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Biomedical subjects

S Hilal

Publications and source records attributed to S Hilal.

12 recordsLinked to original sources
PubMed1992

A prospective controlled study of magnetic resonance imaging of the brain in gay men and parenteral drug users with human immunodeficiency virus infection.

To detect the earliest structural changes in the brain in human immunodeficiency virus (HIV) infection, 118 gay men and 115 parenteral drug users enrolled in a study of the natural history of HIV infection underwent magnetic resonance imaging evaluations. Routine T2-weighted and heavily T2-weighted scans for quantification of brain water were obtained, blinded to HIV serostatus. Atrophy and foci of increased signal did not correlate with any medical, immunologic, neurologic, or neuropsychologic parameters in the group as a whole, or in the gay men or parenteral drug user subgroups. Three subjects had progressive multifocal leukoencephalopathy and one had central nervous system lymphoma. In a subgroup in whom intracranial water percent was calculated, correlations were found with CD4 counts and CD4/CD8 ratios. We conclude that standard magnetic resonance imaging of the brain does not differentiate asymptomatic and mildly symptomatic HIV-positive individuals from HIV-negative individuals, regardless of risk group. However, intracranial water percent may distinguish HIV-positive from HIV-negative individuals because it correlates with raw CD4 counts and CD4/CD8 ratios.

Adolescent↗
PubMed1992

Structural brain imaging abnormalities associated with schizophrenia and partial trisomy of chromosome 5.

Chromosomal abnormalities occurring in association with mental illness provide a unique opportunity to study the interaction of genetic abnormalities and the brain in mental illness. Four individuals from a family in which schizophrenia was found to cosegregate with a partial trisomy of chromosome 5 were studied with computed tomography and magnetic resonance imaging. Temporal lobe atrophy was found in the two trisomic males and in the asymptomatic balanced translocation female. In addition, a large cavum septum pellucidum and a cavum vergae were found in the older trisomic individual. Scans from the normal male were free of abnormalities. These results suggest that molecular studies of the translocation breakpoints in this chromosomal abnormality may be of interest, and encourage further studies of brain structure in other chromosomal abnormalities associated with psychosis.

Adult↗
PubMed1990

Focal headache during balloon inflation in the internal carotid and middle cerebral arteries.

Although a number of reports are available on the occurrence of headache in patients with ischemic cerebrovascular disease, most studies have recorded the frequency but not the specific sites of the pain. We report 18 patients who underwent balloon inflation in the distal internal carotid artery and middle cerebral artery stem during embolization therapy for intracerebral arteriovenous malformations. Eleven patients had reproducible patterns of headache during balloon inflation. Inflation in the proximal middle cerebral artery stem produced pain primarily in the ipsilateral temple, that in the middle of the middle cerebral artery stem produced pain referred primarily retro-orbitally, and inflation in the distal middle cerebral artery stem produced pain referred primarily to the forehead. Experimental studies have demonstrated similar patterns of referred pain. The fact that these areas of referred pain are so reproducible is of potentially great clinical importance in the approach to management of patients with cerebrovascular disease.

Adult↗
PubMed1989

Cerebral hyperemia, stroke, and transfusion in sickle cell disease.

To investigate cerebral hemodynamics in sickle cell disease (SCD), we used the 133Xenon inhalation technique of quantifying cerebral blood flow (CBF) in 67 patients. Clinical examinations and cerebral magnetic resonance imaging also were performed in all patients. Compared with age-matched healthy controls, CBF was elevated by 68% in patients, and inversely related to hematocrit. An experimental index of cerebral blood volume, pr4, was also elevated in the patients in a similar manner. Cerebral blood volume was positively correlated to CBF in SCD patients but not in controls. History of stroke and current neurologic symptoms were associated with lower flow and higher cerebral blood volume. Transfusion therapy reduced the hyperemia, the reduction being greater than expected by hematocrit elevation alone. These findings document a vasodilatory hyperemia in SCD. This dilatation may be a risk factor for ischemic distal-field infarctions, as visualized by MRI, due to a limitation of cerebrovascular reserve capacity.

Adolescent↗
PubMed1988

Brain infarction in sickle cell anemia: magnetic resonance imaging correlates.

Brain infarction is a well-known but poorly understood complication of sickle cell disease. Seventy-three sickle cell disease patients underwent neurological examinations and high-field, heavily T2-weighted axial cranial magnetic resonance image (MRI) scanning. Eighteen of the 73 had a history of stroke, defined as an acute, focal neurological sign lasting longer than 1 hour; in the event of a convulsive onset, an MRI abnormality as a correlate was necessary. Sixteen of the 18 stroke patients demonstrated focal MRI abnormalities consistent with arterial borderzone infarctions. Fifty-five of the 73 patients had no history of stroke. Six of the 55 (11%) had focal MRI abnormalities suggesting previous subclinical stroke. Five of these lesions were in borderzone regions. The distinguishing feature in 21 of the 22 patients with MRI abnormalities was the predilection for lesions in the high cortical convexity, in the general regions of arterial borderzones between the major cerebral arteries and adjacent deep white matter. The pattern of MRI lesions suggests two pathogenetic mechanisms: (1) proximal large-vessel disease with inadequate cerebral perfusion (distal field insufficiency syndrome) and (2) distal small-vessel disease (sludging syndrome).

Adolescent↗
PubMed1986

The effects of nuclear magnetic resonance imaging on ocular tissues.

Nuclear magnetic resonance, an imaging technique with great promise for detecting cerebral abnormalities, was studied to determine its possible deleterious effects on the mammalian eye. Young (3.5-week-old) Columbia-Sherman rats were exposed simultaneously to a constant magnetic field of 2.7 tesla and radio frequency pulses of 29 MHz at 800-ms intervals for six hours at field strengths representing the maximum used in a clinical setting. The six-hour exposure is many times greater than the four to six minutes currently employed in most diagnostic protocols. The animals were examined by slit-lamp biomicroscopy and ophthalmoscopy at regular intervals. Autoradiograms of lenses from animals injected with tritiated thymidine prior to exposure did not reveal any disturbances in cell-cycle kinetics. Eyes from rats not previously injected with the isotope were processed for cytopathologic analysis at various intervals. A two-year follow-up has indicated that at both the slit-lamp biomicroscopic and the light microscopic levels, there were no discernable effects on the rat eye.

Animals↗
PubMed1979

Acute posterior multifocal placoid pigment epitheliopathy associated with cerebral vasculitis and homonymous hemianopia.

An 18-year-old man developed acute posterior multifocal placoid pigment epitheliopathy and homonymous hemianopia. Cerebral angiography showed cerebral vasculitis probably with occipital infarction. To the best of our knowledge, this is the first reported case with such concomitant visual defects. Other published reports suggest that such cerebral vasculitis may not be unusual in acute posterior multifocal placoid pigment epitheliopathy.

Acute Disease↗
PubMed1979

BCNU and steroids in the viral-induced dog brain tumor.

Schmidt-Ruppin strain of Rous Sarcoma was inoculated intracerebrally into 27 newborn beagle dogs. Fourteen days after viral inoculation, 13 of the dogs were given intravenous BCNU (1 mg/kg). The other 14 were given the same volume of intravenous saline in a randomized, double-blinded fashion. Ninety percent of all dogs developed intracranial tumors. Radionuclide (mercury 197) brain scans were done on each dog at 2-week intervals. Median survival was 113 days in the BCNU group and 115 days in the placebo group (P > .99). Unequivocally positive radionuclide brain scans were detected in 5 dogs treated with BCNU and in 2 of the controls. There were no gross or microscopic differences at autopsy between treated and nontreated animals. BCNU, as given in this animal brain tumor model, did not demonstrate any oncolytic effect. An improvement in sequential brain scans was detected in 2 other dogs in response to Dexamethasone, which was given in a double-blinded, cross-over controlled fashion. Computerized tomography clearly demonstrated the tumor in two cases.

Animals↗
PubMed1976

Computerized tomography correlated with CSF protein concentrations.

The authors present a case of hydrocephalus complicated by ventriculitis in which it was possible to correlate the numerical printout of sequential computerized tomograms (CT-Scans) with cerebrospinal fluid protein concentrations obtained by direct ventricular puncture. Different protein levels were unambiguously associated with changes in the absorption numbers on the scan but they did not bear a simple linear relationship to one another. The value of the numerical printout in diagnosis and follow-up is discussed.

Brain Diseases↗