Cystic brain stem necrosis in a premature infant after prolonged bradycardia

Dorsal brain stem syndrome: MR imaging location of brain stem tegmental lesions in neonates with oral motor dysfunction

The anatomic extent of brain stem damage may provide information about clinical outcome and prognosis in children with hypoxic-ischemic encephalopathy and oral motor dysfunction. The aim of this study was to retrospectively characterize the location and extent of brain stem lesions in children with oral motor dysfunction. From January 2005 to August 2009, 43 infants hospitalized at our institution were included in the study because of a history of hypoxic-ischemic events. Of this group, 14 patients showed oral motor dysfunction and brain stem tegmental lesions detected at MR imaging. MR imaging showed hypoxic-ischemic lesions in supra- and infratentorial areas. Six of 14 patients revealed only infratentorial lesions. Focal symmetric lesions of the tegmental brain stem were always present. The lesions appeared hyperintense on T2-weighted images and hypointense on IR images. We found a strong association (P < .0001) between oral motor dysfunction and infratentorial lesions on MR imaging. Oral motor dysfunction was associated with brain stem tegmental lesions in posthypoxic-ischemic infants. The MR imaging examination should be directed to the brain stem, especially when a condition of prolonged gavage feeding is necessary in infants.

Anatomic distribution of apoptosis in medulla oblongata of infants and adults

The aim of the study was to evaluate the distribution of apoptosis in the medullary nuclei of infants and adults who died of hypoxic-ischaemic injury. Apoptosis was studied by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labelling (TUNEL) in brainstems from 22 adults (7 subjects who died of opiate intoxication, 15 who died of other hypoxic-ischaemic injury) and 10 infants. The nuclei examined included the hypoglossal, dorsal motor nucleus of the vagus, nucleus tractus solitarii, nucleus of the spinal trigeminal tract, cuneate, vestibular and inferior olivary nuclei. A morphometric analysis with the optical disector method was performed to calculate the mean percentages (+/- standard deviation) of TUNEL-positive neuronal and glial cells for the sample populations. Opiate deaths did not have higher apoptotic indices than other adult hypoxic-ischaemic deaths. Statistically significant differences between adults and infants were found in the neuronal apoptotic indices of the cuneate (28.2 +/- 16.3% vs. 6.9 +/- 8.7%), vestibular (24.7 +/- 15.0% vs. 11.3 +/- 11.4%), nucleus tractus solitarii (11.2 +/- 11.2% vs. 2.3 +/- 2.4%), dorsal motor nucleus of the vagus (6.8 +/- 8.5% vs. 0.1 +/- 0.2%) and hypoglossal (6.6 +/- 5.7% vs. 0.1 +/- 0.2%), indicating higher resistance of the neuronal populations of these infant medullary nuclei to terminal hypoxic-ischaemic injury or post-mortem changes. Differences in neuronal apoptotic index were also statistically significant among nuclei, suggesting differential characteristics of survival. Nuclei with higher neuronal apoptotic indices were the cuneate, vestibular and nucleus of the spinal trigeminal tract, which are located in the lateral medullary tegmentum and share the same vascular supply from the posterior inferior cerebellar artery.

Fetal brain injury in experimental intrauterine asphyxia and inflammation in Göttingen minipigs

OBJECTIVE

To examine fetal brain injury in the Göttingen minipig following intrauterine asphyxia and infection/inflammation induced at 3/4 of gestational length.

METHODS

We performed laparotomy after anesthesia in six pregnant sows. We randomized 29 fetuses to one of four groups: pretreatment with saline or endotoxin followed by 30 min of umbilical cord occlusion or no occlusion. After 48 h we performed a re-laparotomy and examined the fetal brains.

RESULTS

After total asphyxia, brain stem injury was present in the group pretreated with saline (P < 0.01 vs. controls) and with endotoxin (P < 0.005 vs. controls). Microglia activation was more marked in the brain stem (P < 0.05) and posterior white matter (P < 0.05) in the asphyxia group than in controls. Two of five fetuses in the asphyxia group had white matter injury, while no white matter lesions were found in the asphyxia/inflammation or endotoxin only groups.

CONCLUSIONS

In this Göttingen minipig model, a species closer to humans than animals commonly used in experimental studies of perinatal brain injuries, intrauterine asphyxia following pretreatment with saline caused brain stem and white matter injury. This model can be further developed to study the impact of other intrauterine exposures on brain injury.

Brainstem cranial-nerve lesions in an infant with hypoxic cerebral injury

Recent studies have revealed that the brainstem is characteristically involved in hypoxic encephalopathy in infants. However, few reports have described clinical and cranial magnetic resonance findings in detail because most patients with brainstem lesions die during delivery or soon afterward. Reported here is a patient who manifested selective brainstem injury caused by perinatal hypoxic cerebral injury and exhibited palsy of the lower-brainstem cranial nerves. Magnetic resonance imaging was used to demonstrate lesions of brainstem cranial nerves, which were consistent with symptoms of brainstem dysfunction.

Brainstem lesions in children with perinatal brain injury

Several distributive patterns of hypoxic-ischemic cerebral injury have been recognized in asphyxiated newborns. Lesions of the brainstem have been rarely noted on magnetic resonance images in previous reports because they are difficult to detect. In this study, we demonstrate subtle but definite uniform symmetric brainstem lesions in children with perinatal brain injury. The areas of abnormal intensity were judged to comprise the central tegmental tract. The clinical manifestations in our patients were less severe than those previously described in patients with brainstem lesions. Two patients had difficulty of eye movement, but otherwise had no significant symptoms of brainstem cranial nerve nuclei involvement. All patients had lesions of white matter or cortex. Therefore, the abnormality in the dorsal brainstem revealed by magnetic resonance images is possibly as a result of secondary degeneration of the neurons that send axons into that tract.

Hypoxic-ischemic encephalopathy with cystic brain stem necroses and thalamic calcifications in a preterm twin

A severe and rare ischemic brain lesion in a preterm twin boy is reported. The boy was born after two weeks of anhydramnios and amnionic infection at 24 weeks of gestation. Following a difficult Caesarean section and prolonged umbilical cord compression he developed prenatal acidosis with an umbilical cord pH of 6.96. At the age of 7 h, heart rate variability narrowed due to severely disturbed brain stem function and the patient developed clinical signs of hypoxic-ischemic encephalopathy. Sonography demonstrated extensive symmetrical brain stem and basal ganglia lesions. After a prolonged comatose and apneic state, death occurred at the age of 25 days. Autopsy confirmed columnar bilateral cavitation of basal ganglia, diencephalon, brain stem and spinal gray matter, as well as focal calcifications in the palladium, thalamus, and brain stem. The findings highly resemble those observed after experimental or clinical cardiac arrest.

Solitary tract nuclei in acute heart failure

BACKGROUND AND PURPOSE

Symmetrical necrosis of the brain stem nuclei has been described as a consequence of severe transitory cerebral hypoxia mainly in neonates or young adults who experienced an episode of acute ischemia due to transitory acute heart failure. We report selective bilateral lesions of the solitary tract nuclei in 5 adults with short survival intervals after acute heart failure.

METHODS

In 5 patients who died due to cardiovascular pathology, histological examination was performed on multiple samples of cerebral hemispheres, on transverse sections of the midbrain and pons, and on transverse serial sections of the medulla stained with hematoxylin-eosin, Klüver-Barrera, and Luxol fast blue. The 3-dimensional reconstruction of the extension and topography of the medullary lesions was obtained with computed image analysis.

RESULTS

In 4 subjects who died soon after an episode of acute heart failure (range of survival 10 hours to 2 days), the dorsal portion of the solitary tract nuclei showed an eosinophilic roundish aspect bilaterally. In their context, the neurons showed changes characteristic of ischemic coagulation necrosis. In a fifth patient, a 32-year-old man who died 15 days after an episode of cardiac arrest, 2 circumscribed symmetrical infarcts with macrophagic and astrocytic reactions were found at the same level. The topography of the lesions and the inflammatory reaction and gliosis of patient 5 suggest that the findings in the other 4 patients correspond to initial features of selective lesions of the solitary tract nuclei after acute heart failure: the short interval of survival prevented the evolution of the reactive process. The nucleus is localized at the watershed zone between the terminal branches of the medullary collateral vessels of the vertebral arteries, thus representing the last meadow in the case of sudden fall of the systemic blood flow due to acute heart failure. The absence of lesions of other medullary and pontine nuclei accounts for a selective vulnerability of the neurons of the solitary tract nuclei, and the selective dendritic lesions suggest an excitotoxic component to ischemic cell death.

CONCLUSIONS

The commonly accepted resistance of the medullary centers to ischemic hypoxia in adults apparently could be due to the rapidity of death, which prevents the evolution of lesions that can be diagnosed. In addition, minor lesions in the medullary tegmentum after acute heart failure could play a role in the prevention of the resumption of autonomous cardiac and respiratory functions despite life-saving procedures.

Oxidative stress, brain white matter damage and intrauterine asphyxia in fetal lambs

In order to examine the role of oxidative stress in asphyxia-induced perinatal brain damage, near-term fetal lambs were subjected to umbilical cord occlusion for approximately 60min until fetal arterial pH diminished to less than 6.9 and base excess to less than -20 meq/l. The levels of superoxide, hydrogen peroxide, glutathione (GSH) and thiobarbiturate-reactive substances (TBARS) within brain grey and white matter were determined at 72h to correlate with morphological changes. Although the topography and extent of brain damage varied somewhat from case to case, ranging from focal infarction in grey or white matter to subtle and patchy alterations of white matter, the telencephalic white matter appeared to bear the brunt of damage as compared to other regions. The parietal white matter, in particular was often the seat of early pathological changes that could be seen in isolation. These white matter changes were accompanied by significant increases in hydrogen peroxide and TBARS levels as compared to those in grey matter. In another set of experiments, 8 different brain regions were assayed for TBARS, GSH and superoxide dismutase (SOD). A highly significant rise in the levels of TBARS was again noted in the parietal and frontal white matter. SOD levels were higher in the frontal and parietal white matter, basal ganglia and cerebellum. Cerebral cortical and hippocampal neurons were relatively unaffected until accompanied by more severe damage to grey and white matter at other sites. These results suggest that the developing telencephalic white matter appears to be most vulnerable to the effects of intrauterine fetal asphyxia and that oxidative stress may be a major contributing factor in the pathogenesis of perinatal hypoxic-ischemic encephalopathy.