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  • Author or Editor: Michael Gaab x
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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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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, Wulf-Rüdiger Niendorf and Michael R. Gaab

Object. The purpose of this prospective investigation was to determine the rate of complications associated with endoscopic third ventriculostomy (ETV).

Methods. Between March 1993 and October 2001, 193 ETVs were performed in 188 patients at a single institution. The age of the patients ranged from 1 month to 85 years (mean age 39 years). One procedure had to be abandoned because a severe venous hemorrhage blurred the surgeon's view; however, third ventriculostomy was successfully accomplished in that patient 14 days later. In addition, there were two cases in which significant venous hemorrhages could be controlled endoscopically by using irrigation. Postoperative imaging revealed three subdural collections, one tiny thalamic contusion, one cortical hemorrhage at the puncture site, and one severe subarachnoid hemorrhage (SAH). There were two deaths (1% mortality rate) related to the endoscopic procedure; causes of death were one SAH from a torn basilar perforating artery and one wound infection leading to meningitis and septic multiorgan failure. Three permanent deficits occurred (confusion, oculomotor palsy, and diabetes insipidus [1.6% permanent morbidity rate]). Transient deficits included four cases of meningitis, three cases of cerebrospinal fluid leak, two cases of herniation syndrome, two cases of confusion, one case in which there was a decrease of consciousness, two cases of oculomotor palsy, and one case in which there was loss of thirst (7.8% transient morbidity rate). Misplacement of the fenestration was the main reason for severe complications. During the course of the study, the complication rate dropped significantly (no incidences of mortality or permanent morbidity occurred during the last 100 procedures).

Conclusions. All permanent and fatal complications occurred during the authors' very early experience, indicating that a steep learning curve was associated with the procedure. Endoscopic third ventriculostomy, if performed correctly, is a safe, simple, and effective treatment option for various forms of noncommunicating hydrocephalus.

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Henry W. S. Schroeder, Michael R. Gaab and Wulf-Rüdiger Niendorf

✓ A prospective study of seven consecutive patients with congenital arachnoid cysts treated endoscopically is reported. The ages of the patients at the time of diagnosis ranged from 6 to 47 years with three patients under 15 years. Two cysts were located in the posterior cranial fossa, four in the middle cranial fossa, and one in the suprasellar—prepontine area. The patients' symptoms included headache, seizures, vomiting, nausea, dizziness, balance problems, and precocious puberty. The authors performed cystocisternostomies and ventriculocystostomies via burr holes with the aid of a universal neuroendoscopic system. Minor bleeding was easily controlled by rinsing. In one case, the endoscopic procedure had to be abandoned because of significant bleeding, which obscured a clear operative view, and an open microsurgical cyst fenestration was performed. The follow-up review periods in this group of patients ranged from 15 to 30 months. There was no mortality or morbidity. Symptoms were relieved in five patients and improved in one. Precocious puberty in one case continued. In six cases, follow-up magnetic resonance images or computerized tomography scans revealed a decrease in the size of the cysts. Although the follow-up period is too short to make statements on long-term outcome, the authors recommend the minimally invasive endoscopic approach for treatment of arachnoid cysts as the first therapy of choice. Should the endoscopic procedure fail, established treatment options such as microsurgical fenestration or cystoperitoneal shunting can subsequently be performed without causing additional risk to the patient.

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Henry W. S. Schroeder, Wolfgang Wagner, Wolfgang Tschiltschke and Michael R. Gaab

Object. Frameless computerized neuronavigation has been increasingly used in intracranial endoscopic neurosurgery. However, clear indications for the application of neuronavigation in neuroendoscopy have not yet been defined. The purpose of this study was to determine in which intracranial neuroendoscopic procedures frameless neuronavigation is necessary and really beneficial compared with a free-hand endoscopic approach.

Methods. A frameless infrared-based computerized neuronavigation system was used in 44 patients who underwent intracranial endoscopic procedures, including 13 third ventriculostomies, nine aqueductoplasties, eight intraventricular tumor biopsy procedures or resections, six cystocisternostomies in arachnoid cysts, five colloid cyst removals, four septostomies in multiloculated hydrocephalus, four cystoventriculostomies in intraparenchymal cysts, two aqueductal stent placements, and fenestration of one pineal cyst and one cavum veli interpositi. All interventions were successfully accomplished. In all procedures, the navigational system guided the surgeons precisely to the target. Navigational tracking was helpful in entering small ventricles, in approaching the posterior third ventricle when the foramen of Monro was narrow, and in selecting the best approach to colloid cysts. Neuronavigation was essential in some cystic lesions lacking clear landmarks, such as intraparenchymal cysts or multiloculated hydrocephalus. Neuronavigation was not necessary in standard third ventriculostomies, tumor biopsy procedures, and large sylvian arachnoid cysts, or for approaching the posterior third ventricle when the foramen of Monro was enlarged.

Conclusions. Frameless neuronavigation has proven to be accurate, reliable, and extremely useful in selected intracranial neuroendoscopic procedures. Image-guided neuroendoscopy improved the accuracy of the endoscopic approach and minimized brain trauma.

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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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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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Henry W. S. Schroeder, Joachim Oertel and Michael R. Gaab

Object. Epidermoid tumors located in the cerebellopontine angle (CPA) are challenging lesions because they grow along the subarachnoid spaces around delicate neurovascular structures and often extend into the middle cranial fossa. The purpose of this study was to determine the value of endoscopic assistance in the microsurgical resection of these lesions, in which total removal is the therapy of choice.

Methods. Eight patients harboring an epidermoid tumor of the CPA were treated using an endoscope-assisted microsurgical technique. A retrosigmoid suboccipital approach was used in five patients and a pterional transsylvian approach was chosen in the other three. In four patients the lesion was resected microsurgically and the endoscope was used repeatedly to verify complete tumor removal, whereas most of the tumor mass was removed with the aid of an operating microscope in the other four. Tumor parts extending into other cranial compartments that were not visible through the microscope were removed under endoscopic view by using rigid rod-lens scopes with 30 and 70° angles of view.

All epidermoids were completely evacuated and the membranes were widely resected. Large tumors occupying both the middle and posterior cranial fossa were removed through a single small opening without enlarging the craniotomy. Permanent hearing loss and permanent hypacusis were observed in one patient each. One patient with facial and one with abducent nerve palsy recovered within 6 and 4 months, respectively. A transient weakness of the chewing muscles was encountered in one patient. Postoperative magnetic resonance imaging revealed no residual tumor in any patient. To date no recurrences have been observed (follow up range 12–98 months).

Conclusions. The endoscope-assisted microsurgical technique enables safe removal even when tumor parts are not visible in a straight line. Tumor extensions into adjacent cranial compartments can be removed with the same approach without retracting neurovascular structures or enlarging the craniotomy.