Hakan Seçkin

Neuroprotective Effects of Mesenchymal Stem Cells Derived from Human Embryonic Stem Cells in Transient Focal Cerebral Ischemia in Rats

Embryonic mesenchymal stem cells (eMSCs) were first derived from human embryonic stem cells (hESCs) overexpressing green fluorescence protein (GFP). They expressed CD29, CD44, CD73, CD105, CD166 and nestin, but not CD34, CD45, CD106 SSEA-4 or Oct3/4. Twenty million eMSCs in 1mL of phosphate-buffered saline (PBS) were injected into the femoral veins of spontaneously hypertensive rats after transient middle cerebral artery occlusion. The migration and differentiation of the eMSCs in the ischemic brain were analyzed. The results revealed that eMSCs migrated to the infarction region and differentiated into neurons, which were positive for β-tubulin III, microtubule-associated protein 2 (MAP2), HuC, neurofilament and human nuclear antibody, and to vascular endothelial cells, which were positive for von Willebrand factor (vWF). The transplanted cells survived in the infarction region for at least 4 weeks. Adhesive removal function significantly improved in the first week after cell transplantation, and rotarod motor function significantly improved starting from the second week. The infarction volume in the eMSC group was significantly smaller than that in the PBS control group at 4 weeks after infusion. The results of this study show that when administered intravenously, eMSCs differentiated into neuronal and endothelial cells, reduced the infarction volume, and improved behavioral functional outcome significantly in transient focal cerebral ischemia.

Freehand C1 lateral mass screw fixation technique: our experience.

BACKGROUND Although C1 lateral mass fixation technique is frequently performed in upper cervical instabilities, it requires the guidance of fluoroscopic imaging. The fluoroscopy guidance is time-consuming and has the risks of accumulative radiation. Biplane fluoroscopy is also difficult in upper cervical pathologic conditions because of the use of cranial fixations. This study aimed to demonstrate that unicortical C1 lateral mass screws could be placed safely and rapidly without fluoroscopy guidance. METHODS Between 2002 and 2008, 32 C1 lateral mass screws were inserted in 17 consecutive patients with various pathologic conditions involving either atlantoaxial or occipitocervical instability. RESULTS C1 screw lengths ranged from 18 to 32 mm. The atlantoaxial fixation was performed in 13 patients, and C1 lateral mass screws were added to the occipitocervical construct in 3 patients, to the posterior cervical construct in 2 patients, and to the cervicothoracic construct in 1 patient. In 2 patients, because C1 lateral mass screws could not be inserted unilaterally, C1 pedicle screw analogs were inserted. There were no screw malpositions or neurovascular complications related to screw insertion. Operation time and intraoperative bleeding of the isolated atlantoaxial fixations were retrospectively evaluated. The mean follow-up was 32.3 months (range, 7-59 months). No screw loosening or construct failure was observed within this period. Postoperatively, 4 patients complained of hypoesthesia, whereas one patient had superficial wound infection. CONCLUSION C1 lateral mass screws may be used safely and rapidly in upper cervical instabilities without intraoperative fluoroscopy guidance and the use of the spinal navigation systems. Preoperative planning and determining the ideal screw insertion point, the ideal trajections, and the lengths of the screws are the most important points.

Lamotrigine attenuates cerebral vasospasm after experimental subarachnoid hemorrhage in rabbits.

BACKGROUND Increasing evidence implicates voltage-dependent sodium and potassium channels, in addition to calcium channels of various types, in the pathophysiological development of cerebral vasospasm. This study investigated the ability of LTG, an antiepileptic drug with multi-ion channel inhibition properties, to prevent cerebral vasospasm and subsequent neural ischemia in a rabbit model of SAH. METHODS Thirty-five New Zealand white rabbits were assigned to 1 of 3 groups: (1) control (no SAH, saline injection); (2) SAH alone; (3) SAH + LTG, 20 mg/kg daily. Animals were killed 72 hours after SAH, then basilar artery lumen areas and arterial wall thickness were measured in all groups. The histological sections of the CA1 and CA3 regions and dentate gyri of the hippocampi were evaluated semiquantitatively for neural tissue degeneration. RESULTS In the SAH group, the mean luminal cross-sectional area of the basilar artery was reduced by 62% after SAH as compared with the non-SAH controls (P < .0001). After SAH, the vasospastic response was attenuated by 36% in animals treated with 20 mg/kg of LTG compared with the SAH group (P < .005). The mean luminal cross-sectional areas of the basilar artery were 279000 +/- 27000 microm(2) in the control group, 173000 +/- 17600 microm(2) in the SAH group, and 236000 +/- 10000 microm(2) in the SAH + LTG group. The differences between the SAH group and the LTG-treated group were statistically significant (P < .0001). Histological examination was done in 12 control, 12 SAH, and 9 SAH + LTG-treated animals. The mean degeneration score for the control group and SAH + LTG group was statistically significant (P = .012). The difference between the SAH group and SAH+ LTG group was also statistically significant (P = .006). CONCLUSIONS These findings demonstrate that oral administration of LTG has marked neuroprotective effect and significantly attenuates cerebral vasospasm after SAH, thus providing additional support for the role of non-L-type calcium channels and voltage-dependent sodium channels in vasospasm.

Spinal subdural abscess: A rare cause of low back pain

Spinal subdural abscess (SSA) is a rare but well-described entity. It may occur secondary to a systemic infectious focus or following a surgical procedure. There are only two SSA cases in the literature that are unrelated to such conditions and without any well-documented etiology. SSA is a neurosurgical emergency and diagnosis may be difficult. Progressive neurological deficits and severe pain with fever suggest the diagnosis. Surgical drainage and subsequent prompt antimicrobial therapy should be performed without delay. We report a patient with SSA unrelated to any predisposing condition and discuss underlying mechanisms of this disease.

Metabolic changes during successful medical therapy for brain hydatid cyst: case report

BACKGROUND Medical therapy for hydatid disease of the brain has been reported with encouraging results especially in small or medium-sized cysts. To date, no other case correlating the metabolite levels of the cyst with albendazole treatment has been reported. CASE DESCRIPTION A 52-year-old woman presented with left hemiparesis and seizure. Cranial magnetic resonance revealed a right frontal cystic mass lesion. A diagnosis of hydatid cyst was made, and she was put on medical therapy with albendazole. An MRS before the medical therapy was begun revealed the typical findings of a hydatid cyst with resonance of alanine, acetate, and succinate that were specific for hydatid disease, and additional nonspecific lactate peaks with an additional small peak of choline. Comparison between the multiple MRS examinations was made by comparing the metabolite ratios specific for hydatid disease to choline, which seemed stable from the beginning. Two sequential MRS imaging revealed a prominent decrease of the succinate and acetate resonance, accompanied by a smaller decline of the alanine resonance progressively, correlated with the conventional MRI findings of the cyst, which had a smaller size with blurred margins in the meantime. After 5 months of medical treatment, the cyst had completely disappeared. The patient has been monitored for 5 years and remains well without recurrence. CONCLUSIONS This case provides additional proof that the brain hydatid cyst is a medically treatable disease in appropriate cases. Furthermore, the changes in the metabolic profile of the cyst, especially those regarding succinate and acetate may represent the efficacy of the medical treatment.

Sulcal and gyral anatomy of the orbitofrontal cortex in relation to the recurrent artery of Heubner: an anatomical study

The aim of this study is to investigate the sulcal and the gyral anatomy of the orbitofrontal cortex with its arterial supply. Ten gross formaline fixed adult brains (20 hemispheres) were used to show the gyral and sulcal anatomy of the inferior frontal lobe, and its arterial supply. The arteries were investigated with special attention to the relationship between the recurrent artery of Heubner (RAH) and the gyrus rectus (GR). Medial and lateral orbital sulci were connected in 4 right hemispheres, and in 7 of the left. The orbital sulci were connected with olfactory sulcus in one right hemispheres, but not in the left. In the right hemispheres, the RAH traveled across the GR in 7 hemispheres and looped over the posterior aspect of the GR in 3 hemispheres. In the left hemispheres, RAH crossed the GR in 8 and looped over the posterior aspect of the GR before entering the anterior perforating substance in 2 hemispheres. There are considerable variations among the gyri and sulci of the orbitofrontal cortex and it is difficult to describe a precise architectural pattern. The RAH demands special attention during GR resection in aneurysm surgery.

Microsurgical anatomy of the posterior spinal artery via a far-lateral transcondylar approach

OBJECT The posterior spinal artery (PSA) is a clinically significant vessel that may frequently be encountered during the far-lateral transcondylar approach. There have been a limited number of reports on the specific origin of the PSA in the literature. The aim of this study was to demonstrate the origin of the PSA. METHODS Thirteen cadaveric heads (26 sides) were injected with colored silicon. A bilateral far-lateral transcondylar approach was performed on each side. In every specimen the site of the origin of the PSAs, as well as their course, branching pattern and anastomoses, external diameters, and neighboring vascular and nervous structures were recorded. Microanatomical dissections were performed using the surgical microscope. In addition, 8 surgical cases in which the far-lateral approach was used were collected prospectively to record the course and origin of the PSA. Altogether, a total of 34 sides were analyzed for their PSA origin and course. RESULTS In the cadaveric specimens, the PSA was found to originate from the vertebral artery (VA) in 25 sides (96%). In 13 specimens (50%) the PSA originated from the V(4) segment of the VA intradurally. In 12 specimens (46%) the PSA originated from the V(3) segment of the VA extradurally. In 1 specimen (4%), in whom the posterior inferior cerebellar artery (PICA) had an early origin from the VA extradurally at the C-1 level, the PSA originated from the PICA. Of the 8 surgical cases, 2 patients had extradural origin of the PSA from the V(3) segment of the VA, whereas 6 patients had intradural origin of the PSA from the V(4) segment. CONCLUSIONS Although the usual origin of the PSA is from the VA either intra- or extradurally, its origin is closely related to the origin of the PICA. The PSA originates from the PICA in cases in which the PICA originates extradurally from the VA. In the far-lateral transcondylar approach, the dura is opened in close proximity to the VA. Knowledge of the origin and course of the PSA is critically important when executing the far-lateral approach to avoid its injury.

Topiramate attenuates hippocampal injury after experimental subarachnoid hemorrhage in rabbits

Abstract Objective: The aim of this study was to investigate the ability of topiramate (TPM) to prevent neural injury in a rabbit model of subarachnoid hemorrhage (SAH). The effect of TPM on cerebral vasospasm was also evaluated. Methods: Fifty-three New Zealand white rabbits were allocated into three groups randomly. SAH was induced by injecting autologous blood into the cisterna magna. The treatment groups were as follows: (1) sham operated (no SAH (n=18); (2) SAH only (n=17); (3) SAH + TPM (n=18). Hippocampal sections were evaluated for neural tissue degeneration, using the previously described neural degeneration scoring system. The ApopTag peroxidase in situ apoptosis detection kit (Serologicals Corp., former Intergen) was used to assess apoptosis in the hippocampal sections and the effect of TPM on the apoptotic response. Basilar artery lumen areas and arterial wall thickness were also measured in all groups. Results: There was a statistically significant difference between the mean degeneration scores of the control and SAH only groups (p<0.05). The level of neural degeneration in TPM treated group was significantly lower compared with SAH only group (p<0.05), but not significantly higher than the control group (p>0.05). There were no statistically significant differences between arterial cross-sectional area and arterial wall thickness measurements of the SAH group and SAH + TPM group. Conclusion: These findings demonstrate that TPM has marked neuroprotective effect in an experimental model of SAH in rabbits. This observation may have clinical implications suggesting that this antiepileptic drug could be used as a possible neuroprotective agent in patients without major adverse effects.

Level I to III craniofacial approaches based on Barrow classification for treatment of skull base meningiomas: surgical technique, microsurgical anatomy, and case illustrations

OBJECT Although craniofacial approaches to the midline skull base have been defined and surgical results have been published, clear descriptions of these complex approaches in a step-wise manner are lacking. The objective of this study is to demonstrate the surgical technique of craniofacial approaches based on Barrow classification (Levels I-III) and to study the microsurgical anatomy pertinent to these complex craniofacial approaches. METHODS Ten adult cadaveric heads perfused with colored silicone and 24 dry human skulls were used to study the microsurgical anatomy and to demonstrate craniofacial approaches in a step-wise manner. In addition to cadaveric studies, case illustrations of anterior skull base meningiomas were presented to demonstrate the clinical application of the first 3 (Levels I-III) approaches. RESULTS Cadaveric head dissection was performed in 10 heads using craniofacial approaches. Ethmoid and sphenoid sinuses, cribriform plate, orbit, planum sphenoidale, clivus, sellar, and parasellar regions were shown at Levels I, II, and III. In 24 human dry skulls (48 sides), a supraorbital notch (85.4%) was observed more frequently than the supraorbital foramen (14.6%). The mean distance between the supraorbital foramen notch to the midline was 21.9 mm on the right side and 21.8 mm on the left. By accepting the middle point of the nasofrontal suture as a landmark, the mean distances to the anterior ethmoidal foramen from the middle point of this suture were 32 mm on the right side and 34 mm on the left. The mean distance between the anterior and posterior ethmoidal foramina was 12.3 mm on both sides; the mean distance between the posterior ethmoidal foramen and distal opening of the optic canal was 7.1 mm on the right side and 7.3 mm on the left. CONCLUSIONS Barrow classification is a simple and stepwise system to better understand the surgical anatomy and refine the techniques in performing these complex craniofacial approaches. On the other hand, thorough anatomical knowledge of the midline skull base and variations of the neurovascular structures is crucial to perform successful craniofacial approaches.

Prognostic Factors in Oligodendrogliomas: a Clinical Study of Twenty-Five Consecutive Patients

BACKGROUND The purpose of this study was to evaluate the prognostic significance of Ki-67 and subjective microvascular density (SMVD) indexes together with other factors in patients with oligodendroglioma. MATERIALS AND METHODS In this retrospective study, oligodendroglioma specimens obtained from twenty-five consecutive patients were evaluated for Ki-67 and SMVD indices to help determine histological grading and investigate the fidelity of these markers in clinical prognosis. Other potentially prognostic factors were Karnofsky performance scale, tumor histological grade, and adjuvant radiotherapy. RESULTS The Ki-67 proliferation index appeared to have a strong correlation with the grade of the tumor and the survival. Age, gender, adjuvant radiotherapy, surgical resection type (complete versus incomplete) did not have any influence on recurrence. The SMVD index correlated significantly with the 3 to 5-year survival. CONCLUSIONS Ki-67 and MVD indexes are important and useful markers in estimating the prognosis of oligodendrogliomas.