Preoperative grading of supratentorial gliomas using high or standard b-value diffusion-weighted MR imaging at 3T.

PURPOSE: The goal of this study was to compare diffusion-weighted magnetic resonance imaging (DW-MRI) using high b-value (b=3000s/mm2) to DW-MRI using standard b-value (b=1000s/mm2) in the preoperative grading of supratentorial gliomas. MATERIALS AND METHODS: Fifty-three patients with glioma had brain DW-MRI at 3T using two different b-values (b=1000s/mm2 and b=3000s/mm2). There were 35 men and 18 women with a mean age of 40.5±17.1 years (range: 18-79 years). Mean, minimum, maximum, and range of apparent diffusion coefficient (ADC) values for solid tumor ROIs (ADCmean, ADCmin, ADCmax, and ADCdiff), and the normalized ADC (ADCratio) were calculated. A Kruskal-Wallis statistic with Bonferroni correction for multiple comparisons was applied to detect significant ADC parameter differences between tumor grades by including or excluding 19 patients with an oligodendroglioma. Receiver operating characteristic curve analysis was conducted to define appropriate cutoff values for grading gliomas. RESULTS: No differences in ADC derived parameters were found between grade II and grade III gliomas. Mean ADC values using standard b-value were 1.17±0.27×10-3mm2/s [range: 0.63-1.61], 1.05±0.22×10-3mm2/s [range: 0.73-1.33], and 0.86±0.23×10-3mm2/s [range: 0.52-1.46] for grades II, III and IV gliomas, respectively. Using high b-value, mean ADC values were 0.89±0.24×10-3mm2/s [range: 0.42-1.25], 0.82±0.20×10-3mm2/s [range: 0.56-1.10], and 0.59±0.17×10-3mm2/s [range: 0.40-1.01] for grades II, III and IV gliomas, respectively. ADCmean, ADCratio, ADCmax, and ADCmin were different between grade II and grade IV gliomas at both standard and high b-values. Differences in ADCmean, ADCmax, and ADCdiff were found between grade III and grade IV only using high b-value. CONCLUSION: ADC parameters derived from DW-MRI using a high b-value allows a better differential diagnosis of gliomas, especially for differentiating grades III and IV, than those derived from DW-MRI using a standard b-value.

Anterior transcallosal approach to the colloid cysts of the third ventricle: case series and review of the literature.

OBJECTIVES: To evaluate the results of the anterior transcallosal approach to the colloid cysts of the third ventricle. PATIENTS AND METHODS: A retrospective analysis of the patients operated on between 1986 and 2003 was carried out. There were 19 patients (10 female, 9 male) with a median age of 43. The main presenting symptom was headache. One of the patients presented with acromegaly due to a pituitary tumor. The size of the cysts ranged from 15 to 43 mm. An anterior transcallosal approach was used in all patients. RESULTS: The cysts were excised totally in all cases. Postoperatively no recent memory loss has been detected in any patient. One patient with hemorrhagic papil stasis experienced temporary visual worsening. In one patient with hydrocephalus a ventriculoperitoneal shunt was needed. One patient with postoperative superior frontal gyrus venous infarction had a seizure. The follow-up period was from 1 month to 13 years (mean 5.2 years). To date, there has been no recurrence so far. CONCLUSION: The anterior transcallosal approach is a safe method for the treatment of third ventricular colloid cysts.

Multimodality management of 26 skull-base chordomas with 4-year mean follow-up: experience at a single institution.

OBJECTIVE: To analyze a series of patients with pathologically confirmed skull-base chordoma, and to develop an algorithm for the management of this challenging disease based on the data, our experience, and the current literature. MATERIAL AND METHODS: Between the years 1986 and 2001, 26 chordoma patients received multimodality treatment with various combinations of conventional surgery, skull-base surgical techniques, and gamma-knife surgery at the Marmara University Faculty of Medicine. A total of 57 procedures (43 tumor excision surgeries, 7 gamma-knife procedures, and 7 other operations to treat complications) were performed. The mean follow-up period was 4 years (48.5 months). Karnofsky scoring was used to follow the patients' clinical conditions, and magnetic resonance image analysis was used to measure tumor volume over time. RESULTS: Seven patients died during follow-up. Two of the deaths were due to surgical complications, four resulted from clinical deterioration related to tumor recurrence, and one was unrelated to neoplasia. The rate of tumor recurrence after the first surgical treatment was 58%. Residual tumor volume was lower in the cases in whom skull-base approaches were used as first-line management. The 19 survivors showed little change in clinical status from initial diagnosis to the most recent follow-up check. The mean follow-up time after gamma-knife treatment was 23.3 months. During this period, mean tumor volume increased 28% above the mean volume at the time of gamma-knife surgery. The mean Karnofsky score decreased by 6% during the same time frame. CONCLUSIONS: The most effective first-line treatment for chordoma patients is surgery. The findings for residual tumor volume indicated that skull-base approaches are the best surgical option, and the complication rates for these techniques are acceptable. However, it is rare that surgery ever biologically eradicates this disease, and the data showed that these chordomas almost always progress if the tumor volume at the time of diagnosis exceeds 20 cm(3). Based on our experience and the biological character of the disease, we now advocate radiosurgical treatment (gamma-knife in our case) immediately after the first-line skull-base surgery when the tumor residual volume is <30 cm(3).

MR imaging, CT, and angiography features of endolymphatic sac tumors: report of two cases.

Low-grade adenocarcinoma of endolymphatic sac origin is a rare tumor of the temporal bone. There are some difficulties in its differential diagnosis from other vascular and non-vascular tumors of the temporal bone. However its radiological differentiation from other tumors of the temporal bone is important for surgical planning. We present a report on two endolymphatic sac tumors with some specific radiological findings which can support a correct diagnosis.

Phenytoin toxicity with mandibular tremor secondary to intravenous administration.

The parenteral form of phenytoin is the most commonly used antiepileptic agent during the perioperative period in neurosurgery clinics. We report observations in a 52-year-old male patient with hypoalbuminemia and phenytoin intoxicity following 1 day preoperative administration and a 7-day postoperative intravenous administration of the drug with no modification of the oral dose. This report emphasizes the need for careful surveillance of phenytoin-induced toxicity during parenteral therapy, especially in debilitated patients.

Giant pericallosal artery aneurysm: case report and review of the literature.

Pericallosal artery aneurysms comprise 5% of all intracranial saccular aneurysms and are usually small. Giant cerebral aneurysms mostly occur in major arteries. To date, 12 cases of giant pericallosal artery aneurysm have been reported in the literature. An unusual giant thrombosed pericallosal artery aneurysm is reported here. A 65-year-old female presented with headache and personality changes. Computed tomography, magnetic resonance imaging, and cerebral angiography revealed a right-sided giant thrombosed pericallosal artery aneurysm. The patient was operated via an anterior interhemispheric approach and the neck of the aneurysm was successfully clipped. The postoperative period was uneventful. This rare lesion is one of few cases presented in the literature in which neuroradiologic and neuropathologic evaluation was completely performed and the neck of the aneurysm was clipped.

Solid-calcified colloid cyst of the third ventricle.

We report a 65-year-old female with a solid-calcified colloid cyst in the third ventricle that was demonstrated on computed tomography scan and magnetic resonance images. The lesion was surgically excised using the anterior transcallosal-transforaminal approach. Complete preservation of the surrounding neural and vascular structures was achieved.

Cervical spinal cord intramedullary abscess. Case report.

A case of progressive symptoms and signs of cervical spinal cord damage due to intramedullary abscess is reported. The literature is reviewed and the radiological features, particularly magnetic resonance image, are analyzed.

Fiber dissection technique: lateral aspect of the brain.

OBJECTIVE: The fiber dissection technique involves peeling away the white matter tracts of the brain to display its three-dimensional anatomic organization. Early anatomists demonstrated many tracts and fasciculi of the brain using this technique. The complexities of the preparation of the brain and the execution of fiber dissection have led to the neglect of this method, particularly since the development of the microtome and histological techniques. Nevertheless, the fiber dissection technique is a very relevant and reliable method for neurosurgeons to study the details of brain anatomic features. METHODS: Twenty previously frozen, formalin-fixed human brains were dissected from the lateral surface to the medial surface, using the operating microscope. Each stage of the process is described. The primary dissection tools were handmade, thin, wooden spatulas with tips of various sizes. RESULTS: We exposed and studied the myelinated fiber bundles of the brain and acquired a comprehensive understanding of their configurations and locations. CONCLUSION: The complex structures of the brain can be more clearly defined and understood when the fiber dissection technique is used. This knowledge can be incorporated into the preoperative planning process and applied to surgical strategies. Fiber dissection is time-consuming and complex, but it greatly adds to our knowledge of brain anatomic features and thus helps improve the quality of microneurosurgery. Because other anatomic techniques fail to provide a true understanding of the complex internal structures of the brain, the reestablishment of fiber dissection of white matter as a standard study method is recommended.

Arteries of the insula.

OBJECT: The insula is located at the base of the sylvian fissure and is a potential site for pathological processes such as tumors and vascular malformations. Knowledge of insular anatomy and vascularization is essential to perform accurate microsurgical procedures in this region. METHODS: Arterial vascularization of the insula was studied in 20 human cadaver brains (40 hemispheres). The cerebral arteries were perfused with red latex to enhance their visibility, and they were dissected with the aid of an operating microscope. Arteries supplying the insula numbered an average of 96 (range 77-112). Their mean diameter measured 0.23 mm (range 0.1-0.8 mm), and the origin of each artery could be traced to the middle cerebral artery (MCA), predominantly the M2 segment. In 22 hemispheres (55%), one to six insular arteries arose from the M1 segment of the MCA and supplied the region of the limen insulae. In an additional 10 hemispheres (25%), one or two insular arteries arose from the M3 segment of the MCA and supplied the region of either the superior or inferior periinsular sulcus. The insular arteries primarily supply the insular cortex, extreme capsule, and, occasionally, the claustrum and external capsule, but not the putamen, globus pallidus, or internal capsule, which are vascularized by the lateral lenticulostriate arteries (LLAs). However, an average of 9.9 (range four-14) insular arteries in each hemisphere, mostly in the posterior insular region, were similar to perforating arteries and some of these supplied the corona radiata. Larger, more prominent insular arteries (insuloopercular arteries) were also observed (an average of 3.5 per hemisphere, range one-seven). These coursed across the surface of the insula and then looped laterally, extending branches to the medial surfaces of the opercula. CONCLUSIONS: Complete comprehension of the intricate vascularization patterns associated with the insula, as well as proficiency in insular anatomy, are prerequisites to accomplishing appropriate surgical planning and, ultimately, to completing successful exploration and removal of pathological lesions in this region.

Treatment of the subarachnoid-pleural fistula. Case report.

Subarachnoid-pleural fistula is a rare type of cerebrospinal fluid (CSF) fistula, and there are only several cases reported in the literature. The authors describe a 65-year-old male patient in whom a diagnosis of T7-8 disc herniation had been made. He underwent surgery via a right lateral extracavitary approach. Postoperatively he developed progressive respiratory distress and headache. A chest x-ray film revealed a pleural effusion, and computerized tomography (CT) myelography demonstrated a subarachnoidal-pleural fistula at the level at which the herniated disc had been removed. The patient had been managed via a CSF drainage system and a chest tube. He was discharged after relief of symptoms was attained. Subarachnoid-pleural fistulas can be secondary to traumatic injury and surgery, or they can be spontaneous. Patients present with rapidly filling pleural effusion and headache. A diagnosis can be established using CT myelography or myeloscintigraphy. Treatment is conservative, with the placement of a chest tube and insertion of a CSF drainage catheter, and surgical repair should be considered only if the conservative therapy fails.

Topographic anatomy of the insular region.

OBJECT: The insula is one of the paralimbic structures and constitutes the invaginated portion of the cerebral cortex, forming the base of the sylvian fissure. The authors provide a detailed anatomical study of the insular region to assist in the process of conceptualizing a reliable surgical approach to allow for a successful course of surgery. METHODS: The topographic anatomy of the insular region was studied in 25 formalin-fixed brain specimens (50 hemispheres). The periinsular sulci (anterior, superior, and inferior) define the limits of the frontoorbital, frontoparietal, and temporal opercula, respectively. The opercula cover and enclose the insula. The limen insula is located in the depths of the sylvian fissure and constitutes the anterobasal portion of the insula. A central insular sulcus divides the insula into two portions, the anterior insula (larger) and the posterior insula (smaller). The anterior insula is composed of three principal short insular gyri (anterior, middle, and posterior) as well as the accessory and transverse insular gyri. All five gyri converge at the insular apex, which represents the most superficial aspect of the insula. The posterior insula is composed of the anterior and posterior long insular gyri and the postcentral insular sulcus, which separates them. The anterior insula was found to be connected exclusively to the frontal lobe, whereas the posterior insula was connected to both the parietal and temporal lobes. Opercular gyri and sulci were observed to interdigitate within the opercula and to interdigitate the gyri and sulci of the insula. Using the fiber dissection technique, various unique anatomical features and relationships of the insula were determined. CONCLUSIONS: The topographic anatomy of the insular region is described in this article, and a practical terminology for gyral and sulcal patterns of surgical significance is presented. This study clarifies and supplements the information presently available to help develop a more coherent surgical concept.

The transcallosal-transforaminal approach to the third ventricle with regard to the venous variations in this region.

Surgical approaches to lesions located in the anterior and middle portions of the third ventricle are challenging, even for experienced neurosurgeons. Various exposures involving the foramen of Monro, the choroidal fissure, the fornices, and the lamina terminalis have been advocated in numerous publications. The authors conducted a microsurgical anatomical study in 20 cadaveric brain specimens (40 hemispheres) to identify an exposure of the third ventricle that would avoid compromising vital structures. An investigation of the variations in the subependymal veins of the lateral ventricle in the region of the foramen of Monro was performed, as these structures are intimately associated with the surgical exposure of the third ventricle. In 16 (80%) of the brain specimens studied, 19 (47.5%) of the hemispheres displayed a posterior location of the anterior septal vein-internal cerebral vein (ASV-ICV) junction, 3 to 13 mm (average 6 mm) beyond the foramen of Monro within the velum interpositum, not adjacent to the posterior margin of the foramen of Monro (the classic description). Based on this finding, the authors advocate opening the choroidal fissure as far as the ASV-ICV junction to enlarge the foramen of Monro posteriorly. This technique achieves adequate access to the anterior and middle portions of the third ventricle without causing injury to vital neural or vascular structures. The high incidence of posteriorly located ASV-ICV junctions is a significant factor influencing the successful course of surgery. Precise planning of the surgical approach is possible, because the location of the junction is revealed on preoperative neuroradiological studies, in particular on magnetic resonance venography. It can therefore be determined in advance which foramen of Monro qualifies for posterior enlargement to gain the widest possible access to the third ventricle. This technique was applied in three patients with a third ventricular tumor, and knowledge of the venous variations in this region was an important resource in guiding the operative exposure.

Is there a superior occipitofrontal fasciculus? A microsurgical anatomic study.

OBJECTIVE: Using a fiber-dissection technique, our aim was to expose and study the myelinated fiber bundles of the brain to achieve a clearer conception of their configurations and locations. During the course of our study, the superior occipitofrontal fasciculus became the focus of our interest. Many publications have defined this as a bundle of association fibers, located between the corpus callosum and the caudate nucleus, that connects the frontal and occipital lobes. By examining this area using fiber dissection, we realized that the descriptions of the anatomy are inadequate; thus, we focused on the elucidation of the anatomic structures of this region and, in particular, that known as the superior occipitofrontal fasciculus. METHODS: Twenty previously frozen, formalin-fixed human brains were dissected under the operating microscope using the fiber-dissection technique. RESULTS: On coronal sections of the brain, a structure on the superolateral aspect of the caudate nucleus usually has been identified as the superior occipitofrontal fasciculus. However, our fiber dissections revealed that this structure is the superior thalamic peduncle, that it is composed of projection fibers rather than association fibers, and that it does not interconnect the occipital and frontal lobes. CONCLUSION: The structures of the brain are better understood when the fiber-dissection technique is used to explore their configurations and locations. The resulting information is especially beneficial for planning strategies and tactics of neurosurgical procedures.

The arteries of the corpus callosum: a microsurgical anatomic study.

OBJECTIVE: The corpus callosum is the major commissural pathway connecting the hemispheres of the human brain. It is particularly important, because various tumors and vascular lesions can be located in and around the corpus callosum, and it is a route through which pass several surgical approaches. Performing accurate surgery in this region and avoiding damage to normal structures require that the neurosurgeon have adequate knowledge of the anatomy of the intricate blood supply to this area. METHODS: In 20 cadaver brains, the arteries of the corpus callosum were examined under the operating microscope, with particular attention to the origin, course, anastomoses, number, and caliber of the arteries. RESULTS: In all specimens, the pericallosal and posterior pericallosal arteries were found to be the main sources of blood supply to the corpus callosum. In 80% of the specimens, the anterior communicating artery gave rise to either a subcallosal artery or a median callosal artery, each of which made a substantial contribution to the blood supply of the corpus callosum. A detailed examination of the anatomic features of all the main arteries of supply revealed anastomoses within the callosal sulcus that formed the pericallosal pial plexus. This network supplied the corpus callosum, the radiation of the corpus callosum, and the cingulate gyrus. CONCLUSION: Familiarity with the details of the vascularity of the corpus callosum is crucial when performing surgery in this region. The additional, significant data described expands the knowledge of this anatomy, which can enhance the surgeon's ability to accomplish a more accurate and successful exploration.

Intradiploeic and cerebral hydatidosis: a case report and review of literature.

A case of disseminated hydatidosis is reported in a 3-year-old male child who presented with intradiploeic, cerebral, pulmonary and hepatic hydatid cysts. The literature is reviewed for similar cases with skull involvement and the differential diagnosis of cystic skull lesions is discussed.