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PubMed1989

Distribution of phenylethanolamine N-methyltransferase cell bodies, axons, and terminals in monkey brainstem: an immunohistochemical mapping study.

Adrenaline (epinephrine) is an important candidate transmitter in descending spinal control systems. To date intrinsic spinal adrenergic neurons have not been reported; thus adrenergic input is presumably derived from brainstem sites. In this regard, the localization of adrenergic neurons in the brainstem is an important consideration. Maps of adrenergic cell bodies and to a lesser extent axons and terminal fields have been made in various species, but not in monkeys. Thus, the present study concerns the organization of adrenergic systems in the brainstem of a monkey (Macaca fascicularis) immunohistochemically mapped by means of an antibody to the enzyme phenylethanolamine N-methyltransferase (PNMT). PNMT-immunostained cell bodies are distributed throughout the medulla in two principal locations. One concentration of labeled cells is in the dorsomedial medulla and includes the nucleus of the solitary tract (NTS), the dorsal motor nucleus of the vagus (X), and an area ventral to X in a region of the reticular formation (RF) known as the central nucleus dorsalis (CnD) of the medulla. A few scattered cells are observed in the periventricular gray just ventral to the IVth ventricle and on midline in the raphe. The second major concentration of PNMT-immunostained cells is located in the ventrolateral RF, lateral and dorsolateral to the inferior olive (IO), including some cells in the rostral part of the lateral reticular nucleus (LRN). Terminal fields are located in the NTS, X, area postrema (AP), and the floor of the IVth ventricle in the medulla and pons. A light terminal field is also observed in the raphe, particularly raphe pallidus (RP). A heavy terminal field is present in locus coeruleus (LC). Fibers labeled for PNMT form two major fiber tracts. One is in the dorsomedial RF extending as a well-organized bundle through the medulla, pons, and midbrain. A second tract is located on the ventrolateral edge of the medulla and caudal pons. Fibers in this tract appear to descend to the spinal cord. A comparison with maps of other catecholamine neurons in primates is discussed, confirming that the distribution of the adrenergic system in monkeys is similar to that described in the human.

Adrenergic Fibers↗
PubMed1992

Projections from the commissural subnucleus of the nucleus of the solitary tract: an anterograde tracing study in the cat.

The commissural subnucleus (COM) of the nucleus of the solitary tract (NTS) is known to receive primary afferents from the lungs and other viscera innervated by the vagus nerve, and thus to participate in central autonomic and respiratory control. The aim of the present study was to identify the areas of terminal arborizations of COM neurons in order to examine brainstem sites which may be involved in reflex responses mediated by these neurons. The projections were studied in cats, using biocytin as an anterograde tracer. Labeled fibers and terminal boutons were visualized by horseradish-peroxidase histochemistry, 2-3 days after microinjection of the tracers into the COM 1-2 mm caudal to the obex. Labeled axons were examined in the brainstem from the rostral pons to the caudal medulla and were found bilaterally, with an ipsilateral predominance, mainly in the following regions: (1) The dorsolateral rostral pons. Terminal boutons were observed in the lateral and medial parabrachial nuclei, Kölliker-Fuse nucleus, and around the mesencephalic trigeminal tract. This area corresponds to the pontine respiratory group also known as the "pneumotaxic center." (2) The pontine area dorsolateral to the superior olivary nucleus. This region contains the A5 noradrenergic cell group; (3) Near the ventral surface, below the facial nucleus. This area overlaps with the 'retrotrapezoid nucleus.' (4) Respiration-related areas of the medulla, including the dorsal and ventral respiratory groups, and the Bötzinger complex. (5) The dorsal motor nucleus of the vagus. These results suggest that the COM is involved in reflex arcs, which have both respiratory functions and autonomic functions. The pathway to the dorsolateral pons, which has been identified in our recent electrophysiological study is likely to play a role in mediating respiratory responses from pulmonary rapidly adapting receptors. Other pathways may represent additional projections from second-order neurons receiving input from this group of lung receptors, or projections from as yet unidentified neurons that relay information from different afferents terminating in the COM.

Animals↗
PubMed1995

Noradrenergic system in the chicken brain: immunocytochemical study with antibodies to noradrenaline and dopamine-beta-hydroxylase.

A light microscopic immunocytochemical study, using antisera against noradrenaline (NA) and dopamine-beta-hydroxylase (DBH), revealed the noradrenergic system in the brain of the chicken (Gallus domesticus). NA- and DBH-immunoreactive (ir) elements showed a similar distribution throughout the whole brain. The neurons immunoreactive for the monoamine were confined to the lower brainstem, the pons, and the medulla. In the pons, a rather dense group of cells was found in the dorsal, most posterior part of the locus coeruleus and in the caudal nucleus subcoeruleus ventralis. A few labeled cells appeared in and around the nucleus olivaris superior in the most caudal part of the metencephalic tegmentum. In the medulla oblongata, noradrenergic cells could be visualized at the level of the nucleus of the solitary tract and in a ventrolateral complex. Virtually all regions of the brain contained a rather dense innervation by NA- and DBH-immunopositive varicose fibers. Noradrenergic fibers and terminals were especially abundant in the ventral forebrain and in the periventricular hypothalamic regions. DBH-ir and NA-ir fibers, varicosities, and punctate structures could be observed in close association with immunonegative perikarya in several brain regions, more specifically in the ventral telencephalon, in the mid- and tuberal hypothalamic region, and in the dorsal rostral pons. Some perikarya in these brain areas were completely surrounded by noradrenergic structures that formed pericellular arrangements around the cells. The present study on the distribution of the noradrenergic system in the brain of the chicken combined with the results of a previous report on the distribution of L-Dopa and dopamine in the same species (L. Moons, J. van Gils, E. Ghijsels, and F. Vandesande, 1994, J. Comp. Neurol. 346:97-118) offers the opportunity to differentiate between the various catecholamines in the brain of this vertebrate. The results are discussed in relation to catecholaminergic systems previously reported in avian species and in the mammalian brain.

Adrenergic Fibers↗
PubMed2007

Diffusion-weighted magnetic resonance imaging differentiates Parkinsonian variant of multiple-system atrophy from progressive supranuclear palsy.

Progressive supranuclear palsy (PSP) and the parkinsonian variant of multiple-system atrophy (MSA-P) may present with a similar phenotype. Magnetic resonance diffusion-weighted imaging (DWI) has been shown to be a sensitive discriminator of MSA-P from Parkinson's disease (PD). We studied 20 PSP, 11 MSA-P, 12 PD patients and 7 healthy controls in order to investigate whether regional apparent diffusion coefficients (rADCs) help distinguish PSP and MSA-P; whether rADCs are correlated with clinical disease severity scores; and the relationship between brainstem and cerebellar volumes and rADCs in PSP and MSA-P. The Unified Parkinson's Disease Rating Scale, Hoehn and Yahr score, Mini Mental State Examination, and frontal assessment battery were recorded in all patients. Regional ADCs were measured in the middle cerebellar peduncle (MCP), caudal and rostral pons, midbrain, decussating fibers of the superior cerebellar peduncle, thalamus, putamen, globus pallidus, caudate nucleus, corpus callosum, frontal and parietal white matter, as well as the centrum semiovale. In MSA-P, rADCs in the MCP and rostral pons were significantly greater than in PSP (P < 0.001 and 0.009) and PD (P < 0.001 and = 0.002). Stepwise logistic regression revealed that the MCP rADC distinguishes MSA-P from PSP with a sensitivity of 91% and a specificity of 84%. Increased brainstem rADCs were associated with motor deficit in MSA-P and PSP. Increased rADCs in the pons and MCP were associated with smaller pontine and cerebellar volumes in MSA-P. rADCs distinguish MSA-P from PSP. These have a clinical correlate and are associated with reduced brainstem and cerebellar volumes.

Aged↗
PubMed2003

Visualization of alpha5 subunit of GABAA/benzodiazepine receptor by 11C Ro15-4513 using positron emission tomography.

Although [(11)C]Ro15-4513 and [(11)C]flumazenil both bind to the central benzodiazepine (BZ) receptors, the distributions of the two ligands are not identical in vivo. Moreover, the in vivo pharmacological properties of [(11)C]Ro15-4513 have not been thoroughly examined. In the present study, we examined the pharmacological profile of [(11)C]Ro15-4513 binding in the monkey brain using positron emission tomography (PET). [(11)C]Ro15-4513 showed relatively high accumulation in the anterior cingulate cortex, hippocampus, and insular cortex, with the lowest uptake being observed in the pons. Accumulation in the cerebral cortex was significantly diminished by the BZ antagonist flumazenil (0.1 mg/kg, i.v.), but not that in the pons. Using the pons as a reference region, the specific binding of [(11)C]Ro15-4513 in most of the cerebral cortex including the limbic regions clearly revealed two different affinity sites. On the other hand, specific binding in the occipital cortex and cerebellum showed only a low affinity site. Zolpidem with affinity for alpha1, alpha2, and alpha3 subunits of GABA(A)/BZ receptor fully inhibited [(11)C]Ro15-4513 binding in the occipital cortex and cerebellum, while only about 23% of the binding was blocked in the anterior cingulate cortex. Diazepam with affinity for alpha1, alpha2, alpha3, and alpha5 subunits inhibited the binding in all brain regions. Since Ro15-4513 has relatively high affinity for the alpha5 subunit in vitro, these in vivo bindings of [(11)C]Ro15-4513 can be interpreted as the relatively high accumulation in the fronto-temporal limbic regions representing binding to the GABA(A)/BZ receptor alpha5 subunit.

Animals↗
PubMed2002

Magnetization transfer measurements of brain structures in patients with multiple system atrophy.

To determine whether magnetization transfer imaging (MTI) demonstrates abnormalities in the brain structures of patients with multiple system atrophy (MSA), we examined 12 patients with clinically probable MSA and 11 control subjects. We calculated magnetization transfer ratios (MTRs) using region of interest analysis from MTI and assessed abnormal signal changes on T2-weighted images. MTRs of the base of the pons, middle cerebellar peduncle, putamen, and white matter of the precentral gyrus were significantly lower in the MSA patients than in the controls. Abnormal signal changes on T2-weighted images were observed in the base of the pons (n = 6), middle cerebellar peduncle (n = 7), and putamen (n = 7). MTRs of regions with abnormal signals were significantly lower than those of regions without abnormal signals and those in the controls. Even the MTRs of the regions without abnormal signals were lower than those in the controls. MTRs of the pyramidal tract, including white matter of the precentral gyrus, posterior limb of the internal capsule, cerebral peduncle, and base of the pons, were significantly lower in patients with pyramidal tract sign (n = 7) than in the controls. Patients with asymmetrical parkinsonism (n = 5) showed significantly lower MTRs in the putamen contralateral to the predominant side of parkinsonian symptoms than the ipsilateral side, although asymmetry of abnormal signal changes on T2-weighted images was not evident in more than half of those patients. This study showed that MTI demonstrates abnormalities in the brains of patients with MSA that seem to reflect underlying pathological changes and that the pathological changes detected by MTI seem to give rise to clinical symptoms. This study also showed that the abnormalities are detected more sensitively and over a larger area by MTI than by conventional magnetic resonance imaging.

Aged↗
PubMed1976

An experimental study of the corticofugal system following cerebral lesions in the albino rats.

Following neonatal lesion in the sensorimotor and adjacent cortex (SMC) in the albino rats, a corresponding region in the contralateral intact cortex gave rise to a bilateral corticofugal projection to the pretectal area, superior colliculus, pons, gracile and cuneate nuclei, the nucleus of Bischoff, caudal medullary reticular formation and the spinal cord. The anomalous growth response was greatest when the initial lesion was made within the first three days after birth, but became much reduced as the initial lesion was made at a progressively older age. A significant amount of anomalous projection could, however, still be demonstrated in the pons even in animals first lesioned as late as 20 days postnatal. The sprouting phenomenon was precise and ordered and in the various regions studied, the pattern of anomalous projection mirrored that of the normal projection. The anomalous fibres reached their specific target cells either by deflecting ipsilaterally at the pyramidal decussation to reach the spinal cord and the caudal medulla or by running across the mid-line to the contralateral pons, superior colliculus, pretectal area and the thalamic ventrobasal complex. In contradistinction to the findings of Hicks and D'Amato (1975) no anomalous fibres could be traced to the trigeminal complex and the rostral reticular formation in the medulla. A mechanism of competitive occupation of vacant synaptic sites was proposed to explain the sprouting phenomenon.

Animals↗
PubMed1990

Localization of growth hormone-releasing factor-like immunoreactivity in the hypothalamo-hypophysial system of some teleost species.

An antiserum to growth hormone-releasing factor (GRF) 1-44 was applied on brain and pituitary sections of nine teleost species. Immunoreactive (ir) perikarya were demonstrated in parvo- and magnocellular portions of the preoptic nucleus (PON) and occasionally in the nucleus lateralis tuberis. The two tracts originating in the PON ran ventro-laterally toward the optic chiasm and then caudally in the basal hypothalamus. In the pars distalis (PD) of the eel, carp, goldfish and salmonids, GRF-ir fibers did not enter the rostral PD and few fibers passed close to somatotropes. In Myoxocephalus and Mugil, a variable number of ir-fibers passed close to cells of the rostral and proximal PD. In the neurointermediate lobe, GRF-ir fibers were located exclusively in the neural tissue of the eel and trout. In goldfish, carp and Myoxocephalus, GRF-ir fibers entered the intermediate lobe. This antiserum also labeled corticotrops and, to a lesser extent, melanotrops in the pituitary of cyprinids. A variable number of perikarya contained both GRF and vasotocin in the PON of the eel. In all teleost species studied so far, the distribution patterns of GRF are different, and the function of the various adenohypophysial cell types appears to be differently modulated, according to the variable distribution of GRF in the pituitary.

Anguilla↗
PubMed1989

Chronic administration of clomipramine prevents the increase in serotonin and noradrenaline induced by chronic stress.

The effects of chronic clomipramine administration (15 mg/kg daily for 23 days) on changes in serotonin (5-hydroxytryptamine, 5-HT), 5-hydroxyindoleacetic acid (5-HIAA) and noradrenaline (NA) induced by chronic stress have been studied in the rat brain. Chronic stress increased 5-HT in midbrain, pons and hippocampus, 5-HIAA in frontal cortex, midbrain, pons and hippocampus, and NA in midbrain and striatum. Chronic clomipramine significantly decreased the levels of 5-HT in most regions. In hypothalamus, hippocampus and perhaps in frontal cortex this effect possibly reflects decreased synthesis caused by an action on presynaptic 5-HT receptors. However, in midbrain, pons and striatum decreased 5-HT could not be attributed to a decrease in its synthesis since 5-HIAA also increased. This drug treatment also reduced NA in all regions except the striatum. Nevertheless, conclusions on NA synthesis or turnover cannot be drawn since only NA levels were measured. When administered concurrently, chronic clomipramine prevented the increases in 5-HT, 5-HIAA and NA produced by chronic stress. These results are in good accordance with previous findings showing that chronic antidepressant treatment also prevented behavioural disturbances induced by chronic stress.

Animals↗
PubMed1984

Comprehension of nonverbal communication: a reexamination of the social competencies of learning-disabled children.

This study was designed to determine whether learning-disabled (LD) children differed from nondisabled (NLD) children in their ability to comprehend nonverbal communication when potential attentional differences between the groups were controlled. In addition, the relationship between nonverbal comprehension and social competence was assessed. Thirty LD and 30 NLD boys between 9 and 12 years of age were administered a short form of the Profile of Nonverbal Sensitivity (PONS) to assess nonverbal comprehension; social competence measures included teachers' ratings of aggressive and withdrawn behaviors using the Behavior Problem Checklist, and "blind" judges' ratings of performance on a role-play of friendship-making skills. Under attention-incentive conditions, no performance differences between LD and NLD children were found on the PONS; however, LD children were judged to be more withdrawn and less socially skilled. While PONS scores were not related to other social competence measures, they were associated with academic achievement and IQ. Results emphasize the importance of considering the presence of attentional problems in LD children that may interfere with an accurate assessment of their skills.

Achievement↗
PubMed1991

Metallothionein-I induction by stress in specific brain areas.

The distribution of metallothionein-I (MT) in several areas of the brain and its induction by immobilization stress has been studied in the rat. MT content was highest in hippocampus and midbrain and lowest in frontal cortex and pons plus medulla oblongata. Immobilization stress for 18 hours (which was accompanied by food and water deprivation) significantly increased MT levels in the frontal cortex, pons plus medulla oblongata and hypothalamus, but not in midbrain and hippocampus. The effect of stress on MT levels was specific as food and water deprivation along had no significant effect on MT levels in any of the brain areas studied. The effect of stress on MT levels was independent of changes in cytosolic Zn content; this was generally unaffected by stress or food and water deprivation but decreased in pons plus medulla oblongata from stressed rats. The results suggest that MT is induced more significantly in the brain areas that are usually involved in the response of animals to stress.

Analysis of Variance↗
PubMed1990

Monoamine and amino acid content in brain regions of Brattleboro rats.

Monoamine and amino acid content were measured in brain regions from 12 week old male, homozygous Brattleboro (DI, n = 12) and Long-Evans control (LE, n = 12) rats. Norepinephrine (NE) content was significantly elevated (16-25%) in the spinal cord, pons-medulla and anterior hypothalamus of DI rats when compared to LE controls. NE content of the neurointermediate lobe of pituitary in DI rats was almost twice that of LE controls. Serotonin content was also significantly elevated in the spinal cord, pons-medulla, anterior hypothalamus and forebrain of DI rats relative to the LE controls. Taurine content in DI rats was increased (31-42%) above that of LE rats in the anterior hypothalamus, striatum and forebrain. Glutamine content was also greater in DI rats than LE in the spinal cord, pons-medulla, anterior hypothalamus, striatum, hippocampus and forebrain. The changes in monoamine and amino acid content were discussed in relation to the cardiovascular and osmoregulatory deficits that are present in DI rats due to arginine vasopressin (AVP) deficiency. The possible role of AVP in modulating NE turnover was also discussed. The increase in brain TAU content in DI rats may be a physiological response to hypernatremia.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1992

Neurochemical changes in rats chronically treated with a high concentration of manganese chloride.

Several neurochemical parameters were studied in brain regions of rats chronically treated with a high concentration of manganese chloride (20 mg MnCl2.4H2O per ml. of drinking water) throughout development until adulthood. Large increases in Mn accumulation were found in all brain regions (hypothalamus, +530%; striatum, +479%; other regions, +152 to +250%) of Mn-treated adult rats. In these animals, Ca levels were decreased (-20 to -46%) in cerebellum, hypothalamus, and cerebral cortex but were increased (+186%) in midbrain. Mg levels were decreased (-12 to -32%) in pons and medulla, midbrain, and cerebellum. Fe levels were increased (+95%) in striatum but were decreased (-28%) in cerebral cortex. Cu levels were increased (+43 to +100%) in pons and medulla and striatum but Zn levels were decreased (-30%) in pons and medulla. Na levels were increased (+22%) in striatum but those of K and Cl remained unchanged. Type A monoamine oxidase activities were decreased (-13 to -16%) in midbrain, striatum, and cerebral cortex, but type B monoamine oxidase activities decreased (-13%) only in hypothalamus. Acetylcholinesterase activities were increased (+20 to +22%) in striatum and cerebellum. The results are consistent with our hypothesis that chronic manganese encephalopathy not only affects brain metabolism of Mn but also that of other metals.

Acetylcholinesterase↗
PubMed1992

Changes in brain regional manganese and magnesium levels during postnatal development: modulations by chronic manganese administration.

Manganese (Mn) and magnesium (Mg) levels in hypothalamus, cerebellum, pons and medulla, striatum, midbrain, and cerebral cortex of control and Mn-treated (10 mg MnCl2.4H2O per ml of drinking water) rats during postnatal development were studied using instrumental neutron activation analysis. The age-dependent Mn accumulation showed regional variation: at day 5, this accumulation was most marked in striatum (12.05 micrograms/g wet weight) but least marked in cerebral cortex (0.85 micrograms/g wet weight). By day 10, pons and medulla, and hypothalamus were regions with, respectively, the highest (4.73 micrograms/g wet weight) and the lowest (0.52 micrograms/g wet weight) Mn levels. By contrast, brain regional Mn variations were less pronounced in weanling and adult rats. The age-dependent Mg accumulation showed regional variation at day 5, being most marked in pons and medulla (720 micrograms/g wet weight) and least marked in cerebral cortex (295 micrograms/g wet weight). Mg levels in all regions decreased after day 5; by day 120, only Mg level in cerebral cortex was lower than levels in other regions (the latter being very similar). In general, the age-related decreases in Mn and Mg levels paralleled the decreases in water content and increases in tissue weight, suggesting that the maturation of the blood-brain barrier may play important role(s) in brain Mn and Mg homeostasis. Chronic Mn-treatment from conception onwards altered the regional Mn and Mg distribution patterns during development. Our results are consistent with the hypothesis that chronic Mn toxicity exerts modulatory effects on brain regional metabolism and homeostasis of Mn and other metals during development.

Aging↗
PubMed1991

Stereotactic anatomy of the posterior cranial fossa. A study of the transcerebellar approach to the brainstem.

The stereotactic transcerebellar (suboccipital) approach to the brainstem is one of the most accessible routes to reach targets located in the pons or in the medulla oblongata. Its use requires a perfect knowledge of the stereotactic anatomy of the posterior cranial fossa, and a standard reference system related to structures of the brainstem itself which can easily be visualized by Nuclear Magnetic Resonance. The present work consists in a three-dimensional variability study of the human posterior cranial fossa with its main contents, based on the investigation of 30 normal specimens (hemifossae). A new stereotactic reference system is proposed for the pons and the medulla, comprising three orthogonal** planes: the midsagittal plane, the IVth ventricular floor plane and the pontomedullary junction plane. A standard "safety access tunnel" was defined for the transcerebellar approach to the pons and, with some limitations, to the medulla. A complementary investigation, based upon angiographic studies, was carried out to define a safe "entry zone" to the posterior cranial fossa of the occipital bone beneath the transverse venous sinus.

Adult↗
PubMed2001

Regional metabolite levels of the normal posterior fossa studied by proton chemical shift imaging.

MR spectroscopy of the posterior fossa is pitted with numerous technical difficulties. It is, however, of great clinical interest in the study of the degenerative diseases and tumors of this area. We have developed a method to perform 2D CSI of this area, by using a sagittal slice and a careful positioning of outer volume saturation. We performed this acquisition in 30 healthy volunteers to determine the normal metabolic ratios in five voxels of this area (mesencephalon, pons, medulla oblongata, vermis, cerebellar white matter). The main technical difficulty was magnetic field inhomogeneity in the lower brainstem generated by dental alloys. However, 88% of the voxels were of sufficient quality to be analyzed. The statistically significant regional variations were a higher NAA/Cr ratio in the pons than in the medulla oblongata, higher Cho/Cr in the pons than in the mesencephalon and higher Cho/Cr in the cerebellar white matter than in the vermis. We conclude that 2D CSI of the brainstem, although technically delicate can be performed in most patients.

Brain↗
PubMed2002

Characteristic MRI findings in multiple system atrophy: comparison of the three subtypes.

We reviewed MRI findings in 29 patients with probable multiple system atrophy (MSA) to see whether there were common and or less common neuroradiological findings in the various clinical subtypes. We divided the patients into three clinical subtypes according to initial and predominant symptoms: 14 with olivopontocerebellar atrophy (OPCA), eight with the Shy-Drager syndrome (SDS) and seven with striatonigral degeneration (SND). The patients showed atrophy of the brain stem and cerebellum, high signal on T2-weighted images of the base of the pons and middle cerebellar peduncles, high and low signal on T2-weighted images of the putamen and atrophy of frontal and parietal lobes. The degree of atrophy of the middle cerebellar peduncle and cerebellum was greater in OPCA patients and a high-signal lateral rim to the putamen more frequent in SND. However, all findings were observed in all subtypes, and the degrees of atrophy of the putamen and pons and the frequency of high signal in the base of the pons were similar in the subtypes. We also found atrophy of the cerebral hemispheres, especially the frontal and parietal lobes, but its degree was not significantly different in the various subtypes. Our findings suggest that, although MSA can be divided clinically into three subtypes, most of the features on MRI are common and overlap in the subtypes, independently of the clinical presentation.

Brain↗
PubMed2006

Paediatric brain-stem gliomas: MRI, FDG-PET and histological grading correlation.

BACKGROUND: MRI and FDG-PET may predict the histological grading of paediatric brain-stem gliomas. OBJECTIVE: To assess MRI findings and metabolic imaging using FDG-PET of brain-stem gliomas based on histological grading. MATERIALS AND METHODS: Included in the study were 20 paediatric patients (age 3-14 years, mean 8.2 years) with brain-stem glioma (five glioblastomas, ten anaplastic astrocytomas and five low-grade astrocytomas). MR images were assessed for the anatomical site of tumour origin, focality, pattern of tumour growth, and enhancement. RESULTS: All glioblastomas were located in the pons and showed diffuse pontine enlargement with focally exophytic features. Eight anaplastic astrocytomas were located in the pons and demonstrated diffuse pontine enlargement without exophytic features. Low-grade astrocytomas were located in the pons, midbrain or medulla and showed focally exophytic growth features and peripheral enhancement. In 12 patients in whom FDG-PET was undertaken, glioblastomas showed hypermetabolic or hypometabolic lesions, anaplastic astrocytomas showed no metabolic change or hypometabolic lesions and low-grade astrocytomas showed hypometabolism compared with the cerebellum. CONCLUSION: MRI findings correlated well with histological grading of brain-stem gliomas and MRI may therefore predict the histological grading. FDG-PET may be helpful in differentiating between anaplastic astrocytoma and glioblastomas among high-grade tumours.

Adolescent↗