Researcher:
Sasani, Mehdi

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Mehdi

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Sasani

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2015 - 2019122020 - 202313

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    Dynamic stabilization of the lumbar spine using the Dynesys® system
    (Turkish Neurosurgical Soc, 2020) Cevik, Orhun Mete; Akyoldaş, Göktuğ; Süzer, Süleyman Tuncer; Sasani, Mehdi; Öktenoğlu, Bekir Tunç; Özer, Ali Fahir; Faculty Member; Faculty Member; Faculty Member; Faculty Member; Faculty Member; School of Medicine; School of Medicine; School of Medicine; School of Medicine; School of Medicine; 203677; 221691; 219451; 220898; 1022
    AIM: To present the clinical results in patients with minor instability with "Dynesys (R)"a soft spinal stabilization system. Material and Methods: A total of 83 patients were operated upon and the Dynesys (R) system was applied. Indications for surgery included painful degenerative disc disease, degenerative spondylolisthesis and lumbar canal stenosis. Results: The results for the Dynesys (R) system were satisfactory, and we have calculated the overall complication rate to be 20.4% (n=17), which is in agreement with the literature. Conclusion: The Dynesys (R) dynamic stabilization system effectively protects lumbar motion and achieves lumbar stability in patients with lumbar spinal problems. Our clinical result support literature that Dynesys (R) system is a strong alternative to fusion and instrumentation system in patient with chronic instabilities.
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    Lumbar dynamic stabilization with 2-stage surgery: early results
    (Elsevier, 2022) HekimoǧLu, Mehdi Akgül, Turgut Özbek, Muhammet Arif; Özer, Ali Fahir; Ateş, Özkan; Sasani, Mehdi; Öktenoğlu, Bekir Tunç; Günerbüyük, Caner; Aydın, Ahmet Levent; Başak, Ahmet Tulgar; Faculty Member; Faculty Member; Faculty Member; Faculty Member; Teaching Faculty; Doctor; Doctor; School of Medicine; School of Medicine; School of Medicine; School of Medicine; School of Medicine; Koç University Hospital; School of Medicine; 1022; 118533; 219451; 220898; 380939; N/A; N/A
    Background: Screw loosening, which is a major problem in dynamic systems, can be easily overcome with 2-stage surgery. In this article, the clinical and radiological results of patients undergoing dynamic stabilization with a Dynesys device in 2 stages are discussed. Methods: A total of 10 male and 13 female adult patients were included in this single-center retrospective study conducted between 2018 and 2021. The mean age of the patients was 65.6 years. All of the patients had pain complaints that affected their daily lives. Bone density T scores were determined with the dual-energy x-ray absorptiometry method before patients were admitted for surgery. In the first surgery, Dynesys system pedicle screws were inserted. After 6 months of osteointegration, Dynesys system spacers and elastic bandages were placed. Preoperative, early postoperative, and late postoperative visual analog pain scale (VAS) scores and Oswestry Disability Index (ODI) scores were determined and statistically compared. Results: Patients were followed for an average of 30 months. Complications and recurrence were not observed. Neurological deficits were not observed after patients recovered from anesthesia. Significant improvement was observed in the ODI and VAS parameters in the preoperative (ODI: 66.2%, VAS: 7.8), early postoperative (ODI: 20.3%, VAS: 2.4), and late postoperative (ODI: 6.8% and VAS: 1.1) periods. Symptomatic improvement was seen in all patients. No screw breakage or loosening was detected by radiological evaluation in any of the patients during the 2-year follow-up period. Conclusions: In our experience, the insufficiency of the proximal and distal end screws is eliminated when 2 stages of dynamic system stabilizations are completed after osteointegration of the screws.
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    Complications of 2-level dynamic stabilization: a correlative clinical and radiological analysis at two-year follow-up on 103 patients
    (2018) Yılmaz, Atilla; Erbulut, Deniz Ufuk; N/A; Çıplak, Necati Mert; Süzer, Süleyman Tuncer; Şentürk, Salim; Yaman, Onur; Sasani, Mehdi; Öktenoğlu, Bekir Tunç; Özer, Ali Fahir; Doctor; Doctor; Doctor; Doctor; Faculty Member; Faculty Member; Faculty Member; N/A; N/A; N/A; N/A; School of Medicine; School of Medicine; School of Medicine; Koc University Hospital; N/A; 221691; N/A; 219524; 219451; 220898; 1022
    AIM: To investigate the postoperative complications, such as screw loosening, screw breakage and adjacent segment disease (ASD), in patients who underwent surgery with 2-level dynamic stabilization systems. MATERIAL and METHODS: Postoperative complications, clinical improvements and radiological parameters in patients who underwent surgery using a dynamic system for 2-level lumbar stabilization were retrospectively reviewed. A total of 103 patients with lumbar degenerative spinal instability underwent 2-level dynamic stabilization. Clinical findings were reviewed at 2-year follow-up. Screw breakage and loosening were evaluated during this duration together with clinical findings. ESULTS: Visual analog scale (VAS) and Oswestry Disability Index (ODI) scores were significantly decreased at the four-month evaluation, and they were also decreased at the 1-year follow up and at the 24th postoperative month. ASD was diagnosed in twelve (8 females, 4 males) of the 103 patients in the follow-up radiological and clinical controls. There were 9 screw breakages and 4 screw loosening cases. The complication rate of 2-level dynamic stabilization was high in this study. CONCLUSION: Our results showed that complications (screw loosening or breakage and adjacent segment disease) are not rare after 2-level dynamic stabilization, unlike the acceptable results with the single-level dynamic system. The most probable explanation is that the instrument system behaves more rigidly with every additional segment.
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    Should iliac wing screws be included in long segment dynamic stabilization?
    (Cureus Inc, 2021) Hekimoglu, Mehdi; Cerezci, Onder; Basak, Ahmet T.; N/A; Özer, Ali Fahir; Aydın, Ahmet Levent; Ateş, Özkan; Öktenoğlu, Bekir Tunç; Sasani, Mehdi; Faculty Member; Doctor; Faculty Member; Faculty Member; Faculty Member; School of Medicine; N/A; School of Medicine; School of Medicine; School of Medicine; N/A; Koç University Hospital; N/A; N/A; N/A; 1022; N/A; 118533; 220898; 219451
    Background In this article, clinical sAtışfaction and radiological results are discussed in a series of patients where the iliac wings participate in dynamic stabilization. Dynamic stabilization is an effective alternative surgical treatment method, especially in clinical pictures that go with pain due to minor instabilities. Practically the unique surgical instrument used in multilevel instabilities is the Dynesys system. The most important drawback of the Dynesys system is that the S1 screws become loose in time. In this article, our aim is to find solution to S1 insufficiency by extension of the system to the iliac wings. Methods Nineteen patients (eight females, 11 males) with a mean age of 54.16 were included in the study. Patients had multilevel (level 2 and above) instability, iliac wings were included in the stabilized segments, and Visual Analog Scale (VAS) and Oswestry Disability Index (ODI) were used for patient follow-up. Results First year results showed a significant improvement in VAS and ODI. Regarding the complications, infection developed in one patient, loosening in the proximal iliac wing in one patient, and both S1 and iliac proximals in one patient, but no clinical findings were encountered. Conclusion When more than two levels of dynamic systems are used in chronic instability, especially in the elderly patients, S1 screws are loosened. In these patients, if the iliac bones are also included in stabilization, this problem is solved successfully. However unfortunately, Dynesys system does not have a screw suitable for the iliac bones.
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    Foraminoplasty with partial pediculectomy in degenerative spondylolisthesis cases with nerve compression
    (Elsevier Inc., 2023) Toklu, Sureyya; N/A; Akgün, Mehmet Yiğit; Günerbüyük, Caner; Ateş, Özkan; Aydın, Ahmet Levent; Baran, Oğuz; Öktenoğlu, Bekir Tunç; Sasani, Mehdi; Özer, Ali Fahir; Doctor; Teaching Faculty; Faculty Member; Doctor; Faculty Member; Faculty Member; Faculty Member; Faculty Member; N/A; School of Medicine; School of Medicine; N/A; School of Medicine; School of Medicine; School of Medicine; School of Medicine; Koç University Hospital; N/A; 380939; 118533; N/A; 291138; 220898; 219451; 1022
    Background: Degenerative spondylolisthesis refers to a forward displacement of a vertebra relative to the underlying vertebra. Patients with radicular pain and/or neurogenic claudication are considered suitable candidates for surgical intervention. The aim of this study was to present clinical results of dynamic stabilization applied after pediculectomy and neural foramen enlargement in patients with degenerative spondylolisthesis and normal spinal sagittal balance. Materials and Methods: All patients who underwent pediculectomy and dynamic stabilization for lumbar degenerative spondylolisthesis were retrospectively identified. Diagnosis was made with detailed neurological and radiological imaging examinations for the anatomical location of the pain. Demographic data, visual analog scale scores, and quality-of-life scores were obtained. Results: Patients included 3 (33.3%) men and 6 (66.7%) women with a mean age of 61.3 ± 13.0 years (range, 46–80 years) at initial symptom onset. Grade 1 degenerative spondylolisthesis was present in 5 (55.6%) patients, and grade 2 was present in 4 (44.4%) patients. Pathology was detected in L4-5 in 4 patients (44.4%) and L5-S1 in 5 patients (55.6%). In all patients, at the 3-month follow-up, statistically significant decrease in visual analog scale and Oswestry Disability Index scores was observed. At the last follow-up, no implant-related complications requiring revision were observed. Conclusions: In patients without any pathology in the sagittal balance, the optimal physiological treatment modality can be created by applying posterior dynamic stabilization together with pediculectomy to support the posterior tension band. © 2023 Elsevier Inc.
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    An update on anterior approaches: thoracotomy - mini-thoracotomy - thoracoscopy
    (Türk Nöroşirurji Derneği, 2018) Şentürk, Salim; Sasani, Mehdi; Doctor; Faculty Member; N/A; School of Medicine; Koç University Hospital; N/A; N/A; 219451
    Anterior and non-anterior approaches are performed in the surgical treatment of degenerative thoracic spinal diseases. Anterior approaches allow access to the pathology without touching the spinal cord, but the opening of the thorax causes an increase in mortality and morbidity. Non-anterior approaches are the first choice in thoracic spine pathologies. Anterior approaches include thoracotomy, mini-thoracotomy and thoracoscopy. The complication rate of thoracotomy is higher than mini-thoracotomy and thoracoscopy. Thoracoscopic surgery is preferred as it is minimally invasive, but the training period is longer. Anterior approaches may be preferred, especially in the surgical treatment of giant, calcified thoracic disc herniations. The experience of the surgeon and location of the pathology on the spine determines which surgical approach will be applied. / Dejeneratif torakal omurga hastalıklarının cerrahi tedavisinde anterior ve non-anterior yaklaşımlar kullanılır. Anterior yaklaşımlar, omuriliğe temas etmeden omurgadaki patolojiye ulaşmaya olanak sağlar, ancak toraksın açılması mortalite ve morbiditenin artmasına neden olmaktadır. Bu durum, torakal omurga patolojilerinde non-anterior yaklaşımların ilk tercih olmasını sağlamaktadır. Anterior yaklaşımlar torakotomi, mini torakotomi ve torakoskopi şekillerinde yapılmaktadır. Torakotomi yaklaşımında, mini torakotomi ve torakoskopiye göre komplikasyon oranları daha yüksektir. Torakoskopik cerrahi minimal invazif olması dolayısıyla tercih edilir, ancak eğitim süreci daha uzundur. Özellikle dev, kalsifiye torakal disk hernilerinin cerrahi tedavisinde anterior yaklaşımlar tercih edilebilir. Omurgadaki patolojinin lokalizasyonu ve cerrahın tecrübesi hangi cerrahi yaklaşımın uygulanacağını belirler.
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    Preoperative magnetic resonance imaging abnormalities predictive of lumbar herniation recurrence after surgical repair
    (Elsevier Science Inc, 2022) Karadag, Mehmet Kursat; Akinci, Ahmet Tolgay; Basak, Ahmet Tulgar; Hekimoglu, Mehdi; Yildirim, Hakan; Akyoldaş, Göktuğ; Aydın, Ahmet Levent; Ateş, Özkan; Öktenoğlu, Bekir Tunç; Sasani, Mehdi; Akgün, Mehmet Yiğit; Özer, Ali Fahir; Günerbüyük, Caner; Faculty Member; Doctor; Faculty Member; Faculty Member; Faculty Member; Doctor; Faculty Member; Teaching Faculty; N/A; School of Medicine; School of Medicine; School of Medicine; School of Medicine; N/A; School of Medicine; School of Medicine; Koç University Hospital; 203677; N/A; 118533; 220898; 219451; N/A; 1022; 380939
    Objective: There are currently no standard criteria for evaluating the risk of recurrent disk herniation after surgical repair. This study investigated the predictive values of 5 presurgical imaging parameters: paraspinal muscle quality, annular tear size, Modic changes, modified Phirrmann disk degeneration grade, and presence of sacralization or fusion. Methods: Between 2015 and 2018, 188 patients (89 female, 99 male, median age 50) receiving first corrective surgery for lumbar disk herniation were enrolled. Micro-diskectomy was performed in 161 of these patients, and endoscopic translaminar diskectomy approach was performed in 27 patients. Clinical status was evaluated before surgery and 4, 12, and 24 months post surgery using a visual analog scale, Oswestry Disability Index, and Short Form 36. Results: Recurrent disk herniation was observed in 21 of 188 patients. Seventeen of the recurrent disk herniations were seen in those who underwent microdiskectomy and 4 in those who underwent endoscopic translaminar diskectomy. There were significant differences in visual analog scale, Oswestry Disability Index, and Short Form 36 scores at 4, 12, and 24 months between patients with recurrence and the 167 no-recurrence patients. The median annular tear length was significantly greater in patients with recurrence than without recurrence. In addition, there were significant differences in recurrence rate according to Modic change type distribution, sacralization or fusion presence, Pfirmann disk; degeneration grade distribution, dichotomized annular tear size, dichotomized Modic change; and type and simplified 3-tier muscle degeneration classification distribution. Conclusions: Patients with poor clinical scores and recurrence exhibited additional radiologic abnormalities before surgery, such as poor paraspinal muscle quality, longer annular tears, higher Modic change type, higher modified Phirrmann disk degeneration grade, and sacralization or fusion. This risk evaluation protocol may prove valuable for patient selection, surgical planning, and choice of postoperative recovery regimen.
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    Comparison of two minimally invasive techniques with endoscopy and microscopy for extraforaminal disc herniations
    (Elsevier Science Inc, 2020) Sasani, Hadi; Üçer, Melih; Hekimoğlu, Mehdi; N/A; Aydın, Ahmet Levent; Sasani, Mehdi; Öktenoğlu, Bekir Tunç; Özer, Ali Fahir; Doctor; Faculty Member; Faculty Member; Faculty Member; N/A; School of Medicine; School of Medicine; School of Medicine; Koç University Hospital; N/A; 219451; 220898; 1022
    OBJECTIVE: Extraforaminal disc herniations ate, extraordinary herniations because they are located outside the foraminal bony borders and compress the root exiting at the corresponding level, whereas in median or paramedian herniations, the root 1 level below is compressed. Percutaneous endoscopic discectomy (PED) and microscopic extraforaminal discectomy (MEFD) are 2 popular contemporary techniques that have been performed extensively for these herniations since the 1970s. METHODS: In this study, we retrospectively analyzed 118 patients who underwent either PED (66 patients) or MEFD (52 patients). All the patients were clinically evaluated for neurologic examination findings, visual analog scale (VAS) scores for leg pain and Oswestry Disability Index (ODI) preoperatively and on the seventh postoperative day as well as 6 and 12 months after surgery. The complication rates and types of both techniques were discussed. RESULTS: The preoperative VAS score and ODI were all comparable. Improvements in VAS scores 6 months postoperatively and improvements in ODI at all follow-up periods were statistically significant in favor of PED. However, there was great discrepancy regarding the postsurgical complications in favor of MEFD. CONCLUSIONS: PED is more prone to complications because this technique is strictly dependent on the tubular system and the ideal anatomy of the Kambin triangle. Variations in or degeneration of the Kambin triangle can lead to devastating complications in the PED technique, but normal anatomic conditions are feasible in only approximately 20% of patients. The most important feature of this study was that both techniques were performed by the same experienced team, who developed their own concept.
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    A new concept of motion preservation surgery of the cervical spine: PEEK rods for the posterior cervical region
    (Ios Press, 2020) Erbulut, Deniz Ufuk; N/A; Aydın, Ahmet Levent; Sasani, Mehdi; Öktenoğlu, Bekir Tunç; Özer, Ali Fahir; Doctor; Faculty Member; Faculty Member; Faculty Member; N/A; School of Medicine; School of Medicine; School of Medicine; Koç University Hospital; N/A; 219451; 220898; 1022
    Background: Laminectomy may cause kyphotic postoperative deformity in the cervical region leading to segmental instability over time. Laminoplasty may be an alternative procedure to laminectomy, as it protects the spine against post-laminectomy kyphosis; however, similar to laminectomy, laminoplasty may cause sagittal plane deformities by destructing or weakening the dorsal tension band. Objective: Using finite element analysis (FE), we attempted to determine whether a posterior motion preservation system (PEEK posterior rod system concept) could overcome the postoperative complications of laminectomy and laminoplasty and eliminate the side effects of rigid posterior stabilization in the cervical region. Methods: We compared PEEK rods in four different diameters with a titanium rod for posterior cervical fixation. The present study may lead to motion preservation systems of the cervical vertebra. RESULTS: When PEEK rod is compared with titanium rod, considerable increase in range of motion is observed. Conclusions: PEEK rod-lateral mass screw instrumentation systems may be useful in motion preservation surgery of the posterior cervical region.
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    Lumbar foraminal stenosis classification that guides surgical treatment
    (Elsevier, 2022) Hekimoǧlu, Mehdi; Çevik, Orhun Mete; Çerezci, Önder; Özer, Ali Fahir; Sasani, Mehdi; Öktenoğlu, Bekir Tunç; Süzer, Süleyman Tuncer; Akyoldaş, Göktuğ; Aydın, Ahmet Levent; Faculty Member; Faculty Member; Faculty Member; Faculty Member; Faculty Member; Doctor; School of Medicine; School of Medicine; School of Medicine; School of Medicine; School of Medicine; Koç University Hospital; 1022; 219451; 220898; 221691; 203677; N/A
    Background: There are numerous radiological and anatomical studies on lumbar foramina in the literature, but there are no distinctive studies about the relationship between treatment and the type of foraminal stenosis. This study was conducted to better evaluate foraminal stenosis and to plan treatment accordingly. Methods: Foraminal stenosis was divided into 2 groups: Stable and unstable stenosis. Both groups were also divided into 4 subgroups in relation to the cause and type of compression and based on the structure of the intervertebral disc. The visual analog scale for leg pain (VAS-LP) and Oswestry Disability Index (ODI) scores were investigated before and after surgery. Results: A total of 115 patients (59 women and 56 men) underwent surgery for lumbar foraminal stenosis. The mean patient age was 56.1 years (range 17-80 years). The mean follow-up was 29 months (range 24-39 months). There were 36 patients (32%) with stable foraminal stenosis and 79 patients (68%) with unstable foraminal stenosis. The majority of the patients were identified as having unstable type 1 foraminal stenosis (45 of 115). The VAS-LP and ODI scores for each group decreased gradually during the follow-up periods and showed significant decrease during the last follow-up (P < 0.001). Interobserver and intraobserver agreement in the classification of foraminal stenosis was found to be nearly perfect. No patients experienced postoperative radiculopathy complication. Only 2 patients experienced superficial operation site infection and 1 showed deep wound infection. The patient who had a deep wound infection needed to repeat surgery for the infection. Conclusions: We introduced a novel classification system for lumbar foraminal stenosis. We aimed to guide appropriate treatment modality depending on the determined classification. This classification helps to determine the optimal treatment. In the light of our findings, the patients who were operated according to our classification experienced satisfactory clinical outcomes and low complication rates. Level of Evidence: 3.