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2.  Predicting the “usefulness” of 5-ALA-derived tumor fluorescence for fluorescence-guided resections in pediatric brain tumors: a European survey 
Acta Neurochirurgica  2014;156(12):2315-2324.
Background
Five-aminolevulinic acid (Gliolan, medac, Wedel, Germany, 5-ALA) is approved for fluorescence-guided resections of adult malignant gliomas. Case reports indicate that 5-ALA can be used for children, yet no prospective study has been conducted as of yet. As a basis for a study, we conducted a survey among certified European Gliolan users to collect data on their experiences with children.
Methods
Information on patient characteristics, MRI characteristics of tumors, histology, fluorescence qualities, and outcomes were requested. Surgeons were further asked to indicate whether fluorescence was “useful”, i.e., leading to changes in surgical strategy or identification of residual tumor. Recursive partitioning analysis (RPA) was used for defining cohorts with high or low likelihoods for useful fluorescence.
Results
Data on 78 patients <18 years of age were submitted by 20 centers. Fluorescence was found useful in 12 of 14 glioblastomas (85 %), four of five anaplastic astrocytomas (60 %), and eight of ten ependymomas grades II and III (80 %). Fluorescence was found inconsistently useful in PNETs (three of seven; 43 %), gangliogliomas (two of five; 40 %), medulloblastomas (two of eight, 25 %) and pilocytic astrocytomas (two of 13; 15 %). RPA of pre-operative factors showed tumors with supratentorial location, strong contrast enhancement and first operation to have a likelihood of useful fluorescence of 64.3 %, as opposed to infratentorial tumors with first surgery (23.1 %).
Conclusions
Our survey demonstrates 5-ALA as being used in pediatric brain tumors. 5-ALA may be especially useful for contrast-enhancing supratentorial tumors. These data indicate controlled studies to be necessary and also provide a basis for planning such a study.
doi:10.1007/s00701-014-2234-2
PMCID: PMC4232748  PMID: 25248327
5-ALA; Gliolan; Pediatric brain tumor; Medulloblastoma; Ependymoma; Glioblastoma; Anaplastic astrocytoma; Fluorescence-guided resection
3.  Uptake of the antisecretory factor peptide AF-16 in rat blood and cerebrospinal fluid and effects on elevated intracranial pressure 
Acta Neurochirurgica  2014;157:129-137.
Background
AF-16 is a 16-amino-acid-long peptide derived from the amino-terminal part of the endogenous protein, antisecretory factor (AF). AF-16 in vivo has been shown to regulate dysfunctions in the water and ion transport system under various pathological conditions and also to counteract experimentally increased tissue pressure.
Methods
Rats were subjected to a cryogenic brain injury in order to increase the intracranial pressure (ICP). The distribution of AF-16 in blood and CSF after intravenous or intranasal administration was determined in injured and control rats. ICP was monitored in freely moving, awake rats, by means of an epidural pressure transducer catheter connected to a wireless device placed subcutaneously on the skull. The continuous ICP registrations were achieved by means of telemetry.
Results
Intranasal administration of AF-16 resulted in a significantly higher CSF concentrations of AF-16 in injured than in control rats, 1.3 versus 0.6 ng/ml, whereas no difference between injured and control rats was seen when AF-16 was given intravenously. Rats subjected to cryogenic brain injury developed gradually increasing ICP levels. Intranasal administration of AF-16 suppressed the increased ICP to normal values within 30 min.
Conclusion
Optimal AF-16 concentrations in CSF are achieved after intranasal administration in rats subjected to a cryogenic brain injury. The ability of AF-16 to suppress an increased ICP was manifested.
doi:10.1007/s00701-014-2221-7
PMCID: PMC4281356  PMID: 25248325
AF-16 uptake; Intranasal administration; Brain oedema; Intracranial pressure; Telemetry; Continuous recording; Rat
4.  Factors associated with external ventricular drain placement accuracy: data from an electronic health record repository 
Acta neurochirurgica  2013;155(9):1773-1779.
Background
We evaluated external ventricular drain placement for factors associated with placement accuracy. Data was acquired using an electronic health record data requisition tool.
Method
Medical records of all patients who underwent ventriculostomy from 2003–2010 were identified and evaluated. Patient demographics, diagnosis, type of guidance and number of catheter passes were searched for and recorded. Post-procedural hemorrhage and/or infection were identified. A grading scale was used to classify accuracy of catheter placements. A multiple logistic regression model was developed to assess features associated with accurate catheter placement.
Results
One hundred nine patients who underwent 111 ventriculostomies from 2003–2010 were identified. Patient diagnoses were classified into vascular (63%), tumor (21%), trauma (14%), and cyst (2%). Procedures were performed freehand in 90 (81%), with the Ghajar guide in 17 (15%), and with image guidance in 4 (4%) patients. Eighty-eight (79%) catheters were placed in the correct location. Trauma patients were more likely to have catheters misplaced (p=0.007) whereas patients in other diagnostic categories were not significantly associated with misplaced catheters. Post-procedural hemorrhage was noted in 2 (1.8%) patients on post-procedural imaging studies. Five (4.5%) definite and 6 (5.4%) suspected infections were identified.
Conclusions
External ventricular drain placement can be performed accurately in most patients. Patients with trauma are more likely to have catheters misplaced. Further development is required to identify and evaluate procedure outcomes using an electronic health record repository.
doi:10.1007/s00701-013-1769-y
PMCID: PMC3744605  PMID: 23700258
Ventriculostomy; Cerebral ventricle; Frontal lobe; Intracranial hemorrhage; Bacterial meningitis; Electronic health record
5.  Endoscopic lateral orbitotomy 
Acta Neurochirurgica  2014;156(10):1897-1900.
Background
Lateral orbitotomy can be minimalized using contemporary endoscopy.
Methods
Anatomy of the temporal fossa/orbital wall junction is described. The attachment of the temporal fascia is cut off from the orbital rim through a 1.5 cm skin incision in the lateral orbital wrinkle. The temporal muscle is detached from the bone to create a space for the telescope. An appropriate bone opening in the lateral orbital wall is created with the aid of neuronavigation to handle intraorbital pathology.
Conclusion
Endoscopic lateral orbitotomy is an original alternative to the microsurgical Krönlein approach and yields good functional and cosmetic results.
Electronic supplementary material
The online version of this article (doi:10.1007/s00701-014-2205-7) contains supplementary material, which is available to authorized users.
doi:10.1007/s00701-014-2205-7
PMCID: PMC4166432  PMID: 25160850
Lateral orbitotomy; Endoscopy; Orbit
7.  Are patients open to elective re-sampling of their glioblastoma? A new way of assessing treatment innovations 
Acta Neurochirurgica  2014;156(10):1855-1863.
Background
This is a qualitative study designed to examine patient acceptability of re-sampling surgery for glioblastoma multiforme (GBM) electively post-therapy or at asymptomatic relapse.
Methods
Thirty patients were selected using the convenience sampling method and interviewed. Patients were presented with hypothetical scenarios including a scenario in which the surgery was offered to them routinely and a scenario in which the surgery was in a clinical trial.
Results
The results of the study suggest that about two thirds of the patients offered the surgery on a routine basis would be interested, and half of the patients would agree to the surgery as part of a clinical trial. Several overarching themes emerged, some of which include: patients expressed ethical concerns about offering financial incentives or compensation to the patients or surgeons involved in the study; patients were concerned about appropriate communication and full disclosure about the procedures involved, the legalities of tumor ownership and the use of the tumor post-surgery; patients may feel alone or vulnerable when they are approached about the surgery; patients and their families expressed immense trust in their surgeon and indicated that this trust is a major determinant of their agreeing to surgery.
Conclusion
The overall positive response to re-sampling surgery suggests that this procedure, if designed with all the ethical concerns attended to, would be welcomed by most patients. This approach of asking patients beforehand if a treatment innovation is acceptable would appear to be more practical and ethically desirable than previous practice.
doi:10.1007/s00701-014-2189-3
PMCID: PMC4167439  PMID: 25085543
Asymptomatic relapse; Ethics; Glioblastoma; Innovation; Qualitative research; Re-sampling
8.  Aneurysms of the anterior and posterior cerebral circulation: comparison of the morphometric features 
Acta Neurochirurgica  2014;156(9):1647-1654.
Background
Intracranial aneurysms (IAs) located in the posterior circulation are considered to have higher annual bleed rates than those in the anterior circulation. The aim of the study was to compare the morphometric factors differentiating between IAs located in the anterior and posterior cerebral circulation.
Methods
A total number of 254 IAs diagnosed between 2009 and 2012 were retrospectively analyzed. All patients qualified for diagnostic, three-dimensional rotational angiography. IAs were assigned to either the anterior or posterior cerebral circulation subsets for the analysis. Means were compared with a t-test. The univariate and stepwise logistic regression analyses were used to determine the predictors of morphometric differences between the groups. For the defined predictors, ROC (receiver-operating characteristic) curves and interactive dot diagrams were calculated with the cutoff values of the morphometric factors.
Results
The number of anterior cerebral circulation IAs was 179 (70.5 %); 141 (55.5 %) aneurysms were ruptured. Significant differences between anterior and posterior circulation IAs were found for: the parent artery size (5.08 ± 1.8 mm vs. 3.95 ± 1.5 mm; p < 0.05), size ratio (2.22 ± 0.9 vs. 3.19 ± 1.8; p < 0.045) and aspect ratio (AR) (1.91 ± 0.8 vs. 2.75 ± 1.8; p = 0.02). Predicting factors differentiating anterior and posterior circulation IAs were: the AR (OR = 2.20; 95 % CI 1.80–270; Is 270 correct or should it be 2.70 and parent artery size (OR = 0.44; 95 % CI 0.38–0.54). The cutoff point in the ROC curve was 2.185 for the AR and 4.89 mm for parent artery size.
Conclusions
Aspect ratio and parent artery size were found to be predictive morphometric factors in differentiating between anterior and posterior cerebral IAs.
doi:10.1007/s00701-014-2173-y
PMCID: PMC4137168  PMID: 25034507
Aneurysms; Morphometry; Anterior; Posterior circulation
10.  Risks and benefits of CT angiography in spontaneous intracerebral hemorrhage 
Acta Neurochirurgica  2014;156(5):911-917.
Background
Few studies have examined the risk of computed tomography angiography (CTA) during the acute phase of spontaneous intracerebral hemorrhage (ICH), while the benefits of CTA in ICH have been well-documented. The present study investigated both the benefits of identifying spot signs, which are supposed to indicate hematoma enlargement after admission, and risks of CTA performed during the acute phase of ICH.
Methods
We retrospectively assessed 323 consecutive patients with spontaneous ICHs admitted to our hospital between April 2009 and March 2012 and who underwent CTA on admission.
Results
In 80 patients (24.7 %), spot signs were demonstrated on CTA source images. Multivariate analysis revealed two independent factors correlated with presence of the spot sign: age and hematoma volume (p < 0.05 each). The presence of spot sign was associated with unfavorable outcomes at discharge and hematoma growth after admission (p < 0.05 each). Adverse events related to CTA occurred in 17 patients (5.2 %), including transient renal dysfunction in 16 patients and allergy to contrast medium in one patient. All adverse events completely resolved within 1 week.
Conclusions
Presence of the spot sign indicated the possibility of hematoma growth and unfavorable outcomes. A small number of adverse events occurred in association with CTA, but without any permanent deficits. Given the potential benefits and risks, we believe that CTA performed at admission in all patients with ICH is beneficial to improve the outcomes.
doi:10.1007/s00701-014-2019-7
PMCID: PMC3988523  PMID: 24604136
Computed tomography angiography; Intracerebral hemorrhage; Side effect; Spot sign
11.  Abnormal expression of an ADAR2 alternative splicing variant in gliomas downregulates adenosine-to-inosine RNA editing 
Acta Neurochirurgica  2014;156(6):1135-1142.
Background
RNA editing is catalyzed by adenosine deaminases acting on RNA (ADARs). ADAR2 is the main enzyme responsible for recoding editing in humans. Adenosine-to-inosine (A-to-I) editing at the Q/R site is reported to be decreased in gliomas; however, the expression of ADAR2 mRNA was not greatly affected.
Methods
We determined ADAR2 mRNA expression in human glioblastoma cell lines and in normal human glial cells by real-time RT-PCR. We also determined ADAR2 mRNA expression in 44 glioma tissues and normal white matter. After identifying an alternative splicing variant (ASV) of ADAR2 in gliomas, we performed sequencing. We then classified glioblastomas based on the presence (+) or absence (–) of the ASV to determine the correlations between ASV + and malignant features of glioblastomas, such as invasion, peritumoral brain edema, and survival time.
Results
There were no significant differences in ADAR2 mRNA expression among human glioblastoma cell lines or in gliomas compared with normal white matter (all p > 0.05). The ASV, which contained a 47-nucleotide insertion in the ADAR2 mRNA transcript, was detected in the U251 and BT325 cell lines, and in some glioma tissues. The expression rate of ASV differed among gliomas of different grades. ASV + glioblastomas were more malignant than ASV – glioblastomas.
Conclusions
ADAR2 is a family of enzymes in which ASVs result in differences in enzymatic activity. The ADAR2 ASV may be correlated with the invasiveness of gliomas. Identification of the mechanistic characterization of ADAR2 ASV may have future potential for individualized molecular targeted-therapy for glioma.
doi:10.1007/s00701-014-2004-1
PMCID: PMC4030101  PMID: 24509948
Glioma; ADAR2; Self-editing; ASVs
12.  Four-year trends in the treatment of cerebral aneurysms in Poland in 2009-2012 
Acta Neurochirurgica  2014;156(5):861-868.
Background
The dilemma concerning the appropriate treatment of the intracranial aneurysms (IAs) has not yet been resolved and still remains under fierce debate. This study refers to the recent trends in the use of and outcomes related to coiling compared with clipping for unruptured and ruptured IAs in Poland over a 4-year period.
Methods
The analysis refers to treatment of IAs performed in Poland between 2009-2012. Patients’ records were cross-matched by ICD-9 codes for ruptured SAH (430) or unruptured cerebral aneurysm (437.3) along with codes for clipping (39.51) and coiling (39.79, 39.72, or 39.52). Multivariable logistic regression was used to compare in-hospital deaths, hospital length of stay (LOS), therapy allocation and aneurysm locations in unruptured vs. ruptured and clipped vs. coiled groups. Differences in the number of procedures between 16 administrative regions were standardized per 100,000 people.
Results
In 2009-2012, 11,051 procedures were identified, including 5,968 ruptured and 5,083 unruptured aneurysms. Overall increase was 2.3 % in clipping and 13.1 % in coiling; a significant trend was found in endovascular procedures (p = 0.044). Ruptured aneurysms were clipped more frequently (OR = 1.66;); in unruptured IAs, endovascular procedure was preferred 3.5 times more than clipping. The annual in-hospital mortality was 7.6 % in clipping and 6.7 % in endovascular treatment. LOS was two times longer after clipping in unruptured aneurysms (OR = 2.013). After the procedures were standardized per 100,000 people, the average for Poland was established as 9.09 in 2009, 10.86 in 2010, 10.55 in 2011, and 11.49 in 2012. This index had the highest values in Mazovia (12.9, 2009; 15.4, 2010; 17.4, 2011; 18.6, 2012.
Conclusions
Data analysis revealed an increase in overall number of IAs treated in Poland between 2009-2012. A significant upward trend of endovascular procedures was found, whereas the number of clipped aneurysms remained relatively steady over the study period.
doi:10.1007/s00701-014-2006-z
PMCID: PMC3988525  PMID: 24499992
Intracranial aneurysms; Clipping; Endovascular treatment; Trends
13.  Cranioplasty with autologous cryopreserved bone after decompressive craniectomy. Complications and risk factors for developing surgical site infection 
Acta Neurochirurgica  2014;156(4):805-811.
Background
Renewed interest has developed in decompressive craniectomy, and improved survival is shown when this treatment is used after malignant middle cerebral artery infarction. The aim of this study was to investigate the frequency and possible risk factors for developing surgical site infection (SSI) after delayed cranioplasty using autologous, cryopreserved bone.
Methods
This retrospective study included 74 consecutive patients treated with decompressive craniectomy during the time period May 1998 to October 2010 for various non-traumatic conditions causing increased intracranial pressure due to brain swelling. Complications were registered and patient data was analyzed in a search for predictive factors.
Results
Fifty out of the 74 patients (67.6 %) survived and underwent delayed cranioplasty. Of these, 47 were eligible for analysis. Six patients (12.8 %) developed SSI following the replacement of autologous cryopreserved bone, whereas bone resorption occurred in two patients (4.3 %). No factors predicted a statistically significant rate of SSI, however, prolonged procedural time and cardiovascular comorbidity tended to increase the risk of SSI.
Conclusions
SSI and bone flap resorption are the most frequent complications associated with the reimplantation of autologous cryopreserved bone after decompressive craniectomy. Prolonged procedural time and cardiovascular comorbidity tend to increase the risk of SSI.
doi:10.1007/s00701-013-1992-6
PMCID: PMC3956933  PMID: 24493001
Cranioplasty; Craniectomy; Autologous; Cryopreserved; Surgical site infection; Complications
14.  Patients’ anxiety around incidental brain tumors: a qualitative study 
Acta Neurochirurgica  2013;156(2):375-381.
Background
Incidental findings are common on MRI. Our study examined how patients are told about their incidental finding as well as anxiety until the neurosurgical consultation and afterward.
Methods
Qualitative research methodology was used. Thirty-two participants were interviewed using open-ended questions. Answers were transcribed and analyzed for themes.
Results
The level of patient satisfaction for the initial breaking of the news averaged 4.1 (range 1–5). Four themes were identified: (1) emotional stress over incidental findings are partially dependent on how the news was communicated; (2) breaking worrisome news is best done in person, but telephone communication can sometimes be acceptable; (3) patients are divided about how much information they wish to get about incidental findings before going for an MRI; (4) waiting for the neurosurgical consultation is a stressful time without adequate support.
Conclusions
When dealing with an unexpected MRI finding, patients are anxious about the situation. Our study exposes ways the experience could be made more comfortable for patients right from the start, from being told the news in a calm and sympathetic manner, to providing support for patients while they wait for a meeting with a neurosurgeon, to expediting the neurosurgical consultation.
doi:10.1007/s00701-013-1935-2
PMCID: PMC3898365  PMID: 24272523
Incidental findings; Brain MRI; Neurosurgery; Qualitative; Worrisome news
15.  Influence of variation in the catechol-O-methyltransferase gene on the clinical outcome after lumbar spine surgery for one-level symptomatic disc disease: a report on 176 cases 
Acta Neurochirurgica  2013;156(2):245-252.
Background
This study was aimed at the evaluation of the relationship between genetic polymorphisms of catechol-O-methyltransferase (COMT) (rs4680:A > G—Val158Met, rs6269:A > G, rs4633:C > T, rs4818:C > G) and pain sensitivity after lumbar discectomy.
Methods
All patients had one-level symptomatic disc herniation from L3 to S1. The primary data recorded included visual analogue pain scales assessing back and leg pain, Oswestry Disability Questionnaire assessing quality of life and pain intensity, received/filled pre- and postoperatively. Each subject was genotyped for single-nucleotide polymorphism in the COMT gene. Clinical outcome was measured by difference between pre- and postoperative values and those results were analyzed with genetics findings.
Results
Pain intensity was associated with the COMT polymorphism. Carriers of rs6269 AA, rs4633 TT, rs4818 CC, and rs4680 AA genotypes were characterized by the lowest preoperative scores related to pain intensity and lower pain intensity at 1 year after the surgery. The rs4633 CC, rs4680 GG genotypes demonstrated significant clinical improvement in VASBACK score at 1 year after the surgery. Patients with COMT haplotype associated with low metabolic activity of enzyme (A_C_C_G) showed better clinical outcome measured by ODI score and VASBACK score 1 year after surgery. We did not observe any significant correlation between leg pain and single-nucleotide polymorphisms in the COMT gene.
Conclusions
The results of our study indicate that polymorphism in the COMT gene may play an important role in the mechanism of pain perception, which may have a potential implication for clinical decision-making in the future.
doi:10.1007/s00701-013-1895-6
PMCID: PMC3898361  PMID: 24178190
COMT; Lumbar discectomy; Clinical outcome; Genetic variations; Lumbar disk herniation; Pain
16.  Anatomical variation of superior petrosal vein and its management during surgery for cerebellopontine angle meningiomas 
Acta Neurochirurgica  2013;155(10):1871-1878.
No systematic study is yet available that focuses on the surgical anatomy of the superior petrosal vein and its significance during surgery for cerebellopontine angle meningiomas. The aim of the present study was to examine the variation of the superior petrosal vein via the retrosigmoid suboccipital approach in relation to the tumor attachment of cerebellopontine angle meningiomas as well as postoperative complications related to venous occlusion. Forty-three patients with cerebellopontine angle meningiomas were analyzed retrospectively. Based on the operative findings, the tumors were classified into four subtypes: the petroclival type, tentorial type, anterior petrous type, and posterior petrous type. According to a previous anatomical report, the superior petrosal veins were divided into three groups: Type I which emptied into the superior petrosal sinus above and lateral to the internal acoustic meatus, Type II which emptied between the lateral limit of the trigeminal nerve at Meckel’s cave and the medial limit of the facial nerve at the internal acoustic meatus, and Type III which emptied into the superior petrosal sinus above and medial to Meckel’s cave. In both the petroclival and anterior petrous types, the most common vein was Type III which is the ideal vein for a retrosigmoid approach. In contrast, the Type II vein which is at high risk of being sacrificed during a suprameatal approach procedure was most frequent in posterior petrous type, in which the superior petrosal vein was not largely an obstacle. Intraoperative sacrificing of veins was associated with a significantly higher rate of venous-related phenomena, while venous complications occurred even in cases where the superior petrosal vein was absent or compressed by the tumor. The variation in the superior petrosal vein appeared to differ among the tumor attachment subtypes, which could permit a satisfactory surgical exposure without dividing the superior petrosal vein. In cases where the superior petrosal vein was previously occluded, other bridging veins could correspond with implications for the crucial venous drainage system, and should thus be identified and protected whenever possible.
doi:10.1007/s00701-013-1840-8
PMCID: PMC3779012  PMID: 23990034
Attachment; Classification; Cerebellopontine angle; Meningioma; Petrosal vein; Venous complication
17.  Fluorescein for vascular and oncological neurosurgery 
Acta Neurochirurgica  2013;155(8):1477-1478.
doi:10.1007/s00701-013-1778-x
PMCID: PMC3719004  PMID: 23793965
18.  Complex middle cerebral artery aneurysms: a new classification based on the angioarchitecture and surgical strategies 
Acta Neurochirurgica  2013;155(8):1481-1491.
Background
Because of the diversity of aneurysm morphology, complicated arterial anatomy and hemodynamic characteristics, tailored surgical treatments are required for cases of individual complex middle cerebral artery (MCA) aneurysms.
Methods
During an 8-year period, 59 complex MCA aneurysms in 58 patients were treated microsurgically in our department. Complex aneurysms were defined as having large (10–24 mm in diameter) or giant (diameter ≥ 25 mm) size or non-saccular morphology (fusiform, dissecting or serpentine).
Results
Direct clipping of the aneurysmal necks was achieved in eight patients, while reconstructive clipping was performed in 25 patients. Indirect aneurysm occlusion was performed in 25 cases, including trapping or resecting the aneurysm in four cases, trapping or resecting the aneurysm with extra-intracranial (EC) or intra-intracranial (IC) bypass in 21 cases and internal carotid artery (ICA) sacrifice with EC-IC bypass in one case. Forty-eight aneurysms (81.4 %) were completely obliterated. Graft patency was confirmed in 20 of 21 cases (95.2 %) with bypass. A recurrent aneurysm was detected in one case and a re-operation was performed. Two patients with Hunt-Hess grade IV aneurysms died during the perioperative period. Overall, 52 cases (88.1 %) had good outcomes (Glasgow Outcome Scale ≥ 4) during the late follow-up period.
Conclusion
The surgical modality and strategy for treating complex MCA aneurysm are decided according to the morphology of the aneurysm, vascular anatomy and the hemodynamic characteristics of each case. Thus, we developed a new classification based on the angioarchitecture. Favorable outcomes can be achieved by treating complex MCA aneurysms with appropriate surgical modalities, strategies and techniques.
doi:10.1007/s00701-013-1751-8
PMCID: PMC3718994  PMID: 23715946
Middle cerebral artery; Complex aneurysm; Bypass surgery; Clipping
19.  Impact of anterior clinoidectomy on visual function after resection of meningiomas in and around the optic canal 
Acta Neurochirurgica  2013;155(7):1293-1299.
Background
Meningiomas of the anterior and middle skull base frequently involve the optic nerve and cause progressive visual impairment. Surgical decompression of the optic nerve is the only option to preserve visual function. Depending on the invaded structures, optic nerve decompression can be part of a complete tumor removal or the main surgical intention in terms of local debulking. However, bony decompression of the optic canal including anterior clinoidectomy for optic nerve decompression is still a surgical maneuver under discussion.
Methods
From 2006 to 2011, 46 consecutive patients with skull base meningiomas in and around the optic canal were operated. The pterional approach was tailored for each patient. Resection included bony decompression of the optic canal with or without anterior clinoidectomy. Visual acuity and fields were evaluated pre- and postoperatively.
Results
Fifty-three percent of patients underwent anterior clinoidectomy, 23 % optic canal unroofing, and 24 % any bony decompression. In 21 patients (46 %), gross total resection (GTR, Simpson grade I or II) was achieved, while 25 patients (54 %) received subtotal resection (STR, Simpson grade III or IV). Sixty-three percent of patients presented with preoperative visual impairment. Postoperative visual changes were significantly related to preoperative visual function. While all patients with normal preoperative vision remained unchanged, in patients with impaired vision, surgery caused improvement in 70 % and deterioration in 10 % of patients (p < 0.0001). In patients with anterior clinoidectomy, vision improved more frequently than without anterior clinoidectomy (p < 0.05).
Conclusions
Anterior clinoidectomy is safe and may improve visual outcome in meningiomas in and around the optic canal.
doi:10.1007/s00701-013-1741-x
PMCID: PMC3683144  PMID: 23665725
Anterior clinoid process; Optic nerve; Visual function; Skull base; Meningioma
20.  Operative field temperature during transnasal endoscopic cranial base procedures 
Acta Neurochirurgica  2013;155(5):903-908.
Background
Data regarding the safety of endoscopic skull base exploration are very scarce. With this method, fragile vital structures (cranial nerves, the optic complex, brainstem, hypothalamus or cerebral ventricles) are exposed to direct illumination within a closed space. Also, high-speed drills, cauterization and ultrasonic aspiration deliver a significant load of thermal energy. The aim of this study was to record the temperature close to the structures of the skull base and in the intradural space during the procedures performed using extended endoscopic transnasal approaches.
Methods
The temperature of the skull base was continuously recorded during six transnasal endoscopic procedures. Implantable copper-constantan thermocouples were inserted: one into the esophagus and another through the nostril to reach the operative field at the skull base.
Results
At the beginning of the procedure, the temperature of the operative field was on average 36.8 °C ± 0.80 °C, i.e. only 1 °C higher than the esophageal temperature. Then it grew continuously during the whole procedure, to eventually reach a level of 42–43 °C at the final stage, whereas the esophageal temperature remained stable. Occasionally, the temperature increased up to 45 °C during cauterization and ultrasonic aspiration, and even up to 62 °C during high-speed drilling.
Conclusion
Endoscopic skull base surgery is associated with an incessant increase of the temperature of the intraoperative field. The temperature can peak suddenly to levels which can potentially harm neural structures and influence the rate of postoperative complications.
doi:10.1007/s00701-013-1674-4
PMCID: PMC3627044  PMID: 23494137
Endoscopy; Transnasal; Extended approach; Cranial base; Temperature
21.  Ultrasound imaging in neurosurgery: approaches to minimize surgically induced image artefacts for improved resection control 
Acta Neurochirurgica  2013;155(6):973-980.
Background
Intraoperative ultrasound imaging is used in brain tumor surgery to identify tumor remnants. The ultrasound images may in some cases be more difficult to interpret in the later stages of the operation than in the beginning of the operation. The aim of this paper is to explain the causes of surgically induced ultrasound artefacts and how they can be recognized and reduced.
Methods
The theoretical reasons for artefacts are addressed and the impact of surgery is discussed. Different setups for ultrasound acquisition and different acoustic coupling fluids to fill up the resection cavity are evaluated with respect to improved image quality.
Results
The enhancement artefact caused by differences in attenuation of the resection cavity fluid and the surrounding brain is the most dominating surgically induced ultrasound artefact. The influence of the artefact may be reduced by inserting ultrasound probes with small footprint into the resection cavity for a close-up view of the areas with suspected tumor remnants. A novel acoustic coupling fluid developed for use during ultrasound imaging in brain tumor surgery has the potential to reduce surgically induced ultrasound artefacts to a minimum.
Conclusions
Surgeons should be aware of artefacts in ultrasound images that may occur during brain tumor surgery. Techniques to identify and reduce image artefacts are useful and should be known to users of ultrasound in brain tumor surgery.
doi:10.1007/s00701-013-1647-7
PMCID: PMC3656245  PMID: 23459867
Ultrasound; Neurosurgery; Brain tumors; Resection control; Ultrasound artefacts; Enhancement artefact; Ultrasonography; Intraoperative imaging
22.  Proteins involved in regulating bone invasion in skull base meningiomas 
Acta Neurochirurgica  2012;155(3):421-427.
Background
Bone invasive skull base meningiomas are a subset of meningiomas that present a unique clinical challenge due to brain and neural structure involvement and limitations in complete surgical resection, resulting in higher recurrence and need for repeat surgery. To date, the pathogenesis of meningioma bone invasion has not been investigated. We investigated immunoexpression of proteins implicated in bone invasion in other tumor types to establish their involvement in meningioma bone invasion.
Methods
Retrospective review of our database identified bone invasive meningiomas operated on at our institution over the past 20 years. Using high-throughput tissue microarray (TMA), we established the expression profile of osteopontin (OPN), matrix metalloproteinase-2 (MMP2), and integrin beta-1 (ITGB1). Differential expression in tumor cell and vasculature was evaluated and comparisons were made between meningioma anatomical locations.
Results
MMP2, OPN, and ITGB1 immunoreactivity was cytoplasmic in tumor and/or endothelial cells. Noninvasive transbasal meningiomas exhibited higher vascular endothelial cell MMP2 immunoexpression compared to invasive meningiomas. We found higher expression levels of OPN and ITGB1 in bone invasive transbasal compared to noninvasive meningiomas. Strong vascular ITGB1 expression extending from the endothelium through the media and into the adventitia was found in a subset of meningiomas.
Conclusions
We have demonstrated that key proteins are differentially expressed in bone invasive meningiomas and that the anatomical location of bone invasion is a key determinant of expression pattern of MMP1, OPN, and ITGB1. This data provides initial insights into the pathophysiology of bone invasion in meningiomas and identifies factors that can be pursued as potential therapeutic targets.
doi:10.1007/s00701-012-1577-9
PMCID: PMC3569595  PMID: 23238945
Bone invasion; Integrins; Matrix metalloproteinase; Meningioma; Osteopontin; Transbasal meningioma
23.  Volume and densities of chronic subdural haematoma obtained from CT imaging as predictors of postoperative recurrence: a prospective study of 107 operated patients 
Acta Neurochirurgica  2012;155(2):323-333.
Background
Chronic subdural haematoma (CSDH) is a common entity in neurosurgery with a considerable postoperative recurrence rate. Computerised tomography (CT) scanning remains the most important diagnostic test for this disorder. The aim of this study was to characterise the relationship between the recurrence of CSDH after treatment with burr-hole irrigation and closed-system drainage technique and CT scan features of these lesions to assess whether CT findings can be used to predict recurrence.
Methods
We investigated preoperative and postoperative CT scan features and recurrence rate of 107 consecutive adult surgical cases of CSDH and assessed any relationship with univariate and multivariate regression analyses.
Results
Seventeen patients (15.9 %) experienced recurrence of CSDH. The preoperative haematoma volume, the isodense, hyperdense, laminar and separated CT densities and the residual total haematoma cavity volume on the 1st postoperative day after removal of the drainage were identified as radiological predictors of recurrence. If the preoperative haematoma volume was under 115 ml and the residual total haematoma cavity volume postoperatively was under 80 ml, the probability of no recurrence was very high (94.4 % and 97.4 % respectively).
Conclusions
These findings from CT imaging may help to identify patients at risk for postoperative recurrence.
doi:10.1007/s00701-012-1565-0
PMCID: PMC3552365  PMID: 23229873
Chronic subdural haematoma; Computerised tomography; Densities; Multiple regression; Recurrence; Volume
25.  Diagnosis and surgical strategy for sacral meningeal cysts with check-valve mechanism: technical note 
Acta Neurochirurgica  2012;155(2):309-313.
Objective
There is agreement that symptomatic sacral meningeal cysts with a check-valve mechanism and/or large cysts representing space-occupying lesions should be treated surgically. This study investigated factors indicating a need for surgical intervention and surgical techniques for sacral meningeal cysts with a check-valve mechanism.
Methods
In ten patients presenting with sciatica and neurological deficits, myelography, computed tomography (CT) myelography, and magnetic resonance imaging (MR imaging) detected sacral meningeal cysts with a check-valve mechanism. One patient had two primary cysts. Ten cysts were type 2 and one cyst was type 1. Nine of the ten patients had not undergone previous surgery, while the remaining case involved recurrent cyst. For the seven patients with normal (i.e., not huge or recurrent) type 2 cysts and no previous surgery (eight cysts), suture after collapse of the cyst wall was performed. For the recurrent type 2 cyst, duraplasty and suture with collapse of the cyst wall were performed to eliminate the check-valve mechanism. For the remaining type 2 cyst, a primary root was sacrificed because of the huge size of the cyst. For the type 1 cyst, the neck of the cyst was ligated.
Results
In all cases, chief complaints disappeared immediately postoperatively and no deterioration of clinical symptoms has been seen after a mean follow-up of 27 months.
Conclusions
The presence or absence of a check-valve mechanism is very important in determining the need for surgical intervention for sacral meningeal cysts.
doi:10.1007/s00701-012-1550-7
PMCID: PMC3552371  PMID: 23160631
Sacral meningeal cyst; Check-valve mechanism; Surgical strategy

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