patent 7 to 31 months after surgery.

Conclusions

Aqueductal CSF flow after endoscopic aqueductoplasty is similar to aqueductal CSF flow in healthy volunteers. The data indicate that endoscopic aqueductoplasty seems to restore physiological aqueductal CSF flow.

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Joachim Oertel, Ekaterina von Buttlar, Henry Werner Siegfried Schroeder and Michael Robert Gaab

The benefit of the current strategy for diagnosis (magnetic resonance [MR] imaging) and treatment (surgery, chemotherapy, radiotherapy) of gliomas, in contrast to the standard treatment in use before MR imaging and the micro-surgical era, has not yet been determined. A retrospective statistical analysis was performed for all patients with glioma who underwent surgery at a single institution between 1965 and 1974 (Group I, 88 patients) or 1986 and 1995 (Group II, 249 patients). There were no major differences in symptomatology, tumor localization, and number of surgical procedures. The mean time until tumor diagnosis was significantly shorter in Group II (Group I, 48 weeks; Group II, 19.5 weeks). Also, the mean time from initial symptoms to surgery was significantly shorter for high-grade gliomas in Group II (Group I, 16.3 weeks; Group II, 11.7 weeks). For high- as well as low-grade gliomas, there was a clear reduction of the perioperative morbidity and mortality rates in Group II. Nevertheless, for the postoperative duration of survival, no significant differences were demonstrated for high- or low-grade gliomas. Based on the results of this study, the perioperative morbidity and mortality rate as well as the time from diagnosis to treatment have been remarkably reduced within the last 30 years. Nevertheless, the overall prognosis for patients with gliomas has not changed from the 1970s until today. Thus, the introduction of modern diagnostic modalities and surgical procedures has not improved the outcome in patients with glioma. Further research to improve the treatment of this disease is urgently needed.

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Henry W. S. Schroeder, Rolf W. Warzok, Jamal A. Assaf and Michael R. Gaab

In recent years, endoscopic third ventriculostomy has become a well-established procedure for the treatment of various forms of noncommunicating hydrocephalus. Endoscopic third ventriculostomy is considered to be an easy and safe procedure. Complications have rarely been reported in the literature. The authors present a case in which the patient suffered a fatal subarachnoid hemorrhage (SAH) after endoscopic third ventriculostomy.

This 63-year-old man presented with confusion and drowsiness and was admitted in to the hospital in poor general condition. Computerized tomography scanning revealed an obstructive hydrocephalus caused by a tumor located in the cerebellopontine angle. An endoscopic third ventriculostomy was performed with the aid of a Fogarty balloon catheter. Some hours postoperatively, the patient became comatose. Computerized tomography scanning revealed a severe perimesencephalic-peripontine SAH and progressive hydrocephalus. Despite emergency external ventricular drainage, the patient died a few hours later.

Although endoscopic third ventriculostomy is considered to be a simple and safe procedure, one should be aware that severe and sometimes fatal complications may occur. To avoid vascular injury, perforation of the floor of the third ventricle should be performed in the midline, halfway between the infundibular recess and the mamillary bodies, just behind the dorsum sellae.

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Waltraud Kleist-Welch Guerra, Michael R. Gaab, Hermann Dietz, Jan-Uwe Mueller, Jürgen Piek and Michael J. Fritsch

Object

Decompressive craniectomy has been performed since 1977 in 57 patients with traumatic brain injury. The authors assess the efficacy of this treatment and the indications for its use.

Methods

The clinical status of the patients, their computerized tomography (CT) scans, and intracranial pressure (ICP) levels were documented prospectively in a standard protocol. At the beginning of the study, all patients older than 30 years were excluded. As of 1989 patients older than 40 years were excluded until 1991; since that time patients older than 50 years have been excluded. Primary brain or brainstem injury with fully developed bulbar brain syndrome, loss of auditory evoked potentials (AEPs), and/or oscillation flow in a transcranial Doppler ultrasound examination were contraindications to decompressive craniectomy. A positive indication for decompression was given in the case of progressive therapy-resistant intracranial hypertension in correlation with clinical (Glasgow Coma Scale [GCS] score, decerebrate posturing, dilating of pupils) and electrophysiological (electroencephalography, somatosensory evoked potentials, and AEPs) parameters and with findings on CT scans. Unilateral decompressive craniectomy was performed in 31 patients and bilateral craniectomy in 26 patients. In all cases, a wide frontotemporoparietal craniectomy was followed by a dura enlargement covered with temporal muscle fascia.

The outcomes of the treatment were surprisingly good. Only 11 patients (19%) died, three of whom died of acute respiratory disease syndrome. Five patients (9%) survived, but remained in a persistent vegetative state; six patients (11%) survived with a severe permanent neurological deficit, and 33 patients (58%) attained social rehabilitation. Two patients (3.5%) did not have a follow-up examination. The GCS score on the 1st day posttrauma and the mean ICP turned out to be the best predictors for a good prognosis. The results demonstrate the importance of decompressive craniectomy in the treatment of traumatic brain swelling.

Conclusions

Surgical decompression should be routinely performed when indicated before irreversible ischemic brain damage.

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Peter Grunert, Michael R. Gaab, Dieter Hellwig and Joachim M. K. Oertel

Endoscopy plays an important part in current minimally invasive neurosurgery. The concepts, indications, and standards of current neuroendoscopy were developed in the beginning of the 1990s by several groups of neurosurgeons. Several factors contributed to its success and acceptance, including technical development, influence of other disciplines, and adaptation to neurosurgical requirements. This historical survey focuses on the period when this technique initially emerged, including the scientific discussions of each group as well as the arguments and reasons that led to present intraventricular neuroendoscopy. Interestingly, despite the almost independent development of neuroendoscopic systems and techniques, the available systems and techniques applied these days grossly correspond. Rigid rod-lens endoscopes are generally accepted as the best option among the various available instrument sets. Nevertheless, frameless as well as frame-based stereotactic endoscopy and flexible steerable endoscopes might have their applications as well.