Search PubMed⌕ Search

Biomedical subjects

D Norman

Publications and source records attributed to D Norman.

303 records · Page 17Linked to original sources
PubMedDate not supplied

Transluminal angioplasty of the vertebral and basilar artery.

Transluminal angioplasty of brachiocephalic vessels for atherosclerotic lesions is now being performed in selected cases. We have thus far treated 17 cases of vertebral artery stenosis and one case of basilar artery stenosis by intravascular balloon dilatation techniques. Clinical presenting symptoms included vertebral basilar insufficiency, repeated transient ischemic attacks (TIAs), and multiple strokes. We performed successful transluminal angioplasty in 16 patients with marked narrowing (greater than 70%) of the dominant vertebral artery from atherosclerosis. One patient with basilar artery stenosis with tandem atherosclerotic lesions was also treated by angioplasty techniques. Repeat angiography at 3- to 12-month intervals has revealed continued patency at the angioplasty site. Complications occurred in our one patient with basilar artery angioplasty, who suffered a brainstem infarction after treatment, and in one patient who had a TIA after bilateral vertebral artery angioplasty. Two other patients had residual vertebral stenosis but remained asymptomatic after the procedure. All other patients who had successful dilatation were asymptomatic at 6 months to 2 years (mean, 15 months) of follow-up. These initial studies indicate that vertebral artery angioplasty may be effective for treating high-grade atherosclerotic lesions and for improving blood flow to the posterior circulation. Angioplasty of the basilar artery is technically more difficult and has a higher degree of risk because of the many perforating branches supplying the brainstem.

Aged↗
PubMedDate not supplied

MRI of normal brain maturation.

The unprecedented gray/white differentiation obtained with magnetic resonance imaging (MRI) has created a unique opportunity to trace the normal process of myelination. Fifty-nine children referred for evaluation of a nonneurologic problem or a nonspecific neurologic complaint were studied with MRI using spin-echo technique. Children ranged in age from term (40 weeks intrauterine) to 16 years. Scans were reviewed for quantitative and qualitative changes with age. T1 and T2 relaxation times were measured for 13 regions of interest in 37 children. With increasing age a sharp decrease in both T1 and T2 values, most pronounced during the first year of life, was seen. The prolonged relaxation times in the newborn infant correspond to the known high water content of the neonatal brain; the subsequent decline corresponds to the decrease in water content and increase in myelination observed in autopsy studies of infants. Qualitative changes in the MRI appearance of the brain with age using a spin-echo sequence (2 sec repetition time) demonstrated that the process of myelination was most rapid during the first 2-3 years of life. Myelination appeared to occur earliest in the posterior fossa, with the middle cerebellar peduncle identifiable at only 3 months. By the age of 1 year, all major white matter tracts including the corpus callosum, subcortical white matter, and the internal capsule were well defined. However, due to subtle changes in appearance, the refined configuration of the adult brain was not attained until early adolescence.

Adolescent↗
PubMedDate not supplied

Normal perfusion pressure breakthrough occurring during treatment of carotid and vertebral fistulas.

Of the 185 carotid and vertebral fistulas treated by the authors over the past 10 years, five developed neurologic deficits after abrupt closure of their fistulas. The earliest case, treated initially by proximal surgical carotid occlusion, presented 32 years later with cerebral steal symptoms from the large, long-standing carotid cavernous fistula. Upon completion of a surgical trapping procedure, there was immediate massive cerebral edema, brain herniation, and death. In the remaining four patients (three vertebral fistulas and one with carotid cavernous fistula), all treated by transvascular embolization techniques, neurologic deficits occurred coincidentally with the abrupt closure of the fistula and resolved with reestablishment of fistula flow. This indicated that the cerebral vasculature is unable to tolerate the reestablishment of normal cerebral perfusion after abrupt closure of the fistula. All four patients were treated with staged or slow occlusion of their fistulas, which resulted in complete fistula closure without permanent neurologic sequelae. All five patients who developed symptoms consistent with normal perfusion pressure breakthrough had large, long-standing fistulas, ranging in duration from 9 to 32 years. Two of the five patients developed slowly progressive neurologic deficits consistent with cerebral steal prior to treatment. This sign was not observed in the 180 patients who did not develop symptoms during treatment. We conclude that patients with carotid or vertebral fistulas of long duration, particularly those with cerebral steal symptoms, are at risk to develop neurologic deficits related to perfusion breakthrough if their fistulas are abruptly closed. Staged or gradual closure may prevent this potentially devastating complication.

Adult↗
PubMedDate not supplied

Posterior pituitary ectopia: an MR feature of pituitary dwarfism.

Using high-field-strength, 1.5-T, high-resolution MR, we identified the following complex of neurohypophyseal abnormalities in each of five pituitary dwarfs: (1) severe hypoplasia or total absence of the infundibulum; (2) absence of the posterior pituitary bright spot in its normal location; and (3) a 3-8-mm tissue nodule at the median eminence exhibiting lipidlike signal on T1-weighted images. On the basis of its signal features and the clinical absence of diabetes insipidus in these patients, the median eminence nodule appears to represent an ectopic and functional posterior pituitary gland. We propose that this anatomic derangement is the end result of a localized defect of developmental origin, possibly ischemic in nature, and involving principally the infundibular stem. Thus, human growth hormone deficiency could result from perinatal disruption of the peri-infundibular hypophyseal portal system, which in turn impairs anterior pituitary function through deprivation of direct delivery of crucial hypothalamic-releasing factors. Finally, we suggest that the trophic influence of continued axonal neurosecretion at the median eminence engages proliferation of rest cell pituicytes; a process that induces formation of an ectopic and functional posterior pituitary gland, complete with its characteristic bright spot.

Adolescent↗
PubMedDate not supplied

MR imaging of orbital and ocular disease.

Magnetic resonance (MR) images of 27 patients with ocular and orbital pathology were reviewed retrospectively and correlated with computed tomography (CT), funduscopic examination, and tissue histology. Disease processes were classified by location into ocular, extraconal, intraconal, optic nerve, and orbital apex. The diagnostic efficacy of MR differed at each location. MR was very sensitive in detecting ocular, extraconal, and intraconal lesions larger than 5 mm but was insensitive in imaging smaller lesions and in detecting pathology of the optic nerve. The limitations of MR were related to 7 mm slice thickness and 2.6 mm interslice gap. The diagnostic accuracy is expected to improve markedly with further developments in thin-section imaging and use of surface coils.

Adolescent↗
PubMedDate not supplied

Nuclear magnetic resonance imaging of syringomyelia.

Five patients with syringomyelia were examined with a 3.5 kG nuclear magnetic resonance (NMR) imager. Syrinx cavities were visualized in all five cases, and image quality compared favorably with metrizamide computed tomography (CT). Axial images were optimal for identifying syrinx cavities, and sagittal views were useful in providing an overview of cord morphology and in examining the craniocervical junction. Inversion-recovery images were less valuable than the spin-echo sequences. By varying spin-echo imaging parameters, tissue relaxation times could be determined and the fluid nature of the syrinx cavities confirmed. This limited study suggests that NMR may challenge the current role of CT in the diagnostic workup of syringomyelia.

Diagnosis, Differential↗
PubMedDate not supplied

Preoperative demonstration of postinflammatory syringomyelia.

Syringomyelia secondary to arachnoiditis is a rarely reported entity, which has not been described in the radiographic literature. A series of eight patients who had either postinfectious, posthemorrhagic, iatrogenic, or idiopathic arachnoiditis was examined recently with metrizamide computed tomography (CT). These patients presented with progressive neurologic deficits that could not be attributed to the level of arachnoid changes on myelography. On immediate and/or delayed CT scans, metrizamide accumulation within the central part of the cord was identified, both at and above the level of the arachnoiditis. In some patients, the cord diameter was normal. Syrinx cavities were demonstrated and shunted at surgery with subsequent partial relief or arrest of the symptoms. The mechanism of development of postinflammatory syringomyelia is discussed.

Adult↗
PubMedDate not supplied

NMR of the normal and pathologic eye and orbit.

Nuclear magnetic resonance (NMR) images of the eye and orbit were reviewed in a series of 100 normals and in four patients with orbital or ocular pathology. A rich retrobulbar fat content rendered the orbit well suited for NMR imaging. The lens, vitreous, optic nerve, and extraocular muscles were well visualized with spin-echo technique. However, NMR spatial resolution was inferior to that of high-resolution computed tomography (CT). NMR was comparable to CT in demonstrating choroidal melanoma and orbital pseudotumor. NMR exhibited a particular sensitivity in displaying tissue contrast for infiltrative orbital fat lesions with a relatively long T1. This initial experience suggests a promising role for NMR in orbital imaging.

Adolescent↗
PubMedDate not supplied

Relative uptake of low- and high-osmolality contrast media in CT of brain tumors.

The magnitude and time course of contrast enhancement in spontaneous canine brain tumors was determined for two contrast agents: meglumine iothalamate and sodium meglumine ioxaglate. Tumor enhancement during contrast infusion and at 5, 10, 15, 30, and 45 min was measured using quantitative computed tomography. Blood iodine was measured using x-ray fluorescence. Peak contrast enhancement occurred during the infusion, and the magnitude was the same for both agents. Per gram of iodine infused, blood iodine was 12.4% higher with ioxaglate than iothalamate. The monoionic dimer ioxaglate is as effective as iothalamate for enhancement of canine brain tumors.

Animals↗
PubMedDate not supplied

CNS manifestations of hereditary hemorrhagic telangiectasia.

Hereditary hemorrhagic telangiectasia (HHT) is a familial angiodysplastic disorder. Dermal, mucosal, and visceral vascular lesions of this disorder are well known. However, central nervous system (CNS) manifestations, occurring in as many as one-third of patients, have not been well appreciated until recently. The etiology of neurologic symptomatology includes hypoxemia or ischemia secondary to pulmonary arteriovenous shunting, vascular lesions of the brain and spinal cord ranging from aneurysms to arteriovenous malformations, brain abscesses secondary to pulmonary arteriovenous fistulas, and portal systemic encephalopathy. Angiographic and computed tomographic findings in four patients with CNS involvement in HHT are reported.

Adult↗
PubMedDate not supplied

Traumatic aneurysms of cavernous internal carotid artery with secondary epistaxis.

The syndrome of delayed epistaxis and monocular blindness following nonpenetrating head injury is reviewed. Bleeding results from rupture of a traumatic cavernous internal carotid artery aneurysm into the sphenoid sinus. There were 96 patients with this syndrome found in the literature and another four are added in this report. In 73% of the patients, the cause of the epistaxis was not appreciated until 4 months after the initial episode. No antemortem diagnosis was made in 15% of the patients. More frequent use of carotid angiography in patients with posttraumatic mononuclear blindness and delayed epistaxis might help reduce the reported mortality of 30%.

Adolescent↗
PubMedDate not supplied

Cisternal enhancement after subarachnoid hemorrhage.

Abnormal computed tomographic enhancement in the basal cisterns and cortical sulci was observed in 21 of 42 patients after subarachnoid hemorrhage. The appearance is similar to that described in granulomatous infection and metastatic disease. The enhancement was associated with an increased incidence of hydrocephalus, but it did not correlate with clinical grade, arterial spasm, location of bleed, or temporal relation to bleed. Presumably, abnormal cisternal enhancement is due initially to increased vascular permeability and later to increased vascularity associated with arachnoiditis.

Adolescent↗
PubMedDate not supplied

Multiplanar metrizamide-enhanced CT imaging of the foramen magnum.

Definition of masses and malformations at the foramen magnum has been less than optimal with traditional radiographic techniques. The use of intrathecal metrizamide with computed tomographic (CT) scanning improves contrast resolution and facilitates detection of abnormalities that may not be apparent on Pantopaque cisternography, plain films, or conventional axial CT alone. Fifty patients with clinically suspected foramen-magnum lesions were evaluated with this technique. Forty were abnormal with the following findings: 14 cases of the Chiari malformation (five cases had associated syringomyelia), five meningiomas, three neuromas, a chondrosarcoma, a chordoma, and five cervical and three brainstem gliomas. Six cases of syringomyelia, a large posterior-fossa subarachnoid cyst, and an anomaly of the cisterna magna were also diagnosed. Sagittal and coronal images were beneficial in defining tonsillar position, configuration of the fourth ventricle, and the relations of mass lesions to the spinal canal and subarachnoid space. Metrizamide CT cisternography provides superior spatial and contrast resolution of lesions at the foramen magnum not obtainable with other radiographic techniques. Morbidity is minimal because of the low dose of metrizamide used. Multiplanar reformations are particularly helpful in assessing anatomic detail not readily recognized on axial scans alone.

Adolescent↗
PubMedDate not supplied

ABO-incompatible heart transplantation: a special case for the A2 donor.

Limited clinical experience concerning heart transplantation across ABO blood group barriers suggests a high incidence of hyperacute rejection and poor patient outcome. Reported is a case of the short-term survival of an ABO-mismatched cardiac graft without evident adverse immunologic effects. A 41-year-old man with blood type O underwent heart transplantation receiving a blood type A2 donor organ. Cyclosporine-based immunosuppression was augmented with daily plasmapheresis and OKT3 therapy. Circulating anti-A antibodies were reduced quickly and held to a very low level with this regimen. The patient remained hemodynamically stable until retransplantation 4 days later. The explanted heart showed no evidence of cellular infiltrate or antibody deposition. Long-term success with the use of type A2 organs in type O recipients has been shown in select series with other types of solid organ transplants. Although this patient underwent retransplantation early, the lack of rejection phenomena gives evidence that the relatively low antigenicity of the A2 subtype may allow planned heart transplantation across this blood group barrier, either as a bridge or on a permanent basis.

ABO Blood-Group System↗