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result(s) for
"Petkov, Martin"
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Comprehensive neurosurgical and visceral surgical therapy of retroperitoneal nerve tumors: a descriptive and retrospective analysis
2024
Nerve tumors in the retroperitoneal space are a rarity. Radical surgery according to soft tissue tumors can lead to persistent pain and neurological deficits. This study aims to evaluate clinical outcomes of patients treated by a visceral- / neurosurgical approach. 33 patients with a retroperitoneal nerve tumor underwent surgery between 01/2002 and 12/2022 at our department. A visceral surgeon provided access to the retroperitoneal space, followed by micro-neurosurgical tumor preparation under neuromonitoring. Clinical examination and MRI were performed 12 weeks after surgery and further 3 months (WHO grade > 1) or 12 months (WHO grade 1). Further examinations were based on MRI findings and residual symptoms with median follow-up time of 24 months. One patient was treated for two distinct masses resulting in a total of 34 histological findings. Schwannomas (
n
= 15; 44.1%) and neurofibromas (
n
= 10; 29.4%) were the most common tumors. Long-term improvements were noted in radicular pain (15/18 patients; 83.3%), motor deficits (7/16 patients; 43.8%), abdominal discomfort and pain (5/7 patients; 71.4%). Recurrences were observed in 3/33 (9,1%) patients. This study represents the largest series of retroperitoneal BPNSTs treated with microsurgical techniques. Prospective multicenter studies are warranted to establish standardized treatment guidelines.
Journal Article
Clinical Outcome After Surgical Treatment of Traumatic Peroneal Nerve Injury: An Analysis of Risk Factors After Different Surgical Approaches
2025
Background: This study aims to analyze potential risk factors that may influence the clinical outcomes following surgical treatment of traumatic peroneal nerve lesions. Methods: We conducted a retrospective analysis of patients with traumatic peroneal nerve injuries treated with decompression, split repair, or nerve grafting between 2010 and 2020. Motor function and potential risk factors were evaluated. Results: Out of 93 patients, 42 (45%) underwent decompression, 15 (16%) received split repair, and 36 (39%) required autologous nerve grafting. Up to one year after surgery, weakness of the anterior tibial muscle improved from a median of M0 to M3. After one year following nerve decompression, functional recovery was observed in 28 (65%) cases, in 9 (21%) cases after split repair, and in 7 (16%) cases following autologous nerve grafting. A defect greater than 8 cm was associated with significantly poorer improvement of extensor hallucis longus (p = 0.037, HR 0.109). We found no significant associations between age, diabetes mellitus, arterial hypertension, obesity, and postoperative outcomes. Conclusions: According to the present data, a significant number of patients achieved functional improvement following surgical treatment, indicating that this procedure should be considered an important treatment option in selected cases.
Journal Article
Theme A: Three-dimensional Seismic Analysis of Tsankov Kamak Dam (double curvature concrete arch dam). Formulation and synthesis of the results
2025
ICOLD Committee on Computational Aspects of Analysis and Design of Dams organized the 17th ICOLD Benchmark Workshop on Numerical Analysis of Dams in Sofia, Bulgaria, in April 2025. Theme A concerns the modelling of the static and seismic behaviour of a large concrete double curvature arch dam ideally inspired to Tsankov Kamak Dam. The study proposed in the Theme A is intended to continue and improve the work carried out in previous Benchmark Workshops focused on seismic analyses. The most recent investigation on this topic was proposed in Theme A of the 15th ICOLD Benchmark Workshop in Milan, Italy (2019), titled “Seismic Analysis of Pine Flat Concrete Dam”: it was a 2D structural problem where the simple geometry was specifically chosen with the objective to facilitate the adoption of advanced methods able to consider the semi-unbounded size of the foundation and the dynamic interactions of the dam with the foundation and the reservoir. In the present study, to accurately define the structural response of the concrete arch dam, it is necessary to consider the three-dimensionality of the problem and the non-linear behaviour of the system. In the case of the 3D modelling of arch dams, the foundation cannot be idealized with a flat box model (semi-unbounded half-space), but the presence of the canyon must be conveniently considered; in addition, the vertical joints greatly influence the behaviour of these structures. Theme A included six case studies, each featuring one or more tasks, with certain tasks designated as mandatory and others as optional. Twelve teams, representing eleven countries, submitted solutions. The comprehensive synthesis of the main outcomes of Theme A provides significant contribution to the seismic analysis of arch dams subjected to earthquakes capable of triggering the non-linear structural behaviour, summarizing the most recent methods for carrying out such analyses, and offers important insights for interpreting and understanding their results.
Journal Article
Epigenetic Modifications of the Liver Tumor Cell Line HepG2 Increase Their Drug Metabolic Capacity
2019
Although human liver tumor cells have reduced metabolic functions as compared to primary human hepatocytes (PHH) they are widely used for pre-screening tests of drug metabolism and toxicity. The aim of the present study was to modify liver cancer cell lines in order to improve their drug-metabolizing activities towards PHH. It is well-known that epigenetics is strongly modified in tumor cells and that epigenetic regulators influence the expression and function of Cytochrome P450 (CYP) enzymes through altering crucial transcription factors responsible for drug-metabolizing enzymes. Therefore, we screened the epigenetic status of four different liver cancer cell lines (Huh7, HLE, HepG2 and AKN-1) which were reported to have metabolizing drug activities. Our results showed that HepG2 cells demonstrated the highest similarity compared to PHH. Thus, we modified the epigenetic status of HepG2 cells towards ‘normal’ liver cells by 5-Azacytidine (5-AZA) and Vitamin C exposure. Then, mRNA expression of Epithelial-mesenchymal transition (EMT) marker SNAIL and CYP enzymes were measured by PCR and determinate specific drug metabolites, associated with CYP enzymes by LC/MS. Our results demonstrated an epigenetic shift in HepG2 cells towards PHH after exposure to 5-AZA and Vitamin C which resulted in a higher expression and activity of specific drug metabolizing CYP enzymes. Finally, we observed that 5-AZA and Vitamin C led to an increased expression of Hepatocyte nuclear factor 4α (HNF4α) and E-Cadherin and a significant down regulation of Snail1 (SNAIL), the key transcriptional repressor of E-Cadherin. Our study shows, that certain phase I genes and their enzyme activities are increased by epigenetic modification in HepG2 cells with a concomitant reduction of EMT marker gene SNAIL. The enhancing of liver specific functions in hepatoma cells using epigenetic modifiers opens new opportunities for the usage of cell lines as a potential liver in vitro model for drug testing and development.
Journal Article
Pupillomotor Dysfunction and Outcomes After Decompressive Craniectomy in Pediatric Patients
2026
Background: Decompressive craniectomy (DC) is a life-saving intervention for refractory intracranial pressure (ICP). While outcomes in adults are well documented, pediatric data, especially concerning pupillomotor dysfunction, remain limited. Anisocoria is generally considered a marker of severe neurological compromise, but its clinical relevance in children undergoing DC has not been adequately studied. Methods: We retrospectively reviewed 25 pediatric patients treated with DC between 2004 and 2024. Demographic, radiological and clinical data included age, sex, hospital stay, operative time, etiology, side of craniectomy, preoperative midline (ML) shift, Marshall score, Rotterdam score, Glasgow Coma Scale (GCS) and pupillary status before surgery. Functional outcomes were assessed using the pediatric version of the Glasgow Outcome Scale Extended (pGOS-E) at discharge, after 3 months, 1, 2 and 4 years. Results: The majority of patients were school-aged children with a median age of 10 (range 0–17) years. Traumatic brain injury accounted for 16 cases and represented the leading etiology for DC. Pupillomotor dysfunction (anisocoria or bilateral fixed pupillary dilatation) was observed in 15 of 25 patients, 47% of whom died during hospitalization, demonstrating a significant association with in-hospital mortality (p = 0.02). However, survivors with primary pupillomotor dysfunction demonstrated a favorable recovery at 12 months with a median pGOS-E of 6 (range 4–8), indicating moderate disability. A preoperative ML-shift > 5 mm was not associated with lower pGOS-E scores during follow-up (p > 0.05). Bone flap autolysis was observed in 12 out of 14 children (86%) receiving autologous cranioplasty, and 8 (57%) patients required revision surgery with synthetic material. Conclusions: In pediatric patients, pupillomotor dysfunction is associated with higher early mortality but does not reliably exclude favorable long-term outcomes. Compared with adult cohorts, children appear to have a greater potential for neurological recovery, suggesting that severe initial clinical findings alone should not preclude timely surgical intervention.
Journal Article
The Role of Transcranial Ultrasound Imaging in Intensive Care Treatment of Decompressive Hemicraniectomy Patients: A Retrospective Single-Center Analysis
by
Becker, Ralf
,
Knoll, Andreas
,
Pala, Andrej
in
Cerebrospinal fluid
,
Complications
,
Critical care medicine
2024
Background: Post-hemicraniectomy patients often need extended intensive care treatment. While computed tomography (CT) is considered the gold standard for regular imaging, its frequent use could be linked to adverse clinical outcomes. This study aimed to assess bedside transcranial ultrasound (TUS) to capture intracranial anatomical structures and pathologies. Methods: We analyzed 19 patients treated in our neurosurgical ICU from 1 January 2023 to 1 February 2024. Six physicians from our unit (three residents and three attending physicians) conducted a retrospective evaluation. A total of 158 sessions, including multiple freeze frames and video footage, were analyzed, including 7 imaging categories, using a Likert scale. Subsequently, correlation between CT and TUS was evaluated for midline (ML) shift, subdural space, lateral ventricular width (LVW), and extent of intracerebral hematoma using the Pearson’s correlation coefficient (r). Results: TUS was performed on average on 8.32/19.53 days (mean inpatient stay). It provided the lowest Likert scores for the imaging categories ventricular system, midline, subdural space, intraventricular catheter placement, and cortical gyration. Residents reported slightly inferior assessability, resulting in higher scores on the Likert scale (0.02–0.93 mean difference compared with attending physicians). A high correlation was shown in terms of ML shift, LVW, and intracerebral hematomas. No relevant correlation was shown in subdural space. Conclusions: TUS is a safe, cost-, and time-efficient method, potentially gaining relevance for imaging post-hemicraniectomy patients. In our setting, the method seemed effective in depicting intraventricular catheter placement, hydrocephalus, ML shift, and space-occupying lesions. Further improvement in image quality could potentially reduce the overall number of indicated CT scans.
Journal Article
The impact of SARS-Covid-19 pandemic on peripheral nerve surgery – A single centre report
by
Knoll, Andreas
,
Petkov, Martin
,
Wirtz, Christian Rainer
in
Brachial plexus
,
Compression
,
Compression syndrome
2024
SARS-Cov-19 pandemic totally changed daily routine work in German hospitals. As hospital capacity was reduced, many surgeries were postponed or even cancelled. On March 25th 2020 the German Society of Neurosurgery (DGNC) published a statement in which urgent non-elective surgeries were defined for each neurosurgical domain, whereas elective interventions were deferred. The present work examines the impact of these Covid strategies focusing on patients with peripheral lesions who were conducted to our department during this period of time.
All patients who underwent any peripheral nerve surgery at our department from January 2018 until December 2022, were included. The complete range of surgeries including peripheral nerve lesions was examined encompassing compression syndromes, traumatic lesions of brachial plexus, traumatic lesions and tumors of single peripheral nerves. The numbers of surgical procedures were compared before, during and after pandemic. Pearson correlation coefficient was analysed.
From 2018 to 2022 the total number of surgical procedures involving peripheral nerves included 2422 procedures. Compression syndromes made up the largest proportion (1433 operations, 59%), followed by peripheral nerve lesions (445 operations, 18%), peripheral nerve tumors (344 operations, 14%) and lesions of the brachial plexus (142 operations, 6%). The average was 40,5 interventions per month, the range was 7–63. Two declines in the number of peripheral nerve surgeries were noted during this period. The first was in April and May 2020 with an average drop of 65% and 41% respectively. In these months the average number of operations was 37. The second decrease was from October 2021 until January 2022, where number of surgeries was reduced by 16%, 36%, 83% and 18% with an average number of 50 operations. Both declines showed a significant and strong correlation with the lower number of compression syndrome treatments (r = 0.952, p < 0.001 and r = 0.968, p < 0.001), while no drop and no significant correlation was found in the treatment of traumatic peripheral nerve injuries (p = 0.769, r = 0.095 and p = 0.243, r = 0.366) and traumatic brachial plexus injuries (p = 0.787, r = 0.088 and p = 0.780, r = 0.09). A weak significant correlation was seen in the treatment numbers of peripheral nerve tumors (p = 0.017, r = 0.672 and p = 0.015, r = 0.67).
Covid-19 pandemic lead to a significant decrease in the number of nerve decompressions, since, according to the German Society of Neurosurgery, those were considered as elective surgeries.
•There was a significant decrease in surgically treated compression syndromes during SARS-Covid-19 pandemic.•Treatment of patients with traumatic lesions of peripheral nerves could be ensured even under pandemic conditions.•There was a weak significant decline in surgically treated peripheral nerve tumors during SARS-Covid-19 pandemic.
Journal Article
Mortality During In-Hospital Stay and the First 24 h After Decompressive Craniectomy in Severe Traumatic Brain Injury: A Multi-Center, Retrospective Propensity Score-Matched Study
by
Pala, Andrej
,
Bracht, Hendrik
,
Petkov, Martin
in
Blood pressure
,
Consciousness
,
Emergency medical care
2025
Objectives: Early death after trauma has been described several times. Little is known about it after traumatic brain injury (TBI) and decompressive craniectomy (DC). The aim of this study was to characterize patients who die after a TBI and DC during their in-hospital stay. Methods: In a subgroup analysis of a retrospective, multicenter, and observational study, non-survivors from in-hospital stays treated for severe TBI and DC were included. Propensity score matching (PSM) was used. Results: A total of 223 patients with severe TBI were treated with DC, and there were 65 (29.1%) patients who did not survive. Of these, 22 (33.8%) died within the first 24 h. Non-survivors were older (p = 0.010), and pupillomotor dysfunction and a higher heart rate on admission were more common (p < 0.001). PSM patients for overall survival (41, 18.4%) differed in mean heart rate from the deceased (p = 0.030). In a multivariate model, age (OR: 1.045, p = 0.013, CI95%: 1.010 to 1.082), Quick value (OR: 0.965, p = 0.049, CI95%: 0.931 to 1.000), and heart rate (OR: 1.099, p = 0.030, CI95%: 1.009 to 1.197) were confirmed as predictive factors. Conclusions: Even after DC, known factors, such as chronological age and comorbidities, have a significant influence on mortality. The value of DC in an aging society for a particular severity of TBI should be further assessed on the basis of prospective studies.
Journal Article
The Integration of Micro-CT Imaging and Finite Element Simulations for Modelling Tooth-Inlay Systems for Mechanical Stress Analysis: A Preliminary Study
2025
This study presents a methodology for developing and validating digital models of tooth-inlay systems, aiming to trace the complete workflow from clinical procedures to simulation by involving dental professionals—dentists for manual cavity preparation and dental technicians for restoration modelling—while integrating micro-computed tomography (micro-CT) imaging with finite element analysis (FEA). The proposed workflow includes (1) the acquisition of high-resolution 3D micro-CT scans of a non-restored tooth, (2) image segmentation and reconstruction to create anatomically accurate digital twins and mesh generation, (3) the selection of proper resin and the 3D printing of four typodonts, (4) the manual preparation of cavities on the typodonts, (5) the acquisition of high-resolution 3D micro-CT scans of the typodonts, (6) mesh generation, digital inlay and onlay modelling and material property assignment, and (7) nonlinear FEA simulations under representative masticatory loading. The approach enables the visualisation of stress and deformation patterns, with preliminary results indicating stress concentrations at the tooth-restoration interface integrating different cavity alternatives and restorations on the same tooth. Quantitative outputs include von Mises stress, strain energy density, and displacement distribution. This study demonstrates the feasibility of using image-based, tooth-specific digital twins for biomechanical modelling in dentistry. The developed framework lays the groundwork for future investigations into the optimisation of restoration design and material selection in clinical applications.
Journal Article