Central demyelination in the pathogenesis of trigeminal neuralgia associated with cerebellopontine angle tumors: case report with ultrastructural trigeminal root analysis.

OBJECTIVE: To describe the surgical and ultrastructural findings in the trigeminal root of a patient with trigeminal neuralgia (TN) associated with a cerebellopontine epidermoid tumor, and to relate these to literature reports of patients with vascular compression-related TN. CLINICAL PRESENTATION: A 39-year-old woman presented with right TN. She had a 10-year history of lancinating pain paroxysms in the second and third trigeminal branches. Pain exhibited trigger areas and improved partially with carbamazepine. Cranial magnetic resonance imaging revealed an epidermoid tumor in the right cerebellopontine angle that distorted and compressed the right trigeminal root. TECHNIQUE: The tumor was resected. At operation, the trigeminal root appeared distorted and compressed by the tumor. A small partial rhizotomy was performed, and the biopsy was processed for ultrastructural study. Complete relief of the symptoms was achieved with no deficits after the procedure. Pathologic changes in the biopsy included axonal loss, demyelination, and the presence of abundant collagen infiltrates and myelin debris. No inflammatory cells were present. In some areas, myelin-denuded axons were in close apposition, allowing the presence of axon-to-axon interactions. These findings are similar to others described previously regarding patients with vascular compression-related TN. CONCLUSION: Compression injury to the trigeminal root leading to demyelination is a major determinant in the pathogenesis of TN.

Cerebellopontine angle paraganglioma - report of a case and review of literature.

Majority of the cerebellopontine angle (CPA) tumors are acoustic neuromas, while bulk of the non-acoustic tumors are formed by meningiomas and epidermoid cysts. Primary paraganglioma is a rare tumor in this location, with only two such cases having been reported in the literature, till date. Recently, a case has been described wherein a paraganglioma was apparently arising as a primary lesion in the cerebellar hemisphere. We report another case of an intracranial paraganglioma of the CPA in a 40-year-old female, which did not have any vascular attachment but had focal cerebellar extension.

Intracranial malignant fibrous histiocytoma: characterization of GFAP-positive cells in the tumor.

A case of malignant fibrous histiocytoma (MFH) arising in the cerebellopontine angle of a 57-year-old woman was reported. The immunohistochemical and electron microscopic findings indicated distinct fibrohistiocytic nature and myofibroblastic differentiation of this peculiar tumor. Immunohistochemistry disclosed that the tumor cells expressed monocyte/macrophage markers including CD-68, MAC 387, and alpha-1-antichymotrypsin. In addition, the neoplasm contained scattered glial fibrillary acidic protein (GFAP)-positive cells which made small nests in some areas. These GFAP-positive cells had bundles of densely packed intermediate filaments and scanty organellae in the cytoplasm, as demonstrated by an immunostained-semithin and serial-ultrathin section method. By immunostaining of MIB-1 and GFAP, and silver nucleolar organizer region (AgNOR) impregnation on serial sections, the GFAP-positive cells were not labeled by MIB-1 and their AgNOR counts averaged 1.13/nucleus. Thus, these GFAP-positive cells seem to have lower proliferating activity than neoplastic astrocytes. It is concluded that they may be nonneoplastic astrocytic cells involved by MFH.

[A case of chondroma of the cerebello-pontine angle and clivus]. / Przypadek chrzestniaka kata mostowo-mózdzkowego i stoku.

A 42-year old woman with a rare intracranial tumour-chondroma of the cerebello-pontine angle and clivus is presented. Clinical signs of the disease appeared when the tumour attained a huge size. Despite grave postoperative course the prognosis in our patient was good.

Late onset cerebello-pontomesencephalic degeneration.

Two siblings are presented with late onset, rapidly progressive truncal ataxia, paralysis of down-gaze and loss of up-gaze saccades in association with other oculomotor dysfunctions as well as dementia. Electron microscopic muscle studies revealed abnormal distribution and form of the mitochondria, probably being the ultrastructural basis of the pathologic changes. A neurological syndrome as that described here has not been reported before.

A review of recent observations concerning the synaptic organization of the basilar pontine nuclei.

Ultrastructural studies are described that have identified in the basilar pontine nuclei (BPN), the synaptic boutons formed by the corticopontine, cerebellopontine, tectopontine, and dorsal column nuclei-pontine afferent projection systems. In addition, immunocytochemical studies visualized neuronal somata, dendrites, and synaptic boutons that contain immunoreactivity for GABA or the synthesizing enzyme glutamic acid decarboxylase (GAD). Based upon differences in the mode of degeneration and postsynaptic locus of degenerative synaptic boutons in the BPN, it is suggested that two types of cortical neurons and three classes of deep cerebellar nuclear cells project to the BPN. For similar reasons, it appears that two types of neurons in the dorsal column nuclei project to the BPN while only one type of afferent synaptic bouton takes origin from the superior colliculus. Furthermore it appears that the population of BPN neurons projecting to the paramedian lobule receives convergent inputs from the cutaneous periphery and the corresponding region of sensorimotor cortex. Studies employing GAD immunohistochemistry indicate that GABA-ergic neurons and axon terminals are present in the BPN and thus support the suggestion that a local inhibitory interneuron is present within the BPN. Taken together these observations suggest that basilar pontine neurons might play a more active role in the integration of various types of information destined for the cerebellar cortex than has previously been recognized.

Subependymoma: a case report with ultrastructural study.

A case history illustrating the potential clinical significance of subependymoma is presented. Fine structural studies indicate that the tumor is composed of cells having the cytoplasmic features of ependyma, astrocytes, and transitional cells. Its composition and structure are alike those in the adult mammalian subependymal layer.