Tsutomu Hitotsumatsu

Microvascular decompression for treatment of trigeminal neuralgia, hemifacial spasm, and glossopharyngeal neuralgia : three surgical approach variations : technical note

OBJECTIVEWe have used three different approaches, namely, the infratentorial lateral supracerebellar approach, the lateral suboccipital infrafloccular approach, and the transcondylar fossa approach, for microvascular decompression for treatment of trigeminal neuralgia, hemifacial spasm, and glossopharyngeal neuralgia, respectively. Each approach is a variation of the lateral suboccipital approach to the cerebellopontine angle (CPA); however, each has a different site of bony opening, a different surgical direction, and a different route along the cerebellar surface. METHODSThe infratentorial lateral supracerebellar approach is used to access the trigeminal nerve in the superior portion of the CPA through the lateral aspect of the cerebellar tentorial surface. The lateral suboccipital infrafloccular approach is directed through the inferior part of the cerebellar petrosal surface to reach the root exit zone of the facial nerve below the flocculus. The transcondylar fossa approach is used to access the glossopharyngeal nerve in the inferior portion of the CPA through the cerebellar suboccipital surface, after extradural removal of the jugular tubercle as necessary. RESULTSIn all three approaches, the cerebellar petrosal surface is never retracted transversely, that is, the cerebellar retraction is never directed parallel to the longitudinal axis of the VIIIth cranial nerve, dramatically reducing the risk of postoperative hearing loss. CONCLUSIONThe greatest advantage of the differential selection of the surgical approach is increased ability to reach the destination in the CPA accurately, with minimal risk of postoperative cranial nerve palsy.

Expression of neurofibromatosis 2 protein in human brain tumors: An immunohistochemical study

Abstract The neurofibromatosis 2 (NF2) gene-encoded protein, named merlin, may function as a molecular linkage connecting cytoskeleton and plasma membrane. Merlin is thought to play a crucial role as a tumor suppressor not only in hereditary NF2-related tumors, but also in sporadic tumors such as schwannomas, meningiomas and gliomas. Using a merlin-expression vector system, we raised specific antiserum against merlin. We observed the intracellular distribution of merlin in cultured glioma cells, and further investigated merlin expression in 116 human brain tumors. Immunofluorescence microscopy revealed that merlin was localized beneath the cell membrane and concentrated at cell-to-cell adhesion sites, where actin filaments are densely associated with plasma membrane. By immunohistochemistry, none of the schwannomas from either NF2 patients or sporadic cases showed any immunoreactivity, while normal Schwann cells of cranial nerves were immunopositive. In meningiomas, merlin expression was frequently seen in the meningothelial subtype (8/10, 80%), but no expression could be detected in either the fibrous or the transitional variant. Most normal astrocytes were negative; however, reactive astrocytes often expressed merlin. Glioblastomas and anaplastic astrocytomas were found to be strongly positive, and focal positive staining was observed in fibrillary and pilocytic astrocytomas. Thus, the loss of merlin appears to be integral to schwannoma formation and the differential pathogenesis of meningioma subtypes. However, merlin alterations do not appear to play a critical role in either the tumorigenesis or malignant transformation of neoplastic astrocytes.

Micro-anatomical study of the carotid cave

SummaryThe surgical treatment of aneurysms located in the carotid cave is often hazardous and difficult. We studied the micro-anatomy of the carotid cave and its neighbourhood by microscopic observation and histological examination using 50 sides from 25 autopsy cases. The carotid caves were found in 34 out of the 50 sides (68%) examined and were usually located in the posteromedial aspect of the carotid dural ring. They were classified into three types according to the topographic micro-anatomy: the slit-type (17/50, 34%) which showed a small, thin recess of the dura mater with fine connective tissue loosely adhered to the carotid wall; the pocket-type (12/50, 24%) which had a definite dural pouch with the apex attached to the vessel wall; and the mesh-type (5/50, 10%) which formed a slit- or pocket-type dural cave covered with a mesh-like dural roof. The remaining 16 sides (32%) showed tight dural attachment without any caval structure around the dural ring. The posteromedial portion of the carotid dural ring had no contact with any bony structure, and this distinct anatomical feature thus appear to facilitate the formation of the carotid cave. Furthermore, the availability of this potential space and the closely situated origin of the superior hypophyseal artery as well as the haemodynamic effect of the internal carotid artery may allow the development of the carotid cave aneurysm.

Cytoplasmic inclusions of astrocytic elements of glial tumors : special reference to round granulated body and eosinophilic hyaline droplets

Round granulated body (RGB) and eosinophilic hyaline droplets (EHDs) have been described as cytoplasmic inclusions of certain astrocytic tumors. In the previous literature, however, these inclusions have been described using various terms or regarded as nosologically the same entity. Light microscopically, RGB apeared as a round discrete body filled with fine uniform granules, while EHDs demonstrated a cluster of bright eosinophilic, round objects of various size. They could be clearly distinguished even by conventional histochemical staining such as the Masson trichrome stain and the phosphotungstic acid hematoxylin preparation. Both RGB and EHDs expressed positive immunoreactions for glial fibrillary acidic protein, several lysosomal markers, and some stress-response proteins. The ultrastructural appearances of these inclusions were distinct, however, one common feature was that they consisted of aggregations of numerous membrane-bound electron-dense bodies. Thus, both inclusions appear to be produced by neoplastic astrocytes and are possibly related to the lysosomal system. We examined the presence of RGB and EHDs in 138 astrocytic tumors. Both inclusions occurred most frequently in pleomorphic xanthoastrocytomas, followed by gangliogliomas and pilocytic astrocytomas. Subependymal giant cell astrocytomas exhibited only RGBs. RGBs and EHDs were not seen in any abundance in glioblastomas, gliosarcomas, fibrillary astrocytomas, protoplasmic astrocytomas, or oligo-astrocytomas. Some glioblastomas, however, showed only EHDs in small numbers. Several anaplastic astrocytomas were associated with a large number of RGBs and/or EHDs, and they revealed only rare mitosis despite marked cellular pleomorphism. Although RGB and EHDs have different morphological features, the presence of these inclusions in abundance may represent either a degenerative change, a long-standing lesion, or an indolent growth of the astrocytic tumors.

Toxic myocardial damage due to intravenous phenytoin administration.

Intravenous phenytoin administration can, uncommonly, cause cardiovascular side effects including hypotension, bradycardia, and atrial and ventricular conduction abn~rmalitiesl-~ as well as an allergic reaction leading to hypersensitivity myo~ardi t is~?~, To our knowledge, myocardial damage due to cytotoxicity of intravenous phenytoin has not yet been morphologically documented. We report a patient in whom, at autopsy, we found toxic myocardial damage following intravenous phenytoin administration.

Gliosarcoma arising from oligodendroglioma (Oligosarcoma): A case report with genetic analyses: A case report of oligosarcoma

Gliosarcomas are a type of bimorphic tumor composed of glial and sarcomatous elements, and are considered to be a variant of glioblastoma, WHO grade IV. To date, only rare cases of gliosarcoma with oligodendroglial components (oligosarcoma) have been reported. We report a case of oligosarcoma consisting of gliosarcoma arising from recurrent oligodendroglioma. A 53‐year‐old man, who had undergone a gross total resection of oligodendroglioma (WHO grade II) 11 years earlier, presented with a local tumor recurrence. The patient underwent a second gross total resection, whereupon a histopathological examination further revealed residual features of classical oligodendroglioma, and newly‐developed sarcomatous characteristics. Both the primary and recurrent tumors showed 1p/19q co‐deletion and mutation of the isocitrate dehydrogenase 1 (IDH1) gene, consistent with being oligodendroglial in nature. Loss of heterozygosity (LOH) of chromosome 1p/19q and IDH1 mutation have seldom been analyzed in previous reports of oligosarcomas. We report a rare case study supported by the results of genetic analyses. Our analyses have revealed that the sarcomatous component represents a metaplastic change occurring in the oligodendroglial element.