Biomedical subjects
Publications and source records attributed to R D Zimmerman.
A 28-year-old man had headache and unilateral third-nerve palsy as the presenting features of acute syphilitic meningitis, accompanied by an asymptomatic cerebral gamma.
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Herpes simplex is the most common cause of sporadic viral encephalitis. The recent development of specific antiviral chemotherapeutic agents offers new optimism for patients with this disorder if therapy is begun on or before the fifth day of the disease. Eight patients with herpes simplex encephalitis were studied by CT, and a characteristic but not pathognomonic pattern was observed. In each case a low density lesion was noted in the medial portion of the temporal lobe with extension into the Island of Reil. Sparing of the lenticular nucleus was observed in all cases. Mass effect and streaky linear enhancement after contrast administration was also seen. Unfortunately, the findings may be subtle or absent before the fifth day of disease, and thus CT scans must be examined with a high index of suspicion if the correct diagnosis is to be made at a time when therapy may prove useful. Hemorrhagic areas are rarely observed on CT in this disorder despite the frequent occurrence on pathologic studies. The full extent of involvement may not be appreciated on scans obtained during the first 10 days of the disease.
Cysticercosis is a parasitic infestation that commonly affects the central nervous system. This is a report of computed tomography findings in a patient with a noncalcified cyst causing asymmetric lateral ventricular obstruction at the foramen of Monro. The lesion was isodense and uniformly enhancing, an unusual finding possibly related to presentation early in the course of the disease. This disease should be considered in the differential diagnosis of the lesions at the foramen of Monro in patients with appropriate residence or travel history.
Eight patients with Herpes simplex encephalitis had computed cranial tomography (CT). In every case, areas of decreased attenuation were found in the temporal lobe(s); these areas extended to the insular cortex and often to the frontal or parietal lobes. This change developed between the third and the eleventh day of illness. It was present, sometimes only in retrospect, in patients who were alert as well as patients who were comatose. Compared to the isotopic brain scan, electroencephalogram, and cerebral angiogram, CT demonstrates changes that are indicative of H simplex early enough in the course of the illness to be therapeutically useful.
The association between meningomyelocele and various cranial abnormalities, particularly Chiari II malformation is well established. Cranial CT scans in 47 patients with meningomyelocele proved to be a safe and effective method of elucidating the type and extent of anatomic abnormalities associated with this disorder, and evaluating and following the degree of hydrocephalus seen in these patients. Of the 47 patients, 43 (92%) showed CT findings indicative of an abnormally low fourth ventricle, the hallmark finding in Chiari II malformation. In 67% the fourth ventricle was not visualized, and in 25% it was directly visualized in an abnormally caudal position. Other findings included hydrocephalus (85%), a striking and possibly unique heart-shaped psuedomass in the posterior fossa (58%), and abnormal configuration of the lateral ventricles ("vampire bat" configuration). Calvarial abnormalities, in particular lacunar skull, were also noted at CT.
Four patients with well documented Reye syndrome were examined with noncontrast computed tomography. Acute findings are those of diffuse cerebral edema with low density in deep white matter, increased gray-white matter differentiation, and evidence of secondary ventricular compression. The diffuse nature of the changes is unlike the more focal pattern often seen in true viral encephalitis. Residual changes after severe diseases are those of nonspecific cerebral degeneration and are most pronounced in the frontal lobes. Atrophic ventricular dilatation was observed in two cases. Computed tomography findings correlate with all known pathologic studies and with the subsequent clinical courses in the patients examined.
Seven cases of ring blush following spontaneous and post-traumatic, subacute and chronic intracerebral hematoma are presented. As such a hematoma ages, a ring blush may be seen following contrast-agent enhancement. Serial CT demonstrates disappearance of the ring blush from two to six months after the first scan. The CT appearance of the ring blush is not specific for hematoma, but its peripheral location and lack of mass effect may be considered suggestive of hematoma with appropriate clinical findings. The characteristic serial changes permit correct diagnosis without surgical intervention in most cases.
Bands of increased density representing the free edges and lateral margins of the tentorium were routinely identified on 100 sequential, normal, contrast-enhanced axial CT scans of good quality. Because the tentorium has a complex shape, the exact configuration of these bands varies with the level and the angle of the CT section. Comparison of CT scans with anatomic specimens permits an understanding of these varying configurations, and provides a means to estimate the position of the tentorium on non-contrast CT studies. The CT manifestations of diverse non-neoplastic diseases including subarachnoid hemorrhage, arteriovenous malformation, venous sinus thrombosis and Dandy-Walker malformation may be understood, in part, in terms of the configuration and density of these tentorial bands.
Most juxtatentorial lesions may be localized accurately on contrast-enhanced axial section CT scans by use of the opacified tentorial bands. Lesions that lie lateral edge of the diverging bands are supratentorial. Lesions that lie medial to the V-shaped tentorial bands are infratentorial and/or incisural. Flattening of the tentorial border of a lesion helps to identify its location. Use of the tentorial bands identifies transincisural extension of meningioma reliably, but does distinguish well between true transtentorial growth of meningioma and marked upward bulging of the tentorium from purely infratentorial meningioma.
Orbital pseudotumor is a benign inflammatory lesion of the orbit. Computed tomography is a new method for evaluation of orbits. Scleral uveal rim thickening with contrast enhancement was found in eight of 15 patients with pseudotumor (53%). Similar rim thickening was seen in one postoperative patient and two cases of recent trauma. Therefore, the sign presumably represents inflammation. It was not seen in 47 cases of thyroid disease and 66 cases of neoplasm.
We investigated the efficacy of magnetic resonance imaging (MRI) in the detection and delineation of acute hemorrhagic cerebral infarction and evaluated the role of gradient-echo imaging in these patients. This study was performed prospectively. Entry criteria were: (1) Clinical evidence of acute supratentorial infarction later confirmed by at least one imaging study, and (2) unenhanced computed tomography (CT) and MRI scans performed within 72 hours of ictus. The first 50 patients who met these criteria were included. Comparison of CT and spin-echo (SE) and gradient-echo (GE) MRI at 0.6 T for the visualization of infarction and for the detection or exclusion of hemorrhage were done. There were no cases in which CT was superior to MRI for the diagnosis of either bland or hemorrhagic infarction. All 50 infarcts were detected on long TR SE MRI and 30/50 on GE scans. Eighteen infarcts were judged to be hemorrhagic on the basis of well-established CT and MRI criteria. In all these cases, hemorrhage was most obvious on GE scans as focal areas of marked hypointensity, including 10 cases in which SE MRI and CT demonstrated subtle, equivocal, or no evidence of hemorrhage. In addition, GE MRI allowed for the exclusion of hemorrhage in five cases with equivocal findings of hemorrhage on long TR SE MRI. GE MRI is a valuable adjunct to SE sequences for the detection or exclusion of hemorrhage in acute infarcts with equivocal or mild intensity changes on SE MRI. With further improvements in fast-scanning techniques and a greater understanding of the pathophysiology and clinical implications of hemorrhagic infarction, it may be possible to replace CT with a combination of SE and GE MRI as the primary imaging modality in the evaluation of acute infarction.
The purpose of our study was to define the neuroimaging features of the cardiolipin antibody syndrome. Thirty-eight patients with elevated anticardiolipin antibody titers were studied with magnetic resonance imaging or computed tomography or both. Two patients underwent cerebral angiography. All patients had recurrent transient ischemic attacks, amaurosis, or strokes. One patient had normal imaging findings. The remaining patients had a combination of infarction and atrophy. Focal infarcts, the most common finding, were seen in 32 patients. Cerebral atrophy was seen in 26 patients and was the only radiographic finding in 5. Angiography demonstrated dramatic abnormalities in the distal portions of the anterior and posterior circulations, with multiple stenosis and occlusions and extensive pial and transdural collateral networks. The cardiolipin antibody syndrome should be suspected in young patients with transient ischemic attacks or strokes in the absence of the usual risk factors for cerebrovascular disease. The presence of raised anticardiolipin antibody titers or the cardiolipin antibody syndrome in patients with lupus, in those with other connective tissue diseases, and in patients without overt manifestations of an autoimmune disorder should be viewed as a risk factor for future ischemic cerebrovascular events. Further understanding of the precise role of these antibodies in the pathogenesis of vascular thrombosis may lead to a better understanding of the mechanisms underlying certain forms of stroke.
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The MR findings of a clinically severe case of serologically documented Epstein-Barr virus encephalomyelitis are presented, demonstrating hyperintensity on T2-weighted sequences throughout cervical spinal cord, the basal ganglia, and the insular cortex. It is not known whether the preferential involvement of gray matter structures in this case is a typical or unusual feature of this rare entity.
Diffusion-tensor imaging is an emerging technique that can supply microscopic structural information about tissue in vivo. With this technique it is possible to measure the amount of anisotropy of water diffusion within tissues and to assess the degree to which directionally ordered tissues have lost their normal integrity. This study was performed in four patients to evaluate the feasibility of applying this technique in clinical situations in which there is known or suspected damage to white matter tracts.
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BACKGROUND AND PURPOSE: Quantifying changes in the human brain that occur as part of normal aging may help in the diagnosis of diseases that affect the elderly and that cause structural changes in the brain. We sought to assess diffusion changes that are inherently related to brain structure during aging. METHODS: MR scans were obtained from 11 healthy volunteers and 27 patients (ages 26 to 86 years [53.4 +/- 17.0 years]). Images acquired from the patients either showed no abnormalities, contained minimal periventricular white matter changes, or revealed focal lesions. Maps of the average diffusion constant (D(av)) were calculated for each subject. Changes in D(av) were determined with distribution analysis (histogram) for the entire brain and compared with region-of-interest measurements from the periventricular white matter and thalamus. RESULTS: Mean D(av) of the entire brain (0.74 +/- 0.02 x 10(-5) cm2/s) showed weaker age dependency compared with the periventricular white matter D(av)(0.76 +/- 0.04 x 10(-5) cm2/s). The D(av) of the thalamus D(av) (0.75 +/- 0.03 x 10(-5) cm2/s) had no age dependency. The age-dependent changes of entire brain D(av) may be significant for subjects older than 60 years compared with younger subjects. CONCLUSION: In this study, we observed minimal changes in the D(av) of the entire brain with aging. The mean D(av) of the human brain is nearly constant throughout most of adulthood.