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.

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.

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.

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.

Spinal meningioma surgery in the elderly: who can benefit from it?

BACKGROUND: With increasing life expectancy and increasing demands on quality of life more spinal meningiomas will limit quality of life in elderly in the coming decades. We investigated whether elderly can improve neurologically and gain self-dependence postoperatively. METHODS: Medical records of consecutive spinal meningioma patients from 2004-2015 were retrospectively analyzed. Age, gender, preoperative duration and quality of symptoms, pre- and postoperative McCormick score, Karnofsky Performance Status (KPS), American Society of Anesthesiologists Physical Status (ASA), modified Clinical Scoring System (mCSS) and tumor characteristics were included. Elderly were defined by ≥70 years. RESULTS: One hundred and twenty-nine patients were included, of whom 44 were 70 years or older. Younger patients were significantly better preoperatively in McCormick, KPS, ASA and mCSS within the first postoperative year. Both younger and elderly patients improved significantly postoperatively in McCormick, KPS and mCSS. Surgical complication rate was similar for younger and elderly patients (5.9 vs. 6.8%). Systemic complication rate was higher in elderly (0 vs. 6.8%). CONCLUSIONS: Surgery for spinal meningioma in elderly (KPS≥40 and ASA≤III) leads to a significant improvement of McCormick, KPS and mCSS postoperatively. This leads to a higher rate of self-dependency and thereby probably to an improvement of quality of life in elderly. However, special attention for systemic complications is necessary.

Contribution of mTOR and PTEN to Radioresistance in Sporadic and NF2-Associated Vestibular Schwannomas: A Microarray and Pathway Analysis.

The use of radiation treatment has increased for both sporadic and neurofibromatosis type 2 (NF2)-associated vestibular schwannoma (VS). However, there are a subset of radioresistant tumors and systemic treatments that are seldom used in these patients. We investigated molecular alterations after radiation in three NF2-associated and five sporadically operated recurrent VS after primary irradiation. We compared these findings with 49 non-irradiated (36 sporadic and 13 NF2-associated) VS through gene-expression profiling and pathway analysis. Furthermore, we stained the key molecules of the distinct pathway by immunohistochemistry. A total of 195 differentially expressed genes in sporadic and NF2-related comparisons showed significant differences based on the criteria of p value < 0.05 and a two-fold change. These genes were involved in pathways that are known to be altered upon irradiation (e.g., mammalian target of rapamycin (mTOR), phosphatase and tensin homolog (PTEN) and vascular endothelial growth factor (VEGF) signaling). We observed a combined downregulation of PTEN signaling and an upregulation of mTOR signaling in progressive NF2-associated VS after irradiation. Immunostainings with mTOR and PTEN antibodies confirmed the respective molecular alterations. Taken together, mTOR inhibition might be a promising therapeutic strategy in NF2-associated VS progress after irradiation.

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.

Interoptic, Trans-lamina Terminalis, Opticocarotid Triangle, and Caroticosylvian Windows From Mini-Supraorbital, Frontomedial, and Pterional Perspectives: A Comparative Cadaver Study With Artificial Lesions.

Introduction: The mini-supraorbital (MSO) and pterional (PT) approaches have been compared in a number of studies focusing on the treatment of aneurysms, craniopharyngiomas, and meningiomas. The goal of this study was to analyze the surgical exposure to different artificial lesions through interoptic (IO), trans-lamina terminalis (TLT), opticocarotid triangle (OCT), and caroticosylvian (CS) windows from the MSO, frontomedial (FM), and PT perspectives. Methods: The MSO, PT, and FM approaches were performed sequentially in two fixed cadaver heads. Three colored spheres were placed around the optic chiasm: (1) between the optic nerves; (2) between the optic nerve and the internal carotid artery; and (3) between the internal carotid artery and the oculomotor nerve. The surgical exposures to these structures by using the IO, TLT, OCT, and CS windows were compared. Results: (1) IO window: from the MSO and PT approaches, the total surgical exposure mainly allows visualization of contralateral lesions. The FM approach was superior for exploration of both sides of the area between the optic nerves. (2) TLT pathway: the MSO and PT approaches mainly expose the contralateral third ventricle wall. (3) OCT window: the PT approach allows exposure of a larger part of the sphere between the optic nerve and the internal carotid artery than the MSO approach. (4) CS window: the PT approach allows a better exposure of lateral structures such as the oculomotor nerve and of the medial prepontine area in comparison to the MSO approach. Conclusion: Simulation of the surgical situation with artificial lesions is a good model for comparing surgical perspectives and for analyzing feasibility of lesion exposure and resection.

3D Exoscope System in Neurosurgery-Comparison of a Standard Operating Microscope With a New 3D Exoscope in the Cadaver Lab.

BACKGROUND: For decades, the operating microscope has been the "gold standard" visualization device in neurosurgery. The development of endoscopy revolutionized different surgical disciplines, whereas in neurosurgery, the endoscope is commonly used as an additional device more than as single visualization tool. Invention of a 3D exoscope system opens new possibilities in visualization and ergonomics in neurosurgery. OBJECTIVE: To assess the prototype of a 3D exoscope (3D exoscope, year of manufacture 2015, FA Aesculap, Tüttlingen, Germany) as neurosurgical visualization device in comparison to a standard operating microscope. METHODS: A pterional approach was performed in 3 ETOH-fixed specimens (6 sides). A standard operating microscope was compared to a 3D exoscope prototype. Dimensions like visual field, magnification, illumination, ergonomics, depth effect, and 3D impression were compared. RESULTS: In all approaches, the structures of interest could be clearly visualized with both devices. Magnification showed similar results. The exoscope had more magnification potential, whereas the visual quality got worse in higher magnification levels. The illumination showed better results in the microscope. Surgeons felt more comfortable with the 3D exoscope, concerning ergonomic considerations. Depth effect and 3D impression showed similar results. None of the surgeons felt uncomfortable using the exoscope. CONCLUSION: The operating microscope is the gold standard visualization tool in neurosurgery because of its illumination, stereoscopy, and magnification. Nevertheless, it causes ergonomic problems. The prototype of a 3D exoscope showed comparable features in visual field, stereoscopic impression, and magnification, with a clear benefit concerning the ergonomic possibilities.

Surgical Management of Primary Cerebellopontine Angle Melanocytoma: Outcome, Recurrence and Additional Therapeutic Options.

OBJECTIVE: Meningeal melanocytomas of the central nervous system are extremely rare, with an incidence of 1 per 10 million individuals. Cases of primary cerebellopontine angle melanocytoma (PCPAM) have only been described in single case reports. The goal of the present study was to analyze the surgical management of PCPAM, with a particular focus on early and late treatment outcomes and recurrence rates. METHODS: The patients who had undergone surgery for PCPAM from January 2004 to May 2018 were identified by a local database query. The patients were evaluated for initial symptoms, pre- and postoperative facial and cochlear nerve function, complications, and recurrence rate by reviewing the patients' medical records. RESULTS: We identified 4 patients with PCPAM of >1500 cerebellopontine angle lesions (∼0.2%) that had been surgically treated at our department in the past 14 years. Of the 4 patients, 2 were men and 2 were women, with a mean age of 47 years. Anatomical facial and cochlear nerve preservation was achieved in all 4 patients. One patient experienced a new moderate facial palsy immediately after surgery (House-Brackmann grade III). Of the 4 patients, 3 had undergone radiotherapy and 1 had undergone ion beam therapy for tumor recurrence (6 years after surgery). Of the 4 patients, 3 had presented with tumor recurrence at 2, 3, and 6 years of follow-up respectively. The long-term follow-up examination had not yet been conducted for 1 patient. CONCLUSIONS: At long-term follow-up, 3 patients had developed recurrence. Because of the high recurrence rate of PCPAM, we believe that radiotherapy in addition to surgery should be considered in the future to avoid early recurrence.

Two-Micron Continuous-Wave Laser-Assisted Neuroendoscopy: Clinical Experience of Two Institutions in 524 Procedures.

OBJECTIVE: To present the clinical experience of 2 neurosurgical centers with the use of a 2-micron continuous-wave laser (2µ-cwL) system as standard tool in neuroendoscopic procedures and to discuss the safety and efficacy of this system. METHODS: In total, 469 patients underwent neuroendoscopic procedures using 2µ-cwL between September 2009 and January 2015. All patient data were retrospectively reviewed. In total, 241 (51%) patients were children and 228 (49%) adults. Mean age was 27.5 years (range: 3 days to 83 years). Intraoperative ultrasonography or neuronavigation were used to guide ventricular or cyst puncture and for intraventricular or intracystic orientation if necessary. RESULTS: A total of 524 neuroendoscopic procedures using 2µ-cwL were performed. Laser-assisted endoscopic third ventriculostomy was the most common procedure in 302 (64%) patients. Cyst fenestration was performed in 124 (26%), septostomy in 45, tumor biopsy in 41, tumor resection in 8, and choroid plexus coagulation in 3 patients. There was no intraoperative complication directly attributable to the use of laser and an overall procedural complication rate of 4.8%. CONCLUSIONS: This large series of 2µ-cwL as a routine tool in neuroendoscopic procedures demonstrates that 2µ-cwL is safe for endoscopic third ventriculostomy, septostomy, cyst fenestration, and intraventricular tumor biopsy or resection. As a cutting and coagulation tool, it combines the action of mechanical tools like forceps, balloons, and scissors plus those of electric tools. It therefore renders neuroendoscopic procedures more straightforward with a minimum need to change tools.

Retrosigmoid Transmeatal Endoscope-Assisted Approach in Semi-Sitting Position for Resection of Vestibular Schwannoma: 2-D operative Video.

We present a case of a mid-sized vestibular schwannoma (T3b according to the Hannover classification) that was resected through a retrosigmoid transmeatal approach in semi-sitting position under endoscopic assistance. The patient is a 52-year-old male with acute loss of functional hearing on the right side. Audiometry confirmed a loss of up to 60 dB and lost speech discrimination, there were no associated symptoms such as tinnitus or vertigo. This 2D video demonstrates positioning, OR set-up, anatomical and surgical nuances of the skull base approach and the operative technique for microdissection of the tumor from the critical neurovascular structures, especially the facial and cochlear nerves. A gross total resection was achieved and the patient discharged home after four days with unaltered function of the facial nerve (HB I). At one year follow up there was no indication of residual or recurrence. In summary, the retrosigmoid transmeatal approach is an important and powerful tool in the armamentarium for the microsurgical management of all kinds of vestibular schwannomas. Provided the necessary anesthesiological precautions and intraoperative procedures the semi-sitting position is safe and effective. If needed, the approach can be complemented by the use of an endoscope for visualization of the distal internal auditory canal. The link to the video can be found at: https://youtu.be/pPKT4_5nIn0 .

Resection of a Petroclival Meningioma via the Endoscope-Assisted Retrosigmoid Approach: 2-D Operative Video.

We present a case of a petroclival meningioma that was resected through an endoscope-assisted retrosigmoid approach via corridors above and below the facial-vestibulocochlear nerve complex. The patient is a 61-year-old female with complaints of left-sided hypesthesia and neuralgia of the infraorbital and zygomatic region, intermittent periorbital myokymia, and a slight facial palsy (HB II). This 2D video demonstrates the operative technique, anatomical and surgical nuances of the skull base approach and microdissection of the tumor from the critical neurovascular structures. A gross total resection was achieved. The patient's facial and trigeminal symptoms resolved completely within a few weeks. At 2 year follow up there was no indication of residual or recurrence. In summary, the retrosigmoid approach with endoscopic assistance is an important and powerful tool in the armamentarium for the microsurgical management of meningiomas of the lateroventral skullbase of the posterior fossa. The link to the video can be found at: https://youtu.be/Px4XIRDoALc .

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.

Postoperative Tinnitus After Vestibular Schwannoma Surgery Depends on Preoperative Tinnitus and Both Pre- and Postoperative Hearing Function.

OBJECTIVE: Tinnitus is one of the most common symptoms before and/or after the surgical removal of a vestibular schwannoma (VS) affecting almost half of the patients. Although there is increasing evidence for the association of hearing impairment and VS-associated tinnitus, the effect of hearing deterioration due to surgery and its relation to the postoperative tinnitus (postTN) is poorly investigated. This knowledge, however, might (i) enlighten the pathophysiology of VS-associated tinnitus (i.e., peripheral or central origin) and (ii) improve preoperative patient counseling. The aim of this study was to understand the predisposition factors for a postTN in relation to hearing outcome after surgery. METHODS: This retrospective study analyzed the presence of tinnitus in 208 patients with unilateral VS before and after surgical removal. A binomial logistic regression was performed to ascertain the effect of pre- and postoperative hearing as well as age, gender, tumor side, and size, and intraoperative cochlear nerve resection (CNR) on the likelihood of postoperative VS-associated tinnitus. RESULTS: Preoperative tinnitus was the strongest predictor of postTN. In addition, deterioration of functional hearing was increasing, while functional deafferentation (i.e., postoperative hearing loss) of non-functional hearing was reducing the risk of postTN. At the same time, patients with no preoperative tinnitus but complete hearing loss had the lowest risk to suffer from postTN. Patient age, gender, tumor side, and size as well as CNR played a subordinate role. CONCLUSION: While the presence of preoperative tinnitus was the strongest predictor of postTN, there is a distinct relationship between hearing outcome and postTN depending on the preoperative situation. Functional or anatomical deafferentation due to surgical tumor removal does not prevent postTN per se.

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.

Implications of Vestibular Schwannoma Consistency: Analysis of 140 Cases Regarding Radiologic and Clinical Features.

OBJECTIVE: To evaluate the effects of vestibular schwannoma (VS) consistency on internal auditory canal (IAC) widening, magnetic resonance imaging appearance, presenting symptoms, and facial nerve outcome. MATERIAL AND METHODS: We performed a retrospective analysis of 140 consecutive patients presenting with unilateral VS who underwent surgical treatment at the Department of Neurosurgery, Tuebingen University, Germany. Operative videos were analyzed, and the tumors were classified into soft and firm according to resectability with an ultrasonic aspirator at 40% power. IAC opening was measured in preoperative bone-window computed tomography on the pathologic and healthy sides, and the percentage of widening between both sides was calculated. Tumor signal intensity was assessed on T2-weighted magnetic resonance imaging scans. Preoperative and postoperative findings in the patient reports were documented. RESULTS: Widening of the IAC due to presence of the VS occurred in 118 patients (84.3%). The degree of IAC widening on the tumor side compared to the other side ranged from 0.1 to 10.1 mm (mean 2.6 mm). The mean widening of the IAC in relation to the healthy side was 1.9 mm in soft tumors and 3.6 mm in firm tumors. A significant correlation was found between tumor consistency and degree of widening of the IAC (P < 0.0001). No significant correlation was found between tumor intensity (on T2-weighted imaging) and tumor consistency. In the early postoperative course, patients with soft tumors had better facial nerve function than those having firm tumors. However, at the last examination no difference between both groups was found. CONCLUSION: The consistency of VS has an impact on the immediate postoperative outcome. Widening on bony computed tomography scan, but not T2 intensity on magnetic resonance imaging, predicts whether the tumor is soft or firm.

The role of intraoperative neuromonitoring in adults with Chiari I malformation.

OBJECT: Suboccipital decompression and duraplasty is considered the treatment of choice for Chiari-I-malformation. Several studies have shown improvement of neurophysiological parameters during decompressive surgery in pediatric patients. However, there is no evidence of the beneficial role of intraoperative neuromonitoring in adults. METHODS: A total of 39 consecutive patients (25 female, age 41.1±14.5 years [mean±SD]) underwent suboccipital decompression for the treatment of symptomatic Chiari-I-malformation senior neurosurgeon and his team. Continuous intraoperative monitoring of somatosensory-evoked potentials of the median nerve (m-SSEPs) and the posterior tibial nerve (t-SSEPs) and motor-evoked potentials to the hand (APB-MEPs) and foot (TA-MEPs) were applied to all patients, alone or in combination. The m-SSEP-N20, t-SSEP-P40, APB-MEP and TA-MEP amplitudes and latencies were recorded at the beginning of the surgery (baseline) and after dura closure. Neurological assessments of the patient were performed prior to surgery, after surgery and during each follow-up visit (3, 6 and 12 months). RESULTS: There was no significant change in m-SSEP-N20, t-SSEP-P40 or APB-MEP and TA-MEP amplitudes or latencies between the baseline and final measurements (p>0.05, Student's t-test). The average time between both recordings was 125±48min (mean±SD). Postoperatively, none of the patients presented new neurological deficits. During the mean follow-up period of 22.4±20.3 months, 92.6% of the symptoms improved or remained stable. Three patients (8.1%) exhibited a relapse of symptoms after 25.7±7.6 months, and only one patient (2.5%) needed secondary decompression after 24 months. CONCLUSION: Intraoperative neuromonitoring (INM) during the primary treatment of Chiari-I-malformation shows only subtle non-significant changes in SSEPs/MEPs without clinical correlation during suboccipital decompression. INM is not considered a prerequisite for a safe suboccipital decompression when operated by an experienced surgical team.

Improved CT Imaging for Mastoid Emissary Vein Visualization Prior to Posterior Fossa Approaches.

Background The clinical relevance of emissary veins (EVs) is often neglected. However, for posterior fossa approaches, especially in semisitting positions, these transosseous connections become potentially life threatening. Therefore, knowledge of the presence and configuration of EVs is essential in preoperative planning. We report on the use of preoperative computed tomography (CT) imaging techniques to visualize EVs reliably. Methods A total of 100 consecutive patients were evaluated by helical CT in bone window mode reconstructed using the standard technique (4.5-mm slices) and the high-resolution technique (1 mm) for the posterior fossa. The presence and size of the EVs, their entry point in the sigmoid sinus, their predilection site, and their visibility using either CT technique were evaluated. Statistical analyses included a comparison of the data from both sides of the head. Results We noted impressive anatomical variations (high standard deviations) in the number, size, and intraosseous length of the EVs among the study population and between the sides (right and left) of an individual patient; however, no statistical significance was observed for any of these parameters. The detection rate of EVs in thin-slice CT scans versus standard CT scans is significantly different (p = 0.0001 on both sides). Conclusions Thin-slice CT is essential in the preoperative planning of posterior fossa approaches to identify the presence and the course of EVs, reducing preventable approach-related morbidity during surgery.