Multicystic encephalomalacia after first-trimester intrauterine fetal death in monochorionic twins

Multicystic encephalomalacia occurs in approximately 20% of surviving cotwins after second- and third-trimester intrauterine fetal death of one twin in monochorionic pregnancies. We report a case of multicystic encephalomalacia after the demise of a cotwin in the first trimester diagnosed by magnetic resonance imaging and confirmed pathologically.

GROSS AND MICROSCOPIC LESIONS OF POLIOENCEPHALOMALACIA IN A LLAMA (LAMA GLAMA)

A 14-wk-old female llama (Lama glama) developed progressive neurologic disease characterized by stiff gait, circling, decreased mentation, and seizures. At necropsy, lesions were limited to the brain and consisted of bilateral necrosis of the cortical gray matter of the occipital lobes of the cerebral cortex. The primary microscopic alteration was bilateral laminar cerebrocortical necrosis, affecting mainly the deep laminae. Clinical disease, and gross and microscopic lesions were consistent with those of polioencephalomalacia.

Multicystic encephalomalacia

Antepartum death of a fetus in a multiple gestation can be associated with mortality or major morbidity in the survivor. This article reports a rare case of multicystic encephalomalacia that occurred in the survivor twin with antepartum death of its co-twin. Its pathology and pathogenesis are discussed with review of literature.

Polioencephalomalacia in captive harbour seals (Phoca vitulina)

In a colony of 11 harbour seals (Phoca vitulina Linné 1758) two episodes of central nervous disorders occurred within 2 years causing fatalities in seven adult animals. Clinical signs comprised dyspnoea, anorexia, apathy, incoordination and lateral recumbency. Vitamin B complex therapy was successful once. Pathomorphological examination of seven carcasses revealed acute and subacute malacia of the cerebellar grey matter. Additional acute malacic lesions located in the cerebral cortices and basal ganglia were observed. Mesencephalic nuclei were less severely affected and displayed acute changes. Despite intense search for environmental toxins and infectious agents, the cause of the fatalities remained undetermined. However, the type and pattern of the lesions are most suggestive of a thiamine deficiency.

Biochemical changes in apparently normal sheep from flocks affected by polioencephalomalacia

Blood samples were obtained for determination of the activities of lactate, pyruvate and erythrocyte transketolase, and faeces as samples for estimation of thiaminase, from 190 apparently healthy sheep from 19 flocks in which at least one animal had been diagnosed with polioencephalomalacia (PEM), from 59 control animals and from 7 affected by PEM. Feed and pasture grass samples were collected for thiaminase analysis and thiaminase was assayed in ryegrass and fescue. Decreased erythrocyte transketolase activity, accompanied by a corresponding rise in the thiamin pyrophosphate effect, and estimation of the thiaminase content in faeces, may be useful diagnostic procedures by which to identify periods of greater risk, during which animals could develop PEM. The changes in the diet probably acted as a primary factor for microbial production of thiaminases in replacement ewes. In these, the prevalence was higher in the spring months.

A case of pulmonary hypoplasia associated with intrauterine brainstem necrosis

An infant with intrauterine brain death accompanied by pulmonary hypoplasia is reported. The fetus was delivered after 36 weeks gestation, 5 weeks after fetal movements ceased. The child died 4 h after birth. Pulmonary hypoplasia and remote brainstem necrosis associated with multicystic encephalomalacia were found at autopsy.

CONCLUSION

These findings suggest that damage to brainstem respiratory centres had led to pulmonary hypoplasia through the absence of fetal respiratory movement.

Magnetic resonance imaging of cerebral cortical necrosis (polioencephalomalacia) in a dog

A 3-year-old neutered female mixed breed dog was examined because of severe, generalized seizure activity, tetraparesis, and encephalopathic signs. Cerebrospinal fluid (CSF) evaluation was unremarkable except for a mild increase in protein. Serum and CSF titers for infectious diseases were negative. Magnetic resonance (MR) imaging examination of the brain was performed and lesions were found within the cerebral gray matter of the temporal and parietal lobes. The lesions had increased signal intensity on T1, T2, and proton density-weighted images. There was mild inhomogeneous enhancement following intravenous contrast medium administration. Neurologic status improved and the seizures were well controlled, but the dog never regained normal mentation and euthanasia was performed 10 weeks after initial evaluation. At necropsy, severe cerebral cortical necrosis was found in the regions corresponding to the lesions seen on MR imaging examination. Large numbers of fat-containing macrophages (gitter cells) were found within these areas, and are thought to be responsible for the characteristic hyperintensity seen on the MR images.

Obstructive hydrocephalus caused by intraventricular collapse of malacotic brain. Case report

The authors present the case of a 68-year-old man who experienced acute obstructive hydrocephalus after having suffered an infarction in the occipital lobe. Histopathological and serial neuroimaging examinations revealed that portions of a large disintegrating occipital infarct had entered the lateral ventricle and obstructed the passage of cerebrospinal fluid (CSF). Ventricular drainage was performed for 2 weeks until the patient's hydrocephalus resolved. The CSF initially contained a high concentration of protein (1070 mg/dl), a high leukocyte count of 115 cells/mm3, and a rich fibrinous exudate. Findings in the present case indicate that collapse of a periventricular ischemic lesion into the ventricles may sometimes occur not only after cerebral hemorrhage but also after cerebral infarction.

Magnetic resonance imaging features of equine nigropallidal encephalomalacia

Magnetic resonance imaging (MR) was used to make a diagnosis of equine nigropallidal encephalomalacia in a horse. Equine nigropallidal encephalomalacia is a neurodegenerative disease that has many characteristics with Parkinson-like diseases in humans. Historically, horses were euthanized based on clinical signs and exposure to the toxic weed, yellow star thistle (Centaurea solstitialis). Previously, the disease has only been confirmed on necropsy. MR imaging can provide accurate and sensitive visualization of typical lesions seen in the brain of horses affected with equine nigropallidal encephalomalacia. Lesions were seen on T1-weighted, T2-weighted and proton density images. There was no contrast enhancement following Gd-DTPA administration. Lesions seen on MR were confirmed at necropsy. Using MR to confirm a diagnosis of equine nigropallidal encephalomalacia will prevent unnecessary suffering of horses and expense to owners that would otherwise incur, while further diagnostics are performed.

Arthrogryposis and multicystic encephalopathy after acute fetal distress in the end stage of gestation

The natural history of the rare association "multicystic encephalopathy-arthrogryposis" was traced in a fetus carefully followed after artificial insemination. The fetus exhibited normal viability and brain morphology up to the 32nd week. At 36 weeks, active movements diminished and at 37 weeks, hydramnios and signs of fetal distress led to cesarean section. The infant presented with severe arthrogryposis of the limbs and spine, but not with the other elements of a long-lasting akinesia. US showed multicystic encephalopathy. Both the clinical and the neuropathological findings established that multicystic encephalopathy was neither the cause nor the sequential consequence of the fetal akinesia, but the result of a recent diffuse, acute malacic process that also involved the anterior horn cells. Acute fetal distress, responsible for major ischemic damage to CNS but compatible with fetal survival, remains an obscure condition which allows for the development of severe arthrogryposis in a few weeks.

Update on sulfur-related polioencephalomalacia

Sulfur-related polioencephalomalacia is frequently associated with a high total sulfur intake by ruminants. The onset of clinical signs coincides with excessive ruminal sulfide production. Measurement of ruminal gas cap hydrogen sulfide makes it possible to identify cattle with potentially hazardous total sulfur intake. Evaluation of all potential sulfur sources is necessary to estimate total dietary sulfur concentration, which can lead to prevention strategies.

Acquisition and transfer of new verbal information in amnesia: retrieval and neuroanatomical constraints

Four experiments examined new associative learning in amnesia by contrasting the performance of 2 amnesic participants-1 (C.C.) with basal forebrain damage and the other (R.H.) with medial temporal lobe damage--and 3 controls. Both amnesic individuals were severely impaired on explicit memory measures but showed intact perceptual priming. On the new associations measures, only C.C., not R.H., exhibited learning by producing correct targets (HIJACKER) in the absence of perceptual cues for them (e.g., STAFF shot ???). When the perceptual cue (e.g., MEDICINE cured _I_C_P) was provided, both C.C. and R.H. showed learning. Transfer to information containing conceptually related targets (e.g., TERRORIST or BELCH) was reliably observed only in C.C. This finding was replicated with further reduction in perceptual overlap across original (LIGHTNING torched JUNGLE) and transfer (LIGHTNING burned WILDERNESS) sentences. Together, these findings delineate the role of experimental conditions, severity of amnesia, and different neuroanatomical structures in mediating new verbal learning in amnesia.

Distribution of cells immunopositive for AM-3K, a novel monoclonal antibody recognizing human macrophages, in normal and diseased tissues of dogs, cats, horses, cattle, pigs, and rabbits

The monoclonal antibody AM-3K, which was developed using human pulmonary macrophages as the immunogen, immunocytochemically labels most human macrophages except for blood monocytes and dendritic cell populations. AM-3K also shows cross-reactivity in some animal species. To evaluate the usefulness of AM-3K, the present study investigated the detailed distribution of AM-3K-immunopositive macrophages in normal and diseased tissues of dogs, cats, horses, cattle, pigs, and rabbits. Zamboni's solution-fixed, paraffin-embedded sections were the most available for the immunocytochemistry with AM-3K. In all animal species examined, AM-3K labeled most macrophages in splenic red pulp, lymph node sinuses and thymus, and tissue macrophages in the interstitium of various organs and sites such as the kidneys, lungs, heart, pancreas, intestines, and skin. Alveolar macrophages and perivascular microglial cells were also immunoreactive for AM-3K. Interestingly, Kupffer cells of dogs, cats, and horses were labeled for AM-3K, but those of cattle, pigs, and rabbits were not. Furthermore, in tumor tissues and inflammatory lesions such as liver fibrosis and encephalomalacia that were obtained from dogs, infiltrating macrophages were stained with AM-3K, but not all infiltrating macrophages reacted to AM-3K. In addition, only 30-50% of pulmonary and peritoneal macrophages obtained from cats and dogs were reactive for AM-3K. AM-3K did not react with blood monocytes, dendritic cell populations, and osteoclasts. These observations indicate that AM-3K specifically labels most exudate and tissue macrophages in the animal species examined. However, the expression of antigens recognized by AM-3K on macrophages may be dependent on differential maturation stages or different functions evoked by some conditions. AM-3K immunoreaction products were seen on the cytoplasmic membrane of macrophages by immunoelectron microscopy. AM-3K would be useful for detection of macrophage populations in the animal species examined here.

Toxicology of Astragalus lusitanicus Lam

Astragalus lusitanicus is a toxic legume grown in Morocco and in some other Mediterranean countries. In small ruminants, poisoning by this plant is dominated by nervous signs characterized by many cycles of excitement-depression. Macroscopic examination of poisoned animals showed congestive lesions and oedema in the brain and lungs. Microscopic lesions consisted mainly of vacuolar degeneration in neurons, hepatocytes and in spleen and kidney cells. Serum activity of AST and CK as well as blood glucose and urea were increased as a result of poisoning. However, serum activity of alpha-mannosidase was not modified as is the case in locoism. Chemical investigations showed that A. lusitanicus does not contain swainsonine or miserotoxin and its selenium concentration is very low. However, this legume contains indolizidin alkaloids and a first compound was purified and identified.

Cerebellar encephalomalacia on magnetic resonance imaging after removal of acoustic tumor

MRI is widely used for postoperative surveillance of patients undergoing surgery for removal of acoustic neuroma. The purpose of this study was to investigate the frequency and pattern of postoperative changes in the cerebellum and brain stem on MRI after removal of acoustic neuroma. A retrospective study was conducted in 30 consecutive patients who underwent postoperative MRI between 1994 and 1995. The timing of the scans after surgery ranged from 12 months to 10 years. T2 -weighted turbo spin-echo images revealed cerebellar encephalomalacia in 17 of 30 cases. Cerebellar encephalomalacia was found more consistently in patients who had large tumors and was more frequent after the suboccipital approach. Encephalomalacia is largely caused by gliotic changes in the adjacent cerebellar tissues after tumor removal.

Association of excess sulfur intake and an increase in hydrogen sulfide concentrations in the ruminal gas cap of recently weaned beef calves with polioencephalomalacia

During a 2-week period, 16 of 150 recently weaned calves developed signs of polioencephalomalacia (PEM). One calf was examined and treated at our veterinary teaching hospital and a necropsy was performed on a calf that died. During the peak of the outbreak, clinicians visited the ranch. Ruminal hydrogen sulfide (H2S) and blood thiamine concentrations were measured in 10 clinically normal penmates of PEM-affected calves. Ruminal H2S concentrations were high (> 0.695 mg/L [> 500 ppm]) in all cattle (mean, 12.19 mg/L [8,770 ppm]). All blood thiamine values were within the reference range. Within 12 hours after measurement of blood thiamine concentrations, 2 of the calves from which samples were obtained developed clinical signs of PEM. Dietary analysis revealed an estimated sulfur intake of 0.9% per calf on a dry-matter basis. Hay contributed most of this sulfur. In the investigation reported here, an outbreak of PEM was associated with high ruminal H2S concentrations and excess sulfur intake without evidence of thiamine deficiency.

Amprolium-induced cerebrocortical necrosis (CCN) in dromedary racing camels

Amprolium was successfully used to induce cerebrocortical necrosis (CCN) in dromedary racing camels, only when they were fed on a barley diet. Camels which were fed on hay ad libitum did not suffer form CCN, although their thiamine pyrophosphate (TPP) reached similar levels as in camels fed on barley. The reason for this phenomenon is discussed. Five camels which suffered from CCN had TPP values of 80-115% and were euthanized on humane grounds when they were in lateral recumbency. Pathohistological investigations revealed a polioencephalomalacia of the dorsal cerebral cortex with oedema and status spongiosus. Cerebral autofluorescence was observed under ultraviolet light. The major clinicopathological changes were a slight anemia and a decreased potassium value whereas glucose, muscle enzymes, leucocyte counts and differential counts were elevated. A TPP effect of 12% was found during this study in healthy dromedary racing camels and symptoms were observed when TPP values reached 80-115%. The test is now being widely used during the camel racing season.

Repin-induced neurotoxicity in rodents

Russian knapweed is a perennial weed found in many parts of the world, including southern California. Chronic ingestion of this plant by horses has been reported to cause equine nigropallidal encephalomalacia (ENE), which is associated with a movement disorder simulating Parkinson's disease (PD). Repin, a principal ingredient purified from Russian knapweed, is a sesquiterpene lactone containing an alpha-methylenebutyrolactone moiety and epoxides and is a highly reactive electrophile that can readily undergo conjugation with various biological nucleophiles, such as proteins, DNA, and glutathione (GSH). We show in this study that repin is highly toxic to C57BL/6J mice and Sprague-Dawley rats and acutely induces uncoordinated locomotion associated with postural tremors, hypothermia, and inability to respond to sonic and tactile stimuli. We also show that repin intoxication reduces striatal and hippocampal GSH and increases total striatal dopamine (DA) levels in mice. Striatal microdialysis in rats, however, has demonstrated a significant reduction of extracellular DA levels. These findings, coupled with the absence of any demonstrable change in striatal DOPAC levels, suggest that repin acts by inhibiting DA release, a hypothesis that is further supported by our demonstration that, in cultured PC12 cells, repin inhibits the release of DA without affecting its uptake. We believe, therefore, that inhibition of DA release represents one of the earliest pathogenetic events in ENE, leading eventually to striatal extracellular DA denervation, oxidative stress, and degeneration of nigrostriatal pathways. Since the neurotoxic effects of repin appear to be mediated via oxidative stress, and since repin is a natural product isolated from a plant in our environment that can cause a movement disorder associated with degeneration of nigrostriatal pathways, clarification of the mechanism of repin neurotoxicity may provide new insights into our understanding of the pathogenesis of PD.

Encephalomalacia associated with vitamin E deficiency in commercially raised emus

Thirteen of 64 emus on a commercial emu farm in Ohio exhibited neurological signs that included backward staggering, incoordination, generalized weakness, and sitting on their hocks with head retracted backward. Eight of the birds showing such signs were found dead. Two of these emus were necropsied, and no significant gross lesions were observed. Major histopathological lesions were found in the cerebellum and included multiple malacic foci in association with neuropil rarefaction and astrogliosis within the white matter of folia. In addition, the hepatic vitamin E level of one emu was determined at the Michigan State University Animal Health Diagnostic Laboratory (MSU-AHDL) to be 14.61 micrograms/g dry weight. This vitamin E level was in the lower percentile (35%) of 30 emu liver samples examined at MSU-AHDL. A diagnosis of vitamin E-associated encephalomalacia was made based on clinical signs, gross and histological lesions, and liver vitamin E levels.

Clinical and pathological aspects of an outbreak of equine leukoencephalomalacia in Spain

In 1988 an outbreak of leukoencephalomalacia was diagnosed in equids that had eaten corn with a pinkish fungal growth. The fungus was then identified as Fusarium moniliforme. The main symptoms observed appeared acutely and were overexcitement, blindness, incoordination, facial paralysis and death within 24 h. The main pathological changes were restricted to the central nervous system. Macroscopically they consisted of hyperemia and haemorrhages, the consistency was friable and the gyri were somewhat flattened. Microscopically, the lesions were profuse and had extensive haemorrhages, and numerous neurons appeared in different stages of degeneration and necrosis, with satellitosis and neuronophagia. Perivascular cuffs formed by macrophages, plasma cells and lymphocytes were also observed. These lesions were present in both brain and cerebellum, with a marked oedema and massive necrosis of the Purkinje cell layer of the latter.