Nikolay Tonchev

Mr. Nikolay Tonchev

orcid

Research Focus & Metrics

Academic Career Length

6Years (2021-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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11 January 2021 in Diagnostics
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Journal Article
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ИИИван Иванов
Иван Иванов
IPIliyana Pacheva
Iliyana Pacheva
ETElena Timova
Elena Timova
RIRalitsa Iordanova
Ralitsa Iordanova
FPFani Galabova- Petrova
Fani Galabova- Petrova
LFLauren Franz
Lauren Franz
Diagnosis of autism spectrum disorder (ASD) before the age of three years is a challenge. Analyzing the present practice may help reaching that goal. Aim: To investigate developmental abnormalities and diagnostic pathway of ASD patients in pediatric practice. Methods: Retrospective cross-sectional study of 192 children aged 13 months to 17 years 11 months (average 4 years 9 months), investigated in an outpatient and hospital setting from January 2015 to June 2018 by a semi-structured history and clinical examination, and diagnosed with ASD by Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) criteria. Results: Behavioral peculiarities were detected in the history of the first two years of life in 74.8% of the subjects. The first developmental abnormalities were noticed by the parents at ages from 8 to 36 months (mean 15.6 months) and were predominantly in speech (in 94.6%) and non-verbal communication (11.3%). Developmental regression was reported in 42.1% of the patients occurring between the ages of 6 and 50 months (mean 17.9 months), affecting most commonly speech (88.4% of cases), non-verbal communication (29.2%), and behavior (12.8%). By history, the first manifestations of ASD were noticed at ages from 8 months to 84 months (mean 18.5 months), and were disorders of expressive speech (in 66.7% of cases), receptive speech (in 45.8%), non-verbal communication (35.4%), behavior (27.6%), play (8.9%), socialization (5.7%), and joint attention (2.1%). The most common motive for specialized consultation was delay in language development—in 84.6% of children. The age of ASD diagnosis varied between 12 and 132 months (mean 39.7 months), and the time period between first ASD manifestations and diagnosis was in the range of 0 to 79 months (mean 23.3 months). Many symptoms of abnormal social communication, unnoticed by parents, were detected objectively in more than 95% of the cases—absent or rare spontaneous or reciprocal smile; lack of sharing of interest or affect; abnormal eye contact; lack of finger pointing; lack of gaze to a pointed object; poor facial expressions; lack of imaginary play, etc. Conclusions: Almost two years are needed for diagnosing abnormal development in other domains besides speech in ASD patients. Diagnosis before the age of three years can be achieved by focusing parents’ and pediatricians’ attention on social communication and behavior in patients with speech delay or developmental regression.

11 January 2025 in Medicina
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Journal Article
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NTNikolay Tonchev
Nikolay Tonchev
BNBelal Neyazi
Belal Neyazi
KSKlaus-Peter Stein
Klaus-Peter Stein
ISI. Erol Sandalcioglu
I. Erol Sandalcioglu
ARAli Rashidi
Ali Rashidi
Spinal dural arteriovenous fistulas (sDAVFs) are rather uncommon lesions of the spine. In sDAVFs, which represent the most frequent form of vascular malformations of the spine, operative treatment remains the most common treatment modality. In operative surgery, visualization and pathology detection have a key impact on the results of the neurosurgical treatment of an sDAVF. The exoscope is one of the most recent imaging devices developed alongside the microscope and endoscope. The exoscope is being increasingly applied in neurosurgical procedures as an alternative to operative microscopes due to various advantages, such as its non-space-occupying camera, excellent visualization of the anatomical details and the perfect teaching possibilities it thus provides. In this publication, we present our experience in the treatment of a patient with an sDAVF, where surgery was performed exclusively with an ORBEYE-exoscope for the entire duration of the procedure. This report outlines the workflow and some of the technical pitfalls involved in managing this vascular pathology using the exoscopic technique.

21 November 2024 in Journal of Clinical Medicine
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Journal Article
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NTNikolay Tonchev
Nikolay Tonchev
APAnatoli Pinchuk
Anatoli Pinchuk
CDClaudia Dumitru
Claudia Dumitru
KSKlaus-Peter Stein
Klaus-Peter Stein
BNBelal Neyazi
Belal Neyazi
ARAli Rashidi
Ali Rashidi
Background/Objectives: Postoperative hemorrhages (POHs) after pituitary adenoma surgery can have devastating consequences for patients. Many patients take acetylsalicylic acid (ASA) for the primary or secondary prevention of cardiovascular or stroke events. However, the impact of continued low-dose ASA use on the risk of postoperative hemorrhage and the frequency of thromboembolic events after discontinuing ASA in these patients remain poorly understood. This study aims to investigate the potential interaction and correlation between low-dose ASA intake and two of the most common complications after neurosurgical surgery—acute postoperative hemorrhage and thromboembolism. Methods: A retrospective study involving 1862 patients who underwent brain tumor surgery over a decade at our neurosurgical institute examined the risk of postoperative hemorrhage and thromboembolic events. The study compared bleeding rates in patients with pituitary adenomas who received low-dose ASA medication to those who did not. Additionally, the study investigated the occurrence of venous thromboembolism (VTE) or arterial pulmonary embolisms (PEs) following surgery, as well as the impact of laboratory parameters, demographic characteristics and intraoperative factors. Results: A total of 108 patients underwent surgery for primary pituitary tumors between January 2008 and January 2018. Only six patients (5.6%) experienced POH. Among those with POH, just two (1.9%) required revision surgery due to neurological decline. Interestingly, none of the 13 patients (12%) taking ASA preoperatively suffered POH. No correlation was found between laboratory results, demographics and postoperative complications. The study also did not find an increase in VTE or PE events. Conclusions: In this analysis, the perioperative intake of low-dose ASA could not be associated with an increased rate of hemorrhagic complications following pituitary adenoma surgery. Low-dose ASA can be safely continued during brain tumor surgery in patients with a high cardiovascular and cerebrovascular risk.

19 December 2025 in Current Oncology
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Journal Article
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APAnatoli Pinchuk
Anatoli Pinchuk
NTNikolay Tonchev
Nikolay Tonchev
ASAnna Schaufler
Anna Schaufler
CDClaudia Dumitru
Claudia Dumitru
KSKlaus-Peter Stein
Klaus-Peter Stein
ARAli Rashidi
Ali Rashidi
Postoperative hemorrhage (POH) is a rare but serious complication of cranial neurosurgery, often resulting in neurological deterioration and necessitating urgent surgical intervention. Despite its clinical relevance, POH remains underreported and insufficiently understood. This study aimed to identify potential risk factors including perioperative variables and tumor-related characteristics associated with POH requiring surgical evacuation. A total of 1862 cranial tumor procedures were performed in our department over a 10-year period. Data on perioperative parameters and tumor characteristics were retrospectively collected and analyzed. Statistical analyses were conducted to assess associations of them to POH. Statistical analysis revealed several peri- and postoperative variables significantly associated with POH in univariate analyses. These included intraoperative blood loss (p = 0.012) and length of postoperative hospital stay (p = 0.016). Furthermore, the outcomes measured using the Glasgow Outcome Scale (p < 0.001) and the Karnofsky Performance Scale (p < 0.001) showed also statistical relevance as a result of postoperative bleeding in these patients. The findings suggest that specific perioperative factors particularly intraoperative blood loss are associated with an increased risk of POH after intracranial tumor surgery. Additionally, prolonged hospitalization and worsened functional outcomes were linked to the occurrence of postoperative hemorrhage. In contrast, tumor-specific characteristics and routine laboratory values showed no significant association with hemorrhagic complications in this cohort.

10 August 2024 in Current Oncology
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Journal Article
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NTNikolay Tonchev
Nikolay Tonchev
APAnatoli Pinchuk
Anatoli Pinchuk
CDClaudia Dumitru
Claudia Dumitru
BNBelal Neyazi
Belal Neyazi
VSVanessa Magdalena Swiatek
Vanessa Magdalena Swiatek
ARAli Rashidi
Ali Rashidi
Cranial operations are associated with a high risk of postoperative intracranial hemorrhage (pICH) and venous thromboembolic events, along with increased mortality and morbidity. With the use of acetylsalicylic acid (ASA) for prophylaxis becoming more prevalent, the risk of bleeding when ASA is administered preoperatively is unknown, as are the effects of discontinuation upon the occurrence of thromboembolic events, especially in societies with aging demographics. To address these questions, a retrospective analysis was performed using medical records and radiological images of 1862 patients subjected to brain tumor surgery over a decade in our department. The risk of pICH was compared in patients with metastases receiving ASA treatment versus patients not receiving ASA treatment. The occurrence of venous thromboembolic events after surgery was also evaluated. The study group consisted of 365 patients with different types of brain metastases. In total, 20 patients suffered pICH and 7 of these were associated with clinical neurological deterioration postoperatively. Of the 58 patients who took ASA preoperatively, 2 patients experienced pICH, compared with 5 patients in the non-ASA impact group (p = 0.120). Patients who took ASA were not at significantly higher risk of pICH and therefore a worse outcome compared to the group without ASA. Therefore, these data suggest that in patients at high cardiovascular risk, ASA can be safely continued during elective brain tumor surgery.

15 November 2024 in Cancers
Verified
Journal Article
Open access
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APAnatoli Pinchuk
Anatoli Pinchuk
NTNikolay Tonchev
Nikolay Tonchev
CDClaudia Dumitru
Claudia Dumitru
BNBelal Neyazi
Belal Neyazi
KSKlaus-Peter Stein
Klaus-Peter Stein
ARAli Rashidi
Ali Rashidi
Background/Objectives: Patients with gliomas show an increased risk of spontaneous hemorrhages throughout the disease. Simultaneously, the number of patients taking acetylsalicylic acid (ASA) for primary and secondary prophylaxis is rising in daily clinical practice, and interrupting ASA intake before elective or emergency intracranial surgery is not always feasible. This study aims to evaluate the risks associated with continuing ASA use perioperatively while focusing on hemorrhage and potential thromboembolic events that may arise from discontinuing ASA, particularly in multimorbid patients undergoing glioma surgery. Methods: The clinical parameters and imaging data of 7149 patients who underwent intracranial surgery in our department over a 10-year period were retrospectively analyzed. Patients were categorized into two groups based on their ASA status: Group 1 (no ASA impact) included those with no ASA use or who discontinued ASA use more than seven days prior to surgery (low stroke or cardiovascular risk), and Group 2 (ASA impact) included those who continued ASA use within seven days prior to operation (high stroke or cardiovascular risk). Results: In this retrospective study, data from 650 patients with various types of glial tumors who underwent surgery between 2008 and 2018 were examined. Of these patients, 50 experienced a postoperative hemorrhage (POH), and 10 required reoperations due to clinical neurological deterioration and increased intracranial pressure caused by the space-occupying effect of the hemorrhage. In the ASA impact group, 2.7% developed POH, compared to 1.3% in the no ASA impact group (p = 0.098). Our analysis did not show a significantly increased risk of POH after surgery, although patients in the ASA impact group had a one- to two-fold higher risk of developing POH overall. Additionally, other factors contributing to postoperative hemorrhage following glioma surgery were investigated and evaluated. Conclusions: In this cohort, the perioperative use of ASA was not associated with an increased rate of hemorrhagic complications after intracranial glioma surgery, although a trend was observed. In patients with high stroke and cardiovascular risk, ASA can be continued during elective brain tumor surgery.