Biomedical subjects
Publications and source records attributed to F C Guinto.
We present an unusual radiographic manifestation of subclavian steal seen in six patients. These cases differ from the classic form of subclavian steal in that antegrade and bidirectional blood flow in the vertebral-subclavian artery system is seen, resulting in the steal phenomenon.
STUDY OBJECTIVES: To study whether a detailed radiographic examination of neck and upper airway can help identify normal looking patients in whom endotracheal intubation may be difficult; determine whether such parameters as identified by magnetic resonance imaging (MRI) can also be identified in a soft tissue radiograph; and to study the correlation between oropharyngeal appearance, based on Mallampati's classification, and laryngoscopic findings in a large number of patients requiring endotracheal intubation. DESIGN: Prospective. SETTING: University medical center. PATIENTS: 20 adult patients in whom an unanticipated difficult endotracheal intubation was encountered, and a control group of 20 patients in whom endotracheal intubation was easily accomplished. INTERVENTIONS: Difficult-to-intubate patients were identified according to prospectively established criteria. Control subjects, in whom the trachea was easily intubated, were matched for age, gender, height, weight, and oropharyngeal appearance. MEASUREMENTS AND MAIN RESULTS: In all 40 study patients, a soft tissue radiograph and an MRI scan of the neck were obtained. We measured 21 parameters from both radiographic studies. There were no significant differences between the two groups in 20 of 21 measured parameters on MRI scans and soft tissue radiographs. Only one measurement--the distance between the uppermost visible part of the airway and the posterior pharyngeal wall (measured from MRI scans only)--between the two groups achieved statistical significance. The values recorded from MRI and soft tissue radiographs were not significantly different. Airway grading system first suggested by Mallampati had a fair correlation with laryngoscopy findings associated with a difficult endotracheal intubation. CONCLUSIONS: No significant difference between the two groups could be identified on soft tissue radiography or MRI scans.
Magnetic resonance (MR) imaging is useful in evaluating the wide spectrum of diseases that cause nasal masses. MR imaging is most helpful in (a) defining tumor margins and possible intracranial extension and (b) differentiating tumor (which has intermediate, heterogeneous signal intensity on T2-weighted images) from concurrent postobstructive sinusitis and other infectious or inflammatory masses (which have high, homogeneous signal intensity on T2-weighted images if the secretions are well hydrated). The analysis becomes more complicated in cases with desiccated and mixed composition secretions. MR imaging also allows characterization of very vascular tumors, which show flow voids or marked enhancement. Low signal intensity on T1-weighted images and marked low signal intensity on T2-weighted images are characteristic of fungal sinusitis, and fat within a nasal mass indicates a dermoid or epidermoid cyst. Idiopathic midline granuloma, Wegener granulomatosis, and "cocaine nose" manifest as predominantly destructive midline masses. Despite the advantages of MR imaging, computed tomography remains the preferred imaging modality for evaluating nasal masses that contain calcification or originate from bone or cartilage.
Measurements of the magnetic field elicited by a 50 ms long auditory stimulus, from three normal subjects and one head injured subject, are used to estimate the three dimensional distribution of generators in the brain. The resulting images are compared with point source solutions obtained with the usual single current dipole fitting procedures, over a latency range which includes the extrema in the (average) measured signal. In all cases considered, 100 or so epochs time-locked to the stimulus were magnetically recorded. These were averaged, and then analyzed using two techniques; a new distributed current model known as Magnetic Field Tomography (MFT), and the standard single current dipole (SCD) model. Both methods provide estimates of the current generators in the brain. In two of the normal subjects, the MFT solutions are super-imposed onto Magnetic Resonance Images (MRI) of the relevant cortical area. The results show that when the SCD model provides a reasonable description of the data, the MFT estimate shows one dominant localized region in agreement with the current dipole position. In the MFT sequence of solutions the activity evolves smoothly; multiple areas of activity often arise as the focal activity in one region declines while focal activity in another region grows. In contrast the SCD solutions during these intermediate periods fit the data poorly, and may move erratically from one locale to another. We conclude that MFT seems to provide a reasonable description of the activity through cortical and subcortical regions. The evolution of activity, as derived from the average signal, can be traced continuously from the onset of the stimulus, not just at the peaks.(ABSTRACT TRUNCATED AT 250 WORDS)
The effects of transcallosal surgery on interhemispheric transfer of information were investigated in five patients who underwent partial section of the corpus callosum for evacuation of a brain tumor. In comparison with normal controls, postoperative findings indicated subtle motor and/or sensory manifestations of hemispheric disconnection which tended to resolve overtime. However, in no case were the disconnection effects disabling in the performance of daily activities.
Recent improvements in CT software allow rapid and high-quality two-dimensional reformatting of scans of the spine. Reformatting involves computer interpolation of two-dimensional multislice images acquired during routine axial CT scanning in order to generate a three-dimensional volume of data. From this block of data, new images are created and displayed in any desired plane. Reformatted images are acquired within minutes following axial CT scanning.
Metastatic disease to the optic nerve is uncommon. Optic nerve involvement has been described as an extension from choroidal, retinal, orbital, or central nervous system metastatic foci. Isolated optic nerve metastatic disease is extremely rare. We present the case of an isolated circumscribed metastatic lesion to the retrobulbar portion of the optic nerve detected radiographically.
A case of massive epistaxis refractory to nasal packing and bilateral surgical ligation of the internal maxillary and ethmoidal arteries is presented. Angiography revealed a pseudoaneurysm of the cervical portion of the internal carotid artery, and intravascular detachable balloons were used for epistaxis control. The appropriate use of intravascular diagnostic and therapeutic techniques is described.
Patients with the acquired immunodeficiency syndrome (AIDS) commonly display evidence of gross cerebral atrophy, but its true incidence and pathophysiology in the general AIDS population are unknown. In this study, we measured cerebrospinal fluid (CSF) spaces in 64 consecutively autopsied patients with AIDS, compared them with age-matched non-AIDS subjects, and correlated them with the microscopic neuropathology at autopsy. Thirty-seven of the patients with AIDS (58%) had a CSF space index greater than two standard deviations above the mean of the age-matched control subjects. CSF spaces were expanded the most in frontal and temporal lobes; ventricular spaces were expanded more than sulcal spaces. Regression analysis between age and the measured CSF indexes showed that practically none of the deviation in patients with AIDS could be explained by age-related atrophy. Patients with atrophy were much more likely to have human immunodeficiency virus type 1-associated histopathological changes in their brains, but the relationships were too weak to establish the microscopic cause of the atrophy. Measurement of CSF spaces in antemortem computed tomographic (CT) scans from 47 of the patients with AIDS revealed the same regional pattern of brain wasting. CT diagnosis of cerebral atrophy was strongly concordant with the postmortem diagnosis, but its severity was diagnosed slightly more conservatively at autopsy. Thus, quantitative analysis of CSF spaces in a robust sampling of patients with AIDS confirms that cerebral atrophy is a sensitive, common, and frequently subtle indication of central nervous system human immunodeficiency virus type 1 infection that may occur independently from any single specific microscopic abnormality. Its presence, severity, and regional pattern are detected with reasonable consistency using CT scanning.
Fifty patients who sustained mild to moderate closed head injury (CHI) underwent a CT scan, MRI, and neurobehavioural testing. At baseline 40 patients had intracranial hyperintensities detected by MRI which predominated in the frontal and temporal regions, whereas 10 patients had lesions detected by CT. Neurobehavioural data obtained during the first admission to hospital disclosed no distinctive pattern in subgroups of patients characterised by lesions confined to the frontal, temporal, or frontotemporal regions, whereas all three groups exhibited pervasive deficits in relation to normal control subjects. The size of extraparenchymal lesion was significantly related to the initial Glasgow Coma Scale score, whereas this relation was not present in parenchymal lesions. One and three month follow up MRI findings showed substantial resolution of lesion while neuropsychological data reflected impressive recovery. The follow up data disclosed a trend from pervasive deficits to more specific impairments which were inconsistently related to the site of brain lesion. These results corroborate and extend previous findings, indicating that intracranial lesions detected by MRI are present in most patients hospitalised after mild to moderate CHI. Individual differences in the relation between site of lesion and the pattern of neuropsychological findings, which persist over one to three months after mild to moderate CHI, remain unexplained.
A wide spectrum of diseases involve the clivus and paraclival structures. Primary neoplasms, metastatic tumors, and inflammatory, vascular, and hematopoietic disorders are the most common abnormalities to arise from or directly involve the clivus. MR imaging exquisitely shows and helps characterize the diseases that affect this area. Sagittal and coronal MR imaging allows precise localization and evaluation of the signal characteristics of a mass, enabling a more specific diagnosis. The multiplanar capabilities of MR imaging provide superb visualization of the adjacent cranial nerves and vascular structures, aiding in surgical planning and radiation therapy. In this pictorial essay, the MR imaging, CT, and conventional radiographic findings of various clival and paraclival lesions are illustrated.
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Polyvinyl alcohol particles used to embolize an arteriovenous malformation of the tongue were only temporarily successful. Additional embolization therapy was necessary and was complicated by ischemic ulcers of the tongue. We conclude that embolization therapy can be used, but the efficacy of this therapy in the longer term remains to be determined.
Neurobehavioral functioning and magnetic resonance imaging (MRI) were investigated in 25 patients with various Centers for Disease Control (CDC) stages of human immunodeficiency virus (HIV) infection and in a control group of seven normal subjects. Unequivocal slowing of information processing speed and cerebral atrophy were related to the stage of HIV infection, with patients in CDC group IV exhibiting the most abnormal findings. Slowing of response speed was directly related to the severity of cerebral atrophy.
In order to investigate post-traumatic hemispheric disconnection effects, dichotic listening and intermanual tasks were administered to 69 patients who had sustained a closed head injury of varying severity. The manual tasks consisted of naming objects palpated in either hand, transfer of postures from one hand to the other and writing. Consistent with predictions, the degree of ear asymmetry in dichotic listening performance was directly related to the severity of the head injury as reflected by the degree of impaired consciousness. Depth and localisation of parenchymal lesion characterised by magnetic resonance imaging were also related to the degree of ear asymmetry. Parenchymal lesions situated in sites which could potentially interfere with callosal auditory or geniculocortical pathways produced a greater disparity in response to left versus right ear inputs as compared with parenchymal lesions in areas such as the frontal lobes which are purportedly unrelated to asymmetries in dichotic listening performance. The results provide further evidence for the effects of multifocal brain lesions involving the white matter on tasks which require intra and/or interhemispheric integration.
Magnetic resonance imaging (MRI) was performed in a series of 21 children and adolescents who had been hospitalized after sustaining closed head injuries of varying severity at least 6 months previously. Areas of high intensity in the parenchyma were present in 8 of the 11 severely injured patients, whereas MRI findings were normal in all 10 patients with mild-to-moderate head injuries. Lesions involving the subcortical white matter were confined to severely injured patients whose clinical features were compatible with diffuse axonal injury. Neuropsychological assessment disclosed deficits primarily in the severely injured patients; these deficits were significantly associated with persistent lesions visualized by MRI. Serial MRI and neurobehavioral assessment following early injury may be useful in documenting cognitive impairment in relation to structural alterations of the young brain.
Six patients with masses of the anterosuperior portion of the third ventricle were imaged with MR and CT. Four patients had proved colloid cysts, one patient had a proved astrocytoma, and one patient had a presumed colloid cyst. Multiplanar MR imaging provided accurate localization of the anterosuperior third-ventricle mass in all cases. The MR intensity characteristics of the colloid cysts varied and the astrocytoma could not be differentiated from the colloid cysts on MR. The astrocytoma contained a calcification that was clearly demonstrated on CT but was difficult to appreciate on MR. Neither MR nor CT was useful in predicting success of stereotactic aspiration of the colloid cysts in this small series, but the presence of thin, low-viscosity cyst contents could be suggested by both examinations.
Two divers underwent neurobehavioral examinations and magnetic resonance imaging (MRI) while hospitalized during the first 2 weeks after sustaining decompression sickness (DCS). Their neurologic findings included a Brown-Séquard Syndrome consistent with spinal cord lesion, and focal deficits consistent with cerebral lesion(s). MRI revealed subcortical white matter lesions in the brains of both divers, whereas no lesion of the spinal cord was demonstrated. The patients exhibited neurobehavioral sequelae including disturbances of memory, divergent thinking, and visuospatial and motor functioning. Focal neurologic deficits resolved in both patients, and their cognitive and memory problems improved slowly. Findings in these two divers raise the possibility that cerebral insult more frequently accompanies spinal cord injury in DCS than previously thought.