Florian Heinrich Ebner

BACKGROUND:. The maneuver of transmeatal drilling carries the risk of injuring inner ear structures, which may cause immediate or delayed hearing loss.O

Introduction. The endoscope became a highly valued visualization tool in neurosurgery. However, technical limitations caused by the rigidity of current standard endoscopes significantly decrease ergonomy in transcranial neurosurgery. Further technological developments will aid enlarging the surgical applicability. Objective. To evaluate the intraoperative features of a rigid variable-view endoscope in neurosurgery. Methods. We assessed a 4 mm rigid rod lens endoscope (EndoCAMeleon, Karl Storz, Tuttlingen, Germany) in the intraoperative setting. The device offers a variable angle of view from 15° to 90° in one plane. The endoscope was used in 3 cases (aneurysm clipping, vestibular schwannoma surgery, endoscopic third ventriculostomy) for inspection. Results. Direct insertion of the device through the craniotomy/burr hole with the lowest angled view (15°) was always possible. Neurovascular structures crossing the access route could be visualized and avoided. This allowed a targeted positioning of the endoscope’s tip in the operating field. Once the target point was reached, viewing direction was changed in one plane from 15° to 90° according to anatomic demands. As the endoscope’s tip does not move while the lens is rotated, surrounding neurovascular structures are not at risk to be injured. However, turning of the lens-controlling wheel in proximity to delicate structures may be inconvenient. Conclusion. The rigid, variable-view endoscope has the potential to become an appreciated visualization tool in neuroendoscopy. The steerable lens enables a tremendous expansion of the visual field, resulting in higher efficiency for surgeons and increased safety for patients.

Background Aims of modern vestibular schwannoma surgery are complete tumor resection with functional facial nerve and hearing preservation, if possible. Here we present our technique of bimanual dissection for vestibular schwannoma resection through the retrosigmoid approach. Method A slightly curved surgical incision is planned two fingers behind the ear extending from the level of the tip of the ear to 1 cm below the mastoid tip. The retrosigmoid craniectomy exposes the sinus knee, the inferior border of the transverse sinus, the medial border of the sigmoid sinus and horizontal segment of the occipital squama. The dura is opened under the microscope in semilunar fashion parallel to the course of the sigmoid sinus. We open the IAC with a high-speed diamond drill from lateral to medial, opening the canal for 180° of its circumference. The intrameatal part of the vestibular schwannoma is partially removed and the facial nerve identified Thereafter, we open the capsule and debulk the tumor with an ultrasonic surgical aspirator in the CPA. Once the tumor’s mass is significantly reduced, a bimanual dissection of the cleavage plane between capsule and the surrounding arachnoid is performed. Starting from below, the capsule is elevated with a tumor grasping forceps and the arachnoid membrane is peeled off. Following the cleavage plane, the facial nerve is separated in a medial to lateral direction from the VS’s capsule. Throughout the whole procedure the field is irrigated with warm Ringer’s solution. We seal the drilled posterior lip of the IAC as well as eventually opened mastoid air cells with a free muscle or fat patch. Conclusion Vestibular schwannoma surgery through the retrosigmoid approach is a safe procedure that allows gaining good functional results.

Background Pituitary adenomas are often encased in a histological pseudocapsule that separates the tumor from the normal gland. Transsphenoidal adenoma resection may be performed either in an intra- or an extracapsular technique. The extracapsular fashion offers anatomical orientation, removal of a security margin, reduced risk of opening the arachnoid layer with subsequent CSF flow and identification of invasion. Method The sella turcica is approached through the classic endoscopic endonasal route. After opening the dura of the sellar floor, the interface between the compressed tissue and the normal gland is used as a surgical plane for dissection. Performing slight counter-traction with the suction tube, the cleavage plane is identified and stepwise unsealed in an atraumatic fashion with the cotton swab. Once the cleavage plane is partially loosened, repeated twisting movements are performed with the cotton swab to enucleate the pseudocapsule and adenoma. Conclusion Both micro- and macroadenomas presenting a pseudocapsule may be resected in the extracapsular dissection technique with the cotton swab. Operating in an endoscopic three- to four hands technique enables to visualize the anatomic planes and perform twisting movements with the cotton swab separating pseudocapsule and tumor in order to enucleate the adenoma.

The aim of this study is to assess field of view, usability and applicability of a rigid, multidirectional steerable video endoscope (EndActive) in various intracranial regions relevant to neurosurgical practice. In four cadaveric specimens, frontolateral, pterional, transnasal (to sella and clivus), interhemispheric (transcallosal and retrocallosal) and retrosigmoid approaches as well as precoronal burr holes for ventriculoscopy were performed. Anatomical target structures were defined in each region. We assessed field of view as well as optical and ergonomic features of the prototype. The EndActive is a 4-mm-diameter rigid video (endo)scope with an integral image sensor comprising an embedded light source. The viewing direction in a range of 160° can either be controlled by the computer keyboard or a four-way joystick mounted to the handle section of the endoscope. The endoscopic imaging system allows the operator to simultaneously see both a 160° wide-angle view of the site and an inset of a specific region of interest. The surgeon can hold the device like a microsurgical instrument in one hand and control movements precisely due to its reduced weight and ergonomic shape. The multiplanar variable-view rigid endoscope proved to be useful for following anatomical structures (cranial nerves I–XII). The device is effective in narrow working spaces where movements jeopardize the delicate surrounding structures. The multiplanar variable viewing mechanism in a compact device offers advantages in terms of safety and ergonomics. Improving the usability will probably optimize the applicability of endoscopic techniques in neurosurgery.

Neuroendoscopy is increasingly used as an adjunctive tool in intracranial aneurysm surgery. To assess the versatility of a prototype continuously variable-view rigid endoscope in visualizing the anterior cerebral artery complex. In 5 formaldehyde-fixed, arterially injected specimens, a standard frontolateral approach was used on both sides. After meticulous microsurgical dissection using this approach, the prototype of a multivariable rigid endoscope (EndoCAMeleon; Karl Storz GmbH & Co, Tuttlingen, Germany) was inserted. It is a rigid endoscope that is capable of changing its angle of view while remaining stationary and shape invariant. We inspected the anterior cerebral artery complex, using and testing the capabilities of the device. The continuously variable viewing mechanism enables the surgeon to adjust the field of view continuously and to optimize the visualization of the neurovascular structures. Because of the rigid tip combined with the continuously variable viewing mechanism, the need to move the endoscope within the surgical field was minimal. The field of view changes, but the tip itself hardly moves. The EndoCAMeleon was able to enhance both the visibility of the anterior cerebral artery complex and the accessibility of the A1 and A2 arterial walls to a range of approximately 270 degrees. The EndoCAMeleon enhances the visibility of the anterior cerebral artery complex and facilitates endoscope-assisted inspection, planning of clip application, and clip control.

Object: The objective of this study was to evaluate and analyze morphometric and volumetric changes of the skull due to acromegaly in areas relevant for neurosurgical practice, focusing on the surgical implications. Methods: On preoperatively acquired CT scans, cephalometric and volumetric measurements were performed on 45 patients with acromegaly (Group A) and 45 control patients (Group B). The authors determined thickness of the cranial vault, inner and outer diameters of the skull, and the diameter of sphenoidal and maxillary sinus, as well as frontal and maxillary sinus volumetry. The morphometric and volumetric CT data of the patients with acromegaly were compared with the data of a control group and correlated with clinical parameters. Results: Cranial vault thickness differed significantly (p < 0.0001) between the 2 groups. A correlation of the vault thickness with preoperative human growth hormone, insulin-like growth factor–I levels, and duration of clinical history in acromegaly could not be established. The outer anterior-posterior skull diameter of Group A (18.47 ± 0.94 cm) differed significantly (p = 0.0146) from Group B (17.98 ± 0.93 cm) and correlated significantly with preoperative human growth hormone (r = 0.3277; p = 0.0299) and insulin-like growth factor-–I serum levels (r = 0.3756; p = 0.0120). Measurements of the anterior-posterior diameter of the sphenoidal sinus differed significantly (p = 0.0074) between patients with acromegaly and controls. Volumetric analysis of the frontal sinus resulted in a statistically significant difference (p = 0.0382) between patients with acromegaly (14.89 ± 10.85 cm ³ ) and controls (10.06 ± 6.93 cm ³ ). Conclusions: Significant craniometric changes and volumetric remodelling of the paranasal sinus occur in acromegaly. The bone alterations are of surgical importance for using the transsphenoidal approach. Detailed preoperative diagnostic examination and planning as well as selection of appropriate instruments are mandatory for safe and successful pituitary adenoma removal in patients with acromegaly.

The rare case of a patient with SIADH following pituitary adenoma apoplexy is reported. Since apoplexy did not exert any mass effect on surrounding structures, the patient was treated conservatively and the anterior pituitary gland insufficiency has been substituted adequately. Seven days after the apoplexy the patient again showed low serum–Na⁺ levels despite cortisol substitution. Diagnosis of SIADH was made. It is essential to be aware of this rare syndrome in patients with pituitary adenoma apoplexy.