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PubMed2003

MR imaging of the trigeminal ganglion, nerve, and the perineural vascular plexus: normal appearance and variants with correlation to cadaver specimens.

BACKGROUND AND PURPOSE: MR imaging is the method of choice for evaluating the trigeminal nerve. Detection of abnormalities such as perineural tumor spread requires detailed knowledge of the normal MR appearance of the trigeminal nerve and surrounding structures. The purpose of this study was to clarify the normal MR appearance and variations of the trigeminal ganglion, maxillary nerve (V2), and mandibular nerve (V3) with their corresponding perineural vascular plexus. METHOD: S: MR images obtained in 32 patients without symptoms referable to the trigeminal nerve were retrospectively reviewed. The trigeminal ganglion in Meckel's cave, V2 within the foramen rotundum, and V3 at the level of foramen ovale were assessed for visualization and enhancement. The configuration of the perineural vascular plexus was recorded. Correlation to cadaver specimens was made. RESULTS: The trigeminal ganglion and V3 were observed to enhance in 3-4% of patients unilaterally. V2 and V3 were well visualized 93% of the time. The perineural vascular plexus of V2 was observed 91% of the time, and that of V3 in 97% of instances. CONCLUSION: This study characterizes the normal MR appearance of the trigeminal ganglion and its proximal branches. The trigeminal ganglion, V2, and, V3 are almost always reliably seen on thin-section MR studies of the skull base. Enhancement of the perivascular plexus is routinely seen; however, enhancement of the trigeminal ganglion, V2, or V3 alone is seen only on occasion as supported by the avascular appearance of these anatomic structures in cadaver specimens.

Adolescent↗
PubMed2005

Trigeminal ganglion and its divisions: detailed anatomic MR imaging with contrast-enhanced 3D constructive interference in the steady state sequences.

BACKGROUND AND PURPOSE: Visualization of the trigeminal system is important for imaging diagnosis but technically challenging. We assessed how well the trigeminal ganglion, its rootlets, and its branches (V1, V2, and V3) are depicted on three high-resolution pulse sequences. METHODS: Twenty-two patients (44 sides) underwent nonenhanced 3D constructive interference in the steady state (CISS) MR imaging. Two of these patients and another 20 (44 sides) also underwent contrast-enhanced 3D CISS and contrast-enhanced 3D time-of-flight (TOF) MR angiographic (MRA) imaging. Appearances of the ganglion, sinus ganglii, ganglion lip, and sensory and motor rootlets in the Meckel cave were assessed. RESULTS: The trigeminal ganglion was shown on enhanced 3D CISS images in all cases, on nonenhanced 3D CISS images in 77.3%, and on enhanced 3D TOF MRA images in 92.9%. Sinus ganglia and lips were demonstrated on 98% of enhanced 3D CISS images. Sensory rootlets were depicted with all 3D CISS sequences but no 3D TOF sequences. V1, V2, and V3 were displayed with all enhanced 3D TOF MRA sequences, 79.5-100% of enhanced 3D CISS sequences, and 0-50% of nonenhanced 3D CISS sequences. CONCLUSION: The enhanced 3D CISS sequence was best for displaying the trigeminal ganglion, sinus ganglii, and sinus lips, whereas the enhanced 3D TOF sequence best displayed the emerging V1, V2, and V3 roots. The enhanced 3D CISS sequence was most useful. Complete MR imaging evaluation of the trigeminal ganglion and roots is best performed by using enhanced 3D CISS and enhanced 3D TOF MRA sequences.

Adult↗
PubMed1991

Morphogenesis and territorial coverage by isolated mammalian retinal ganglion cells.

Identified retinal ganglion cells were isolated from postnatal cat retinas and their dendrites were removed by trituration and centrifugation. The denuded cells were placed in a cell culture system and allowed to reexpress dendritic arbors in the absence of afferent input, target tissue, and interactions with neighboring ganglion cells. The retinal ganglion cells were grown above a feeder layer of astrocytes on glass coverslips equipped with paraffin pedestals. The spatial patterns of the reexpressed neurites were quantitatively analyzed using a number of measures, including an estimate of the Hausdorff dimension, H, which was used as a scale-independent metric for how well the neurite patterns filled in a restricted spatial domain. As assessed by the estimation of the Hausdorff dimensions, the neurites from a single cell achieve uniform coverage of a restricted territory independent of the total neurite length or the total number of inter-branch-point segments. A comparison with H values of ganglion cells from the intact retina revealed a similar trend. These results suggest that these cultured ganglion cells can express an intrinsic growth strategy for the uniform coverage of a restricted territory. The arbors expressed in the culture system displayed a limited range of diameters and exhibited morphology similar to the alpha-, beta-, and gamma-ganglion cells of the intact retina in the absence of afferent input or the influences of neighboring cells and target tissue. Time-lapse video data revealed that individual cultured cells showed extensive dendritic remodeling during their growth; however, after about 3 d in culture, this remodeling did not appreciably affect the territorial coverage of a cell. In the intact retina, the existence of dendritic sheets that independently and uniformly sample visual space may result from this intrinsic ability to elaborate dendrites that uniformly cover or fill in a restricted territory.

Animals↗
PubMed1986

The distribution and significance of aberrant ganglion cells in the facial nerve trunk of the cat.

The distribution and peripheral connections of aberrant ganglion cells in the facial nerve trunk of the cat were studied by means of Klüver-Barrera staining and retrograde transport of horseradish peroxidase (HRP). By the Klüver-Barrera staining, aberrant ganglion cells were observed in the facial nerve trunk between the geniculate ganglion and the junction of the auricular branch of the vagus with the facial nerve trunk, although the number varied considerably with each animal. These cells were generally medium-sized and of round or oval shape, with densely stained Nissl substance, the features of which were essentially similar to those of the geniculate ganglion. In cases where HRP injections were made into the anterior wall of the auricle, several HRP-labeled cells were found ipsilaterally in the facial nerve trunk in addition to cell labeling of the geniculate ganglion. The present study in the cat demonstrated that at least some of the aberrant ganglion cells scattered in the facial nerve trunk are parental to the axons to the auricle, subserving the cutaneous sensory function.

Animals↗
PubMed1984

Degeneration of the distal vagal ganglion cells of the domestic fowl after section of their central processes.

The centrally directed axonal processes of the distal vagal ganglion cells were cut by midcervical vagotomy in nine domestic fowl, and the ganglion cells were examined electron microscopically after intervals of 5-462 days. During the first 5-41 days after operation, peripheral displacement of the nucleus, indentation of the nuclear membrane, dilation of the cisternae of the granular endoplasmic reticulum, depletion of membrane associated ribosomes, and peripheral displacement and fragmentation of the Golgi apparatus were found. These changes are interpreted as reactive responses to the axonal injury. From 207 days onwards, general loss of organelles and extensive vacuolation of the cytoplasm were observed. These changes were regarded as severely degenerative, to the point of cell death. Between 305 and 462 days many ganglion cells were lost, the few survivors apparently being normal except for numerous nuclear pores. Degenerative changes were also seen in satellite cells. It is concluded that severance of the central processes of the distal vagal ganglion cells of this avian species leads to the slow development of reactive and degenerative changes in many of the ganglion cells. These results are compared with those of similar experiments on mammals, in which the sensory ganglion cells appear to be totally unresponsive to the interruption of their centrally directed processes.

Animals↗
PubMed1983

Retrograde transport of nerve growth factor in lesioned goldfish retinal ganglion cells.

Previous experiments have shown that nerve growth factor (NGF) enhances regeneration of goldfish optic nerve after local application of NGF at the site of the lesion. However, the site and mechanism of action of NGF are not yet known. One possibility is that NGF is taken up at the site of the lesion and retrogradely transported to the cell bodies of the retinal ganglion cells and thereby exerts its trophic effects. The present work was carried out to assess the role of retrograde transport of NGF in this enhanced regeneration of goldfish retinal ganglion cells. In intact retinal ganglion cells of the goldfish, 125I-labeled NGF was found not to be retrogradely transported from the optic tectum to the retina, suggesting that retinal ganglion cells do not possess specific NGF receptors. However, if [125I]NGF was injected at the site of an optic nerve lesion at the time of lesion, [125I]NGF was retrogradely transported from the site of a lesion of the optic nerve to the cell body of retinal ganglion cells. The accumulated radioactivity was shown to be intact NGF by SDS-PAGE. The ability of NGF to decrease the time required for recovery of visual function was observed only when NGF was administered at the time of the injury. Likewise, no transport of [125I]NGF was observed when it was injected at the crush site 16 hr or longer after crush. Thus, there is a temporal correlation between the ability of intact [125I]NGF to be retrogradely transported from a lesion site to the retina and the regenerative effect of NGF. Autoradiography showed that the [125I]NGF accumulated only in retinal ganglion cells. The transport of NGF in the lesioned goldfish visual system was not specific for NGF in that other proteins (cytochrome c, bovine serum albumin) were transported equally well. Likewise, transport of [125I]NGF was not prevented by concomitant administration of excess unlabeled NGF. The retrograde transport of [125I]NGF therefore was not selective and did not appear to be mediated by specific NGF receptors in this system. This nonspecific transport of [125I]NGF did not occur in the axotomized spinal motor neurons in the neonatal or adult rat or in the newt. However, receptor-mediated transport is seen in lesioned sensory neurons in both species.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1978

[Reaction of peripheral vestibular ganglion cells on experimental stimulation in guinea pigs].

The effects of adequate stimuli upon the ganglion cells of the ganglion vestibulare and ganglion geniculi n. facialis were studied in the guinea pig labyrinth. During experimental examination, swelling up to 112% as well as shrinkage up to 35% were noticed. These volume changes do not coincide with the changes occurring in the corresponding sensory nuclei during the same stimulus. As the ganglion cells receive their impulses from various sensularies, they are responsible for several types of movement. A periodical increase and decrease of the nuclear volume are assumed to be an expression of the general total activity. The cells of the ganglion geniculi respond very strongly to these movement stimuli, which are not regarded to be adequate. Consequently it was proved that strong inadequate excitations can also influence the neighboring ganglion cells. In the cytoplasm, strong excitations lead to variations in the Nissl content. An intensive material exchange between the cytoplasm and the karyoplasm is assumed to be a cause for the changes of the nuclei volumes. But only the relation between the cell nuclei and the cell somata is altered. The volume of the whole cell remains approximately constant.

Animals↗
PubMed1983

Ganglion cell topography in human fetal retinae.

Whole-mounted human fetal retinae of gestational ages 14-40 weeks have been studied. These preparations clearly show the distribution of retinal ganglion cells or their precursors across the retina, and the pattern of the retinal vessels and vessel primordia. The ganglion cell layer is present at 14 weeks of gestation and distribution of cells in this layer (ganglion cell precursors) is at first uniform. Ganglion cell density gradients that foreshadow those seen in the adult retina become evident by about 20 weeks gestation. Both mature ganglion cells and precursor cells are present in retinae at about 24 weeks and precursor cells are still seen in the peripheral parts of the retina at about 30 weeks of gestation. The development of mature ganglion cells would appear to coincide with the establishment of retinal circulation, and proceeds in centrifugal sequence from central retinal.

Gestational Age↗
PubMed1995

Desensitizing glutamate receptors shape excitatory synaptic inputs to tiger salamander retinal ganglion cells.

AMPA/kainate (KA) receptors mediate a component of ganglion cell excitatory postsynaptic currents (EPSCs). We investigated whether desensitization at these receptors contribute to the shape of transient EPSCs in ON-OFF ganglion cells. Whole-cell, voltage-clamp recordings were made from ganglion cells in the retinal slice or in isolation. EPSCs were evoked by either stimulating the slice with light or puffing K+ at the outer plexiform layer (OPL). The AMPA/KA receptor-mediated component of the EPSCs was isolated by including NMDA receptor antagonists in the bath. Strychnine and picrotoxin blocked inhibitory inputs. In isolated ganglion cells, cyclothiazide (10 microM), which blocks desensitization in non-NMDA receptors, enhanced both the amplitude and the duration of currents evoked by puffs of AMPA or glutamate. EPSCs evoked by K(+)-puffs in the OPL were also enhanced by cyclothiazide (30 microM). When AMPA/KA receptors were blocked with NBQX (10 microM), no enhancement of the EPSCs by cyclothiazide was observed, indicating that cyclothiazide did not act presynaptically. Cyclothiazide also enhanced the amplitude and duration of both the ON and OFF light-evoked (L-) EPSCs recorded in ON-OFF ganglion cells. Current-voltage relationships showed the enhancement was not voltage dependent. When control and enhanced responses where normalized, it was observed that the rate of desensitization of both the ON and OFF L-EPSCs was decreased by cyclothiazide. Cyclothiazide selectively enhanced the AMPA/KA receptor-mediated component of ganglion cells EPSCs, suggesting that desensitization of AMPA/KA receptors shape transient L-EPSCs.

Ambystoma↗
PubMed1993

Vasoconstricting effect of vasopressin on regional vascular beds in conscious rats after ganglionic blockade.

We analyzed the vasoconstrictor effects of arginine vasopressin (AVP) on regional arteries before and after ganglionic blockade with hexamethonium. Simultaneous measurements of mean arterial pressure and regional flows were obtained in conscious rats, using chronically implanted electromagnetic flow probes. Regional vascular resistance was calculated as mean arterial pressure divided by regional flow. AVP was applied intravenously as a bolus, at doses ranging from 5 x 10(-11) to 5 x 10(-8) g/kg. AVP increased mean arterial pressure, decreased superior mesenteric, renal and terminal aortic flows (supplied mainly for the hindquarter vascular area), and increased superior mesenteric, renal and terminal aortic (hindquarter) resistances in a dose-dependent manner. Ganglionic blockade decreased mean arterial pressure and renal resistance significantly, whereas there were no significant differences between changes in resistance before and after ganglionic blockade in superior mesenteric or terminal aortic areas. This suggested the presence of basal sympathetic vasoconstrictor tone in the renal area. After ganglionic blockade, the pressor effect of AVP was enhanced significantly. The increase in renal resistance induced by AVP was augmented after ganglionic blockade, whereas increases in superior mesenteric or terminal aortic resistance remained unchanged following ganglionic blockade. Our data suggest that the vasoconstrictor effect of AVP on renal vascular area is reduced by a mechanism which inhibits renal sympathetic basal tone.

Animals↗
PubMed1993

Intraretinal neurotrophic activity prevents the degeneration of ganglion cells in retinal explants.

The degeneration of ganglion cells was studied in neural retina explanted from the eyes of newborn rats. The ganglion cells were detected by the presence of retrogradely transported horseradish peroxidase injected into the superior colliculus. The time course of cell death among the axotomized ganglion cells in the explants was similar to that found in vivo after axotomy in neonatal rats. The effect of culture media conditioned with retinal cells from either newborn rats or chick embryos was tested on the survival of ganglion cells in the explants. Both conditioned media increased 2- to 3-fold the survival of rat retinal ganglion cells after 2 days in culture. The data show that soluble trophic factors released by retinae of distinct species can influence the survival of ganglion cells within their histotypic microenvironment.

Animals↗
PubMed1994

Targeting and activity-related dendritic modification in mammalian retinal ganglion cells.

We have studied factors that influence the development of dendritic morphology in hamster retinal ganglion cells. By combining fluorescent retrograde tracing with in vitro Lucifer yellow injection into fixed retina, cells with appropriate and inappropriate visuotopic projections have been compared. In adult hamsters, cells with an aberrant ipsilateral projection from the nasal retina display a uniformly sparse dendritic morphology. However, following monocular enucleation at postnatal day 0 (P0), this population displays a significantly enhanced dendritic complexity in the adult. By contrast, removal of one eye at P6 or at P12 produces progressively less effect. These results suggest that dendritic complement of the adult aberrant projection can be regulated by altering the early postnatal axonal environment. The development of aberrant ganglion cells was investigated to determine the relative influences of cell death and dendritic remodeling in shaping the composition of the adult aberrant population. Aberrant cells were found to be indistinguishable from other cells in nasal retina throughout early development. After ganglion cell death (P1-P12) is over, aberrant cells still display a full range of cell types. However, at eye opening (P16) they undergo a rapid loss of dendritic complexity by remodeling. By P22, aberrant cells display a uniformly sparse dendritic morphology. When hamsters were raised in the dark between P12 (the end of ganglion cell death) and P22, this severe remodeling was blocked. This block was maintained when hamsters were dark reared to P42. Hence, both dark rearing and monocular enucleation at P0 produce similar effects on the development of visuotopically inappropriate hamster retinal ganglion cells. We speculate that the patterns of dendritic sculpting that we have observed reflect activity-mediated modulation of dendritic form via retrograde signals from the terminal arbors. This has implications for retinal ganglion cell morphological classification and, more generally, for mechanisms that influence the dendritic development of other neurons in the CNS.

Animals↗
PubMed1993

Foveal ganglion cell loss is size dependent in experimental glaucoma.

PURPOSE: The purpose of this study was to study the pattern of foveal ganglion cell loss in experimental glaucoma. METHODS: Retinal ganglion cell size and number in the foveal region of seven monkey eyes with experimental glaucoma was determined and compared to normal monkey eyes. Serial sections of macular retina were studied in two regions: the plateau of peak density of ganglion cells (800-1100 microns from the fovea), and within 500 microns of the foveal center. RESULTS: In normal eyes, cell densities were 37,900 +/- 2700 in the foveal plateau and 17,200 +/- 1800 cells/mm2 in the foveal center. There was selective loss of larger ganglion cells in glaucoma eyes. The degree of foveal ganglion cell loss was significantly correlated to the degree of nerve fiber loss in the temporal optic nerve of the same eye. CONCLUSIONS: Detection of early, central visual function loss in glaucoma could be enhanced by testing functions subserved by larger retinal ganglion cells.

Animals↗
PubMed1996

Chronic low-dose glutamate is toxic to retinal ganglion cells. Toxicity blocked by memantine.

PURPOSE: It is well known that acute exposure to high concentrations of glutamate is toxic to central mammalian neurons. However, the effect of a chronic, minor elevation over endogenous glutamate levels has not been explored. The authors have suggested that such chronic exposure may play a role in glaucomatous neuronal loss. In the current study, they sought to explore whether a chronic, low-dose elevation in vitreal glutamate was toxic to retinal ganglion cells and whether this toxicity could be prevented with memantine, a glutamate antagonist. METHODS: Rats were injected serially and intravitreally with glutamate to induce chronic elevations in glutamate concentration. A second group of rats was treated with intraperitoneal memantine and glutamate. Control groups received vehicle injection with or without concurrent memantine therapy. After 3 months, the animals were killed, and ganglion cell survival was evaluated. RESULTS: Intravitreal injections raised the intravitreal glutamate levels from an endogenous range of 5 to 12 microM glutamate to 26 to 34 microM. This chronic glutamate elevation killed 42% of the retinal ganglion cells after 3 months. Memantine treatment alone had no effect on ganglion cell survival. However, when memantine was given concurrently with low-dose glutamate, memantine was partially protective against glutamate toxicity. CONCLUSIONS: These data suggest that minor elevations in glutamate concentration can be toxic to ganglion cells if this elevation is maintained for 3 months. Furthermore, memantine is efficacious at protecting ganglion cells from chronic low-dose glutamate toxicity.

Animals↗
PubMed1996

Protection of retinal ganglion cells from natural and axotomy-induced cell death in neonatal transgenic mice overexpressing bcl-2.

Approximately half of the retinal ganglion cells (RGCs) present in the rodent retina at birth normally die during early development. Overexpression of the photo-oncogene bcl-2 recently has been shown to rescue some neuronal populations from natural cell death and from degeneration induced by axotomy of nerves within the peripheral nervous system. Here we study in vivo the role of the overexpression of bcl-2 in the natural cell death of RGCs and in the degenerative process induced in these cells by transection of the optic nerve. We find that in newborn bcl-2 transgenic mice, the number of RGCs undergoing natural cell death is considerably lower than in wild-type pups. Consistently, a vast majority (90%) of the ganglion cells found in the retina of neonatal transgenics are maintained in adulthood, whereas only 40% survive in wild-type mice. After transection of the optic nerve, the number of degenerating ganglion cells, determined by counting pyknotic nuclei or nuclei with fragmented DNA, is substantially reduced in transgenic mice. In wild-type animals, almost 50% of ganglion cells degenerate in the 24 hr after the lesion, whereas almost the entire ganglion cell population survives axotomy in transgenic mice. Therefore, overexpression of bcl-2 is effective in preventing degeneration of this neuronal population, raising the possibility that ganglion cells are dependent on the endogenous expression of bcl-2 for survival. The remarkable rescue capacity of bcl-2 overexpression in these neurons makes it an interesting model for studying natural cell death and responses to injury in the CNS.

Animals↗
PubMed1996

[A case of severe hypertension caused by stellate ganglion block in a patient with facial palsy].

We report a case of severe hypertension following stellate ganglion block. A 61-year old woman received the left stellate ganglion block with 5 ml of 1% mepivacaine for her left facial palsy. Before the stellate ganglion block, blood pressure was 120/68 mmHg and heart rate was 62 b.p.m. Seven minutes after the left stellate ganglion block, blood pressure increased to 230/140 mmHg, but heart rate was unchanged. Systolic blood pressure remained above 190 mmHg for 60 minutes following the stellate ganglion block. We suggest that the extreme increase in blood pressure was due to the vagal nerve block associated with the left stellate ganglion block.

Anesthetics, Local↗
PubMed1998

Dendritic field development of retinal ganglion cells in the cat following neonatal damage to visual cortex: evidence for cell class specific interactions.

A well-known feature of the mammalian retina is the inverse relation that exists in central and peripheral retina between the density of retinal ganglion cells and their dendritic field sizes. Functionally, this inverse relation is thought to represent a means by which retinal coverage is maintained, despite significant changes in ganglion cell density. While it is generally agreed that the dendritic fields of mature retinal ganglion cells reflect, in part, competitive interactions that occur during development, the issue of whether these interactions are cell class specific remains unclear. In order to examine this question, we used intracellular staining techniques and an in vitro, living retina preparation to compare the soma and dendritic field sizes of alpha and beta ganglion cells from normal retinae with those of cells located in matched areas of retinae in which the density of beta ganglion cells had been reduced selectively by neonatal removal of visual cortex areas 17, 18, and 19. Our intracellular data show that while an early, selective, reduction in beta cell density has little or no effect on the cell body and dendritic field sizes of mature alpha cells, it results in a 13% increase in the mean soma area and an 83% increase in the mean dendritic field area of surviving beta cells. This differential effect suggests that the soma and dendritic field sizes of alpha and beta ganglion cells in the mature cat retina result primarily from competitive interactions during development that are cell class specific.

Animals↗
PubMed1998

Contributions of the optic tectum and the retina as sources of brain-derived neurotrophic factor for retinal ganglion cells in the chick embryo.

Retinal ganglion cells (RGC) are supported by brain-derived neurotrophic factor (BDNF), but it is not known if BDNF acts as a target-derived factor or as an afferent or autocrine trophic factor. Here we demonstrate that BDNF mRNA is expressed in the retinorecipient layer of the chick optic tectum as well as in the inner nuclear layer and ganglion cell layer of the retina. Amacrine cells rather than RGC were the main source of BDNF mRNA in the ganglion cell layer, as determined by in situ hybridization that was combined with retrograde labeling of RGC and destruction of RGC by optic stalk transection, followed by quantitative RT-PCR. Cells in the ganglion cell layer as well as the retinorecipient layers of the optic tectum were BDNF-immunolabeled. After injections into the tectum, radio-iodinated BDNF was transported to the retina where autoradiographic label accumulated in the inner plexiform and ganglion cell layers. After intraocular injection, iodinated BDNF accumulated in these same retinal layers and correlated with the distribution of p75 neurotrophin receptor protein. The majority of cross-linked receptor-bound BDNF in the retina immunoprecipitated with p75 antibodies. No difference in the intensity of BDNF immunolabel was observed in the experimental retina or tectum after optic stalk transection, indicating that most of the BDNF in the RGC was not derived from the optic tectum. These data indicate that a substantial fraction of the BDNF in the ganglion cell layer is derived from local sources, afferents within the retina, rather than from the optic tectum via retrograde transport.

Animals↗