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Biomedical subjects

C R Gomez

Publications and source records attributed to C R Gomez.

At least 91 records · Page 5Linked to original sources
PubMed1990

Transcranial Doppler ultrasonographic assessment of intermittent light stimulation at different frequencies.

Seven normal adult volunteers underwent intermittent photic stimulation at frequencies of 5-60 Hz while their posterior cerebral arteries were monitored using transcranial Doppler ultrasound. Baseline measurements were obtained under conditions of total darkness, and sampling was also done during continuous illumination. Overall variation in mean flow velocity between complete darkness and continuous illumination was 9.8%, but the maximal change (expressed as percentage deviation from baseline) occurred consistently when stimulation was undertaken at frequencies of 10 (21%) and 20 (19%) Hz (p = 0.05). Frequencies higher than 20 Hz resulted in mean flow velocity variations that were not significantly different from that found during continuous illumination. The optimal frequency of intermittent visual stimulation required to induce measurable changes in posterior cerebral artery Doppler characteristics appears to be in the range 10-20 Hz.

Adult↗
PubMed1990

Homonymous quadrantic visual field defect resulting from vertebrobasilar insufficiency: report of a case.

A patient showing a congruous homonymous superior quadrantanopsia was found at autopsy to have infarction of the striate cortex. The lesion involved the inferior bank of the calcarine fissure almost entirely and approximately one fifth of the superior bank. Additionally, infarctions of the visual association cortex and the pontine tegmentum were found. No lesions in the corresponding temporal lobe were present. Two types of visual field defects have been described in association with occipital lobe lesions: a monocular temporal crescentic defect if the lesion is anterior and a congruous homonymous hemianopsia if it is posterior. This patient seems to represent a variant of the latter. The most prominent difference with respect to quadrantanopsias resulting from lesions of the optic radiation is the high degree of congruity, especially in the central portion of the field. Association with nonocclusive vascular events related to vertebrobasilar hypoperfusion rather than embolization is also more common.

Cerebral Infarction↗
PubMed1989

Intimal fibroplasia: an unusual etiology of stroke.

Individuals with arterial intimal fibroplasia represent a rare subset of patients with proliferative disorders of the arterial wall. This case describes the successful antemortem management of intimal fibroplasia of the internal carotid artery which had caused ipsilateral cerebral infarction. The noninvasive and invasive imaging characteristics of the lesion are also described.

Carotid Artery Diseases↗
PubMed1989

Characteristics of incidental pineal cysts on magnetic resonance imaging.

Three patients with different neurological complaints were studied by magnetic resonance imaging. Coincidentally, all studies showed cystic changes within the pineal bodies. These cysts appeared hypointense on T1-weighted, spin-echo pulse sequences and hyperintense on T2-weighted images. Spin-density sequences displayed them as hypointense areas, with relaxation times similar to those of the CSF, suggesting their cystic nature. The increased use of magnetic resonance imaging may result in coincidental imaging of involutional cystic pineal changes of many individuals; their characteristic appearance will allow the differentiation between them and pineal neoplastic conditions.

Adult↗
PubMed1989

Microvasculopathy may precede idiopathic cerebral calcifications--case report.

Cerebral and cerebellar calcifications were discovered by computerized tomography (CT) in a man who presented with a dementing illness characterized by progressive memory loss, irritability, and dystonia. He had no known family. Magnetic resonance imaging showed areas of absent signal corresponding to the calcifications and areas of high-intensity signal on the T2-weighted images without counterpart on the CT. These are postulated to be static liquid pools secondary to endothelial membrane incompetence and leakage of plasma-derived fluid.

Basal Ganglia Diseases↗
PubMed1989

Mapping the cerebral blood vessels with high-field MRI: technical and anatomic review.

The technical background and quality of images obtained upon studying the cerebral circulation with high-field MRI are reviewed. Fifty studies were selected as representative of normal cerebral blood vessels to illustrate the anatomic information derived from the review. MRI appears to be a safe, easy, and reliable method of imaging the cerebral circulation noninvasively.

Adult↗
PubMed1989

Evaluation and follow-up of carotid-cavernous fistulas by transcranial Doppler sonography: illustrative case.

The availability of transcranial Doppler sonography has resulted in an easy, noninvasive, reproducible, and highly reliable method for evaluating the flow characteristics of carotid-cavernous sinus fistulas. It also allows the follow-up of the effect of different interventional measures, specifically, embolization with detachable balloons. An illustrative case is reported, in which the findings of serial transcranial Doppler sonograms are correlated with findings on computed tomographic scans and angiograms. The impact of our findings on future approaches to the hemodynamic classification of these acquired vascular shunts is discussed.

Aged↗
PubMed1988

Altered sensorium, confusion, and vertical gaze paresis: the top of the basilar syndrome.

The term "top of the basilar" has been used in reference to a group of signs and symptoms of midbrain, diencephalic, and posteroinferior hemispheric dysfunction. It has been attributed to ischemia in the territory of second- and third-order vessels that arise from the uppermost portion of the basilar artery. We report our experience with four patients who had alteration of consciousness, confusion, and vertical gaze paresis accompanied by other physical abnormalities. Extensive evaluation did not help in documenting the lesions or in understanding their pathogenesis. The top of the basilar syndrome is a not uncommon form of stroke and carries a variable prognosis. Treatment by anticoagulation may prevent further infarction in selected patients who are seen early.

Adult↗
PubMed1988

Noninvasive evaluation of ischemic stroke with SPECT.

Technetium Tc 99m DTPA single photon emission computerized tomography (SPECT) brain scans of 20 patients with acute ischemic stroke were reviewed retrospectively and compared with clinical and radiologic (CT) data. Fourteen of the patients had abnormal SPECT studies. The abnormal findings were demonstrated by static views in eight patients, by the flow study in one patient, and by both sets of images in the other five patients. All abnormalities correlated with the clinical syndrome of presentation, and only two of the patients had no corresponding lesions on CT. Of the six patients with normal SPECT scans, two had abnormal CT studies, and in the other four, no lesions were shown at all. The ability of 99mTc DTPA SPECT to display cerebral infarctions appears to be, at best, comparable to that of CT. SPECT also provides qualitative information regarding flow dynamics in the affected hemisphere of some patients (6/20 in our review). This, we believe, represents the objective demonstration of the preexisting insufficient collateral flow in the hemisphere at risk for ischemic stroke.

Adult↗
PubMed1988

Acute thalamic esotropia.

Three men developed acute esotropia, stupor, and impaired upward gaze. Vestibulo-ocular stimulation showed that the adducted eye remained immobile while the fellow eye responded normally. The alteration of consciousness, the long-tract neurologic signs, and the esotropia quickly resolved. Upgaze paresis and brief bursts of convergence-retraction nystagmus were the major residual signs. Imaging techniques demonstrated lesions of the contralateral posterior thalamus in each patient. Several mechanisms are proposed to explain the acute esotropia. Impairment of monocular projections in the contralateral posterior thalamus could disinhibit neurons in the oculomotor complex, or ischemia of inputs to neurons involved with vergence control in the midbrain could result in tonic activation of the medial rectus. The clinical and radiographic findings are consistent with infarction in the territory of penetrating branches of the basilar-communicating (mesencephalic) artery. Embolism to the top of the basilar artery is presumed to be the precipitating event.

Acute Disease↗
PubMed1987

Unilateral Moya Moya disease in an adult--a case history.

A case of ischemic infarction in a young woman who also had angiographic findings consistent with "Moya Moya" disease is presented. Unusual features of the case, such as the presentation as an infarction rather than subarachnoid hemorrhage and the unilaterality of the angiographic abnormalities, are discussed. The literature is reviewed and emphasis is directed to the importance of the inclusion of this entity in the differential diagnosis of cerebral ischemic events in young adults, owing to the possible therapeutic implications.

Adult↗