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Permanent URI for this collectionhttps://hdl.handle.net/20.500.14288/3
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Publication Metadata only Efficacy of hypofractionated Gamma Knife radiosurgery in treating surgical beds of metastatic brain tumors(Elsevier Sci Ltd, 2024) Samancı, Mustafa Yavuz; Tepebaşılı, Mehmet Ali; Ardor, Gökçe Deniz; Düzkalır, Ali Haluk; Askeroğlu, Mehmet Orbay; Peker, Selçuk; School of Medicine; Koç University HospitalObjective: Surgery alone for metastatic brain tumors (METs) often results in local recurrence due to microscopic residual tumor tissue. While stereotactic radiosurgery (SRS) is commonly used post-surgery, hypofractionation may be required for large surgical beds. This study evaluated the efficacy and safety of hypofractionated Gamma Knife radiosurgery (hf-GKRS) for the first time as a post-operative adjuvant therapy. Methods: This retrospective study involved 24 patients (28 surgical beds) who underwent hf-GKRS within four weeks after surgery. The study primarily focused on local control (LC) rate and analyzed distant intracranial failure (DICF), intracranial progression-free survival (PFS), leptomeningeal disease (LMD), overall survival (OS), and radiation necrosis (RN). Results: During a median follow-up of 9 months, LC was achieved in 89.3 % of surgical beds. LC estimates at 6, 12, and 24 months were 96.4 %, 82.7 %, and 82.7 %, respectively. DICF was observed in 45.8 % of patients, and LMD was identified in two patients (8.3 %). At the end of the follow-up, 58.3 % of patients were alive, and the median OS was 20 months. RN occurred in only one surgical bed (3.6 %). No grade 5 toxicity was observed. The univariate analysis identified a longer interval to GKRS (HR 11.842, p = 0.042) and a larger treatment volume (HR 1.103, p = 0.037) as significant factors for local failure. Conclusions: hf-GKRS shows potential as an effective and safe adjuvant treatment for surgical beds. It offers an alternative to SRS, SRT, or WBRT, particularly for larger volumes or tumors near critical structures. Further research is needed to confirm these results and optimize treatment approaches.Publication Metadata only Gamma Knife radiosurgery for multiple sclerosis-associated trigeminal neuralgia(Elsevier Sci Ltd, 2024) Özlük, Gülşah Özturk; Samancı, Mustafa Yavuz; Düzkalır, Ali Haluk; Şenyürek, Şükran; Askeroğlu, Mehmet Orbay; Peker, Selçuk; School of Medicine; Koç University HospitalBackground: Gamma Knife radiosurgery (GKRS) has well-known efficacy in the treatment of idiopathic trigeminal neuralgia (TN). However, few studies have evaluated the effects of GKRS in the treatment of multiple sclerosis (MS)-related TN. This study analyzed the efficacy and complications of GKRS for MS-related TN. Methods: This retrospective study included 28 MS-related TN patients who underwent GKRS with a median follow-up of 27 (range, 12-181) months. The cisternal segment of the trigeminal nerve was targeted with a median radiation dose of 80 (80-90) Gy. Pain intensity was assessed using Barrow Neurological Institute (BNI)Pain Intensity Scores (BNI-PIS). Before GKRS, all patients suffered from BNI pain levels of 4 or 5. A reduction in pain to BNI 3b or below was deemed as adequate pain relief. Results: The initial proportion of patients who experienced adequate pain relief was 71.4%, with a median interval of 21 (1-45) days. At the final follow-up, 50% of patients had achieved adequate pain relief. Ten patients (35.7%) suffered from complications, including four with facial sensorial dysfunctions, four with a decline in their corneal reflexes, and two with jaw weakness. Among the 20 initial responders, six (30%) patients suffered pain recurrence after a median interval of 35 (12-180) months. Conclusions: GKRS is an effective means of pain relief in MS-related TN, but has side effects that are relevant to other ablative treatments. The benefits and risks of GKRS should be discussed with patients who wish to avoid surgery or when previous treatments fail.Publication Metadata only The clinical value of amplitude-integrated electroencephalography in a historical cohort with neonatal encephalopathy: a comparison of short-term versus prolonged-period monitoring(Elsevier Sci Ltd, 2024) Tekgül, Hasan; Yalaz, Mehmet; Kanmaz, Seda; Terek, Demet; Aktan, Gül; Köroğlu, Özge A.; Yılmaz, Sanem; Akisu, Mete; Kültürsay, Nilgün; Akçay, Ayfer Arduç; School of MedicineBackground: To compare the amplitude -integrated electroencephalography (aEEG) monitoring (short-term versus prolonged -period) for neonatal seizure detection and outcome. Methods: The aEEG monitoring in a historical cohort (n = 88, preterm:42, and term:46) with neonatal encephalopathy between 2010-2022 was re-evaluated for neonatal seizures (electrographic, electro-clinical, and clinical seizures) and EEG background scoring. The cohort was dichotomized: group I (short -period with 6-12 h, n = 36) and group II (prolonged -period with 24-48 h, n = 52). Both monitoring types were evaluated for the diagnostic accuracy of the "patients with seizures" and for outcome characteristics (early death as well as adverse outcomes at 12 months of age). Results: A total of 67 (76 %) neonates of the cohort were diagnosed as "patients with seizures": electrographiconly seizures in 10 (15 %), electro-clinical seizures in 22 (33 %), and clinical -only seizures in 35 (52 %). The aEEG provides the "patients with seizures" in neonates with a 36.5 % rate with both types of monitoring: 17/36 (47.2 %) with short-term and 15/52 (28.8 %) with prolonged -period monitoring. The prolonged period aEEG had higher diagnostic values for seizure detection ( sensitivity = 0.73 and negative predictivity value = 0.81 ). However, the aEEG background scores were similar for both types of aEEG monitoring, respectively ( the mean +/- SD: 4.73 +/- 2.9 versus 4.4 +/- 4. p = 0.837 ). The aEEG scoring was correlated with the magnitude of brain injury documented with MRI, the early death, and the adverse outcome at 12 months of age. Conclusions: Both aEEG types are valuable for monitoring the "patients with seizures" and outcome characteristics.Publication Metadata only Combined central and peripheral demyelination: two case reports(KARGER, 2024) Belen, Buse Gül; Bülbül, Nazlı Gamze; Karşıdağ, Sibel; Köse, Ercan; Özdag, Fatih; Vural, Atay; School of MedicineCombined central and peripheral demyelination (CCPD) is a rare disease characterized by demyelinating lesions in both the central nervous system (CNS) and peripheral nervous system (PNS). CCPD can present with acute, subacute, or chronic onset. The initial symptom may be of CNS origin, PNS origin, or both. The clinical manifestations of CCPD are quite heterogeneous, and there are no well-defined diagnostic criteria. In MRI imaging of CCPD cases, demyelinating lesions can be seen in areas such as the brain, cerebellum, brainstem, optic nerve, and spinal cord. Common electromyography (EMG) findings in patients with CCPD include decreased motor nerve conduction velocities, decreased or absent sensory nerve action potentials, prolonged F-wave latency, and decreased amplitude of compound muscle action potentials. Neurofascin (NF) is a transmembrane protein and anti-neurofascin (anti-NF) antibodies directed against NF can be positive in cases of CCPD. Four main NF polypeptides are produced by alternative splicing: NF 186, NF 180, NF 166, and NF 155. The investigation of anti-NF in CCPD cases is therefore important for etiological considerations. Here, we discussed three cases diagnosed with CCPD based on clinical, neuroimaging, EMG, and anti-NF antibody results in light of the literature.Publication Metadata only The cerebello-hypothalamic and hypothalamo-cerebellar pathways via superior and middle cerebellar peduncle in the rat(Springer, 2018) Bay, Hüsniye Hacıoğlu; Çavdar, Safiye; Özgür, Merve; Kuvvet, Yasemin; Faculty Member; PhD Student; PhD Student; School of Medicine; Graduate School of Health Sciences; Graduate School of Health Sciences; 1995; N/A; N/AThe connections between the cerebellum and the hypothalamus have been well documented. However, the specific cerebellar peduncle through which the hypothalamo-cerebellar and cerebello-hypothalamic connections pass has not been demonstrated. The present study aims to define the specific cerebellar peduncle through which connects the cerebellum to specific hypothalamic nuclei. Seventeen male albino rats received 20-50-nl pressure injections of either Fluoro-Gold (FG) or biotinylated dextran amine (BDA) tracer into the superior (SCP), middle (MCP), and inferior (ICP) cerebellar peduncle. Following 7-10days of survival period, the animals were processed according to the appropriate protocol for the two tracers used. Labeled cells and axons were documented using light or fluorescence microscopy. The present study showed connections between the hypothalamus and the cerebellum via both the SCP and the MCP but not the ICP. The hypothalamo-cerebellar connections via the SCP were from the lateral, dorsomedial, paraventricular, and posterior hypothalamic nuclei, and cerebello-hypothalamic connections were to the preoptic and lateral hypothalamic nuclei. The hypothalamo-cerebellar connections via the MCP were from the lateral, dorsomedial, ventromedial, and mammillary hypothalamic nuclei; and cerebello-hypothalamic connections were to the posterior, arcuate, and ventromedial hypothalamic nuclei. The hypothlamo-cerebellar connections were denser compared to the cerebello-hypothlamic connections via both the SCP and the MCP. The connection between the cerebellum and the hypothalamus was more prominent via the SCP than MCP. Both the hypothlamo-cerebellar and cerebello-hypothalamic connections were bilateral, with ipsilateral prepÖnderance. Reciprocal connections were with the lateral hypothalamic nucleus via the SCP and the ventromedial nucleus via the MCP were observed. Cerebellum takes part in the higher order brain functions via its extensive connections. The knowledge of hypothalamo-cerebellar and cerebello-hypothalamic connections conveyed within the SCP and MCP can be important for the lesions involving the MCP and SCP. These connections can also change the conceptual architecture of the cerebellar circuitry and deepen current understanding.Publication Metadata only Rectification of SEMG as a tool to demonstrate synchronous motor unit activity during vibration(Elsevier Sci Ltd, 2013) Karacan, İlhan; Çidem, Muharrem; Department of Physics; N/A; Sebik, Oğuz; Türker, Kemal Sıtkı; Researcher; Faculty Member; Department of Physics; College of Sciences; School of Medicine; N/A; 6741The use of surface electromyography (SEMG) in vibration studies is problematic since motion artifacts occupy the same frequency band with the SEMG signal containing information on synchronous motor unit activity. We hypothesize that using a harsher, 80-500 Hz band-pass filter and using rectification can help eliminate motion artifacts and provide a way to observe synchronous motor unit activity that is phase locked to vibration using SEMG recordings only. Multi Motor Unit (MMU) action potentials using intramuscular electrodes along with SEMG were recorded from the gastrocnemius medialis (GM) of six healthy male volunteers. Data were collected during whole body vibration, using vibration frequencies of 30 Hz, 35 Hz, 40 Hz or 50 Hz. A computer simulation was used to investigate the efficacy of filtering under different scenarios: with or without artifacts and/or motor unit synchronization. Our findings indicate that motor unit synchronization took place during WBV as verified by MMU recordings. A harsh filtering regimen along with rectification proved successful in demonstrating motor unit synchronization in SEMG recordings. Our findings were further supported by the results from the computer simulation, which indicated that filtering and rectification was efficient in discriminating motion artifacts from motor unit synchronization. We suggest that the proposed signal processing technique may provide a new methodology to evaluate the effects of vibration treatments using only SEMG. This is a major advantage, as this non-intrusive method is able to overcome movement artifacts and also indicate the synchronization of underlying motor units.Publication Metadata only Long-term results of Gamma Knife radiosurgery for facial nerve schwannomas(Taylor & Francis, 2020) Şirin, Alperen; Yılmaz, Meltem; Şengöz, Meriç; N/A; N/A; Akyoldaş, Göktuğ; Peker, Selçuk; Faculty Member; Faculty Member; School of Medicine; School of Medicine; 203677; 11480Objective: Long-term outcomes of eleven cases of facial nerve schwannoma were evaluated and the related literature was reviewed to determine the efficacy of Gamma Knife radiosurgery for treating patients with facial nerve schwannoma. Methods: Eleven patients with facial nerve schwannoma (7 women and 4 men; mean age, 44.2 years; range, 19-73 years) underwent Gamma Knife radiosurgery. The most common symptoms were facial palsy (n = 10) and hearing loss (n = 7). Five patients presented with headache. Two patients had undergone prior resection. The patients' clinical and radiographic data were evaluated retrospectively. Results: For the 11 cases of facial nerve schwannoma, mean tumor volume was 3.1 cm(3) (range, 0.4-7.4 cm(3)) and the mean marginal dose applied was 11.9 Gy (range, 11-13 Gy). The mean follow-up period was 84.3 months (range, 66-117 months). Tumor control was achieved in all patients. At the time of writing, four patients experienced tumor volume regression and the other seven were in stable condition. During follow-up, nine patients experienced no change in their facial function, two experienced deteriorated facial function, and none developed new facial palsy. Ten patients who had serviceable hearing prior to Gamma Knife radiosurgery retained their hearing. Conclusions: Gamma Knife radiosurgery achieves excellent results with respect to tumor control for 7 years on average. In addition, Gamma Knife radiosurgery provides good results in facial nerve and hearing function at long term. Our series demonstrates that Gamma Knife radiosurgery is an effective and safe treatment for patients with either primary or residual facial nerve schwannoma.Publication Metadata only Cerebellar ataxia, neuropathy and vestibular areflexia syndrome (CANVAS): an important cause of late-onset ataxia with unique clinical features(Springer Heidelberg, 2022) Çakar, Arman; Şahin, Erdi; Tezel, Seden; Candayan, Ayşe; Samancı, Bedia; Battaloğlu, Esra; Bilgiç, Başar; Hanağası, Haşmet; Durmuş, Hacer; Parman, Yeşim; N/A; Başak, Ayşe Nazlı; Faculty Member; Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); School of Medicine; 1512Cerebellar ataxia, neuropathy, vestibular areflexia syndrome (CANVAS) is a late-onset, slowly progressive disorder characterized by cerebellar ataxia, sensory neuropathy and bilateral vestibulopathy. Recently, a biallelic intronic AAGGG repeat expansion, (AAGGG)(exp), in the Replication Factor C1 (RFC1) gene was identified as the cause of this disorder. In this study, we describe the phenotypic features of five patients from five different families diagnosed as CANVAS. The mean age at onset was 49.00 +/- 9.05 years (between 34 and 56 years) and the most frequent presenting symptom in CANVAS was gait ataxia, followed by sensory disturbances. Persistent coughing was prominent in three patients, and it preceded the onset of ataxia and sensory symptoms in two patients. Parental consanguinity was present in three patients. Two patients showed symptoms or signs suggesting autonomic involvement. Sural nerve biopsy revealed axonal neuropathy in two patients. The mean age at onset was 49.00 +/- 9.05 years (between 34 and 56 years) and the most frequent presenting symptom in CANVAS was gait ataxia, followed by sensory disturbances. Persistent coughing was prominent in three patients, and it preceded the onset of ataxia and sensory symptoms in two patients. Parental consanguinity was present in three patients. Two patients showed symptoms or signs suggesting autonomic involvement. Sural nerve biopsy revealed axonal neuropathy in two patients. Our study describes clinical findings, histopathological features and diagnostic clues of CANVAS from Turkey, a country with a high consanguineous marriage rate. Repeat expansion in the RFC1 gene should be considered in all cases with late-onset ataxia, especially when sensory disturbances, vestibular involvement and persistent coughing coexist.Publication Metadata only Comparison of cerebral ventricular volumes and cortical thicknesses in normal rats and Genetic Absence Epilepsy (GAERS): A developmental study(Pergamon-Elsevier Science Ltd, 2018) Kirazlı, Özlem; Bay, Hüsniye Hacıoğlu; Çakmak, Yusuf Özgür; Onat, Filiz; Çavdar, Safiye; Faculty Member; School of Medicine; 1995Ventricular enlargement and cortical atrophy have been associated with various central nervous system diseases. The aim of the present study was to measure the volumes of the lateral (LV) and third (3V) ventricles and to determine the cortical thickness for the motor (MCx), somatosensory (SSCx), visual (VCx) and auditory (AuCx) cortex and the striatum of Wistar rats, in a developmental series at 10, 20, 30, and 60 days postnatal, and to compare them with similar data from genetic absence epilepsy rats from Strasbourg (GAERS). Serial sections were taken from the brains of Wistar and GAERS animals and were Nissl stained. Photographs were taken from specific sections of the brain for measurements of ventricular volume, cortical and striatal thickness. The image-j computer program was used for the volume and thickness measurements. The data was statistically analyzed by 3-way ANOVA using SPSS 15. Comparison of the measurements of GAERS and Wistar animals showed no statistically significant differences at any of the developmental stages regarding the ventricular (LV and 3V) volumes. However, at P60 and P30 of the MCx, P30 of the SSCx, P20 of the VCx and AuCx showed a significantly thinner cortical thickness in the GAERS than in the Wistar animals. The striatal measurements showed significant decrease in thickness of the striatum at P30 and P60. Further, brain size measurements (between the two temporal poles) showed significant decrease in the size at P30 and P60 of GAERS animals. The presence of thinner cortical and striatal thicknesses and smaller brain size in GAERS animals may suggests that these changes could be involved in the mechanism of epileptogenicity or be a result of the epileptogenicity.Publication Metadata only The use of modified rio score for determining treatment failure in patients with multiple sclerosis: retrospective descriptive case series study(Springer, 2021) Tütüncü, Mesude; Doğan, Burcu, V; Uygunoğlu, Uğur; İçen, Nilufer Kale; Karakaya, Ayşe Elmalı; Çoban, Eda; Alpaslan, Bengi G.; Sosyal, Aysun; N/A; Altıntaş, Ayşe; Faculty Member; School of Medicine; 11611