Chan-Young Choi

THREE-DIMENSIONAL MICROSURGICAL AND TRACTOGRAPHIC ANATOMY OF THE WHITE MATTER OF THE HUMAN BRAIN

OBJECTIVE We sought to investigate the three-dimensional structure of the white matter of the brain by means of the fiber-dissection technique and diffusion-tensor magnetic resonance imaging to assess the usefulness of the combination of both techniques, compare their results, and review the potential functional role of fiber tracts. METHODS Fifteen formalin-fixed human hemispheres were dissected according to Klinglers fiber-dissection technique with the aid of 36 to 340 magnification. Three-dimensional anatomic images were created with the use of specific software. Two hundred patients with neurological symptoms and five healthy volunteers were studied with diffusion-tensor magnetic resonance imaging (3 T) and tractographic reconstruction. RESULTS The most important association, projection, and commissural fasciculi were identified anatomically and radiologically. Analysis of their localization, configuration, and trajectory was enhanced by the combination of both techniques. Three-dimensional anatomic reconstructions provided a better perception of the spatial relationships among the white matter tracts. Tractographic reconstructions allowed for inspection of the relationships between the tracts as well as between the tracts and the intracerebral lesions. The combination of topographical anatomic studies of human fiber tracts and neuroanatomic research in experimental animals, with data from the clinicoradiological analysis of human white matter lesions and intraoperative subcortical stimulation, aided in establishing the potential functional role of the tracts. CONCLUSION The fiber-dissection and diffusion-tensor magnetic resonance imaging techniques are reciprocally enriched not only in their application to the study of the complex intrinsic architecture of the brain, but also in their practical use for diagnosis and surgical planning.

The claustrum and its projection system in the human brain: a microsurgical and tractographic anatomical study

OBJECT The goal in this study was to examine the microsurgical and tractographic anatomy of the claustrum and its projection fibers, and to analyze the functional and surgical implications of the findings. METHODS Fifteen formalin-fixed human brain hemispheres were dissected using the Klingler fiber dissection technique, with the aid of an operating microscope at x 6-40 magnification. Magnetic resonance imaging studies of 5 normal brains were analyzed using diffusion tensor (DT) imaging-based tractography software. RESULTS Both the claustrum and external capsule have 2 parts: dorsal and ventral. The dorsal part of the external capsule is mainly composed of the claustrocortical fibers that converge into the gray matter of the dorsal claustrum. Results of the tractography studies coincided with the fiber dissection findings and showed that the claustrocortical fibers connect the claustrum with the superior frontal, precentral, postcentral, and posterior parietal cortices, and are topographically organized. The ventral part of the external capsule is formed by the uncinate and inferior occipitofrontal fascicles, which traverse the ventral part of the claustrum, connecting the orbitofrontal and prefrontal cortex with the amygdaloid, temporal, and occipital cortices. The relationship between the insular surface and the underlying fiber tracts, and between the medial lower surface of the claustrum and the lateral lenticulostriate arteries is described. CONCLUSIONS The combination of the fiber dissection technique and DT imaging-based tractography supports the presence of the claustrocortical system as an integrative network in humans and offers the potential to aid in understanding the diffusion of gliomas in the insula and other areas of the brain.

A understanding of the temporal stem.

OBJECTIVE There has been inconsistency about definition of the temporal stem despite of several descriptions demonstrating its microanatomy using fiber dissection and/or diffusion tensor tractography. This study was designed to clarify three dimensional configurations of the temporal stem. METHODS The fronto-temporal regions of several formalin-fixed human cerebral hemispheres were dissected under an operating microscope using the fiber dissection technique. The consecutive coronal cuts of the dissected specimens were made to define the relationships of white matter tracts comprising the temporal stem and the subcortical gray matters (thalamus, caudate nucleus, amygdala) with inferior limiting (circular) sulcus of insula. RESULTS The inferior limiting sulcus of insula, limen insulae, medial sylvian groove, and caudate nucleus/amygdala were more appropriate anatomical structures than the roof/dorso-lateral wall of the temporal horn and lateral geniculate body which were used to describe previously for delineating the temporal stem. The particular space located inside the line connecting the inferior limiting sulcus of insula, limen insulae, medial sylvian groove/amygdala, and tail of caudate nucleus could be documented. This space included the extreme capsule, uncinate fasciculus, inferior occipito-frontal fasciculus, anterior commissure, ansa peduncularis, and inferior thalamic peduncle including optic radiations, whereas the stria terminalis, cingulum, fimbria, and inferior longitudinal fiber of the temporal lobe were not passing through this space. Also, this continued posteriorly along the caudate nucleus and limiting sulcus of the insula. CONCLUSION The temporal stem is white matter fibers passing through a particular space of the temporal lobe located inside the line connecting the inferior limiting sulcus of insula, limen insulae, medial sylvian groove/amygdala, and tail of caudate nucleus. The three dimensional configurations of the temporal stem are expected to give the very useful anatomical and surgical insights in the temporal lobe.

Central core of the cerebrum

OBJECT The purpose of this study was to understand 3D relationships of white matter fibers and subcortical areas of gray matter in the central core. METHODS The lateral and medial aspects of 4 cerebral hemispheres were dissected, applying the fiber dissection technique under the microscope. RESULTS The central core between the insula and midline includes the extreme, external, and internal capsules; claustrum; putamen; globus pallidus; caudate nucleus; amygdala; diencephalon; substantia innominata; fornix; anterior commissure; mammillothalamic tract; fasciculus retroflexus; thalamic peduncles, including optic and auditory radiations; ansa peduncularis; thalamic fasciculus; and lenticular fasciculus. It is attached to the remainder of the cerebral hemisphere by the cerebral isthmus, which is composed of white matter fibers located between the dorsolateral margin of the caudate nucleus and the full circumference of the circular sulcus of insula. The rostral fibers of the corpus callosum are included in the frontal portion of the cerebral isthmus. CONCLUSIONS It is very useful for neurosurgeons to facilitate the understanding of spatial relationships and pertinent surgical approaches in and around the central core with a highly complex anatomy by using fiber dissection.

Intraventricular Cavernous Hemangiomas Located at the Foramen of Monro

Intraventricular cavernous hemangiomas are uncommon. Among them, those occurred at the foramen of Monro in the third ventricle may be of particular interest because of its rarity, development of hydrocephalus, being differentiated from other brain lesions. We present a rare case of intraventricular cavernous hemangioma at foramen of Monro which was resected through microsurgery and also review the relevant literatures.

Cytogenetic and molecular genetic study on granular cell glioblastoma: a case report.

Granular cell astrocytoma is a rare infiltrative malignant glioma with prominent granular cell change. Granular cell astrocytomas are biologically aggressive compared with conventional infiltrating astrocytomas of similar grades, but their genetic alterations are poorly known. We report a case of granular cell glioblastoma and its genetic and molecular features. Histologically, the tumor not only showed features typical of granular cell astrocytoma but also demonstrated frequent mitoses, pseudopalisading necrosis, and vascular endothelial hyperplasia, compatible with glioblastoma. Array-based comparative genomic hybridization and focused molecular genetic analyses demonstrated gain of chromosome 7; losses of chromosome 1p, 8p, 9p, 10, 13q, and 22q; amplification of epidermal growth factor receptor; and homozygous deletion of CDKN2A as well as MGMT promoter methylation. However, neither isocitrate dehydrogenase 1 mutation nor codeletion of 1p/19q was found. Our results indicate that granular cell glioblastomas, despite having its peculiar granular cell changes, share common molecular genetic features with conventional glioblastoma, especially the classical subtype.

An intracranial malignant solitary fibrous tumor.

Intracranial malignant solitary fibrous tumor (SFT) is very rare. It was identified in a 39‐year‐old female patient who underwent malignant transformation over 6 months. MRI revealed an 8 × 5 × 6 cm mass with heterogenous strong enhancement in the left occipital lobe. Histologic findings and immunophenotype (positive for CD34, bcl‐2 and vimentin, and negative for epithelial membrane antigen or S100 protein) of the primary tumor were typical of SFT. However, there was a focal area (<10% of tumor volume) showing hypercellularity, nuclear pleomorphism and increased Ki‐67 labeling index (LI) of 10% (average, 1%). At the second operation, the recurrent tumor revealed full‐blown histologic features of malignant SFT, such as infiltrative brain invasion, marked nuclear pleomorphism, frequent mitotic figures (15/10 high power fields), and high Ki‐67 LI (25%). The presence of atypical histologic finding or increased Ki‐67 LI in the typical SFT, although it is focal, needs to be mentioned in the diagnosis and also may require more aggressive surgical management.

Primary Intracranial Leptomeningeal Melanomatosis

Primary intracranial malignant melanoma is a very rare and highly aggressive tumor with poor prognosis. A 66-year-old female patient presented a headache that had been slowly progressing for several months. A large benign pigmented skin lesion was found on her back. A brain MRI showed multiple linear signal changes with branching pattern and strong enhancement in the temporal lobe. The cytological and immunohiostochemical cerebrospinal fluid examination confirmed malignant melanoma. A biopsy confirmed that the pigmented skin lesion on the back and the conjunctiva were benign nevi. We report a case of primary intracranial malignant melanoma and review relevant literatures.

Middle Cerebral Artery Aneurysm in a Premature Neonate

Intracranial aneurysms in the neonate are very rare and their clinicopathological findings remain unclear. We report a 26-day-old premature neonate who underwent microsurgical clipping on the ruptured middle cerebral artery bifurcation aneurysm successfully with a review of relevant literature.

WITHDRAWN: Cytogenetic and molecular genetic study on glioblastoma arising in granular cell astrocytoma: a case report.

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