PubMed Health⌕ Search

Biomedical subjects

E R Cardoso

Publications and source records attributed to E R Cardoso.

At least 19 recordsLinked to original sources
PubMed1999

Correlation of permittivity and water content during cerebral edema.

Correlation between the permittivity of white matter and cerebral edema was studied. A time domain reflectometer was used to measure the permittivity changes of canine cerebral white matter due to edema produced in vitro by osmosis over a frequency range of 100 MHz to 1 GHz. For all frequencies, a strong correlation was found between the water content and the dielectric constant (R approximately 0.86) and loss factor (R approximately 0.82). The results suggest that it may be possible to estimate both the tissue water content as well as the composition of the accumulated edematous fluid.

Animals↗
PubMed1998

A recessively inherited non-lethal form of popliteal pterygium syndrome.

Two siblings, a 10-year-old boy and a 6-month-old girl, born in a Palestinian family, with manifestations of popliteal pterygium syndrome are presented. This rare form of syndrome is usually assumed to be autosomal dominant. Parental consanguinity and lack of phenotype manifestation in the ancestry of the present family favoured an interpretation of determination by an autosomal recessive trait.

Cleft Palate↗
PubMed1997

Neuropathological changes in chronic adult hydrocephalus: cortical biopsies and autopsy findings.

BACKGROUND: The cortical changes resulting from chronic hydrocephalus in adults are not well defined. METHODS: Retrospective analysis of twenty-one patients (age 64-88 years) with a clinical diagnosis of "normal pressure hydrocephalus" who underwent cortical biopsy at the time of intracranial pressure monitoring or shunt insertion, and eight patients who were biopsied but not shunted. Eleven brains (age 26-92 years), seven from patients who could be considered to have "normal pressure hydrocephalus", were also examined following autopsy. Age- and sex-matched control brains with small ventricles and no history of dementia were compared to the hydrocephalic brains. Senile plaques and neurofibrillary tangles were assessed semiquantitatively and a non-parametric statistical analysis was employed. RESULTS: Five biopsies exhibited both senile plaques and rare neurofibrillary tangles, while two had only neurofibrillary tangles. Neurofibrillary tangles were more prevalent in hydrocephalic brains than in controls. There was no difference in the prevalence of senile plaques between the two groups. Grumose bodies in the substantia nigra were identified in five autopsy brains, a prevalence higher than in control brains. CONCLUSIONS: These pathological features are not specific for hydrocephalus; however, they suggest that long-standing ventriculomegaly is associated with degenerative brain changes in sites beyond the periventricular white matter. The presence of senile plaques in cortical biopsies from hydrocephalic patients does not appear to be a contraindication to shunting; however a prospective study in patients undergoing intracranial pressure monitoring would better address the issue.

Adult↗
PubMed1996

External hydrocephalus in adults. Report of three cases.

The authors report three adult patients who developed a symptomatic extraaxial collection of cerebrospinal fluid (CSF) after an intracranial hemorrhage. The fluid shifted from the extraaxial into the ventricular space as the patients' symptoms progressed. The symptoms resolved after placement of a ventriculoperitoneal shunt. External hydrocephalus, which is frequently observed in children, had not yet been described in adults. It is important to differentiate chronic subdural collections from external hydrocephalus, because ventricular CSF shunting increases the former while it is the treatment for the latter. The authors believe that symptomatic extraaxial fluid collections developed in these three adults during the early phase of posthemorrhagic hydrocephalus because the ventricles presented great resistance to distention at the onset of hydrocephalus. Animal experiments have led to the same result.

Adult↗
PubMed1995

Mentolabial sulcus: a histologic study.

This study deals with the structure of the lower lip in the region of the mentolabial sulcus with particular emphasis on the morphologic factors responsible for producing and maintaining the sulcus. The results of this study provide information about the anatomic framework as it pertains to reconstructive and aesthetic procedures on the lower face deformed by injuries.

Chin↗
PubMed1995

Postburn deformity of lip-chin complex: a method to restore the mentolabial sulcus.

An extensive postburn deformity of the lower lip presents a difficult reconstructive problem. Efforts to reconstruct the resultant defect by conventional methods were found unsatisfactory. In a deformed lower lip, restoration of the contour of the lip with a well-defined mentolabial sulcus should be the aim of any reconstructive effort to bring aesthetic balance to the face. We describe a simple and effective method of restoring the function and form of the lip-chin complex.

Burns↗
PubMed1993

The gravitational shunt: an alternative approach to cerebrospinal fluid shunting.

Current cerebrospinal fluid shunts use complex differential pressure values to regulate drainage. Such systems are prone to overdrainage and obstruction, and thus have an unpredictable effect on intracranial pressure (ICP). The gravitational shunt (GS) introduces an alternative approach. It uses a single, simple valve to balance the pressures generated within a vertical shunt system. The ICP is then regulated by the position of the valve along the cranioabdominal shunt axis and not by the mechanical properties of the valve. Bench testing demonstrated that when using the GS (1) a linear correlation (r = 0.91, p < 0.001) exists between the ICP and the position of the valve along the vertical shunt axis, (2) positive and negative ICPs are maintained, and (3) the ICP can be predicted by an equation derived from theoretical principles. The GS uses a single, simple valve as a pressure regulator and an antisiphon device. It allows the maintenance of a normal negative ICP in the upright position without risk of over-drainage. The other benefits of this system are discussed.

Cerebrospinal Fluid Shunts↗
PubMed1992

Evaluation of intracranial pressure gradients by means of transcranial Doppler sonography.

The authors investigated the effects of intracranial pressure gradients generated by a unilateral intracranial mass on transcranial Doppler (TCD) readings. Eleven patients harbouring a symptomatic chronic or subacute subdural haematoma underwent pre- and post-operative TCD examinations of the intracranial internal carotid and middle cerebral arteries. Mean values of velocity and pulsatility index (PI) were compared to the contra-lateral counterpart. The haematomas were evacuated by means of burr hole drainage under local anaesthesia. Symptomatic subdural haematomas lowered the ipsilateral blood velocity in the internal carotid and middle cerebral arteries by a mean side-to-side difference of 15.64 +/- 3.01 m.sec-1. The ipsilateral PI was higher than the contralateral values by an average of 0.23 +/- 0.04. Low mean velocity and high PI values were associated with high subdural pressure. Abnormal pre-operative ipsilateral TCD readings returned to normal following haematoma drainage. We postulate that intracranial pressure gradients generated by the subdural mass lesion are responsible for the asymmetry of TCD readings. These differences should be considered in the interpretation of post-subarachnoid haemorrhage vasospasm, as it is frequently associated with lateral clots. Our findings also provide a useful method for non-invasive monitoring of intracranial pressure gradients.

Adult↗
PubMed1992

Dielectric measurement of cerebral water content using a Network Analyzer.

At present, no practical method exists for monitoring the progression and severity of cerebral oedema in a clinical setting on a continuous basis. In search for such a method, we investigated the electrical characteristics of cerebral tissue at microwave frequencies to quantify cerebral oedema. The dielectric constants of normal and oedematous canine cerebral white matter were measured using a Network Analyzer and then compared to the tissue's water content. In addition, salt infiltration and time elapsed after excision of the tissue were examined to determine their effects on the measurements. The water content and dielectric constant of the white matter were linearly related (correlation coefficient, r = 0.903), comparable to results obtained with a Time Domain Reflectometer in previous research. The Network Analyzer, however, is a more robust measurement device and, because of this, can potentially be used for long term measurements. Further, it was found that neither an increased tissue salt content nor the amount of time after excision of the tissue significantly affected the results. This indicates that the dielectric constant of cerebral white matter is mainly a function of the tissue's water content.

Body Water↗
PubMed1992

Aggravation of vasogenic cerebral edema by multiple-dose mannitol.

The authors investigated the pharmacokinetics of mannitol administered for treatment of vasogenic cerebral edema. A cortical cold injury was produced in 23 cats maintained under general anesthesia for 5 or 21 hours. Control animals received no mannitol, while treatment groups received either a single dose or five doses administered at 4-hour intervals of 0.33 gm/kg radiolabeled mannitol. Liquid scintillation counting was carried out to determine the concentrations of mannitol in the cerebral tissue, cerebrospinal fluid, plasma, and urine. Cerebral water content and linear progression of edema were also measured. Rapid plasma clearance prevented accumulation of mannitol after multiple intravenous injections, as 84% +/- 2% (mean +/- standard error of the mean) of the infused mannitol was excreted through the urine. However, there was progressive accumulation of mannitol within the cerebral tissue, especially in the edematous white matter where it reached a level of 0.33 +/- 0.03 mg/gm after five doses, exceeding the trough plasma concentrations by a ratio of 2.69:1. Water content measurement showed that a single dose of mannitol failed to reduce cerebral water content or edema progression at 4 hours postinjection, while multiple doses produced a 3% increase in water content in edematous regions (p greater than 0.0003). The results of this study demonstrated a reversal of the osmotic concentration gradient between edematous brain and plasma following multiple mannitol injections, associated with exacerbation of vasogenic cerebral edema.

Animals↗
PubMed1991

Haemodynamic modelling for the arterial pulsatile component of the intracranial pulse wave.

Vasospasm of cerebral arteries narrows the amplitude of the intracranial pressure wave, indicating that the arterial segment of the cerebral circulation is partially responsible for its formation. We investigated the fundamental mechanism of pressure pulse transmission from an artery to the surrounding environment. A mathematical model was derived expressing the amplitude of container pulsation (delta Po) as a function of mean intraluminal pressure (MPi), mean container pressure (MPo) and arterial pulse amplitude (delta Pi): delta Po = (-2(MPi - MPo) + b) (MPo + 1) delta Pi. This mathematical model was experimentally validated using an in vivo system of a single artery sealed inside a fluid-filled elastic container.

Animals↗
PubMed1991

Measurement of canine cerebral oedema using vector impedance methods.

The introduction of distilled water in vitro into brain tissue increases the water content of the cerebral white matter. The increase in water content for canine white matter may be predicted from impedance measurements on the tissue and the empirical equations determined in this study. However, the equations may only be valid for osmotic oedema induced in vitro as the behaviour of impedance related parameters is dependent on the type of oedema induced. The tissue volume measured with this technique may be reduced by the use of a smaller diameter probe. New equations relating impedance parameters to the water content for this probe and more accurate instrumentation may be required.

Animals↗
PubMed1990

Measurement of canine cerebral oedema using time domain reflectometry.

The complex dielectric constant of canine cerebral white matter correlates with its water content. Time domain reflectometry was used to measure the real dielectric constant and loss factor of 27 oedematous brain samples at frequencies of 100, 250, 500, 750, and 1,000 MHz. The real dielectric constant increased with water content at each frequency. Correlation was least for 100 MHz (R = 0.76) and between 0.87 and 0.89 for the other frequencies. The loss factor decreased with frequency with a correlation coefficient from 0.81-0.84. The in vitro results indicate that use of time domain reflectometry can predict oedema at a sensitivity of approximately 1-2% change of tissue water content.

Animals↗
PubMed1990

Method for preservation of water content during prolonged storage of cerebral tissue.

We set out to determine whether prolonged freezing of samples of cerebral tissue would alter specific gravity measurements. Our goal was to devise a method to prevent tissue water evaporation during transportation and storage of human cerebral samples in order to allow accurate measurements of specific gravity and water content at a delayed time. Control cerebral samples from healthy and water-intoxicated anaesthetized adult mice were immediately immersed in a gravimetric column for fresh specific gravity measurements. Cerebral samples from the same animals were also preserved by rapid freezing in liquid nitrogen, followed by deep-freeze storage at -80 degrees C for up to 7 days. The mean specific gravity and standard error of 65 non-oedematous and 18 oedematous fresh cerebral samples was 1,0483 +/- 2 x 10(-4) and 1,0433 +/- 5 x 10(-4), respectively. Freezing for 1 h to 7 days resulted in no significant alteration of specific gravity for 109 non-oedematous and 27 oedematous samples (P greater than 0.05). We describe a rapid freezing technique that is practical for transportation and storage of experimental or surgical cerebral specimens. Our findings indicate that storage of cerebral samples in liquid nitrogen, with or without subsequent deep-freezing, preserves water content of normal and oedematous cerebral tissue, thereby allowing accurate measurements at a later time.

Body Water↗
PubMed1989

Age-dependent changes of cerebral ventricular size. Part I: Review of intracranial fluid collections.

The age distributions of communicating hydrocephalus (CH), pseudotumour cerebri (PC) slit-ventricle syndrome (SVS), and chronic subdural haematomas (CSH) were reviewed in the medical literature. An age-related incidence was found: CH and CSH predominated in neonates less than 2 years and adults older than 55 years, while PC and SVS occurred mainly in older children and young adults. The latter two patient groups seem to show a greater resistance to ventricular dilatation in the presence of decreased CSF absorption. This may be related to larger volume and state of maturity of the cerebrum. On the other hand, neonates and the elderly more readily develop enlarged ventricles, in association with impairment of CSF absorption, or subdural fluid collections. Factors including status of cranial sutures, cerebral atrophy, cerebral water content, degree of cerebral myelination, and glial cell composition, may contribute to the age-related incidence of the four disorders investigated. Similarly, the development of ventriculomegaly may depend upon cerebral elastic properties besides the pri mary disturbance of CSF dynamics. The authors postulate that the size of cerebral ventricles in disorders of the cerebrospinal fluid (CSF) absorption is related to the elastic properties and volume of the brain. Furthermore, cerebral volume and elastic properties may also contribute to the age distribution of chronic subdural haematomas (CSH).

Adolescent↗
PubMed1989

Age-related changes of cerebral ventricular size. Part II: Normalization of ventricular size following shunting.

Thirty-one hydrocephalic patients were investigated prospectively by means of computed tomographic scan performed prior to and one week after cerebrospinal fluid (CSF) shunting. Planimetric measurements of the size of the cerebral ventricles were compared before and after shunting. Children under two years of age and elderly patients showed significantly less reduction of ventricular size (8.5 +/- 6.3% and 9.7 +/- 3.5% respectively) than older children and young adults (61.2 +/- 5.2%). The degree of reduction of ventricular size did not correlate with pre-operative size of ventricles, duration of disease, or clinical improvement. These findings suggest that reduction of ventricular size following CSF shunting is related to age. We postulate that the size of cerebral ventricles in hydrocephalic patients is not exclusively related to CSF dynamics, but also depends upon the intrinsic elastic properties of the cerebral parenchyma which vary with age.

Adolescent↗
PubMed1989

Quantification of abnormal intracranial pressure waves and isotope cisternography for diagnosis of occult communicating hydrocephalus.

Nineteen consecutive patients with suspected occult communicating hydrocephalus were investigated by means of clinical evaluation, neuropsychological testing, isotope cisternography, computed tomography scanning, and continuous intracranial pressure monitoring. Semi-quantitative grading systems were used in the evaluation of the clinical, neuropsychological, and cisternographic assessments. Clinical examination, neuropsychological testing, and computed tomography scanning were repeated 3 months after ventriculoperitoneal shunting. All patients showed abnormal intracranial pressure waves and all improved after shunting. There was close correlation between number, peak, and pulse pressures of B waves and the mean intracranial pressure. However, quantification of B waves by means of number, frequency, and amplitude did not help in predicting the degree of clinical improvement postshunting. The most sensitive predictor of favorable response to shunting was enlargement of the temporal horns on computed tomography scan. Furthermore, the size of temporal horns correlated with mean intracranial pressure. There was no correlation between abnormalities on isotope cisternography and clinical improvement.

Aged↗