Baris Kucukyuruk

Glioma risk associates with polymorphisms of DNA repair genes, XRCC1 and PARP1

Cancer develops through interactions between polygenic and environmental factors, and changes in DNA repair pathway can increase susceptibility to tumours. XRCC1 and PARP1 are two proteins that act cooperatively in base excision repair (BER) of DNA. The polymorphisms of genes coding these proteins may effect their action in BER pathway. In this study, we aimed to investigate the associations between glioma risk and XRCC1 Arg399Gln and PARP1 Val762Ala polymorphisms per se and in combination. XRCC1 Arg399Gln and PARP1 Val726Ala polymorphisms were investigated by PCR–RFLP method in 119 glioma patients and 180 cancer-free control subjects. The results were statistically analysed by calculating the odds ratios (OR) and their 95% confidence intervals (95% CI) using the χ2-tests. Glioma patients in this study had significantly higher frequencies of XRCC1 Arg399Gln polymorphism both in homozygote (GG) and heterozygote (AG) status (31% and 56%, respectively) (p < 0.001), and also increased frequency of 399Gln (G) allele (59%) (p < 0.001). Val/Ala (VA) genotype of PARP1 Val762Ala polymorphism was significantly more in the control group (p = 0.02). The combined genotypes of XRCC1 AG or GG with PARP1 VA or AA, and XRCC1 AG or GG with PARP1 VV were more represented in the glioma patients (p = 0.001 and 0.003, respectively). We conclude that XRCC1 Arg399Gln polymorphism is a significant risk factor, and 399Gln (G) allele carries a 3.5 times greater risk for glioma, while PARP1 Val/Ala genotype may be protective against it. We also suspect that in the presence of a polymorphic (G) allele of XRCC1, the plausible protective effect of PARP1 VA genotype may be greatly suppressed.

Microsurgical anatomy of the temporal lobe and its implications on temporal lobe epilepsy surgery.

Objective. We review the neuroanatomical aspects of the temporal lobe related to the temporal lobe epilepsy. The neuronal, the ventricular, and the vascular structures are demonstrated. Methods. The previous articles published from the laboratory of the senior author are reviewed. Results. The temporal lobe has four surfaces. The medial surface has a complicated microanatomy showing close relation to the intraventricular structures, such as the amygdala or the hippocampus. There are many white matter bundles in the temporal lobe showing relation to the extra- and intraventricular structures. The surgical approaches commonly performed to treat temporal lobe epilepsy are discussed under the light of these data. Conclusion. A thorough knowledge of the microanatomy is necessary in cortical, subcortical, and intraventricular structures of the temporal lobe to achieve better results.

Microsurgical anatomy of the white matter tracts in hemispherotomy.

BACKGROUND: Hemispherotomy is a surgical procedure performed for refractory epileptic seizures due to wide hemispheric damage. OBJECTIVE: To describe the microanatomy of the white matter tracts transected in a hemispherotomy and the relationship of the surgical landmarks used during the intraventricular callosotomy. METHODS: The cortical and subcortical structures were examined in 32 hemispheres. RESULTS: Incision of the temporal stem along the inferior limiting sulcus crosses the insulo-opercular fibers, uncinate, inferior occipitofrontal and middle longitudinal fasciculi, anterior commissure, and optic and auditory radiations. The incision along the superior limiting sulcus transects insulo-opercular fibers and the genu and posterior limb of internal capsule. The incision along the anterior limiting sulcus crosses the insulo-opercular fibers, anterior limb of the internal capsule, anterior commissure, and the anterior thalamic bundle. The disconnection of the posterior part of the corpus callosum may be incomplete if the point at which the last cortical branch of the anterior cerebral artery (ACA) turns upward and disappears from the view through the intraventricular exposure is used as the landmark for estimating the posterior extent of the callosotomy. This ACA branch turns upward before reaching the posterior edge of the splenium in 85% of hemispheres. The falx, followed to the posterior edge of the splenium, is a more reliable landmark for completing the posterior part of an intraventricular callosotomy. CONCLUSION: The fiber tracts disconnected in hemispherotomy were reviewed. The falx is a more reliable guide than the ACA in completing the posterior part of the intraventricular callosotomy. ABBREVIATION: ACA, anterior cerebral artery

The recesses of the sellar wall of the sphenoid sinus and their intracranial relationships.

BACKGROUND: The sellar wall of the sphenoid sinus and its recesses have been previously studied, but their intracranial relationships to the diaphragma sellae, tuberculum, clinoid segment of the internal carotid artery, chiasmatic sulcus, and middle clinoid process need further definition. OBJECTIVE: To describe these intra- and extracranial relationships of the recesses in the anterior sellar wall. METHODS: The middle clinoid was studied in 132 parasellar areas of dry crania. Thirty-eight parasellar areas of formalin-fixed/silicone-colored specimens were dissected. After transsphenoidal endoscopic exposure, the optic, carotid, and sellar prominences; lateral opticocarotid and tuberculum recesses; and caroticosellar and medial opticocarotid points were identified. High-speed drills opened 1-mm perforations at these points to allow study of intracranial relationships. RESULTS: Two recesses and 2 junction points can be recognized in the sphenoid sinus: lateral opticocarotid and tuberculum recesses and medial opticocarotid and caroticosellar points. The lateral opticocarotid recess corresponds to the optic strut base, and the clinoid segment of the internal carotid artery is located medially. The diaphragma sellae attachment is at the level of the tuberculum recess, which in 50% of cases corresponds to the tuberculum. A middle clinoid in base or height greater than 1.5 mm is present in 21.1% and a caroticoclinoid ring in 3%. The middle clinoid is 1 mm inferior and lateral to the caroticosellar point and 4.7 mm inferior to the medial opticocarotid point. CONCLUSION: An understanding of the intra- and extracranial relationships of the recesses of the sphenoid sinus will aid in accurately directing transsphenoidal approaches.

Microsurgical anatomy of the cisternal anterior choroidal artery with special emphasis on the preoptic and postoptic subdivisions

OBJECT The object of this study was to delineate the microsurgical anatomy of the cisternal segment of the anterior choroidal artery (AChA). The authors also propose a new classification of this segment on the basis of its complicated course within the carotid and crural cisterns in relation to important neurovascular structures, and the site of origin, course, and areas of supply of perforating arteries. METHODS Thirty cadaveric cerebral hemispheres injected with colored latex were dissected under surgical magnification to view the cisternal segment of the AChA and its perforators. Fiber dissections using the Klingler technique were performed in two additional latex injected hemispheres to follow the penetration points, courses, and terminal areas of supply of perforating branches that arise from the cisternal segment of the AChA. RESULTS The cisternal segment of the AChA was divided into pre- and postoptic parts that meet at the arterys genu, the most medial extension point of the cisternal segment where the artery makes an abrupt turn after passing under the optic tract. The preoptic part of the AChA extended from its origin at the inferomedial side of the internal carotid artery to the arterys genu, which is commonly located just inferomedial to the initial part of the optic tract. The postoptic part coursed within the crural cistern and extended from the genu to the inferior choroidal point. The genu of the AChA was 8 mm medial to the arterys origin and was located medial to the optic tract in 13% of the hemispheres. The postoptic part was longer than the preoptic part in all hemispheres and had more perforating arteries supplying critical deep structures (preoptic 3.4 per hemisphere vs postoptic 4.6 per hemisphere), and these results were statistically significant (p = 0.01). At the preoptic part, perforating arteries arose from the superolateral portion of the artery and coursed laterally; at the postoptic part, perforators arose from the inferomedial portion of the artery and coursed medially. Perforating arteries from both segments passed most commonly to the optic tract, followed by the anterior segment and apex of uncus in the preoptic part and the cerebral peduncle in the postoptic part. CONCLUSIONS Both parts of the cisternal segment of the AChA come into surgical view during surgeries for different pathologies in and around the perimesencephalic cisterns. However, attending to the arterys genu and defining pre- and postoptic parts during surgery may help the surgeon locate the origin and eventual course of these perforators, and even estimate the terminal areas of supply of most of the perforating arteries. The proposed classification system can prove helpful in planning any operative procedure along the crural cistern and may reduce the probability of inadvertent injury to perforating branches of the cisternal segment.

Endoscopic approach to a collision tumor of growth hormone-secreting adenoma and gangliocytoma in the pituitary gland.

The authors share their experience on a collision tumor of growth hormone (GH)-secreting adenoma and gangliocytoma in the pituitary gland, which was reported by few articles in the literature. Also, an intraoperative view of this tumor, operated via endoscopic endonasal transsphenoidal approach, is presented for the first time. A 39-year-old female patient was admitted with clinical manifestation of acromegaly present in a 2-year period. Laboratory investigations revealed high levels of GH and insulinlike growth factor 1. Sellar computed tomography scan and magnetic resonance imaging showed a sellar mass diagnosed as a pituitary adenoma. Based on clinical, biochemical, and radiologic evaluations, GH-secreting pituitary adenoma was diagnosed and operated by endoscopic endonasal transsphenoidal approach achieving total removal of the tumor. Histopathologic examination revealed a collision tumor of GH-secreting adenoma and gangliocytoma. Postoperative radiologic and biochemical investigations showed no residual tumor and total remission. The endoscopic endonasal transsphenoidal approach promotes a close intraoperative view of sellar pathologies. We believe that a detailed histopathologic workup is necessary to diagnose collision tumors, because even a close intraoperative view does not facilitate to differentiate these tumors from a regular pituitary adenoma.

The selective odontoidectomy: endoscopic endonasal approach to the craniocervical junction.

Objective The resection of the odontoid process via an extended endoscopic endonasal approach has been recently proposed as an alternative to the microscopic transoral method. We aimed to delineate a minimally invasive endoscopic transnasal odontoidectomy and to describe the endoscopic anatomy of the anterior craniovertebral junction (CVJ). Materials and Methods The anterior CVJ of 14 fresh adult cadavers were selectively accessed via a binostril endoscopic endonasal approach using 0- and 30-degree endoscopes. Results The nasopharynx was widely exposed without removing any of the turbinates and without performing a sphenoidotomy. Occipital condyles and lateral masses of the C1 vertebra have been exposed inferiorly at lateral margins of the exposure, in addition to the foramen lacerum, which came into view at the superolateral corner of the operative field. The anterior arch of C1 and the upper 1.5 cm of the odontoid process of C2 have been removed via a minimally invasive endoscopic transnasal approach in all dissections. Conclusions We propose the selective odontoidectomy as a minimally invasive method for the endoscopic endonasal removal of the odontoid process. By using this approach, turbinates and the sphenoid sinus remain unharmed. In addition, this approach may be used in exposing pathologies situated laterally at the anterior CVJ, such as the lateral masses of atlas and occipital condyles.

Pituitary stone: a case report and review of the literature.

A 39-year-old male without any significant complaints or symptoms presented with a calcified lesion located at the sellar region. Total removal of the lesion has been achieved via an endoscopic endonasal transsphenoidal approach. Histopathological examination of the lesion revealed a pituitary stone. This report describes the first pituitary stone formed within a plurihormonal pituitary adenoma and also differs from previous studies in means of chosen surgical method that is the first endoscopic approach to a pituitary stone. Additionally, by reviewing previous cases, a classification has been proposed and possible pathophysiological mechanisms behind this rare entity have been discussed.

Endoscopic endonasal cerebrospinal fluid leak repair on the ventral midline skull base: a single neurosurgical center experience

AIM To present the results of endoscopic endonasal repair of ventral midline skull base cerebrospinal fluid (CSF) leak (VMSBL) at our institution and to discuss the technique and results from a neurosurgical perspective. MATERIAL AND METHODS A retrospective analysis of all VMSBL cases that underwent endoscopic endonasal skull base approach (EESBA) for CSF leak repair at a single tertiary neurosurgical center was performed. Twenty six patients with an average age of 44.4 (range: 17-63) years were included in the study. RESULTS The etiology of VMSBL was spontaneous in 16 patients, traumatic in 7, and iatrogenic in 3. The leakage site was the cribriform plate in 13 patients, ethmoidal cells in 7, and sphenoid sinus in 3. There were multiple leaks in 3 patients. This approach for VMSBL repair was performed 28 times on 26 patients. The success rate was 88.5% (23/26 patients) after primary endoscopic repair and 96% after the second attempt. The location of the leakage site relative to the upper attachment of the middle turbinate played a crucial role in the anteriorly located VMSBL, which made an impact on the surgical repair plan. All the 16 cases with accompanying meningoencephaloceles were treated successfully by EESBA. Use of vascularized pedicled flaps to support the repair site resulted in 100% success after primary repair. CONCLUSION EESBA is safe and highly effective and can be a first-line surgical treatment option for VMSBL. In addition, it enables adequate reconstruction of ventral midline skull base meningoencephaloceles regardless of size and location.

Endoscopic Endonasal Transethmoidal Approach for the Management of a Traumatic Brain Abscess and Reconstruction of the Accompanying Anterior Skull Base Defect.

Abstract Skull base endoscopy in the treatment of brain abscesses has been rarely published. Moreover, endoscopic endonasal transethmoidal approach (EETA) for the treatment of brain abscess following a head trauma has been reported only in a few case reports. We report the management of a patient of intracerebral abscess and reconstruction of the accompanying anterior skull base defect through an EETA. Thirty-year-old male with a frontal lobe abscess due to a penetrating skull base trauma was operated via EETA. After drainage of the abscess, dural and bony defects were repaired to prevent any recurrence. Postoperative radiological imaging revealed prominent decrease in abscess size. The patient did not need any further surgical intervention, and antibiotherapy was adequate. EETA is safe and effective in the management of brain abscesses. Skull base endoscopy provides direct visualization of the abscess cavity through a minimal invasive route, facilitates wide exposure of surrounding neurovascular structures within the operative field, and enables concurrent closure of the skull base defect.