This study explores factors determining axon calibres, using the normal cochlear nerve as a model. The topographic distribution of axon calibres in the cochlear nerve of the guinea pig was found to correspond to its known tonotopic organization. Axons derived from the cochlear apex which carry sounds of low pitch were located centrally in the nerve and were about half as thick as axons derived from the basal turns, which are located at the periphery and carry sounds of high pitch. Intermediate ranges were located in between. If one compares these measurements with physiological data one finds axon calibres matched to characteristic frequency ranges to a degree that should cause mismatching of conduction time.

Animals↗

PubMedDate not supplied

Suprasellar neoplasm with a granular cell component.

A classification of granular cell lesions of neuropathologic interest is presented along with an unique case in which a suprasellar neoplasm having light and electron microscopic features of a meningioma contained multifocal nests of granular cells which apparently persisted in this tumor over a period of nearly five years. A spectrum of cell differentiation suggested the development of granular cells from small, electron-dense mesenchymal elements having numerous mitochondria. No evidence for a Schwann cell origin was found. It is proposed that the pituitary-hypothalamic axis, where intracranial granular cell nests and granular cell tumors are most common may also give origin to rare mixed neoplasms with a granular cell component.

Adult↗

PubMedDate not supplied

The cytogenetic basis for classifying ependymomas.

The phylogeny of ependymal cells and astrocytes can be traced to a single primitive progenitor the ependymoglia or the tanycyte, respectively. Ependymoglia cells have ependymal perikarya having astrocyte-like processes that terminate subpially in primitive glial footplates. Such cells prevail in primitive nervous systems, but they also persist regionally in the mature mammalian brain. Their fine structure has been studied in many species. An electronmicroscopic study of 8 ependymomas reveals that the neoplastic cells possess features characteristic of primitive ependymoglia; in particular they possess cell processes filled with glial filaments, terminating submesenchymally in a primitive, piston-shaped footplate. The perivascular pseudorosettes of ependymomas are the equivalents of these cell poles. The dominant phenomenon of ependymoma structure appears to be a reversion of cellular organization to the stage of primitive ependymoglia cells. On reviewing 43 ependymomas and 71 astrocytomas 11 neoplasms were found having a tissue structure reminiscent of the evolution of piloid astrocytes from ependymoglia or tanycytes, respectively. These features correspond to transitional stages seen in normal primitive brains. Tumors of this type may be characterized as a tanycytic variant of ependymomas. They appear to be relatively common in the spinal cord and present a source of confusion with piloid astrocytomas.

Adolescent↗

PubMedDate not supplied

Naked axon bundles enclosed by single segments of myelin sheaths in the nerves of non-dystrophic C57BL-ob/+mice.

Bundles of axons enclosed by a single myelin sheath were found in the peripheral nerves of heterozygous obese C57BL-ob/+mice. Serial sections showed them to consist of two to forty naked axons encompassed by a common cuff of myelin formed by a single Schwann cell, with adjoining non-myelinated Schwann cells protruding from either side into the cuff. These structures are similar to those found in dystrophic mice, but there were no signs of dystrophy in the obese mice. It is suggested that the axon bundles result from a disturbance of early myelination, presumably of the phase of Schwann cell proliferation or of the communication between Schwann cells and axons.

Animals↗

PubMedDate not supplied

Wernicke's encephalopathy in a child with acute lymphoblastic leukemia treated with polychemotherapy.

We report on a 3 3/4-year-old girl with acute lymphoblastic leukemia. Polychemotherapy caused a complete remission of the tumor. Six months after treatment was started, the patient developed vomiting and diarrhea necessitating parenteral nutrition. Disturbance of eye movements appeared 4 weeks later. The patient died suddenly 3 days after their manifestation. Autopsy revealed Wernicke's encephalopathy. This case demonstrates the need for thiamine substitution in infants with malignant diseases.

Antineoplastic Combined Chemotherapy Protocols↗

PubMedDate not supplied

Leukoencephalopathy after cisplatin therapy.

Cisplatin is a neurotoxic chemotherapeutic agent known to cause sensory peripheral neuropathy or ototoxicity. We report a patient with an oropharynx carcinoma who developed a multifocal, necrotizing leukoencephalopathy after cisplatin treatment. This indicates that cisplatin can induce, similar to other chemotherapeutic agents, demyelinating, necrotizing lesions in the white matter of the cerebrum.

Carcinoma, Squamous Cell↗

PubMedDate not supplied

Multiple unusual leptomeningeal glioneural heterotopias in a case of adult micrencephaly.

An adult patient with micrencephaly combined with unusual multiple glioneural leptomeningeal heterotopias is presented. In spite of the large number of leptomeningeal heterotopias supra- and infratentorially, the cortices of the cerebrum and the cerebellum were well-organized and the white matter was well-myelinated. The heterotopias contained glial tissue and mature neurons, those in the cerebellum resembling Purkinje cells and granular cells, along with axons and mineralizations. The pathogenesis of the leptomeningeal heterotopias and micrencephaly is discussed.

Adult↗