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Biomedical subjects

D Norman

Publications and source records attributed to D Norman.

At least 145 records · Page 8Linked to original sources
PubMed1989

MR imaging in the tethered spinal cord syndrome.

MR examinations of the spine were reviewed in 25 patients with a clinical diagnosis of tethered spinal cord. In 21 patients (84%), the level of the tip of the conus was below the mid L2 vertebral body. The causes of the tethering were spinal lipomas (72%), tight filum terminale syndrome (12%), diastematomyelia (8%), and myelomeningocele (8%). These entities were readily identified in all instances. Bony dysraphisms were well demonstrated by MR. Interestingly, cavitary lesions/myelomalacia of the conus or the cord adjacent to the tethering lesion were seen with appropriate images in nine of 20 patients. This unexpected finding may have diagnostic and/or prognostic significance. Spinal MR was found to be extremely useful in the evaluation of the suspected tethered spinal cord. It was able to visualize the conus medullaris, assess the thickness of the filum terminale, identify traction lesions, and evaluate associated bony dysraphisms.

Adolescent↗
PubMed1989

Interventional neurovascular treatment of traumatic carotid and vertebral artery lesions: results in 234 cases.

Traumatic injuries to the head and neck that result in arteriovenous fistulae are often difficult to treat by direct surgical access. This is because of anatomic location, instability of the acutely injured patient, and difficulty in localizing the exact site of injury. Between 1974 and 1988, 234 consecutive cases of traumatic injuries to the carotid or vertebral artery were evaluated by our group for intravascular embolization therapy. This included 206 cases of direct and seven cases of indirect carotid-cavernous sinus fistulae and 21 cases of traumatic vertebral fistulae. A variety of devices including detachable balloons, liquid tissue adhesives, microcoils, and silk suture were used with the goal of fistula occlusion and preservation of the parent vessel. This was achieved in 193 cases (82%). In the remaining 41 cases (18%), the carotid or vertebral artery had to be occluded by endovascular occlusion techniques because of extensive vascular injury in 28 cases and subtotal occlusion of the fistula in 13 cases. Complications included transient cerebral ischemia in six cases, pseudoaneurysm formation in five cases, stroke in five cases, and peripheral nerve injury in one case. The development of interventional neurovascular techniques has altered the management of these acutely injured patients. The preferred method for treatment has shifted from direct surgical access under general anesthesia to endovascular therapy under local anesthesia.

Adolescent↗
PubMed1989

Revised classification of posterior fossa cysts and cystlike malformations based on the results of multiplanar MR imaging.

MR and clinical data on 31 patients with posterior fossa CSF collections were analyzed. A clear separation of these patients into classical categories was not possible because of new information obtained from the MR images. We present a new classification of these disorders. The Dandy-Walker malformation, Dandy-Walker variant, and mega-cisterna magna seem to represent a continuum of developmental anomalies of the posterior fossa. A possible embryologic basis for this continuum is suggested. Discrete posterior fossa CSF collections that are clearly separate from the fourth ventricle and vallecula are classified as posterior fossa cysts. Posterior fossa CSF collections that communicate with the fourth ventricle and are associated with cerebellar atrophy are classified as prominent cisterna magna. Both the Dandy-Walker complex and posterior fossa cysts can cause enlargement of the posterior fossa and scalloping of the inner table of the occipital bone. The Dandy-Walker complex presents with seizures, developmental delay, and enlarging head size; it requires CSF diversion when associated with hydrocephalus. Posterior fossa cysts present with symptoms of a posterior fossa mass; they generally require surgical resection. Prominent cisterna magna is a result of degenerative disorders and requires no surgical therapy. This new classification facilitates both diagnosis and therapy of these disorders. MR revealed that disorders previously referred to as the Dandy-Walker malformation, the Dandy-Walker variant, and the mega-cisterna magna actually are not separate entities, but appear to represent steps on a continuum of developmental anomalies of the posterior fossa. Because of this, we suggest a new term, the Dandy-Walker complex, be used to describe this continuum.

Adolescent↗
PubMed1989

Production of cytokines by bone marrow cells obtained from patients with multiple myeloma.

Previous work with continuously cultured multiple myeloma lines suggested that cytokine production by tumor cells may mediate some of the medical complications of this disease. To further investigate this issue, we assayed freshly obtained bone marrow (BM) cells from myeloma patients for the in vitro production of cytokines and the presence of cytokine RNA. Production of cytokine protein was assessed by bioassays with the aid of specific neutralizing anticytokine antibodies. These assays detected interleukin-1 (IL-1) and tumor necrosis factor (TNF) secretion by myeloma BM cells, which was significantly greater than secretion from similarly processed BM cells of control individuals. In contrast, lymphotoxin and interleukin-2 (IL-2) production could not be detected. The levels of IL-1 and TNF produced in vitro peaked at 24 hours of culture and correlated with stage and the presence (or absence) of extensive osteolytic bone disease. Northern blot analysis demonstrated the presence of IL-1 beta and TNF RNA in uncultured myeloma BM cells but no detectable IL-1 alpha or lymphotoxin RNA. In addition, the amount of cytokine RNA correlated with protein production, being significantly greater in patients' BM cells than in control marrow. These data suggest a role for IL-1 beta and/or TNF in the pathophysiology of multiple myeloma and argue against a role for lymphotoxin or IL-2.

Aged↗
PubMed1989

A comparison of the effects of 6-hydroxydopamine and reserpine on noradrenergic and peptidergic nerves in rat brown adipose tissue.

While co-existence of noradrenaline and neuropeptide-Y is, by inference, indicated in sympathetic nervous projections to rat interscapular brown adipose tissue by the fact of their coincident disappearance from the tissue following 6-hydroxydopamine treatment of the animals, reserpine treatment produced a divergent effect suggestive of possible differences either in the localisation and/or release mechanisms for noradrenaline and the peptide within the same neurons. Thus reserpine produced a depletion of noradrenaline but not of the immunohistochemically demonstrable neuropeptide-Y in the nerve plexuses of the tissue.

Adipose Tissue, Brown↗
PubMed1988

Absence of white matter changes on magnetic resonance imaging in children treated with CNS prophylaxis therapy for leukemia.

Previous studies have shown that magnetic resonance imaging (MRI) is sensitive to white matter changes in children receiving cranial radiation of 3000 cGy or greater. The current study used MRI to investigate the integrity of white matter in children receiving 1800 to 2400 cGy of cranial radiation. Ten survivors of acute lymphoblastic leukemia (ALL) who received intrathecal methotrexate (MTX) and either 1800 or 2400 cGy of cranial radiation were studied with MRI and neuropsychologic testing. Magnetic resonance (MR) scans were normal in nine of ten patients. One patient had prominent and asymmetrical lateral ventricles and mildly enlarged cortical sulci. White matter tracts were normal in appearance. However, seven of nine children had below average intellectual functioning. Results indicate that children receiving less than 2500 cGy of cranial radiation fail to show white matter changes on MRI, despite evidence of cognitive impairment.

Brain↗
PubMed1988

Neuropeptides in interscapular and perirenal brown adipose tissue in the rat: a plurality of innervation.

The occurrence of neuropeptides in rat brown adipose tissue has been investigated. Immunohistochemical studies on interscapular and perirenal brown fat have demonstrated unequivocally the presence of substance-P (SP)-like, neuropeptide-Y (NPY)-like and calcitonin gene related-peptide (CGRP)-like immunoreactive elements (putative nerves) in adventitial distribution on inter- and intralobular supply arteries and in accompanying nerve bundles. At a more peripheral level, some NPY-like immunoreactive elements and a greater number of CGRP-like immunoreactive elements were observed in the parenchymal field. Somatostatin, bombesin, neurotensin, enkephalin, and vasoactive-intestinal-polypeptide immunoreactivities were not detected. No differences in neuropeptide distribution were noted between interscapular and perirenal brown fat. There is a degree of coincident distribution of SP, NPY and CGRP with that of noradrenergic nervous elements as visualized by condensation histochemistry. Since after 6-hydroxydopamine treatment not all the nerve terminals in rat brown adipose tissue are stigmatized (earlier report), the present results have been discussed in the light of a possible pluralism in innervation of brown adipose tissue.

Adipose Tissue, Brown↗
PubMed1988

Neuropeptide and noradrenaline distributions in rat interscapular brown fat and in its intact and obstructed nerves of supply.

Following demonstration of noradrenergic and peptidergic nerves in rat interscapular brown adipose tissue, neuronal courses were investigated with reference to both the segmentally derived nerve traversing the fat pad and to paravascular projections, employing respectively, sucrose potassium glyoxylic acid and indirect immunofluorescence methodologies. Following ligation of the segmental nerve before its pad entry and distal to the pad, accumulations of noradrenaline, neuropeptide-Y, calcitonin gene-related peptide and substance P were observed immediately proximal to the ligature in all nerve components (T1-5). Two to three days after unilateral nerve resection (proximal to the pad), with or without simultaneous contralateral padectomy, there was, in some sections of the denervated pads either total absence of, or a very sparse distribution of both noradrenergic and peptidergic labelled nerves, thus suggesting minimal paravascular projection of these nerves and a major projection via the defineable segmental nerve route.

Adipose Tissue, Brown↗
PubMed1988

[Magnetic resonance tomography in spondylolysis and spondylolisthesis].

40 patients with spondylolisthesis and/or spondylolysis were studied by magnetic resonance imaging (MR), 12 of whom with correlation to CT. CT proved to be more sensitive in detecting pars defects than MR. Sagittal MR, however, was more accurate in assessing spondylolisthesis than axial CT. At present, CT is superior to MR in demonstrating bony abnormalities. MR appears indicated in the patient undergoing spinal fusion in whom detection of intervertebral disc degeneration in the levels above or below intended fusion may lead to extension of fusion to the degenerated levels. Lack of ionizing radiation makes MR an ideal diagnostic method in evaluating spondylolisthesis in children and adolescents.

Adult↗
PubMed1988

Normal maturation of the neonatal and infant brain: MR imaging at 1.5 T.

The pattern of normal white-matter maturation as demonstrated with high-field-strength magnetic resonance (MR) imaging was investigated. Eighty-two neurologically normal infants were examined with a 1.5-T unit with use of spin-echo T1-weighted and T2-weighted pulse sequences. The infants ranged in age from 4 days to 2 years. The images were assessed for qualitative changes of white matter relative to gray matter in 14 anatomic areas of the brain and correlated with the patient's age. The MR images showed that changes of brain maturation occur in an orderly manner, commencing in the brain stem and progressing to the cerebellum and the cerebrum. Changes caused by brain myelination were seen earlier on T1-weighted images than on T2-weighted images, possibly because of T1 shortening by the components of the developing myelin sheaths. The later changes on the T2-weighted images correlated best with the development of myelination as demonstrated with histochemical methods. T1-weighted images were most useful in the monitoring of normal brain development in the first 6-8 months of life; T2-weighted images were more useful after 6 months. The milestones in the MR appearance of normal maturation of the brain are presented. Persistent areas of long T2 relaxation times are seen superior and dorsal to the ventricular trigone in all infants examined and should not be mistaken for ischemic change.

Brain↗
PubMed1988

Chordomas: MR imaging.

Twenty histologically verified intracranial and upper cervical chordomas were retrospectively studied with both magnetic resonance (MR) imaging and computed tomography (CT), and the advantages of each modality were compared with regard to three criteria: detection of tumor, delineation of extent of tumor, and characterization of tumor. MR imaging and CT were equivalent in permitting the detection of chordomas. MR imaging was considerably better in delineating the full extent of the tumor, which would influence establishment of treatment. MR imaging also provided a degree of histologic specificity that would be useful in prognosis.

Adult↗
PubMed1988

White matter disease in AIDS: findings at MR imaging.

A review of the magnetic resonance (MR) images of 365 patients with acquired immunodeficiency syndrome (AIDS) revealed that 112 (31%) had signal abnormalities confined to the white matter. Four patterns were observed: (a) diffuse: widespread involvement of a large area; (b) patchy: localized involvement with ill-defined margins; (c) focal: well-defined areas of involvement; and (d) punctate: small foci less than 1 cm in diameter. Clinical or pathologic findings were available in 60 of the 112 patients and were correlated with the white matter patterns seen on MR images. The diffuse pattern correlated with AIDS dementia complex (ADC), which was the most common clinical diagnosis. Patchy or punctate lesions may be seen with ADC but are less common. Focal white matter lesions were not seen in patients with ADC but were seen in all six patients with progressive multifocal leukoencephalopathy, in both patients with lymphoma, and in one patient with toxoplasmosis. The authors conclude that white matter lesions are are common in AIDS and are often secondary to direct infection of the brain with human immunodeficiency virus, which causes the ADC and usually produces a diffuse white matter pattern. Biopsy is probably not indicated in these patients. Focal white matter lesions suggest a focal infection or tumor, and biopsy may be warranted.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Unusual type of spinal arteriovenous malformation.

We describe an uncommon type of spinal arteriovenous malformation that is intradural rather than dural and that consists of a true fistula rather than a nidus of abnormal vessels between the anterior spinal artery and a draining vein. Its clinical significance and treatment are discussed.

Adult↗
PubMed1988

MR of neuronal migration anomalies.

Migration anomalies are congenital malformations caused by insults to migrating neuroblasts during the third to fifth gestational months. Included in this group are agyria, pachygyria, polymicrogyria, unilateral megalencephaly, schizencephaly, and gray matter heterotopias. Patients who have these conditions present clinically with developmental delay and seizures, and abnormal motor skills are noted in the more severely affected infants. To determine the utility of MR as a method for imaging in these patients, we used MR to evaluate 13 patients who had the full spectrum of migration anomalies. MR was more sensitive than CT in detecting these anomalies because of its better contrast between gray and white matter. We found that MR was particularly more sensitive in detecting schizencephaly, where recognizing the presence of gray matter lining the cleft is critical to distinguishing that disease from porencephaly, and in detecting polymicrogyria, where critical details of cortical architecture are obscured on CT by the overlying bone. Multiplanar capabilities were also found to be essential, since narrow clefts may not be detected when the imaging plane is parallel to the cleft. MR should be the primary imaging method for infants who have seizures or developmental delay.

Adolescent↗
PubMed1988

MR imaging of schizencephaly.

MR imaging was used to evaluate six patients who had schizencephaly, a disorder of cell migration characterized by holohemispheric, gray-matter-lined clefts. Clinically, these patients presented with intractable seizures and variable developmental delay. Although three of these patients had previous CT scans, the diagnosis was made only by MR. MR was more sensitive than CT in detecting the clefts as well as the accompanying abnormalities, including areas of pachygyria, polymicrogyria, and heterotopic gray matter. The possible pathogenesis of schizencephaly is discussed. MR provides excellent demonstration of the anatomic changes in schizencephaly.

Adolescent↗