Neonatal multifocal encephalomalacia and other lesions in the brains of Georgia chicks: 1991-95

Outbreaks of neonatal multifocal encephalomalacia with sepsis have been reported among flocks of very young chicks in Belgium, Scotland, and the United States. The purposes of the present study were to describe intralesional bacterial cocci in chicks with this type of encephalomalacia and to determine its incidence during 1991-95, and to determine the importance of this lesion with respect to the frequency of all other brain lesions/ diseases during the same time period. All laboratory records of broiler chickens examined at the Georgia Poultry Laboratory from Jan. 1, 1991, through Dec. 31, 1995, where the histopathologic diagnoses included the letter string *encephal* were retrieved for further study. The leading etiology for brain disease was nutritional encephalomalacia (57%), followed by neonatal encephalomalacia (22%), septic meningoencephalitis (16%), and Marek's disease (14%), in turn followed by nonpurulent encephalitis (7%), avian encephalomyelitis (3%), and mycotic meningoencephalitis (3%). Diagnosis of neonatal multifocal encephalomalacia with sepsis in the brains of Georgia chicks is a perennial one. Microscopically, the condition is characterized by mild to maximal multifocal locally extensive fibrin thrombosis of blood capillaries, and necrosis (encephalomalacia, malacia) of surrounding zones of brain stem and/or cerebral hemisphere neuropile. In 44% of cases of neonatal encephalomalacia fibrin thrombosis of blood capillaries was accompanied by intralesional gram-positive coccoid bacteria that were most abundant in medium- and small-sized arterioles or venules. Only gram-positive coccoid bacteria are found in cases of neonatal encephalomalacia (P < 0.05), and only gram-negative rod-shaped bacteria are found in cases of septic meningoencephalitis (P < 0.05). Therefore, bacterial culture and routine light microscopic histopathology are sufficient for diagnosing the condition when the differential diagnosis for neurologic disease in chicks includes neonatal encephalomalacia.

A panencephalopathic type of Creutzfeldt-Jakob disease with selective lesions of the thalamic nuclei in 2 Swiss patients

Creutzfeldt-Jakob disease (CJD), a subacute spongiform encephalopathy, is generally included among the group of human and animal diseases which is transmissible by a non-conventional agent, the prion, whose expression is conditioned by the host's genome. The process leading to neuropathological changes is still unknown. We report the neuropathological findings in 2 cases of the "panencephalopathic" variant of CJD, which is relatively common in Japan, but extremely rare in Europe and North America. When compared with the classical form this variant is characterized by a relatively long clinical course with persistent vegetative state and primary involvement of the white matter presenting in the form of demyelination and gemistocytic gliosis. The selective involvement of certain thalamic nuclei is a particular pathological feature in both our cases. There was practically complete neuronal loss with diffuse gliosis of the anteroventral (AV) and dorsomedial (DM) nuclei, while the neuronal loss in the pulvinar remained moderate: the other nuclei were apparently spared. A similar involvement of the thalamus has been reported in fatal familial insomnia, a recently described prion disease in which these lesions are predominant. A comparable distribution has also been observed in other degenerative neurological diseases such as Steele-Richardson-Olszewski disease, Alzheimer disease, and thalamic dementia (selective thalamic atrophy or with multisystemic degeneration). The AV and DM nuclei, commonly referred to as "limbic thalamus" represent phylogenetically the most recent thalamic structures and would appear to play an important role in the superior functions in man as memory, attention and awareness. In our cases thalamic lesions are selective, bilateral, and symmetric, not explained by Wallerian degeneration. These lesions may be due to the primary pathogenetic properties of the infectious agent. The rapid clinical evolution in a persistent vegetative state could be consequential to precocious and severe disfunction of the limbic thalamus.

Classification of brain compartments and head injury lesions by neural networks applied to MRI

An automatic, neural network-based approach was applied to segment normal brain compartments and lesions on MR images. Two supervised networks, backpropagation (BPN) and counterpropagation, and two unsupervised networks, Kohonen learning vector quantizer and analog adaptive resonance theory, were trained on registered T2-weighted and proton density images. The classes of interest were background, gray matter, white matter, cerebrospinal fluid, macrocystic encephalomalacia, gliosis, and "unknown." A comprehensive feature vector was chosen to discriminate these classes. The BPN combined with feature conditioning, multiple discriminant analysis followed by Hotelling transform, produced the most accurate and consistent classification results. Classification of normal brain compartments were generally in agreement with expert interpretation of the images. Macrocystic encephalomalacia and gliosis were recognized and, except around the periphery, classified in agreement with the clinician's report used to train the neural network.

Expression of beta-amyloid precursor protein in axons of periventricular leukomalacia brains

Human beta-amyloid precursor protein immunoreactivity was demonstrated in axonal swellings (spheroids) around periventricular leukomalacia (PVL) of neonates. Immunoreactive axons were found at the early, but not late stage of PVL. beta-Amyloid precursor protein immunoreactivity was homogeneous in damaged axons at the early stage of PVL manifesting microglial activation, concentrated at the center of axonal swellings at the subsequent stage manifesting astrogliosis, and undetectable at the terminal stage of cavitation or neovasculation. Immunostaining for beta-amyloid precursor protein was useful in localizing PVL lesions at their early stages.

Neuropathology

The surgical neuropathologist who examines corticectomy specimens from infants and children with epilepsy is in a unique position to make observations of fundamental importance in understanding the pathogenesis of seizures as well as the basic neurobiology of brain lesions that are associated with epilepsy. Findings on the resected human tissue using novel immunocytochemical and molecular probes can supplement and even build on relevant findings in experimental models, the goal of which is an understanding of epilepsy at cellular and subcellular levels.

Multicystic encephalopathy: review of eight cases with etiologic considerations

Multicystic encephalomalacia (MCE) is a rare lesion that arises during the perinatal period. Although hypoxic-ischemic insults may be responsible for this lesion, recent evidence suggests that herpesviruses may represent another etiologic agent. To elucidate the pathogenesis of MCE, eight cases collected over a 34-year period were evaluated for destructive lesions in gray and white matter. Immunocytochemical methods, in situ hybridization and polymerase chain reaction (PCR) methodology were employed to search for herpes simplex viruses types 1 and 2 (HSV1 and HSV2), cytomegalovirus (CMV), varicella zoster virus (VZV), Epstein-Barr virus (EBV) and JC variant of papovavirus (JCV). Review of the clinical histories revealed that there had been a complicated labor and delivery in 6/7 cases. Neuropathological lesions consisted of extensive tissue destruction, neuronal loss and gliosis in hemispheric white matter, cerebral cortex, basal ganglia, thalamus, cerebellum and brainstem tegmentum. Only one case showed evidence of latent HSV infection by PCR. CMV, VZV, JCV and EBV were not detected. Arteriopathy was noted in one case. The widespread nature of the lesions and their association with perinatal ischemia suggest that severe hypoxia may be the more common etiology of MCE. Term infants appear especially susceptible to this type of cerebral damage.

Polioencephalomalacia associated with the ingestion of ammonium sulphate by sheep and cattle

In the latter part of 1991 an unusual neurological disease was recognised on several farms in England. This report describes the case histories and clinical, biochemical and pathological findings in six calves and two lambs aged from two to 44 weeks obtained from five of these farms. Laminar cerebrocortical necrosis and severe bilateral necrosis of the thalamus and/or striatum progressing to cavitation were recognised in their brains. These changes are similar to those of experimental sulphate toxicity. Morbidity rates of 16 to 48 per cent and mortality rates of 0 to 8 per cent were recorded. The affected animals did not respond to vitamin B1 treatment; the erythrocyte transketolase levels of in-contact cattle and of one untreated affected calf and one untreated lamb were within the normal range. All five farms had recently introduced a proprietary concentrate ration containing ammonium bicarbonate. After this ration was withdrawn no new cases of nervous clinical disease were observed. It is suggested that, in at least some cases, the morphology and topography of lesions may distinguish sulphate induced polioencephalomalacia from that of sporadic thiamine-dependent cerebrocortical necrosis.

Neuropathologic study of resected cerebral tissue from patients with infantile spasms

Studies to date on the neuropathologic substrates of infantile spasms have largely utilized autopsy material of children who die after a long and complicated seizure history. This makes the interpretation of primary versus secondary changes in the cerebral tissue difficult if not impossible. We have recently had the opportunity to review the neuropathologic changes in cortical tissue resected from infants and children with a history of infantile spasms. The major identifiable abnormalities were destructive lesions, sometimes classifiable as cystic-gliotic encephalomalacia, and dysplastic changes of varying degree. The cortical dysplasias had some similarity to cerebral changes described in tuberous sclerosis, including the presence of bizarre gemistocytic "balloon" cells, and secondary cytoskeletal changes within neuronal cell bodies. Such material provides an opportunity to apply immunohistochemical and molecular techniques to epileptic tissue in an attempt to understand the morphologic substrates of infantile spasms and other types of generalized epilepsy.

Cerebral encephalomalacia in commercial turkeys

A flock of 9 1/2-week-old commercial tom turkeys experienced high mortality after consuming a complete feed containing an unidentified toxic substance. Initially, turkeys were found dead. Clinically, the birds were calm and still but became hyperexcitable with noise. A small percentage of birds exhibited torticollis, opisthotonos, circling, ataxia, and blindness. Findings at necropsy and upon microscopic examination were bilaterally symmetrical areas of necrosis of the cerebral hemispheres in the area of the neostriatum that were well demarcated from the surrounding normal neuropil. A feeding trial with the suspect feed in twelve 4-week-old turkey hens induced clinical disease and gross and microscopic brain changes similar to those observed in the field case. Analyses for the following substances in the suspect feed were either negative or within acceptable limits: salt, selenium, furazolidone, monensin, amprolium, 3-nitro-4-hydroxyphenylarsonic acid, aflatoxin, deoxynivalenol, zearalenone, T-2 toxin, ochratoxin, fumonisin, organophosphates, chlorinated hydrocarbons, and carbamates. The toxic component of the feed remains unidentified.

Cerebral vasculitis associated with cocaine abuse

A variety of central nervous system pathology has been associated with cocaine abuse, including cerebral vasculitis. We report a case of a 25-year-old woman who died of hypoxic encephalopathy following cardiac arrest due to cocaine abuse. Autopsy revealed a distinctive cerebral vasculitis with features characteristic of hypersensitivity drug included vasculitis. The significance of cerebral vasculitis associated with cocaine is reviewed.

Immunohistological study of encephalomalacia in pigs infected with Aujeszky's disease virus

Seven hysterectomy-derived colostrum-deprived pigs aged 4 weeks were inoculated intranasally with 10(3) plaque-forming units (1 ml) of the Yamagata YS-81 strain of Aujeszky's disease virus. One pig died and five developed encephalomyelitis and trigeminal ganglionitis. Three pigs killed on days 12-16 showed prominent malacic degeneration. Associated with the malacic foci were many lysosome-positive cells. IgG- and IgM-containing cells in the perivascular cuffs and glial nodules were first detected on day 7, after which they increased in number. They were thought to be closely associated with the presence of neutralizing antibody. These findings suggest that inflammatory cells in the brain are of haematogenous origin.

Polioencephalomalacia induced with amprolium in buffalo calves: pathologic changes of the central nervous system

Eight apparently healthy male buffalo calves of 6 to 12 months of age were drenched with amprolium (300 mg/kg body weight) till the development of clinical signs. Four buffalo calves of the same age group were drenched with tap water only and these served as controls. Amprolium drenched calves were allowed to die after the onset of clinical signs and control calves were euthanised after the death of amprolium fed calves. Tissues were collected for histopathological studies. Formalin fixed brain slices were examined for autofluorescence with the help of ultraviolet light at 365 nm. Gross and histopathological changes were mainly confined to the brain in amprolium fed calves. Gross lesions included congestion and haemorrhages in the meninges. The cerebral gyri were swollen with yellowish discolouration of cerebral cortex. Microscopic changes in the brain were limited to gray matter structures of cerebral and cerebellar cortex, caudal colliculi of mid brain and thalamus. There was shrinkage of neurons, perivascular and pericellular edema, necrosis of neurons, satellitosis, glial nodule and gliosis. Blood vessel walls were thickened due to hypertrophy and hyperplasia of endothelial and adventitial cells. In the cerebellar cortex, there was degeneration of Purkinje cells. The caudal colliculi of mid brain showed bilateral malacia. In the necrotic areas, neuropils were fragmented, edematous and hypercellular due to increased number of microglial cells and there was neocapillary formation. Subcortical gray matter of the thalamus showed necrosis of neurons, gliosis with formation of glial nodule. Formalin-fixed brain slices of amprolium fed calves showed disseminated areas of greenish yellow autofluorescence in the cerebral cortex when viewed under ultraviolet light at 365 nm.

[Multicystic encephalomalacia in a surviving twin after death of the other twin in utero]

A case of multicystic encephalomalacia in a twin is reported. The other twin died in utero at 32 weeks gestational age. Because there was no evidence of fetal distress the pregnancy was allowed to continue until 36 weeks gestational age. Injuries to the surviving twin due to disseminated intravascular coagulation (DIVC) and vascular thrombosis or to anoxia and ischemia may occur when there are anastomoses between the circulatory systems of the two twins, i.e., in monochorionic pregnancies. The classically recommended strategy is to wait for adequate maturity of the surviving fetus (36 weeks). It is suggested that this attitude may be overly expectant and may deserve reappraisal.

Enterococcus durans infection in young chickens associated with bacteremia and encephalomalacia

Two unrelated flocks of chicks experienced elevated mortality from 4 to 10 days of age. Clinical signs in affected birds included a full range of neurological disorders. Livers and spleens were grossly enlarged at necropsy. Enterococcus durans was isolated from multiple organs, including brains. Histologically, there were multifocal coagulative necrosis in the liver, areas of malacia in brain stem, and cerebellar white matter. Inoculation of 1-day-old chicks with a suspension of E. durans resulted in bacteremia but did not produce the lesions observed in field cases.

Experimental equine leukoencephalomalacia, toxic hepatosis, and encephalopathy caused by corn naturally contaminated with fumonisins

A study to evaluate the effects of dietary fumonisin B1 was conducted using 6 ponies (4 test and 2 control). A ration naturally contaminated with fumonisin B1 was fed in 3 phases: 1) 44 ppm fumonisin B1, 2) less than 1 ppm fumonisin B1, and 3) 88 ppm fumonisin B1. All ponies were monitored daily, weighed weekly, and limit fed at a rate of 0.8% body weight plus hay. Feed intake was measured daily, and a serum chemistry panel was completed once or twice weekly. Four to 7 days after initiation of the trial (Phase 1), all 4 test ponies had decreased feed consumption, and selected serum chemistry parameters were markedly elevated. On day 9, 1 pony died acutely with mild encephalopathy and hepatic necrosis. Another pony, euthanized on day 45, also had mild encephalopathy and hepatic necrosis. The remaining 2 test ponies continued the 44 ppm fumonisin B1 diet for 98 days. Phase 2 consisted of a diet with < 1 ppm fumonisin B1 for 120 days. During this phase, the serum chemistry values of the 2 ponies returned to normal. Following Phase 2, the 2 ponies were fed a diet containing 88 ppm fumonisin B1. After 75 days, 1 animal died of equine leukoencephalomalacia with mild hepatic necrosis. On day 78, the remaining pony was euthanized after showing distress; it also had leukoencephalomalacia and hepatic lesions.

A neuropathological survey of brains submitted under the Bovine Spongiform Encephalopathy Orders in Scotland

Bovine spongiform encephalopathy was not confirmed histologically in 225 of 829 bovine brains submitted for diagnosis. Several previously described disorders of the central nervous system were observed in these brains as well as disorders not previously recognised in Britain, including bilateral vacuolation of the substantia nigra, hippocampal sclerosis with brainstem neuronal chromatolysis and necrosis, focal symmetrical encephalomalacia and meningio-angiomatosis. Severe cerebellar dysplasia consistent with pre-natal bovine viral diarrhoea--mucosal disease virus infection or mineralisation of the blood vessels of the basal ganglia were interpreted respectively as congenital changes or changes due to ageing and were considered to be of no clinical significance.

Web-like malformation of the carotid artery and multicystic encephalomalacia

Multicystic encephalomalacia and hydranencephaly lie within a spectrum of brain lesions linked to ischemic cerebral damage. Causes include vascular malformation, thrombosis, embolism, infection, and toxins. We describe an infant with multicystic encephalomalacia associated with a peculiar web-like malformation of the right common carotid and left subclavian arteries. We postulate that this luminal bridging is a congenital malformation resulting from defective canalization of the medium-sized blood vessels but could represent organized and recanalized thrombi, the etiology of which remains unknown.

The same chemicals induce different neurotoxicity when administered in high doses for short term or low doses for long term to rats and dogs

Dose- and term-dependent differences in the location and nature of brain lesions induced in rats and dogs by 2,5-hexanedione (2,5-HD), misonidazole, clioquinol, and acrylamide are reported. Subchronic neuropathies ("distal axonopathy") were induced by low-dose administration of these neurotoxicants and at high doses, lesions caused by acute or subacute neurotoxicity were found in the central nervous system (CNS). In rats, 2,5-HD induced extracellular edema, nerve cell degeneration, and axonal degeneration in the cerebellar and vestibular nuclei. Similar lesions were observed in misonidazole-treated dogs and clioquinol induced nerve cell degeneration in the hippocampus and malacia in the piriform lobes of these animals. In rats, acrylamide induced degeneration of Purkinje cells. Although the mechanism(s) underlying the differential neurotoxicity of high and low doses of these neurotoxicants remains unclear, we suggest certain biochemical mechanisms, cytotoxic edema and excitotoxicity, as factors in the production of such lesions after high-dose treatment.

Chronic lesions of thrombo-embolic meningo-encephalomyelitis in calves

Six calves showed neurological signs with recumbency for 5 to 30 days. Histologically, they had encephalomyelitis characterized by multiple minute foci of malacia and perivascular microgliosis throughout the central nervous system. Widespread degeneration of the white matter was also detected mainly in the spinal cord. Micro-abscesses and thrombophlebitis, which were occasionally observed in the malacic lesions, suggested that the disease was a feature of infectious thrombo-embolic meningo-encephalomyelitis modified by various factors, including antibiotic therapy.

Cerebral lymphoma and HIV encephalitis in a case of paediatric AIDS, with pre-existing multicystic encephalomalacia

A case of intracerebral malignant B cell lymphoma associated with encephalitis typical of Human Immunodeficiency Virus (HIV) infection is described in a 4 year old child, with post-transfusion Acquired Immune Deficiency Syndrome (AIDS) and severe pre-existing cystic encephalomalacia. This report further documents B cell lymphoma as the commonest cause of an intracerebral mass, and an important cause of death in paediatric AIDS. That more than one pathological process may be responsible for neurological symptoms in paediatric AIDS is also emphasised.

Leukoencephalomalacia in two horses induced by oral dosing of fumonisin B1

Leukoencephalomalacia (LEM) was induced by the oral administration of fumonisin B1 (FB1) to 2 horses: a filly received 59.5 mg/kg of a 50% preparation of FB1, administered in 21 doses of 1.25-4 mg/kg over 33 days; a colt, 44.3 mg/kg of 95% pure FB1 in 20 doses of 1-4 mg/kg in 29 days. Both animals developed nervous signs such as apathy, changes in temperament, inco-ordination, walking into objects, and one showed paralysis of the lips and tongue. Characteristic lesions of LEM were present in the brains. These trials proved conclusively that FB1 can induce LEM in horses.