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Introduction: Stereotactic brain biopsies are essential for obtaining tissue samples from brain lesions, crucial for comprehensive histological analysis and subsequent adjuvant therapies. While most biopsies target supratentorial lesions, those involving the posterior fossa are less frequent but pose significant technical and surgical challenges, necessitating careful patient management., Methods: We present our experience with stereotactic biopsies of the posterior fossa using the Leksell Vantage frame (Elekta, Stockholm, Sweden) and the ZD Inomed frame (Inomed Medizintechnik GmbH, Emmendingen, Germany). For the ZD frame, we either mounted it upside down or employed a frontal approach, while for the Leksell Vantage frame, we utilized a reverse x-axis orientation. Planning was based on 3-T MRI scans and preoperative MRI merged with stereotactic CT for coordinate generation., Results: From 2006 to 2023, we performed 25 stereotactic biopsies of the posterior fossa in our department-9 with the ZD Inomed frame and 16 with the Leksell Vantage frame. The cohort included 14 male and 11 female patients, with an average age of 60.6 years (range 36-80 years). The average surgery duration was shorter with the Leksell Vantage frame (32.6 min vs. 44.8 min, p = 0.05). The average length of the planned trajectory was 41.7 mm for the Leksell Vantage frame and 52.2 mm for the ZD Inomed frame. Postoperativ bleeding occurred in two cases-one managed conservatively, the other required surgical intervention. Additionally, two other cases presented new postoperative focal neurological deficit. The overall mortality rate was 34.8% and a 40-day postoperative mortality rate of 13.0%., Conclusion: Our experience demonstrates that stereotactic biopsies of lesions in the posterior fossa can be effectively managed with different frame systems, though they present a higher degree of complexity. Notably, the Leksell Vantage frame was associated with a significantly shorter surgery duration. This technical note provides valuable insights and detailed technical guidance for neurosurgeons facing similar challenges., Competing Interests: Declarations. Ethical approval: This study protocol was reviewed and approved by ethic committee of the technical university of Dresden, approval number EK224072012. Consent to participate: For using human participant data for this study, in every case the written informed consent was obtained from participants. Conflict of interest: The authors declare no competing interests., (© 2024. The Author(s).)

Background: The optimal targets for deep brain stimulation (DBS) in patients with refractory chronic pain are not clearly defined. We applied sensory functional MRI (fMRI)- and diffusion tensor imaging (DTI)-based DBS in chronic pain patients into 3 different targets to ascertain the most beneficial individual stimulation site., Methods: Three patients with incapacitating chronic pain underwent DBS into 3 targets (periventricular gray (PVG), ventroposterolateral thalamus (VPL), and posterior limb of the internal capsule according to fMRI and DTI (PLIC). The electrodes were externalized and double-blinded tested for several days. Finally, the two electrodes with the best pain reduction were kept for permanent stimulation. The patients were then followed up for 12 months. Outcome measures comprised the numerical rating scale (NRS), short-form McGill's score (SF-MPQ), and health-related quality of life (SF-36)., Results: Continuous pain (mean NRS 6.6) was reduced to NRS 3.6 after 12 months. Only with stimulation of the PLIC pain attacks, that occurred at least 3 times a week (mean NRS 9.6) resolved in 2 patients and improved in one patient concerning both intensity (NRS 5) and frequency (twice a month). The mean SF-MPQ decreased from 92.7 to 50. The health-related quality of life improved considerably., Conclusion: fMRI- and DTI-based DBS to the PLIC was the only target with a significant effect on pain attacks and seems to be the most promising target in chronic pain patients after brachial plexus injury. The combination with PVG or VPL can further improve patients' outcome especially in terms of reducing the continuous pain.

Background: Successful deep brain stimulation is mostly dependent on accurate positioning of the leads at the optimal target points. We investigated whether the identification of the subthalamic nucleus in T2-weighted 3-T MRI, fluid-attenuated inversion recovery 3-T MRI and susceptibility-weighted 3-T MRI is confirmed by intraoperative neurological microelectrode recording., Methods: We evaluated 182 microelectrode recording leads in 21 patients with bilateral deep brain stimulation, retrospectively. Consequently, 728 electrode contact positions in T2-weighted 3-T MRI, 552 electrode contact positions in fluid-attenuated inversion recovery 3-T MRI and 490 electrode contact positions in susceptibility-weighted 3-T MRI were evaluated for a positive nucleus subthalamicus signal., Results: The highest sensitivity was measured for fluid-attenuated inversion recovery 3-T MRI with 82.5 %, while the highest specificity was observed for susceptibility-weighted 3-T MRI with 90.6 %. The negative predictive value was nearly equal for susceptibility-weighted MRI and fluid-attenuated inversion recovery MRI with 87.5 % vs. 87.1 %, but the positive predictive value was higher in susceptibility-weighted 3-T MRI (86.0 %) than in the other MRI sequences., Conclusions: The susceptibility-weighted 3-T MRI-based subthalamic nucleus localization shows the best accuracy compared with T2-weighted and fluid-attenuated inversion recovery 3-T MRI. Therefore, the susceptibility-weighted 3-T MRI should be preferred for surgical planning when the operation procedure is performed under general anesthesia without microelectrode recordings.

Objective: Decompressive craniectomy (DC) is a last treatment option of refractory intracranial hypertension in traumatic brain injury (TBI) patients. Replacement of the autologous bone flap is the preferred method to cover the cranial defect after brain swelling has subsided. Long term outcomes and complications after replacement of the autologous bone flap in pediatric patients were studied in comparison to young, healthy adults., Methods: Medical records of 27 pediatric patients who underwent DC and subsequent replacement of the bone flap between 1998 and 2011 were reviewed retrospectively. Patients were divided into two age groups (group 1: 18 children < 15 years; group 2:9 adolescents 15-18 years). For comparative reasons, a young adult control group of 39 patients between 18 and 30 years was additionally evaluated., Results: With 81.8 % resorption of the bone flap, this was the major complication in young children. In up to 54.4 % of patients, a surgical revision of the osteolytic bone flap became necessary. However, in some pediatric patients, the osteolysis resolved spontaneously and further operations were not required. Probable enabling factors for bone flap resorption were young age (0-7 years), size of craniectomy, permanent shunt placement, and extent of dural opening/duraplasty. Other complications were bone flap infections, loosening of the re-inserted bone flap, and postoperative hematomas., Conclusion: There is an unacceptably high complication rate after reimplantation of the autologous bone following DC in pediatric TBI patients, especially in young children up to seven years of age. Artificial or synthetic cranioplasties may be considered as alternatives to initial bone flap reimplantation in the growing child. Despite the fact that DC is an effective treatment in TBI with persistent intracranial hypertension, it is important to realize that DC is not only combined with replacement of the autologous bone flap but also with a high rate of additional complications especially in pediatric patients.

Deep brain stimulation (DBS) is an established treatment of various diseases, particularly used for idiopathic Parkinson's disease. Frequently, DBS patients are multimorbid and managing them may be challenging, since postoperative complications can become more likely with age. In this article, we present two cases of myocardial infarction after DBS with different therapeutic strategies. Case 1 was anticoagulated with a heparin infusion with a target partial thromboplastine time (PTT) between 50 and 60 s after the myocardial infarction and showed 3 days later, after an initial postoperative inconspicuous cranial computer tomography, an intracerebral haematoma, which was evacuated without explanting the DBS lead. Case 2 was only treated with enoxaparine 40 mg s.c. twice a day after the myocardial infarction without any further complications. Both cases benefited from the DBS with respect to the motor fluctuations, but case 1 continued to suffer from psychomotor slowdown, mild hemiparesis of the left side, visual neglect and a gaze paresis. Unfortunately, there are no established guidelines or therapy recommendations for the management of such patients. An individual therapy regime is necessary for this patient population regarding the bleeding risk, the cardial risk and the symptoms of the patient. Retrospectively, the rejection of the intravenous application of heparin in case 2 seems to be the right decision. But regarding the small number of cases, it remains still an individual therapy. Further experience will help us to develop optimal therapy strategies for this patient population.

Von Hippel-Lindau (VHL) disease is an inherited autosomal dominant neoplastic disorder causing central nervous system haemangioblastomas. The VHL gene (3p25-3p26) is known to be a tumour suppressor gene, with its inactivation being responsible for a predisposition to tumour development. As far as we know, the present report of VHL disease manifestation in identical twins is unique. Genetic inquiry into the family background did not reveal this disease among their progenitors. For presymptomatic diagnosis of 17 presently unaffected family members, constitutional DNA of the twins was screened for VHL germline mutations, using loss of heterozygosity studies and exon-specific DNA sequencing. To determine the influence of somatic mutations of the VHL gene in tumourigenesis, DNA of five surgically removed intracerebral haemangioblastomas of the identical twins was analyzed in comparison with their constitutional DNA by DNA sequencing of the complete VHL coding region. However, no allelic losses were found for the VHL gene or for various other tumour suppressor genes (p53, BRCA1, BRCA2, DCC, and MCC). Furthermore, no mutations were found in the constitutional DNA of either twin sister or in the DNA of all five tumour lesions. Based on our observations, we conclude that in certain VHL families, presymptomatic molecular diagnosis of the disease is not feasible and requires close clinical surveillance of all individuals at risk.

Intraoperative facial nerve monitoring (IFNM) is a suitable technique for intraoperative facial nerve identification and dissection, especially in large vestibular schwannomas (VS) (acoustic neuroma). To evaluate its feasibility for estimating functional nerve outcome after VS resection 60 patients underwent surgery using IFNM. Out of this group the last 40 patients were included in a prospective study evaluating the prognostic value of various IFNM parameters (proximal and distal absolute EMG amplitude, stimulation threshold, and proximal-to-distal amplitude ratio) for prediction of initial postoperative facial nerve function and recovery of function. Stimulation threshold and absolute EMG amplitude proximally at the brain stem were both predictive for postoperative nerve function. Good initial facial nerve outcome (modified House Brackmann grading, mHB degree I and degree II) was found in 15/16 patients with a proximal EMG amplitude greater than 800 microV and in 19/22 patients with proximal stimulation threshold less than 0.3 mA. Sixteen of 16 patients with proximal stimulation threshold equal to or greater than 0.3 mA had moderate-to-severe facial palsy (mHB degree III or worse). Six of six patients without evokable proximal amplitude initially had insufficient nerve function (mHB degree IV). Intraoperative decrease of the proximal amplitude was associated with an unfavourable outcome, whereas distal amplitudes usually stayed unchanged. Mean distal EMG amplitudes were also found to be decreased with poor nerve function, which may mean that the tumour had already affected the nerve. A proximal amplitude of 300 microV or less and a proximal-to-distal amplitude ratio below 1:3 were found in the absence of functional recovery in 6/8 (75%) and 5/6 (83%) patients with initial mHB degree IV, respectively. Two patients with initial mHB degree IV improved to mHB degree III despite intraoperative evidence of missing functional nerve integrity. Therefore, functional recovery cannot be predicted by IFNM in all cases of anatomical nerve preservation. We conclude that a minimum follow-up period of 1 year may still be advisable even in certain patients without evidence of intraoperative functional nerve integrity.