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Biomedical subjects

R L McLaurin

Publications and source records attributed to R L McLaurin.

At least 19 recordsLinked to original sources
PubMed1990

Reversal sign on CT: effect of anoxic/ischemic cerebral injury in children.

A retrospective study was performed to determine the clinical and pathologic features, etiology, and outcome of children with the reversal sign. The reversal sign, a striking CT finding, probably represents a diffuse, anoxic/ischemic cerebral injury. CT features of the reversal sign are diffusely decreased density of cerebral cortical gray and white matter with a decreased or lost gray/white matter interface, or reversal of the gray/white matter densities and relatively increased density of the thalami, brainstem, and cerebellum. Twenty children with the reversal sign were retrospectively analyzed. We divided the patients into three groups: (1) acute reversal, (2) intermediate group, and (3) chronic reversal. There were nine cases of trauma (seven of child abuse); nine hypoxia/anoxia incidents (birth asphyxia, drowning, status epilepticus); one bacterial meningitis; and one degenerative encephalitis. All acute- and intermediate-group patients had respiratory problems requiring ventilator support and intensive care. In five of seven patients who died, autopsy findings were consistent with anoxic/ischemic encephalopathy. Surviving patients have profound neurologic deficits with severe developmental delay. The CT reversal sign carries a poor prognosis and indicates irreversible brain damage.

Brain Edema↗
PubMed1987

Slit-ventricle syndrome: review of 15 cases.

The slit-ventricle syndrome (SVS) has been the subject of diverse opinions and recommendations during the past 2 decades. In an effort to define the clinical features of SVS and to make recommendations concerning management we have reviewed 15 cases treated by a fairly uniform technique during the past 5 years. The syndrome consists of: (1) intermittent, but self-limiting episodes resembling shunt malfunction, usually lasting a few days, (2) nonfilling of the pumping device after compression, and (3) a slit-like ventricular system on CT scan. In all but 2 patients the initial shunt was performed in infancy. The mean interval from the initial shunt to treatment of SVS was 6 years. The age range at onset of SVS varied from 2 to 17 years with a mean of 7 years. All patients in this series were relieved of symptoms by placement of an antisiphon device and, in most patients, upgrading the valve resistance. Analysis of this series has led to the following conclusions: (1) SVS is a characteristic clinical entity, usually distinguishable from persistent shunt malfunction and from low-pressure headache, (2) the pathogenesis is intermittent obstruction of the ventricular catheter, (3) there is no good evidence that changes of brain compliance or La Place principles apply, and (4) placement of antisiphon device and upgrading valve resistance are effective treatments.

Brain Diseases↗
PubMed1987

Radiographic characteristics of skull fractures resulting from child abuse.

Radiographic characteristics of skull fractures in 39 cases of documented child abuse were compared with skull fractures in 95 cases of accidental injury to determine if differential features could be identified. All children were less than 2 years old. Emergency room and hospital records for these patients were also reviewed. The results of this study show that clinical features did not provide any clues as to whether the children had been injured by abuse or by accident. However, it was found that multiple fractures, bilateral fractures, and fractures crossing sutures occurred significantly more often in abuse cases than in accidental injury. When such fractures are present, abuse should be suspected.

Accidents↗
PubMed1986

Management of spina bifida and associated anomalies.

Myelomeningocele and its accompanying deformities are among the most complex and frequent of the malformations to which the developing nervous system is subject. a multidisciplinary approach to management of the patient with myelomeningocele is essential, and with aggressive and continuous care, the results may be extremely gratifying.

Abnormalities, Multiple↗
PubMed1985

Acute responses to experimental blunt head trauma: topography of white matter edema.

The location of edema and territory of extravasation of serum protein were examined in the white matter of cats with different forms of intracranial pathology following an impact-acceleration injury to the head. Edema was tested with an organic density gradient and Evans blue dye was used as a marker for breakdown of the blood-brain barrier. Animals with tissue hemorrhage (contusions) involving both cerebral cortex and white matter had a substantial, progressive accumulation of Evans blue-stained edema near tissue hemorrhage during the 6 h following trauma. In addition, this category of cats had a widespread, mild edema at 15 min after injury that was usually unaccompanied by Evans blue stain. Cats with cortical contusions had rather mild edema neighboring tissue hemorrhage; animals with subarachnoid hemorrhage in the absence of cerebral contusions had neither measurable edema nor (usually) visible Evans blue staining. We conclude that: acute traumatic cerebral edema varies considerably in presence, magnitude and territory with different forms of intracranial pathology; and mechanically induced edema can occur that is independent of spread of fluid from areas of tissue hemorrhage.

Acute Disease↗
PubMed1984

Treatment of CSF shunt infections with intrashunt plus oral antibiotic therapy.

Infections of 12 cerebrospinal fluid (CSF) shunts in 11 children were treated with oral systemic antibiotic therapy plus daily intrashunt injections of antibiotics. Eight patients were infected with Staphylococcus epidermidis (four patients) or Staphylococcus aureus (four patients), and were treated with intrashunt vancomycin, plus oral trimethoprim/sulfamethoxazole (T/S), plus oral rifampin. One of these eight patients was later changed to a course of intrashunt cephapirin and oral cephalexin plus oral rifampin. One patient with Micrococcus varians infection was treated with oral T/S and rifampin, without intrashunt therapy, another patient with Pseudomonas cepacia infection was treated with intrashunt kanamycin plus oral T/S, and a third with Corynebacterium sp. infection was treated with intrashunt vancomycin plus oral T/S. Eight of the 11 patients required some form of shunt surgery, the most common being temporary externalization of the peritoneal end of the catheter. Only two shunts were completely replaced (both were ventriculojugular shunts which were changed to ventriculoperitoneal shunts). Nine of 10 evaluable cases were considered cured of their infections. The patient treated with cephalosporins had an uncorrected shunt malfunction and relapsed 1 month after completing therapy. The authors have shown that CSF shunts infected with Staphylococci can be effectively cleared with daily intrashunt vancomycin plus systemic therapy with oral T/S and rifampin. Less common infections may also be amenable to this form of therapy. Revision surgery, if necessary, should be carried out during the antibiotic therapy.

Administration, Oral↗
PubMed1984

Acute responses to experimental blunt head trauma. Topography of cerebral cortical edema.

Anesthetized cats subjected to impact followed by acceleration and rotation of the skull were sacrificed at 15 minutes or 6 hours after injury and were selected for study if unilateral cerebral contusion was present. Widespread areas of cerebral cortex were examined bilaterally for edema, using measurement of tissue density with an organic gradient, and for breakdown of the blood-brain barrier to plasma protein tagged with Evans blue dye. At both times tested, a halo of vasogenic edema (Evans blue stain plus decreased density) was present in the cortex surrounding areas of contusion. At 15 minutes after injury, animals with deep contusions also had a slight decrease in density without Evans blue staining, interpreted as cytotoxic edema, in some gyri neighboring the contusion. At 6 hours, cytotoxic edema was not evident, but some animals had vasogenic edema in the gyri adjoining the contusion. Most gyri contralateral to contused areas had neither Evans blue staining nor changes in tissue density. These findings suggest that, with the present head-injury model, acute changes in tissue density and vascular permeability occur in the cerebral cortex of hemispheres with contusion. These responses are related topographically to contusion sites, and change over the two times studied. The authors conclude that events in addition to spread of fluid from areas of contusion contribute to the edema of head injury, and that more than one form of edema can follow mechanical trauma to the brain.

Animals↗
PubMed1984

Acetazolamide and cerebral oxygenation in dogs.

Acetazolamide could theoretically impair oxygen delivery to cerebral tissue by inhibiting local acidification of capillary blood. There is considerable evidence, however, that acetazolamide improves cerebral oxygen tension. This experiment was designed to demonstrate increased deep cerebral oxygen tension after acetazolamide. Three groups of dogs were anesthetized with pentobarbital and ventilated with a respirator. A Teflon-coated stainless steel catheter was placed through a craniotomy into the parietal lobe and advanced into the corona radiata to monitor cerebral pO2 and pCO2 with a mass spectrometer. Group one dogs were normoxic and eucapneic. Group two dogs were hypoxemic, and Group three dogs were hypocapneic. After control cerebral and arterial gas tensions had been recorded, acetazolamide (30 mg kg-1) was injected intravenously. Cerebral gas tensions were monitored continuously and arterial gases were analyzed at 30, 60, 90 and 120 min. Cerebral oxygen tension was not decreased by acetazolamide in any of the dogs. Cerebral carbon dioxide tension was increased by acetazolamide in all dogs. We conclude that acetazolamide does not deplete cerebral oxygen tension even in the face of hypoxemia or acute hypocapnea.

Acetazolamide↗
PubMed1983

Penetration of nafcillin, methicillin, and cefazolin into human brain tissue.

To determine the penetration of the antistaphylococcal antibiotics, nafcillin, methicillin, and cefazolin, into brain tissue, we gave to each of 27 patients undergoing craniotomy and brain biopsy one of the antibiotics in a 2-g intravenous infusion just before operation. At the time of brain tissue removal (30 to 225 minutes after the start of the infusion), a serum specimen was obtained, and tissue and serum were assayed for antibiotic concentration. Eleven of 13 brain specimens contained detectable nafcillin concentrations between 0.36 and 11 micrograms/g of tissue (mean, 2.7 micrograms/g for all 13 specimens). Fourteen of 18 brain tissue specimens contained detectable methicillin concentrations between 0.56 and 5.0 micrograms/g of tissue (mean, 2.0 micrograms/g for all 18 specimens). Ten of 11 brain tissue specimens contained detectable cefazolin concentrations between 2.0 and 40 micrograms/g of tissue (mean, 10.6 micrograms/g for all 11 specimens). Each antibiotic penetrated "abnormal" brain tissue better than "relatively normal" brain tissue. Because nafcillin is more active against Staphylococcus aureus, we conclude that nafcillin is preferable to methicillin for the therapy of central nervous system staphylococcal infections. Cefazolin achieves higher brain tissue concentrations than the penicillins, but has not been clinically evaluated for the therapy of central nervous system infections.

Brain Chemistry↗
PubMed1983

Monitoring of antifibrinolytic therapy following subarachnoid hemorrhage. The importance of CSF fibrin/fibrinogen degradation products.

Ten cases of subarachnoid hemorrhage (SAH) from ruptured cerebral aneurysm are reported. Fibrin/fibrinogen degradation product (FDP) levels were determined simultaneously in blood and cerebrospinal fluid (CSF) at an average frequency of 1.7 days, extended over periods of 8 to 63 days. Successful antifibrinolytic therapy (AFT) correlated with FDP levels in CSF of less than 16 micrograms/ml. Five patients failed to respond to AFT. Levels of FDP in the CSF fluctuated widely in these five patients, and remained at or above 16 micrograms/ml for most of the monitoring period. Blood FDP levels were normal or minimally elevated, and could not be used in predicting or preventing rebleeding episodes. A hypothesis is presented to explain the significance of the presence of FDP's in CSF. In spite of the many techniques employed in monitoring AFT and reviewed in this paper, little information has been gained to improve the results and therapeutic strategies. Among the different methods available, FDP measurements in the CSF have correlated best with rebleeding, and thus may be used in modifying and individualizing therapy. Suggestions are given for future studies.

Adult↗
PubMed1983

Acute responses to blunt head trauma. Experimental model and gross pathology.

This study of blunt craniocerebral trauma describes an experimental model that involves delivery of forceful blows to the resting movable skulls of anesthetized cats. Injuries inflicted by this method included skull fractures in 81% of cases, epidural hemorrhages in 50%, subdural hemorrhages in 80%, subarachnoid hemorrhages in 100%, and brain contusions in 84%. In the majority of instances the subdural and epidural hemorrhages were thin films of blood that did not compress or distort the subjacent brain. The distribution of cerebral contusions was restricted to the cerebral parenchyma beneath the locus of cranial impact except for contusions associated with skull fractures. This experimental model recapitulates clinically realistic human cranial trauma and produces pathological lesions suitable for investigation of the pathophysiology of blunt head trauma.

Animals↗
PubMed1982

Cystic thalamic gliomas.

Primary tumours of the thalamus are rare and present several diagnostic and therapeutic problems. Cystic thalamic lesions tend to be low grade astrocytomas and have only been reported in children. Signs and symptoms can be divided into those due to intracranial hypertension and those due to loss of function of thalamic nuclei and surrounding structures. Histologic diagnosis can be established by CT-guided needle biopsy and therapy begun by evacuation of the cyst contents. The prognosis remains uncertain.

Astrocytoma↗
PubMed1982

Oral glycerol for the treatment of traumatic intracranial hypertension.

Hyperosmolar agents are a primary therapeutic modality employed in the treatment of traumatic intracranial hypertension. Profound hyperosmolarity accompanied by systemic dehydration is a potentially serious problem when these drugs are used repeatedly for control of intracranial pressure. Because glycerol, a water-soluble alcohol, is metabolized in the liver, its dehydrating capacity may be reduced in comparison to other agents. A series of 15 patients were treated with oral glycerol (0.5 to 1.0 gm/kg) with only minor changes in serum electrolytes, glucose, and urea nitrogen. Serum osmolarity rose from a baseline of 305 mOsm/liter to 355 mOsm/liter after 10 days of therapy. Glycerol was found to be effective and safe when employed in this protocol and proved to be a valuable adjunct to the standard methods available for control of intracranial hypertension.

Administration, Oral↗
PubMed1981

Dandy-Walker syndrome. Clinical analysis of 23 cases.

A clinical analysis of 23 patients with Dandy-Walker malformation indicates that more than 85% of them were diagnosed at or before 1 year of age, and that the incidence of associated anomalies is approximately 50%, with a 17% incidence for agenesis of the corpus callosum. The significance of the presence of these anomalies is substantiated by the fact that of the seven deaths recorded, six were related to this disease and five were affected by associated anomalies. The high mortality rate (26%) is comparable to that of other series. The differential diagnosis with posterior fossa extra-axial cysts is discussed. Ten patients were primarily treated with excision of the cyst membrane; all of them required subsequent shunting to control the intracranial pressure, demonstrating the futility of this approach. None of the patients treated with lateral ventricle shunting suffered an upward herniation of the posterior fossa contents, suggesting that combined shunting of the lateral and fourth ventricles is rarely necessary. The technical advantages of posterior fossa shunting alone are outlined. Of the 16 survivors, 14 were assessed for their mental development by means of standard psychometric testing. The results of the intelligence quotient (IQ) scoring have indicated that 71% of the patients have subnormal mental development (IQ less than 83). There was no significant relationship between retardation and associated anomalies, although agenesis of the corpus callosum was related to poor intellectual development in the two patients so affected (IQ's of 50 and 73).

Agenesis of Corpus Callosum↗
PubMed1981

Acute changes in regional brain water content following experimental closed head injury.

A Remington humane stunner was used to deliver blows to the skulls of anesthetized cats. The animals were sacrificed at 30 minutes or 1, 2, or 6 hours after trauma and selected for data collection on the basis of the following two categories of gross intracranial pathology: 1) unilateral contusion, with subarachnoid hemorrhage (SAH); or 2) SAH only. For selected cats, specific gravity was measured in 5- to 10-mg samples of uncontused tissue taken from coronal slices at the level of the frontoparietal suture. The regions tested included dorsal cerebral cortex, subcortical white matter, deep white matter, and caudate nucleus. Specific gravity data from injured animals were compared with those from similar areas in uninjured anesthetized cats to test for cerebral edema. At 30 minutes after head injury, contused hemispheres had significant edema of all tested except the caudate nucleus. Edema of the subcortical and deep white matter increased with time after the injury. Increase in water content of the cerebral cortex was transient and appeared unrelated to contusion. The caudate nucleus was edematous only at 6 hours, suggesting movement of fluid from the deep white matter compartment into the nucleus. The hemispheres opposite the contusion and those related to SAH had, with one exception, an absence of edema in the white matter and caudate nucleus, but a transient increase in water content of the cerebral cortex. These findings suggest that, in the presence of contusion, cerebral edema can contribute to brain swelling as early as 30 minutes after closed head trauma. In addition, a transient and minimal cortical edema, perhaps related to ischemia, occurred in all groups of hemispheres examined.

Animals↗
PubMed1981

Pituitary hormone response to head injury.

Measurements of the serum levels of pituitary hormones were made in six patients with uncomplicated head injury. Samples were obtained at 4-hour intervals for 72 hours to evaluate diurnal rhythms. Three of the six patients revealed elevations of serum growth hormone (GH) and prolactin, but no trends could be established. Likewise, three patients had marked elevations of luteinizing hormone and lesser elevations of follicle-stimulating hormone, but no pattern was discernible. The level of thyroid-stimulating hormone was stable and remained in the normal range throughout. GH was measured after intravenous glucose loading. A paradoxical rise reverted to normal at the late follow-up evaluation. It is suggested that the abnormal levels were related to abnormal hypothalamic function rather than to pituitary damage.

Adolescent↗