Brain death: neuropathological findings and forensic implications

'Brain death' is defined pathophysiologically as intracranial circulatory arrest. The morphological features of brain death include cerebral edema, absence of reactive changes, and--after an interval of 15-36 h--the morphological hallmarks of respirator brain: edema, global softening of the brain, dusky discoloration of the gray matter, and often necrotic and sloughing tonsillar herniations. The following implications of brain death for forensic medicine are discussed: discriminating between respirator and autolytic brain, declaration of death, determining the time of brain death versus the time of the traumatic event leading to brain death, and neuropathological control of the clinical diagnosis of brain death. These issues are elucidated and their bearing on forensic practice is illustrated by several real-life situations. Thus, neuropathological examination in the case of clinically diagnosed brain death is--without doubt--necessary in order to answer several questions often or regularly expected.     

Reflexes in brain-dead patients

We report on a patient who suffered an acute, extensive intracerebral haemorrhage, leading to symptoms of cerebral herniation within a few hours. The clinical diagnosis of brain death was made based on a neurological examination, and an apnoea test eight hours after the haemorrhage. A few hours later the diagnosis was changed, as several reflexes reappeared. After six days mechanical ventilation was withdrawn, as the brain damage was considered so serious as to render further therapy futile. It was considered unethical to sustain therapy for a possible organ donation at a later date. A review of relevant the literature, however, shows that brain-dead patients may exhibit such varying degrees of autonomic and spinal reflexes as to cause confusion, thus delaying the physician in making a diagnosis. Often, an opportunity for organ donation is lost. Based on this review, we believe that our patient was indeed brain dead when the first diagnosis was made, and that a cerebral angiography should have been performed. Because organ donation is an important issue, the diagnosis of brain death must be definitive.     

Chronic periodic lateralized epileptiform discharges during sleep in a patient with caudate nucleus atrophy: insights into the anatomical circuitry of PLEDs

Vasa previa is a cause of sudden unanticipated fetal death, with a fetal mortality of 33-100%. Transvaginal sonography (TVS) and color Doppler may aid in making the diagnosis antenatally, allowing elective Cesarean delivery, thereby avoiding fetal death from exsanguination which would occur if the membranes were allowed to rupture in labor. Whilst it is not feasible to screen all pregnant women for vasa previa, antenatal examination with TVS and color Doppler of women at risk, specifically those with low-lying placentas, bi-lobed, multi-lobed and succenturiate-lobed placentas, multiple pregnancies and pregnancies resulting from in vitro fertilization may lead to antenatal diagnosis of the condition. We present the last three cases of vasa previa to have occurred in our institution, two of which were diagnosed antenatally using TVS and color Doppler. In all three cases, routine 20-week obstetric sonography revealed low-lying placentas; in only one of these did the placenta remain low at term. A low-lying placenta at 20 weeks may be a risk factor for vasa previa; we suggest that further studies be carried out to ascertain this. Judicious use of TVS and color Doppler in women considered at risk of vasa previa may help to reduce the mortality from this condition.     

Prenatal ultrasound diagnosis of seizures

We present a case of fetal diagnosed by ultrasound. Clinical aspects of this patient and the differential diagnosis of early neonatal seizures are discussed. A diagnosis of fetal seizures confirmed by ultrasonography is a rare event. Review of the literature shows only four cases of documented fetal seizures. This report describes a case of fetal seizures diagnosed in utero, its management, and the neonatal outcome. We also discuss the differential diagnosis.     

Magnetic resonance imaging of the fetus: a study of 20 cases performed without curarization

Twenty patients underwent magnetic resonance imaging (MRI) at a mean gestational age of 32 weeks. There were 12 patients with suspected fetal brain abnormality and four with intrauterine growth retardation (IUGR), while the remaining four cases were studied for other reasons. The MRI examinations were performed on a 0.5 Tesla machine, with surface coils. One minute acquisition time T1 sequences were used. All the studies were performed without fetal curarization, and only under maternal sedation using flunitrazepam given per os 1 h before MRI examination. Three examinations were incomplete because of fetal movement artefacts. In the remaining cases, MRI allowed the examination of fetal brain anatomy. In five cases, it helped to differentiate isolated hydrocephalus and corpus callosum agenesis. Sub-ependymal nodules were depicted in a case of fetal tuberous sclerosis. One suspected arachnoid cyst was proved to be an ultrasound artefact. Decreased fetal fat on MR images was correlated with low birth weight in cases of IUGR. Due to its better spatial resolution, ultrasonography was more accurate for the diagnosis of facial and lumbar anomalies. Fetal MRI may be performed without curarization. Surface coils allow the detailed analysis of brain parenchyma, and thus MRI is especially useful in the difficult prenatal diagnosis of fetal brain abnormalities.     

Identification and genetic analysis of Schizosaccharomyces pombe cDNAs that suppress deletion of IRA1 in Saccharomyces cerevisiae

OBJECTIVE: To determine the etiology, pregnancy complications, and outcome of isolated fetal pleural effusion diagnosed antenatally and to evaluate the benefits of prenatal fetal interventions. DATA SOURCES: A literature search of MEDLINE was performed for relevant English language publications between 1985-1991. In addition, reference lists of articles were used to identify reported cases of isolated fetal pleural effusion. METHODS OF STUDY SELECTION: Our search uncovered 31 papers published in peer review journals. From these reports, 82 cases met our selection criteria: All fetuses were diagnosed antenatally with pleural effusion and had no other signs of hydrops at initial diagnosis. DATA EXTRACTION AND SYNTHESIS: The etiology of isolated fetal pleural effusion was unknown in most cases. Possible causes included congenital chylothorax, goiter, lung tumors, and infection. Cardiac defects (4.9%), Down syndrome (4.9%), and polydactyly (1.2%) may be associated with isolated fetal pleural effusion. Perinatal mortality was high (36%) and was related to the development of nonimmune hydrops, prematurity, and pulmonary hypoplasia. Early gestational age at diagnosis of isolated fetal pleural effusion (32 weeks or less) was associated with poor outcome and a neonatal death rate of 55%. In contrast, the neonatal death rate approached 31% as gestational age at diagnosis exceeded 32 weeks. Fifty-four cases were managed conservatively whereas 24 received intrauterine intervention, which included either pleuroamniotic shunt or repeated thoracenteses. Neonatal death rates were 37 and 33%, respectively. CONCLUSION: Not enough data exist to support either the conservative approach or intrauterine pleural drainage in cases of isolated fetal pleural effusion diagnosed antenatally.     

Characterization of ATPases of apical membrane fractions from Locusta migratoria Malpighian tubules

Fetal magnetic resonance imaging (FMRI) has gained considerable interest during the last decade, especially in its intracranial applications. Due to its high soft-tissue contrast and presumed safety, FMRI should be accepted as a complementary technique in prenatal diagnosis, useful either to elucidate equivocal findings on routine US studies or to further delineate some pathological entities. Normal patterns of fetal brain maturation, as shown by FMRI, are described because they are of paramount importance to accurately evaluate intracranial diseases. To date, however, FMRI requires specialised facilities and should be considered as an evolving clinical research modality and performed within precise guidelines in a multidisciplinary approach to prenatal pathology.     

Fetal heart rate patterns preceding death in utero

Four cases of intrauterine fetal demise in term infants are presented. From these cases and other published reports, a sequence of fetal heart rate changes preceding intrapartum death is presented. Late or variable decelerations, if unrelieved or uncorrected, lead to baseline heart rate changes of tachycardia and loss of variability reflecting loss of fetal reserve and fetal distress. This is followed by an unstable heart rate, a sinusoidal pattern, or a rapidly changing fetal heart rate. The final event is a profound bradycardia just prior to fetal demise.     

Apoptosis in substantia nigra following developmental hypoxic-ischemic injury

We have previously observed that either hypoxic-ischemic or excitotoxic striatal injury during development is associated with a reduction in the adult number of dopaminergic neurons in the substantia nigra. This decrease occurs in the presence of preserved striatal dopaminergic markers and in the absence of direct nigral injury. We have also observed that natural cell death, with the morphology of apoptosis, occurs in the substantia nigra, and that there is an induced apoptotic cell death event following early striatal excitotoxic injury. We now report that forebrain hypoxic-ischemic injury is also associated with an induced cell death event in the substantia nigra, with both morphological and histochemical features of apoptosis. Induced apoptotic cell death occurs in immunohistochemically defined dopaminergic neurons. While the mechanisms for this induced cell death are not yet known, in the case of the pars compacta it may be related to the loss of normal striatal target-derived developmental support. Since dopaminergic neurons are postmitotic at the time of the injury, we conclude that this induced cell death is responsible for the diminished adult number of dopaminergic neurons. We also conclude that hypoxic-ischemic injury to the developing brain in general causes not only direct, necrotic injury to vulnerable regions, but also induced apoptotic death at remote sites. The significance of this finding is that apoptosis is a distinct death mechanism, with unique regulatory pathways, which can potentially be modified by approaches different from those which might influence cell death in regions of direct injury. In view of the present finding that apoptosis can occur in the setting of hypoxic-ischemic injury, and our previous work demonstrating its occurrence following excitotoxic injury, it seems likely that it may occur following other forms of injury to the immature brain in which excitotoxic injury plays a role, such as seizures, head trauma and hypoglycemia.     

Magnetic resonance imaging of normal and pathologic fetal brain

A total of 78 pregnant patients who had previously been studied by ultrasound (US) underwent magnetic resonance (MRI) because of suspected fetal abnormality. The first 20 cases were performed using fetal curarization. Even in the 27 cases in which the MR examination concerned other body regions, a brain study was always performed to analyze the normal anatomy at different gestational ages. There is a brief discussion on normal MRI anatomy of the fetal brain. There were 45 studies that concerned central nervous system pathology, and the most frequent malformative and neoplastic disorders were revealed. A comparison between MRI and US is proposed for each. In conclusion, MRI can be regarded as a complementary method that can be helpful in the rare cases when the US diagnosis is doubtful.     

Oxidative stress in Huntington's disease

It has been five years since the elucidation of the genetic mutation underlying the pathogenesis of Huntington's disease (HD) (97), however the precise mechanism of the selective neuronal death it propagates still remains an enigma. Several different etiological processes may play roles, and strong evidence from studies in both humans and animal models suggests the involvement of energy metabolism dysfunction, excitotoxic processes, and oxidative stress. Importantly, the recent development of transgenic mouse models of HD led to the identification of neuronal intranuclear inclusion bodies in affected brain regions in both mouse models and in HD brain, consisting of protein aggregates containing fragments of mutant huntingtin protein. These observations opened new avenues of investigation into possible huntingtin protein interactions and their putative pathogenetic sequelae. Amongst these studies, findings of elevated levels of oxidative damage products such as malondialdehyde, 8-hydroxydeoxyguanosine, 3-nitrotyrosine and heme oxygenase in areas of degeneration in HD brain, and of increased free radical production in animal models, indicate the involvement of oxidative stress either as a causative event, or as a secondary constituent of the cell death cascade in the disease. Here we review the evidence for oxidative damage and potential mechanisms of neuronal death in HD.     

Migratory pattern of fetal rat brain cells and human glioma cells in the adult rat brain

The migratory behavior of two human glioma cell lines (D-54MG and GaMG) and fetal rat brain cells grafted into the adult rat brain was studied. To trace the implanted cells, they were stained with the carbocyanine vital dye 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate before injecting them into the white matter above the corpus callosum. The animals were sacrificed 2 h and 7 and 21 days after injection, and the brains were removed and cryosectioned. Fluorescence microscopy showed that both the 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate-stained fetal and tumor cells had the same migratory pattern. Implanted cells were found along myelinated fibers in the corpus callosum and in the perivascular space. After immunostaining for several extracellular matrix (ECM) components (laminin, fibronectin, collagen type IV, and chondroitin sulfate), laminin deposits were observed in the border zone between the host tissue and implanted tumor cells as well as fetal cells. By using two different types of antibodies against fibronectin, it is shown that the fibronectin expression observed in the tumor matrix may be host derived. This was further supported by the fact that tumor spheroids obtained from the two glioma cell lines were negative when immunostained for these ECM components. Several of the ECM components may be host derived. This can be caused by neovascularization and repair synthesis or by a local production of guiding substrates which are important for tumor cell locomotion. The present data suggest that the migratory patterns of fetal and glioma cells are indistinguishable when transplanted into the adult rat brain. Thus, glioma cells may be routed by the same ECM components that play a major role during brain development.     

Rapid trisomy diagnosis (21, 18, and 13) using fluorescent PCR and short tandem repeats: applications for prenatal diagnosis and preimplantation genetic diagnosis

PURPOSE AND METHODS: Prenatal diagnosis of fetal trisomies is usually performed by cytogenetic analysis from amniotic fluid. This requires lengthy laboratory procedures and high costs and is unsuitable for large-scale screening of pregnant women. An alternative method, which is rapid and inexpensive and may potentially be suitable for diagnosing trisomies even from single fetal cells, is the fluorescent polymerase chain reaction (F-PCR) using polymorphic small tandem repeats (STRs). RESULTS: In this paper we present data demonstrating that fluorescent PCR amplification of STRs can be used for rapid diagnosis of trisomy 21, trisomy 18, and trisomy 13 and can be successfully applied to both prenatal diagnosis and diagnosis of single cells. This study also reports significant numbers of prenatal diagnoses using quantitative fluorescent PCR. CONCLUSIONS: We believe that further studies of greater numbers of samples will determine the absolute reliability of this technique. These results also provide a model for trisomy diagnosis from single cells using multiple STR markers for either preimplantation genetic diagnosis or, potentially, diagnosis from fetal cells isolated from maternal blood.     

Pathological evidence of prolonged umbilical cord encirclement as a cause of fetal death

A case is presented in which autopsy findings (deep groove around the fetal waist and buttock), and gross and microscopic umbilical cord and placental examination (linear ulcer of umbilical cord histologically rimmed by fetal epidermal implants with evidence of remote bleeding) established the diagnosis of umbilical cord encirclement as a cause of intrauterine fetal death despite the lack of prenatal or postnatal obstetrical evidence.     

Neuropathological sequelae of traumatic brain injury: relationship to neurochemical and biomechanical mechanisms

Brain injury is the leading cause of death among individuals under the age of 45 years in the United States and Europe. Recently, the neuropathologic classification of posttraumatic brain damage has provided insight into the specific mechanisms underlying traumatically induced neuronal damage and death. Studies regarding the biomechanics of brain trauma have also provided great insight into the pathophysiologic mechanisms underlying specific patterns of posttraumatic cellular death. Based upon recent clinical evaluations and biomechanical studies, laboratory models of human brain injury have been developed that faithfully reproduce a number of important features of clinical brain trauma. Biomechanical models have been used to study both the acute sequelae of brain injury and the role of neurochemical alterations in contributing to the development of secondary or delayed cellular death and damage. This report reviews and integrates the laboratory investigations linking experimental models of brain injury to clinical diagnosis and treatment.     

Trauma in pregnancy: the role of interpersonal violence

OBJECTIVE: Our purpose was to determine what role interpersonal violence as intentional injury plays in the pregnant trauma victim. STUDY DESIGN: We performed a retrospective review of medical records. RESULTS: During a 9-year period in a single university medical and trauma center, 203 pregnant women were treated for a physically traumatic event. Sixty-four women (31.5%) were victims of intentional injury, in most cases by the husband or boyfriend. Although the mean Injury Severity Score was higher in women with fetal death than in women with successful pregnancy outcomes (7.25 vs 1.74, respectively; p < 0.01), 5 of the 8 women with fetal losses incurred these despite an apparent absence of physical injury (maternal Injury Severity Score = 0). CONCLUSIONS: Interpersonal violence during pregnancy is a frequent and increasingly common cause of maternal injury. The inconsistent relationship between Injury Severity Score and serious fetal injury or death is underscored by the loss of 5 fetuses despite an Injury Severity Score of 0.     

Placental chorioangioma: prenatal diagnosis and clinical significance

We report the prenatal diagnosis of placental chorioangioma in a 32-week intrauterine pregnancy associated with polyhydramnios and enlarged fetal cardiac size that resulted in intrauterine fetal death. Ultrasound appearance, pathophysiology, and clinical significance of this entity are discussed.     

Antiphospholipid syndrome. Proposition for management

Antiphospholipid antibodies (antiprothrombinase and anticardiolipin) carry with them for mothers the risks of repeated fetal loss and of disorders of the blood clotting mechanism both before and after delivery. All the same screening does not have to be carried out routinely but should be reserved for patients who have already lost one fetus (intrauterine death after 12 weeks of amenorrhoea) and/or venous or arterial thrombosis. The diagnosis depends on a strict methodology and strict criteria for making a positive diagnosis. The treatment of these antibodies (with corticosteroids and intravenous immunoglobulin) or the prevention of possible thrombotic complications (using platelet antiaggregation/heparin) has to be decided taking into account the level of antibodies, previous obstetric and thrombotic history and the lupus symptomatology as shown by the patients. The overall success rate of treatment is between 53 and 81%.     

Early biopsy versus empiric treatment with delayed biopsy of non-responders in suspected HIV-associated cerebral toxoplasmosis: a decision analysis

OBJECTIVE: To construct and evaluate a decision analytic model of proposed management strategies for HIV-infected patients presenting with cerebral mass lesions, radiographically compatible with toxoplasmosis, lymphoma, or other etiologies, assuming knowledge of Toxoplasma antibody status in serum. METHODS: Using decision analysis, we evaluated two management strategies, for patients found to be either Toxoplasma-seropositive or -negative, for whom an initial choice was made for early brain biopsy (EB) or for empiric therapy with delayed biopsy (ETDB) of non-responders. The outcome to be optimized was the percentage of patients alive at 12 months. Model variables included predictive value of toxoplasmosis serology, probabilities of treatment response and death within 14-21 days conditional on correct diagnosis, probability of operative death, probabilities of non-diagnostic brain biopsy conditional both on correct diagnosis and prior treatment. RESULTS: One and two-way sensitivity analyses, by Toxoplasma serostatus, led to the following conclusions (1) for Toxoplasma-seropositive patients, ETDB gives nearly equivalent outcomes to EB of all patients; (2) for Toxoplasma-seronegative patients, although both strategies have equivalent outcomes under baseline assumptions, EB is preferred if there are even small survival advantages for early versus delayed diagnosis of lymphoma or other conditions, or if risk of death within 14-21 days of ET exceeds 10% when correct diagnosis is not toxoplasmosis. CONCLUSION: Under plausible assumptions, Toxoplasma-seronegative patients will benefit from an early biopsy strategy.     

Construction of a physiologically based pharmacokinetic model for 2,4-dichlorophenoxyacetic acid dosimetry in the developing rabbit brain

A physiologically based pharmacokinetic (PBPK) model that describes the kinetics of organic anions by using 2,4-dichlorophenoxyacetic (2,4-D) as a representative compound was constructed for the developing rabbit brain at near-term pregnancy (Gestation Day 30). The model consisted of brain, body, and venous and arterial compartments for the mother which were linked to the fetus by a placenta. Maternal brain compartments in the model were brain plasma, cerebrospinal fluid (CSF), and brain tissue including hypothalamus, caudate nucleus, hippocampus, forebrain, brainstem, and cerebellum. The fetus consisted of brain, body, amniotic fluid, and venous and arterial compartments. the maternal body had both a central and a deep compartment; the fetal body had only one compartment. Maternal blood flow to the fetus was modeled as blood flowing to the placenta, where it was equilibrated before it reached the fetus. The brain uptake was membrane-limited by the blood-brain barrier, with saturable clearance from the CSF into the venous blood by the choroid plexus in both fetus and mother. The model was used to compare concentrations of 2,4-D in maternal and fetal brain, maternal and fetal plasma, and amniotic fluid over time with experimental data from pregnant rabbits given 2,4-D intravenously (1, 10, or 40 mg/kg). The model adequately simulated the 2-hr time course of 2,4-D concentrations in both mother and fetus. With continued development, this generic PBPK model should be a useful tool for evaluating the safety of organic acid neurotoxicants in the developing brain.