Physiological thresholds for irreversible tissue damage in contusional regions following traumatic brain injury.

Cerebral ischaemia appears to be an important mechanism of secondary neuronal injury in traumatic brain injury (TBI) and is an important predictor of outcome. To date, the thresholds of cerebral blood flow (CBF) and cerebral oxygen utilization (CMRO(2)) for irreversible tissue damage used in TBI studies have been adopted from experimental and clinical ischaemic stroke studies. Identification of irreversibly damaged tissue in the acute phase following TBI could have considerable therapeutic and prognostic implications. However, it is questionable whether stroke thresholds are applicable to TBI. Therefore, the aim of this study was to determine physiological thresholds for the development of irreversible tissue damage in contusional and pericontusional regions in TBI, and to determine the ability of such thresholds to accurately differentiate irreversibly damaged tissue. This study involved 14 patients with structural abnormalities on late-stage MRI, all of whom had been studied with (15)O PET within 72 h of TBI. Lesion regions of interest (ROI) and non-lesion ROIs were constructed on late-stage MRIs and applied to co-registered PET maps of CBF, CMRO(2) and oxygen extraction fraction (OEF). From the entire population of voxels in non-lesion ROIs, we determined thresholds for the development of irreversible tissue damage as the lower limit of the 95% confidence interval for CBF, CMRO(2) and OEF. To test the ability of a physiological variable to differentiate lesion and non-lesion tissue, we constructed probability curves, demonstrating the ability of a physiological variable to predict lesion and non-lesion outcomes. The lower limits of the 95% confidence interval for CBF, CMRO(2) and OEF in non-lesion tissue were 15.0 ml/100 ml/min, 36.7 mumol/100 ml/min and 25.9% respectively. Voxels below these values were significantly more frequent in lesion tissue (all P < 0.005, Mann-Whitney U-test). However, a significant proportion of lesion voxels had values above these thresholds, so that definition of the full extent of irreversible tissue damage would not be possible based upon single physiological thresholds. We conclude that, in TBI, the threshold of CBF below which irreversible tissue damage consistently occurs differs from the classical CBF threshold for stroke (where similar methodology is used to define such thresholds). The CMRO(2) threshold is comparable to that reported in the stroke literature. At a voxel-based level, however (and in common with ischaemic stroke), the extent of irreversible tissue damage cannot be accurately predicted by early abnormalities of any single physiological variable.

Imaging of cerebral blood flow and metabolism in brain injury in the ICU.

The heterogeneity of the initial insult and subsequent pathophysiology has made both the study of human head injury and design of randomised controlled trials exceptionally difficult. The combination of multimodality bedside monitoring and functional brain imaging positron emission tomography (PET) and magnetic resonance (MR), incorporated within a Neurosciences Critical Care Unit, provides the resource required to study critically ill patients after brain injury from initial ictus through recovery from coma and rehabilitation to final outcome. Methods to define cerebral ischemia in the context of altered cerebral oxidative metabolism have been developed, traditional therapies for intracranial hypertension re-evaluated and bedside monitors cross-validated. New modelling and analytical approaches have been developed.

Childhood hypersensitivity pneumonitis due to dove antigens.

A case of hypersensitivity pneumonitis due to doves is reported and compared with other cases due to dove or pigeon antigens reported in children. The diagnosis is substantiated by the presence of precipitating antibody to dove and pigeon serum, clinical improvement after contact with the doves was broken, and a positive response to inhalation challenge with pigeon serum. The insidious nature of this disease is emphasized as well as the importance of having detailed environmental information in children with unexplained respiratory disease.

Munchausen syndrome by proxy.

Munchausen syndrome by proxy is the most difficult form of child abuse. It carries substantial morbidity and mortality. The diagnosis relies on appropriate suspicion and careful investigation. The psychological illness/need of the perpetrator is the main clinical feature. Early recognition and appropriate intervention prevent further abuse and criminal actions.

Metallic neurosurgical implants for cranial reconstruction and fixation: assessment of magnetic field interactions, heating and artefacts at 3.0 Tesla.

The objective of this study was to evaluate the magnetic resonance imaging (MRI) compatibility of metallic neurosurgical implants commonly used for cranial reconstruction and fixation, in association with a 3.0 Tesla (T) MR system. Ten metallic neurosurgical implants used for cranioplasty operations were evaluated. The implants were tested ex vivo for magnetic field interactions (translational attraction and torque), heating (using saline and gel phantoms), and artefact production [using dual echo spin echo (DSE) and gradient echo (GRE) sequences] at 3.0 Tesla. None of the implants displayed translational attraction or torque, and heating was physiologically insignificant (maximal temperature elevation was 0.5 degrees C). MR artefacts were minimal with spin echo sequences; gradient echo sequences produced much larger artefacts. The neurosurgical implants evaluated in this study should not present a risk to patients undergoing MRI in the 3.0 T MR system. Although the implants do produce susceptibility artefacts, especially with gradient echo sequences, useful imaging should still be possible.

Lymphomas and animal-protein consumption.

Geographic comparison reveals a positive correlation between consumption of animal protein, particularly bovine protein, and lymphoma mortality. Allied observations suggest that excessive consumption of animal protein may, through antigen absorption and chronic persistent stimulation, impose considerable wear and tear on lymphoid tissue and thereby encourage malignant changes.

Morbidity in breast-fed and artificially fed infants.

One-half of the healthy newborn infants at a rural medical center were initially breast fed; the proportion declined to 4% by one year of age. Breast-feeding was associated with significantly less illnes during the first year, especially if continued beyond 41/2 months of age. Breat-fedding was associated with a higher level of parental education and, by inference, higher socioeconomic status. The health advantage of breast-feeding was still evident after controlling for parental educational status. In better educated families the difference in significant illness between infants who were artifically fed and those who were breast fed for prolonged periods of time was two- to threefold.

PIP: A study was conducted into the relative morbidity among breast- and bottle-fed infants in a rural area in New York state. The records of 326 infants born at the Mary Imogene Bassett Hospital in Cooperstown, New York, were reviewed. Of these, 253 were seen regularly at the pediatric clinic during the 1st year of life. 1/2 of the newborns were initially breast fed; the proportion dropped to 4% by the end of 1 year. Breast fed babies suffered significantly less illness during the 1st year, especially when the breastfeeding was prolonged beyond 4 1/2 months. The incidence of breast feeding was significantly associated with higher educational levels for both mothers and fathers and with increased maternal age. The health advantages of breast feeding, however, were independent of educational levels and, by inference, the family's socioeconomic status.

Morbidity in breast-fed and artificially fed infants. II.

The advantages of breast-feeding in reducing morbidity was previously shown in a group of rural infants. Those observations are extended and refined. The protection afforded by breast-feeding is greatest during the early months, increases with the duration of breast-feeding, and appears to be more striking for serious illness. It operates independently of the effect of associated factors such as socioeducational status, family size, day-care exposure, and birth weight.

Breast-feeding and health in the 1980s: a global epidemiologic review.

PIP: In view of the significant and articulate minority view among pediatricians that breast feeding is not "worth the bother" in developed countries, this review of the literature delves into the evidence from both developed and developing countries for the advantages of breastfeeding, both in infants and for long-term health. Infants in developed settings experience twice the hospitalization rate and more severe illness from lower respiratory tract infection, primarily respiratory syncytial virus. In developing countries the mortality risk is 4-fold. for otitis media, the relative risks were 3.3-4.3 for Finnish infants. Bacterial meningitis and/or bacteremia had a 4-fold risk for hospitalization in a Connecticut study, and a 3-fold relative risk in 2 developing country studies. Human milk was the best preventative for bacteremia and necrotizing enterocolitis in prematures in British neonatal units. A 20-fold reduction in neonatal deaths occurred in Philippine study of breastfeeding, especially in low birth weight babies. Diarrhea causes the most infant mortality in developing nations, where bottle-feeding raises rates 14-fold. In the U.S. estimated relative risks is 3.7 for diarrheal mortality. Sudden infant death is about 1/5 less common in U.S. breast fed babies than in bottle fed. There is evidence for better long-term health after breast feeding in disorders such as celiac disease, Crohn disease, ulcerative colitis, insulin-dependent diabetes mellitus, thyroid disease, malignant lymphoma, chronic liver disease, atopic dermatitis, and food allergies. The design of good studies of protection conferred by breast feeding, and the possible modes of action of breast milk are discussed.^ieng