In-patient neurosurgical tumor treatments for malignant glioma patients in Germany.

OBJECTIVE: Treatment for malignant gliomas involves multiple disciplines, including neurosurgery, radiation therapy, medical and neuro-oncology, and palliative medicine, with function-preserving neurosurgical tumor removal being crucial. However, real-world data on hospital cases, treatment types, especially regarding surgical approaches, and the associated complication and mortality rates in Germany are lacking. METHODS: We analyzed data on hospital cases involving malignant gliomas (ICD-10-GM code C71) from the German §21 Hospital Remuneration Act, provided by the Institute for the Hospital Remuneration System (InEK GmbH), from 2019 to 2022. Our focus was on neuro-oncological operations defined by the German Cancer Society (DKG) and included specific operation and procedure (OPS) codes. RESULTS: From 2019 to 2022, there were 101,192 hospital cases involving malignant gliomas in Germany. Neurosurgical tumor removal was performed in 27,193 cases (26.9%). Microsurgical techniques were used in 95% of surgeries, intraoperative navigation systems in 84%, fluorescence-guided surgeries in 45.6%, and intraoperative neurophysiological monitoring (IONM) in 46.4%. Surgical or medical complications occurred in 2903 cases (10.7%). The hospital mortality rate was 2.7%. Mortality was significantly higher in patients aged 65 and older (Odds ratio 2.9, p < 0.0001), and lower in cases using fluorescence-guided procedures (Odds ratio 0.8, p = 0.015) and IONM (Odds ratio 0.5, p < 0.0001). CONCLUSIONS: Over the course of 4 years, over 100,000 hospital cases involving adult patients diagnosed with malignant gliomas were treated in Germany, with 27,193 cases undergoing tumor removal using various modern surgical techniques. The hospital mortality rate was 2.7%.

Cystic vestibular schwannoma - a subgroup analysis from a comparative study between radiosurgery and microsurgery.

Some vestibular schwannoma (VS) show cystic morphology. It is known that these cystic VS bear different risk profiles compared to solid VS in surgical treatment. Still, there has not been a direct comparative study comparing both SRS and SURGERY effectiveness in cystic VS. This retrospective bi-center cohort study aims to analyze the management of cystic VS compared to solid VS in a dual center study with both microsurgery (SURGERY) and stereotactic radiosurgery (SRS). Cystic morphology was defined as presence of any T2-hyperintense and Gadolinium-contrast-negative cyst of any size in the pre-interventional MRI. A matched subgroup analysis was carried out by determining a subgroup of matched SURGERY-treated solid VS and SRS-treated solid VS. Functional status, and post-interventional tumor volume size was then compared. From 2005 to 2011, N = 901 patients with primary and solitary VS were treated in both study sites. Of these, 6% showed cystic morphology. The incidence of cystic VS increased with tumor size: 1.75% in Koos I, 4.07% in Koos II, 4.84% in Koos III, and the highest incidence with 15.43% in Koos IV. Shunt-Dependency was significantly more often in cystic VS compared to solid VS (p = 0.024) and patients with cystic VS presented with significantly worse Charlson Comorbidity Index (CCI) compared to solid VS (p < 0.001). The rate of GTR was 87% in cystic VS and therefore significantly lower, compared to 96% in solid VS (p = 0.037). The incidence of dynamic volume change (decrease and increase) after SRS was significantly more common in cystic VS compared to the matched solid VS (p = 0.042). The incidence of tumor progression with SRS in cystic VS was 25%. When comparing EOR in the SURGERY-treated cystic to solid VS, the rate for tumor recurrence was significantly lower in GTR with 4% compared to STR with 50% (p = 0.042). Tumor control in cystic VS is superior in SURGERY, when treated with a high extent of resection grade, compared to SRS. Therapeutic response of SRS was worse in cystic compared to solid VS. However, when cystic VS was treated surgically, the rate of GTR is lower compared to the overall, and solid VS cohort. The significantly higher number of patients with relevant post-operative facial palsy in cystic VS is accredited to the increased tumor size not its sole cystic morphology. Cystic VS should be surgically treated in specialized centers.

Diagnostic and treatment pitfalls in glossopharyngeal neuralgia: evidence from a case series.

BACKGROUND: Glossopharyngeal neuralgia (GN) is a rare pain syndrome often underdiagnosed. This study aimed to assess the challenges in diagnosing GN and identify patients at risk of misdiagnosis. METHODS: Between 2010 and 2019, nine patients underwent microvascular decompression (MVD) of the glossopharyngeal nerve at two tertiary care hospitals. A retrospective analysis examined symptom characteristics, time to correct diagnosis, operative technique, and clinical outcomes. Barrow Neurological Institute (BNI) pain scores were assessed before surgery and on follow-up. RESULTS: Six women and three men, aged 55 ± 14.3 years, with unilateral GN were included. Pain was predominantly in the ear (otalgic type) in four patients (44.4%), the pharynx or base of the tongue (pharyngeal type) in four (44.4%), and mixed in one (11.1%). Five patients reported pain radiating to the mandible, all initially misdiagnosed with trigeminal neuralgia (TN) and treated for 2.4(± 3.1) years before presenting to our institution. One case resulted in MVD of the trigeminal nerve and subsequent thermocoagulation of the Gasserian ganglion due to persistent pain. The correct diagnosis of GN was established later in patients with otalgic or mixed pain (3.8 ± 3.4 years) compared to those with pharyngeal pain (0.5 ± 1.0 years), showing a trend (U = 17.0, p = 0.07). There was a significant association between pain radiation to the mandible and misdiagnosis (x2 = 9.00, p = 0.003). Endoscopically assisted MVD via the median suboccipital subtonsillary approach was performed, resolving neurovascular conflicts with the PICA (9/9) and vertebral artery (3/9). Follow-up after 15.7(± 18.2) months showed significant pain reduction according to the BNI (preoperative BNI = 5.0 ± 0.0, postoperative BNI = 1.7 ± 1.0,t (8) = 10,CI [1.6-5.1], p < 0.001). No permanent surgery-related deficits occurred. CONCLUSION: Patients with GN, especially those with predominant otalgic pain and pain radiating to the mandible, are at higher risk of misdiagnosis due to similarities with TN. Despite the rarity of GN, increased awareness of its various pain manifestations may lead to earlier correct diagnoses, which is crucial for surgical treatment.

Musculoskeletal demands in microsurgery-an explorative study comparing the ergonomics of microscope and 3D exoscope.

To assess neurosurgeons' physical demands and investigate ergonomic aspects when using microsurgical visualization devices. Six neurosurgeons performed micro-surgical procedures on cadaveric specimens using the prototype of a digital 3D exoscope system (Aeos®, Aesculap, Tuttlingen, Germany) and a standard operating microscope (Pentero 900, Zeiss, Oberkochen, Germany) at two different patient positions (semisitting (SS), supine (SP)). The activities of the bilateral upper trapezius (UTM), anterior deltoid (ADM), and lumbar erector spinae (LEM) muscles were recorded using bipolar surface electromyography and neck flexion, arm abduction, and arm anteversion angles by gravimetrical posture sensors. Perceived discomfort frequency was assessed and subjects compared the two systems in terms of usability, posture, physical and mental demands, and working precision. Using the exoscope led to reduced ADM activity and increased UTM and LEM activity during SS position. The neck was extended when using the exoscope system with lower arm anteversion and abduction angles during the SS position. Subjects reported discomfort at the shoulder-neck area less frequently and lower physical demands when using the Aeos®. However, mental demands were slightly higher and two subjects reported lower working precision. The exoscope system has the potential to reduce the activity of the ADM by changing surgeons arm posture which may be accompanied by less discomfort in the shoulder-neck area. However, dependent on the applied patient position higher muscle activities could occur in the UTM and LEM.

Delayed Cerebral Ischemia in Patients with Aneurysmal Subarachnoid Hemorrhage - Serum D-dimer and C-reactive Protein as Early Markers.

BACKGROUND: Identifying patients at risk for delayed cerebral ischemia after an aneurysmal subarachnoid hemorrhage remains challenging and both delayed treatment and over-treatment are reasonable concerns. OBJECTIVE: To evaluate the role of the serum markers C-reactive protein, white blood count, and d-dimer as prognostic factors for the occurrence of delayed cerebral ischemia. METHODS: All patients admitted within 24 hours after an aneurysmal subarachnoid hemorrhage were included over a 6-year period. The World Federation of Neurosurgery and Fisher grading scales as well as the extended Glasgow Outcome Scale were documented at discharge and after a 3-to-6-month follow-up period. C-reactive protein, d-dimer, white blood count, and procalcitonin were assessed on admission, day 1, day 4, day 9, day 14, and at discharge. Radiologically confirmed delayed cerebral ischemia before discharge was the primary endpoint. Severe angiographic vasospasm and outcome were used as secondary endpoints. RESULTS: Delayed cerebral ischemia occurred in 19.6% of the 138 patients included. Delayed cerebral ischemia correlated with severe vasospasm and with a worse outcome. Serum C-reactive protein levels were higher in patients with severe vasospasm during the period of vasospasm. D-dimer levels on admission correlated with Fisher grades. Delayed cerebral ischemia occurred more frequently in patients with Fisher grade IV hemorrhage, if d-dimer levels were higher on admission. The cut-off was .445 µg/ml. CONCLUSION: Our observations support a multifactorial genesis for delayed cerebral ischemia, including vasospasm and microthrombotic and inflammatory processes. Serum d-dimer levels greater than .445 µg/ml might be a predictor for the occurrence of delayed cerebral ischemia in patients with a Fisher grade IV aneurysmal subarachnoid hemorrhage.

Survey of the management of perioperative bridging of anticoagulation and antiplatelet therapy in neurosurgery.

BACKGROUND: A growing number of patients on anticoagulation or antiplatelet therapy (APT) are planned for elective surgery. The management of perioperative anticoagulation and APT is challenging because it must balance the risk of thromboembolism and bleeding, and specific recommendations for the management of bridging in neurosurgical patients are lacking. We surveyed German neurosurgical centers about their management of perioperative bridging of anticoagulation and APT to provide an overview of the current bridging policy. METHOD: From April to August 2016, all German neurosurgical departments were invited to participate in the survey. We used SurveyMonkey to compose ten questions and to conduct the survey, and we defined three different approaches for the perioperative management of patients on a preexisting medication: medication will be discontinued (A) with perioperative "bridging" and (B) without perioperative bridging, or (C) medication will be continued perioperatively. RESULTS: Out of 141 respondents, 84 (60%) partially and 77 (55%) fully completed the questionnaire. No defined policy for the perioperative management of anticoagulation and APT was established in 60.7% (51/84) of participating centers. The perioperative management of anticoagulation and APT varied widely among different centers in all items of the questionnaire; for example, in the group of patients at high risk for thromboembolism, acetylsalicylic acid was discontinued in 22%, bridged in 35%, and continued in 35% of centers. CONCLUSIONS: There is significant uncertainty regarding the management of perioperative bridging of anticoagulation and APT in neurosurgery because of a lack of prospective and limited retrospective data.

The midline suboccipital subtonsillar approach to the cerebellomedullary cistern: how I do it.

BACKGROUND: Lesions lateral to the lower brainstem in an area extending from the foraminae of Luschka to the foramen magnum are rare and include different pathologies. There is no consensus on an ideal surgical approach. METHOD: To gain access to this area, we use the midline suboccipital subtonsillar approach (STA). This midline approach with unilateral retraction of the cerebellar tonsil enables entry into the cerebellomedullary cistern. CONCLUSIONS: The STA offers excellent access with a panoramic view of the cerebellomedullary cistern and its structures and therefore can be useful for a number of different pathologies in the lower petroclival area.

Rigid, Variable-View Endoscope in Neurosurgery: First Intraoperative Experience.

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.

Vestibular schwannoma surgery via the retrosigmoid transmeatal approach.

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.

Late neurological sequelae due to brainstem irradiation for an assumed glioma.

PURPOSE: There is ongoing discussion whether radiotherapy might be beneficial in the treatment of intracranial cavernomas, however long-term sequelae due to brainstem irradiation may exist. CASE REPORT: The case of a 72-year-old female is reported who received radiotherapy in the pre-MRI era due to a suspected intra-axial pontine lesion. Later on she developed severe trigeminal neuropathy and an MRI was performed 27 years after irradiation of the brainstem. On these images a large cavernous malformation with signs of multiple haemorrhages instead of the pontine glioma was seen accompanied by a substantial atrophy of brainstem structures. CONCLUSION: This case impressively demonstrates the long-term outcome of brainstem irradiation and reflects that cavernomas do not respond to radiotherapy.

The risk of intraoperative venous air embolism from neurosurgical procedures performed in the lounging position: an in-depth analysis of detection, management, and outcomes of 1000 consecutive cases.

OBJECTIVE: The overall benefit of employing a sitting/semisitting position for neurosurgical procedures remains under criticism due to concerns for additional risk, especially the risk of intraoperative venous air embolism (VAE). The aim of this single-center cohort study was to evaluate the frequency and severity of VAEs and associated complications in patients undergoing neurosurgery in the lounging position. METHODS: From 2010 to 2020, 1000 patients, including 172 patients with a patent foramen ovale, underwent surgery in the lounging position for different neurosurgical pathologies. All patients were monitored intraoperatively using continuous transesophageal echocardiography (TEE). The anesthesia team documented any observed incidences of VAEs and scored their severity according to the Tuebingen classification system (TCS) for VAE (TCS-VAE). The patients' clinical condition, radiological findings, and hospital course were subsequently analyzed to assess complications in a retrospective analysis of prospectively collected data. RESULTS: In the cohort of 1000 patients, 5 underwent cervical spine surgery and 995 underwent suboccipital craniotomy. VAE was detected by TEE in 51.4% (95% CI 48.4%-54.5%) of patients, with synchronous changes in end-tidal CO2 (grade 2-5 TCS-VAE) noted in 10.2% (95% CI 8.3%-12.3%). None of the patients presented with hemodynamic instability (grade 5 TCS-VAE). Patients with high-grade VAEs were significantly older (p = 0.02) and had lower BMIs (p = 0.001) than the respective mean value of the cohort. VAE grade was not associated with any of the outcome measures such as Karnofsky Performance Scale score, duration of ventilation, length of intensive care unit stay, and length of hospital stay. Postoperative acute respiratory distress syndrome (ARDS) was diagnosed in 0.3% (95% CI 0.0%-0.7%, n = 3) of all cases, and ARDS was associated with perioperative VAE grade (p = 0.001). No patient suffered a new permanent neurological deficit due to a paradoxical VAE. CONCLUSIONS: In this large cohort, the risk of an intraoperative VAE during neurosurgery in the lounging position was assessed, and contrary to the general perception in the field, no permanent sequelae or fatal adverse events attributable to VAEs were observed. Furthermore, the overall incidence of ARDS was very low. This study clearly establishes that experienced interdisciplinary teams can safely use the lounging position for neurosurgical procedures.

Live surgery in neurosurgical training courses: essential infrastructure and technical set-up.

BACKGROUND: Training courses in neurosurgery are essential educational elements of residency. Teaching methods vary due to cultural differences, monetary restrictions and infrastructure conditions. Anatomical dissection courses combined with annotated live surgeries performed by senior surgeons have proved to be best accepted by students. OBJECTIVE: In this technical note, we provide detailed information about the necessary requirements, resources and optimal performance of live surgeries in neurosurgical training courses. METHODS AND RESULTS: From 2007 to 2012, 12 neurosurgical training courses with live surgeries were organised at the Department of Neurosurgery. Here, we share our experience and report the essential set-up for these courses. Our department organised seven skull base, four cervical spine and one spinal cord stimulation hands-on dissection course with live surgeries. The course structure included lectures, cadaver dissections and live surgeries. The technical set-up included video transmission via an IP-based network with fibreglass backbone between the operating theatre (OR) and lecture room. During surgery, bidirectional discussions offered the participants the ability to interject and ask questions. Important issues included the careful selection of live operated patients with clearly presented pathology for the didactic cases used to demonstrate the technique. A live surgery should include the entire procedure: intraoperative set-up, positioning, anaesthesiological procedures and handling of intraoperative situations. CONCLUSION: A professionally prepared step-by-step educational program including surgical anatomy, cadaver dissection and live surgeries with online discussion offers a high level of training and enriches both the participants and instructors.

Extracapsular dissection technique with the cotton swab for pituitary adenomas through an endoscopic endonasal approach -- how I do it.

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.

Actual state of EndActive ventricular endoscopy.

PURPOSE: We assessed usability and applicability of a rigid, multidirectional steerable videoendoscope (EndActive, Karl Storz GmbH, Tuttlingen, Germany) for endoscopic third ventriculostomy and compared our experience with reports about other multidirectional endoscopes. METHODS: The prototype is a 4-mm-diameter rigid videoendoscope with an integrated image sensor comprising an embedded light source, offering a free viewing direction in a range of 160° while the tip itself does not move. In five specimens (ten sides), we introduced the endoscope via precoronal burr holes through the lateral ventricle and foramen of Monro into the third ventricle. The endoscope's tip was positioned at the level of the mamillary bodies and the previously defined anatomical target structures; anteriorly, the optic chiasm, anterior commissure, infundibulum, tuber cinereum and posteriorly, the entrance to the mesencephalic aqueduct and posterior commissure were inspected. RESULTS: A single insertion of the videoendoscope was sufficient to explore with the multiplanar viewing mechanism the entire third ventricle. The prototype videoendoscope may be held like a microsurgical instrument in one hand. It is feasible to control movements precisely due to the reduced weight and ergonomic shape of the device. CONCLUSIONS: The prototype EndActive has the potential to fit in the current concept of ETV and enrich the setting adding working economy and viewing variability.

Developments in neuroendoscopy: trial of a miniature rigid endoscope with a multidirectional steerable tip camera in the anatomical lab.

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.

Efficacy and versatility of the 2-micron continuous wave laser in neuroendoscopic procedures.

Laser-assisted techniques offer a huge potential in neurosurgery, but have achieved little acceptance to date. One reason is the concern regarding heat production, uncontrollable and distant penetration, and tissue interaction.We describe our experience with a 2-micron continuous wave laser (RevoLix jr.; LISA Laser Products OHG, Katlenburg-Lindau, Germany) for neuroendoscopic intraventricular procedures.The laser beam is delivered through flexible fibers. In an aqueous medium, the effect is restricted to <2 mm in front of the tip with tissue penetration depth of 500 µm.Forty-four patients (25 adults, 19 children) were operated on using the endoscopic, laser-assisted technique for treatment of obstructive hydrocephalus (n = 39), pure cyst fenestration (n = 4), or pure tumor biopsy (n = 1). All 53 procedures were successfully performed in those 44 operations, with the laser being the main effective instrument used (except for biopsy). Besides one clinically silent small intracisternal hemorrhage and one worsening of a preexisting oculomotor palsy (following fenestration of multiple midbrain cysts), no procedure-related complications occurred.The 2-micron continuous wave laser is a most valuable and useful tool, in our experience with safe applicability for endoscopic intracranial procedures in patients of all ages.

Management of holocord pilocytic astrocytomas in children and adolescents: an update.

Holocord intramedullary low-grade astrocytomas in children and adolescents - involving most or all of the cervical and thoracic spinal cord - are a rare finding. Most of the tumors seem to be pilocytic astrocytomas. Surgical management strategies might not be as clear as in small and circumscribed intramedullary tumors. On the basis of 20 previously published cases and 3 own patients, we summarize and discuss possible treatment options and their risks and benefits. Surgery should be performed soon after establishment of the diagnosis, which per se is often delayed despite a long-standing presence of attributable symptoms or signs in most cases. Following multilevel laminotomy, excellent results can be achieved by electrophysiologically guided microsurgical tumor removal in a single-staged or multistaged approach. The surgical goal is resection as gross total as possible provided intraoperative monitoring indicates preservation of function. Small tumor remnants often remain stable in the due course. In case of unresectable regrowth or recurrence, chemotherapy or radiotherapy are the adjuvant treatment options.

The impact of subdural air collection on intraoperative motor and somatosensory evoked potentials: fact or myth?

BACKGROUND: Surgery in the semi-sitting position is susceptible to changes in motor (MEP) and somatosensory evoked potentials (SEPs), which are not related to neurological impairment. These changes have been suggested to be caused by the insulating effect of subdural air collection. This study sought to investigate the correlation of MEP and SEP final-to-baseline amplitude ratios to postoperative volumetry of frontoparietal subdural air collection. METHODS: Median nerve SEP and hand MEP findings of 47 patients operated on in the semi-sitting position were compared with 7 patients operated on in the supine position. Computed tomography was routinely performed on the 1st postoperative day in all patients, and subdural air volumetry was calculated. Final-to-baseline MEP and SEP amplitude ratios were calculated and correlated to subdural air volumetry. FINDINGS: SEP changed in 12 patients, and MEP changed in 7 patients. Postoperative subdural air collections were significantly different between the groups (semi-sitting group, mean 31.2 cm(3); supine group, mean 2 cm3; p = 0.000). For the SEP ratios, a moderate negative correlation with subdural volumetry was found in the semi-sitting group (p = 0.044). Conversely, there was no correlation in the subset of patients with SEP attenuation (p = 0.846). As concerns the MEP ratios, no correlation was demonstrated in any group (semi-sitting, p = 0.967; supine, p = 0.193). CONCLUSIONS: Although SEP amplitude reductions were associated with large subdural air collections, this was not observed in the subset of patients with SEP attenuation and for the MEP monitoring, suggesting other pathophysiological mechanisms, such as brain shift, for the artificial amplitude reduction.

Optical requirements on magnification systems for intracranial video microsurgery.

INTRODUCTION: The basic idea of video-microsurgery is the improvement of ergonomic conditions in microsurgical procedures by replacing the bulky operating microscope with a compact videosystem. OBJECTIVE: To specify optical requirements on a videosystem for microsurgical intracranial procedures in neurosurgery. METHODS: During 27 microsurgical intracranial procedures (12 cerebellopontine angle and 15 supratentorial) zoom factor, focus distance and illumination parameters of the operating microscope were continuously recorded. Ergonomic aspects were documented as well. RESULTS: The zoom factor ranged from 1.7 to 13.5 in CPA procedures and from 1.4 to 13.4 in supratentorial procedures. The focus distance ranged from 180 mm to 367 mm in CPA procedures and from 188 mm-472 mm in supratentorial procedures. CONCLUSION: From an optical point of view current operating microscopes meet the requirements of intracranial microneurosurgery. However, ergonomically further developments are highly desirable. Video microsurgery is a promising field and could hold a solution to this problem.

Cortical and subcortical gray matter changes in patients with chronic tinnitus sustaining after vestibular schwannoma surgery.

Tinnitus is attributed to partial sensory deafferentation resulting in a central maladaptive neuroplasticity. Unfortunately, the agent of deafferentation is usually unknown or irreversible. In patients with unilateral vestibular schwannoma (VS), however, the auditory nerve is affected by a benign tumor. Hence, removal of the tumor can cease the tinnitus. In turn, sustaining complaints after surgery indicate cortical neuroplasticity. The present study is a cross sectional study which aims to track cortical structural changes by surface-based morphometry in 46 VS patients with sustained (i.e. centralized) or ceased (i.e. peripheral) tinnitus after surgery. A volumetric analysis of cortical and subcortical gray matter (GM) anatomy was performed on preoperative high-resolution MRI and related to the presence of hearing impairment, pre- and/or postoperative tinnitus. Patients with sustained (i.e. chronic) tinnitus showed an increased GM volume of the bilateral caudate nucleus, the contralateral superior colliculus, the middle frontal and middle temporal gyrus, the fusiform gyrus as well as the ipsilateral pars orbitalis when compared to those patients in whom tinnitus ceased postoperatively. Chronic tinnitus in VS patients is associated with characteristic structural changes in frontal, temporal and subcortical areas. Notably, a significant GM change of the caudate nucleus was detected providing further support for the striatal gaiting model of tinnitus.