Kenan Koc

Endoscopic endonasal transsphenoidal approach for pituitary adenomas invading the cavernous sinus.

OBJECT In this report, the authors describe their experience with surgical access to the cavernous sinus via a fully transnasal endoscopic approach in 20 cases. Clinical and endocrinological follow-up are discussed. METHODS The authors used an endoscopic transsphenoidal approach in 192 patients with pituitary adenomas between September 1997 and January 2008, adding a cavernous sinus approach in 20 patients with invasive tumors during the last 5 years of this period [corrected]. Parasellar extension of the tumor was measured according to the Knosp Scale. Radical tumor removal was achieved in 13 (65%) of 20 patients, and subtotal removal in 7 (35%). The authors used recently defined cavernous sinus approaches in the first 14 cases, including the paraseptal approach in 6, middle turbinectomy in 7, and contralateral middle turbinectomy in 1 case. Combined approaches rather than defined standard cavernous sinus approaches were used in 4 cases and an extended approach in 2. RESULTS The tumors included nonsecretory adenomas in 5 cases (25%), growth hormone-secreting adenomas in 7 (35%), prolactin-secreting adenomas in 4 (20%), and adrenocorticotropic hormone-secreting adenomas in 4 cases (20%). Normal growth hormone and insulin-like growth factor 1 levels were achieved in 4 patients (57%) with growth hormone adenomas, and remission criteria were obtained in 3 patients with prolactinomas and 3 patients with adrenocorticotropic hormone-secreting adenomas. CONCLUSIONS Compared with transcranial and microscopic transsphenoidal surgery, endoscopic transsphenoidal surgery offers a wide exposure for cavernous sinus medial wall adenomas that enables removal of the adenoma from the medial cavernous sinus wall. Because of the necessity for multidisciplinary treatment to achieve satisfactory results, Gamma Knife surgery and medical therapy should be supplementary treatment options after endoscopic transsphenoidal surgery.

Fluorescein sodium-guided surgery in glioblastoma multiforme: a prospective evaluation

We have evaluated the influence of fluorescein-guided resection on gross total resection (GTR) and survival in a series of patients with GBM. Group 1 consisted of 47 patients given fluorescein and group 2 comprised 33 patients, on whom fluorescein was not used. Median survival time was 43.9 weeks in the patients given fluorescein and was 41.8 weeks in the non-fluorescein group. There was no statistically significant difference in survival between the two groups. However, the extent of resection had a powerful influence on the median survival time. Survival was 34.3 weeks after partial resection and 46.5 after GTR. Our data shows that the use of fluorescein injection is a simple procedure, which allows a significant increase in the number of patients having GTR (83 vs. 55%). Our findings are similar to a recently published multicentre Phase III randomized trial in which 5-aminolevulinic acid was used to facilitate resection of malignant glioma.

The learning curve in endoscopic pituitary surgery and our experience

Experience is the important point in reduction of the complications and in the effectiveness of the surgical procedure in pituitary surgery. Endoscopic pituitary surgery differs from microscopic surgery, since it requires a steep learning curve for endoscopic skills. In this article, we evaluate our learning curve in two groups, as early and late experience. Purely endoscopic transsphenoidal operations were performed on 78 patients, which were retrospectively reviewed and grouped as early and late experience groups. We used the purely endoscopic endonasal approach to the sella that was performed via an anterior sphenoidotomy, without the use of a transsphenoidal retractor. All patients with adenomas were evaluated considering operation time, endocrinology, ophthalmology, total removal and, especially, modifications of standard technique. On the basis of the experience gained with the use of the endoscope in transphenoidal surgery over the years, modifications can be performed on the different phases of the endoscopic approach. Reviewing our cases in two groups of period due to our experience showed that the effectiveness of endoscopic surgery increases and operation time decreases. In our study, we identified a learning curve in endoscopic pituitary surgery.

Microsurgical and endoscopic anatomy of Liliequist's membrane and the prepontine membranes: cadaveric study and clinical implications.

BackgroundLiliequist’s membrane is mostly described as having a diencephalic leaf, mesencephalic leaf, and diencephalic-mesencephalic leaves in the literature. Also different descriptions of the prepontine membranes were reported. In this study, we visualized the regular structural forms of membranes without disturbing any attachments and defined infrachiasmatic and prepontine safety zones. We discussed the clinical significance of these structures.Materials and methodsThe study was carried out on 24 adult human cadavers at the Morgue Specialization Department of the Forensic Medicine Institution following the initial autopsy examination. Liliequists membrane and the prepontine membranes were explored after retraction of the frontal lobes. Dissections were performed under the operative microscope. A 0- and 30-degree, 2.7-mm angled rigid endoscope (Aesculap, Tuttlingen, Germany) was advanced through the prepontine cistern from the natural holes of membranes, or small holes were opened without damaging the surrounding structures.ResultsThe basal arachnoid membrane (BAM) continued as Liliequists membrane (LM) without any distinct separation in all specimens. The LM coursed over the posterior clinoids and split into two leaves as the diencephalic leaf (DL) and mesencephalic leaf (ML) in 18 specimens; the medial pontomesencephalic membrane (MPMM) coursed anterolaterally as a continuation of the ML and attached to the medial surfaces of the fifth and sixth nerves, joining with the lateral pontomesencephalic membrane (LPMM), which was also a posterolateral continuation of the ML in all specimens. The medial pontomedullar membrane (MPMdM) and lateral pontomedullar membrane (LPMdM) were observed in 21 specimens. The MPMdM membrane was a continuation of the MPMM, and the LPMdM was a continuation of the LPMM in all 21 specimens.ConclusionWe observed that the LM is a borderless continuation of the BAM. The MPMM and LPMM split from the ML without any interruptions. The MPMdM and LPMdM were a single membrane continuing from the MPMM and LPMM. We determined infrachiasmatic and prepontine areas that can be important for inferior surgical approaches.

Microsurgical anatomy of membranous layers of the pituitary gland and the expression of extracellular matrix collagenous proteins

BackgroundThere are several reports about the microanatomical and histological features of sellar and parasellar membranous structures and clinical studies about MMP proteinase as a predictive factor. However, studies on collagen contents of sellar and parasellar membranous structures are limited. We demonstrated the membranous structures surrounding the pituitary gland and defined extracellular matrix (ECM) collagenous proteins, collagen I-IV expression patterns of sellar and parasellar connective tissues.MethodsThe study was carried out on ten fresh postmortem human bodies at the Forensic Medicine Institution. Cavernous sinuses were resected with sellar structures and were stored at −80°C liquid nitrogen tanks. Medial wall of the cavernous sinus, pituitary capsule and pituitary tissue samples were obtained for RT-PCR. Opposite side specimens were used for histological and immune staining studies. Collagens I-IV were studied by immunohistochemical and reverse transcription polymerase chain reaction (RT-PCR) methods.FindingsThe pituitary capsule and medial wall were identified as two different structures. The fibrous membrane, as the third membrane, was identified as staying whole in eight of ten specimens. Increased type IV collagen was determined in the pituitary gland, medial wall and pituitary capsule, respectively, in both RT-PCR and immunhistochemical studies. Immunhistochemical studies revealed that collagen I was strongly expressed in both the medial wall and pituitary gland.ConclusionIncreased type IV collagen was detected especially in pituitary tissue, the medial wall and the pituitary capsule by immune staining and RT-PCR. Type IV collagen was considered to be an important factor in the progression of adenoma and invasion.

Massive intracerebral haemorrage due to developmental venous anomaly

In cases of intracerebral haematoma associated with developmental venous anomalies (DVAs), there is usually an associated cavernoma, which is thought to be the source of haemorrhage. Only a few cases have been reported in the literature where an intracerebral haemotoma has been caused by a DVA without an associated cavernoma. In this report we describe a case with a massive haematoma due to venous angioma alone.

A new endoscopic surgical classification and invasion criteria for pituitary adenomas involving the cavernous sinus.

AIM There are two major problems for the pituitary adenomas invading the Cavernous Sinus (CS); differentiation of extension and invasion and inability to demonstrate the medial wall via preoperative imaging methods. Two important corridors are defined in endoscopic cavernous sinus approaches; the lateral and medial corridor. MATERIAL AND METHODS A retrospective analysis was performed in 400 endoscopic transphenoidal approaches and 360 pituitary adenomas underwent endoscopic transphenoidal surgery in our department between September 1997 and December 2010. 48 patients affected by the tumours involving the cavernous sinus were included in this study. RESULTS We performed an intraoperative evaluation of cavernous sinus invasion considering visualization of the medial wall defect, intracavernous ICA segments, minor tumour extensions through small focal pit holes of the medial wall of CS or confirming carotid segments of CS by micro-doppler. Cavernous sinus involvement was classified into three types according to the medial and lateral corridor extension of the tumor as 25 isolated medial corridor involvement (Type I), 5 isolated lateral corridor involvement (Type II) and 18 total involvement (Type III). CONCLUSION Our classification depends on fully surgical endoscopic approach supported by neuroimaging techniques and anatomical studies and shows a good predictive value for all cavernous sinus involvement.

Immunohistochemical analysis of TIMP-2 and collagen types I and IV in experimental spinal cord ischemia-reperfusion injury in rats

Abstract Background Thoracic and thoracoabdominal aortic intervention carries a significant risk of spinal cord ischemia. The pathophysiologic mechanisms that cause hypoxic/ischemic injury to the spinal cord have not been totally explained. In normal spinal cord, neurons and glial cells do not express type IV collagen. Type IV collagen produced by reactive astrocytes is reported to participate in glial scar formation. Tissue inhibitors of metalloproteinases (TIMPs) are endogenous inhibitors that regulate the activity of the matrix metalloproteinases (MMPs). TIMP-2 binds strongly with MMP-2, facilitating activation by membrane-type MMP. Imbalance between TIMPs and MMPs can lead to excessive degradation of matrix components. Type IV collagen involved in the blood–brain barrier disruption and glial scar formation, TIMP-2 influences MMP-2 that controls degradation of collagen I and IV. Objective To examine the immunohistochemical analysis of TIMP-2 and collagen types I–IV in experimental spinal cord ischemia–reperfusion in rats. Methods Thirty-two male Wistar rats weighing 250–300 g were divided into four groups: group S: sham group (n = 8); group 0P: 30-minute occlusion without perfusion (n = 8); group 3P: 30-minute occlusion and 3-hour perfusion (n = 8); and group 24P: 30-minute occlusion and 24-hour perfusion (n = 8). Infrarenal aorta was cross-clamped at two sites by using two aneurysm clips for 30 minutes. Reperfusion was provided after removal of the clips. Lumbar spinal cord segments were removed for immunohistochemical analysis. Results TIMP-2 and collagen staining in 3-hour perfused (3P) group were nearly the same with sham group (S). TIMP-2 and collagen staining increased in the 24-hour perfused group. Conclusion Alterations in collagen levels may relate to the biphasic breakdown of the blood–brain barrier and collagen staining in new cell types with relation to glial scar formation. Our results demonstrate that 3-hour perfusion after occlusion in hypoxic/ischemic spinal cord injury seems to be the critical reversible period.

Biochemical effects of experimental epidural hematoma on brain parenchyma of rats

Abstract Introduction: The management of epidural hematoma is classified into surgical or conservative treatment according to clinical and radiologic parameters. In the recent years, the number of paper suggesting conservative management has been increasing. The experimental works that have been performed are based on especially the effects of epidural hematomas. Basic pathophysiologic factors on ischemia result of brain trauma are based on biochemical mediators. Nitric oxide (NO) and malondialdehyde (MDA) are the substances that play important roles in brain damage after trauma. Material and method: In this study, 36 rats are divided into three groups (n=12/group). Epidural hematoma was achieved by 0.1 ml autolog blood in rat epidural space with balloon model. Early and late phase biochemical effects on parenchyma of epidural hematoma operated in a volume which neither alters intracranial pressure (ICP) nor creates shift effect were observed. Biochemical changes of NO and MDA levels were examined in each of three experimental groups. Results: NO values increased significantly in the early group (6 hours) compared with those in the control group. Difference of NO values between the control and late groups was not significant. An increase has been found in MDA values in the control group compared with those in the early group. MDA values of the late group (30 days) were closer to that of the control group. Conclusion: In this study, considering biochemical results, we have found that conservative volumes which neither increase ICP nor cause brain shift do not lead to permanent changes on brain.

Tectocerebellar Dysraphism With Vermian Encephalocele

Tectocerebellar dysraphism is a very rare malformation associated with encephalocele and tectal deformity. This article presents tectocerebellar dysraphism with a solely vermian content of encephalocele and tectal beaking defined by magnetic resonance imaging (MRI) in a 5-month-old girl who was successfully treated surgically and demonstrated excellent prognosis at the 4-year follow-up.