Changing incidence of HIV-induced brain lesions in Oslo, 1983-1994: effects of zidovudine treatment.

OBJECTIVE: To investigate the relation between HIV-induced brain lesions, zidovudine (ZDV) treatment and survival length in a well-defined population of HIV-positive patients. METHODS AND PATIENTS: Ulleval Hospital has the responsibility for treating all AIDS patients from the city of Oslo except haemophiliac patients. The patient population in this autopsy study comprised all adult AIDS patients in Oslo who were treated at our hospital and died during 1983-1994 (n = 171). This represents 86% of all adult AIDS patients from Oslo who died during the same period. Full autopsy, including neuropathological examination of the brain and spinal cord, was performed on 128 (75%) of those who died. RESULTS: No significant differences were found between autopsy and non-autopsy cases with regard to sex, age, risk groups, survival length or ZDV treatment. In the autopsy material, multinucleated giant cells (MGC) in brain tissue were found in 29 cases and diffuse damage of white matter in 52 cases. Analysis shows that ZDV (600 mg per day) reduced the incidence of these brain lesions, but only if continued until death. A second finding was an increased incidence of HIV-induced brain lesions for those with long-term survival. Together these observations may explain a substantial part of the time-trend in the incidence of MGC in Oslo. MGC were frequent (40%) during the first years of the epidemic, although survival length was short in this period. The incidence fell markedly around the time ZDV was introduced and later remained low in those using ZDV until death. The incidence of MGC has, however, increased during the later years, the new cases mainly occurring in patients who had discontinued ZDV use. CONCLUSION: If continued until death, ZDV can reduce the incidence of HIV-induced brain lesions in AIDS patients. When ZDV treatment is terminated a rapid increase occurs in the incidence of HIV encephalitis.

Plasma proteins in normal neurons. Immunohistochemical studies on autopsy material and experimental animals.

Previous observations have shown that plasma proteins are taken up by damaged neurons after trauma, cold injury and anoxic lesions. The present study was undertaken to test whether such uptake also can occur in normal neurons. Normal human brains at different intervals after death as well as normal rat brains after perfusion and immersion fixation were studied. During the first 24 h after death, the human cases showed practically no immunostaining with anti-fibrinogen and vague and inconstant staining with anti-albumin in the cortex and hippocampus, while certain brain stem nuclei were stained with both antisera even at the shortest postmortem intervals. At longer intervals, increased immunostaining of the neurons in the cortex and hippocampus was also demonstrated. Generally, more cells were positive for albumin than for fibrinogen. Perfusion-fixed rat brains showed no immunostaining, whereas rat brains that were immersion-fixed 24 h after death showed positive staining, mainly located in the brain stem. It is concluded that the staining of normal neurons demonstrated with the present method is due to postmortem leakage of proteins. Since practically no uptake of fibrinogen occurs in the cortex or hippocampus during the first 24 h, a definite neuronal staining with anti-fibrinogen at these intervals probably indicates true neuronal damage. In the brain stem, on the other hand, this phenomenon can not be used to demonstrate neuronal damage even at the shortest postmortem intervals.

Neuronal uptake of plasma proteins after transient cerebral ischemia/hypoxia. Immunohistochemical studies on experimental animals and human brains.

Rapid uptake of plasma proteins into damaged neurons has been demonstrated previously after lesions which cause early breakdown of the blood-brain barrier (BBB). The present study was undertaken to see whether a similar uptake occurred after hypoxic/ischemic episodes in men and experimental animals. Forebrain ischemia was produced in rats by a combination of carotid clamping and hypotension for 15 min, followed by recirculation for 6 h, 24 h, 48 h and 5 d. Paraffin sections from the brains were incubated with antiserum against albumin, and parallel sections were stained with hematoxylin and eosin (H & E). Breakdown of the BBB with extravasation of albumin was seen after 6 h in the lateral reticular nucleus of the thalamus, the dorsolateral striatum, and in restricted areas of the cerebral cortex. Uptake of albumin into damaged neurons was seen in the same structures, and partly before reliable changes were observed in routinely stained sections. With longer survival periods, the staining of the neuropil became stronger and more neurons in the damaged areas were positively labeled. After 48 h and 5 d many neurons in the hippocampal sector CA1 had also taken up plasma proteins. A similar uptake of plasma proteins into damaged neurons was seen in brains from patients with histological evidence of hypoxic injury. Even the small leakage of proteins that occurs after hypoxic/ischemic lesions is thus sufficient to give a definite immunostaining of damaged neurons.

Neuronal uptake of plasma proteins in cryogenic brain lesions. An immunoelectron microscopic study.

A previous light microscopic study on cryogenic brain lesions in rats demonstrated uptake of plasma proteins into damaged neurons within a few minutes after the lesion. The protein concentration was much higher inside the nerve cell bodies than in the surrounding neuropil. This is puzzling since the neuropil to a large extent consists of damaged neuronal processes. The present investigation describes the intracellular localization of albumin in this model using a post-embedding immunoelectron microscopic technique. The distribution of albumin in the lesions was studied after 1, 6 and 12 h survival periods. The intraneuronal albumin was mainly bound to the particulate elements of the cytoplasm and nuclei, while the watery parts of the cells showed no immunoreactivity. The intracellular organelles contained very little albumin, indicating that their membranes may be more resistant to freezing than those of the cells. Most of the neuronal and glial processes in the neuropil were swollen and contained almost no albumin. This explains the contrast between the strong immunoreactivity of the neurons and the vague reactivity of the neuropil in light microscopy.

Early entry of plasma proteins into damaged neurons in brain infarcts. An immunohistochemical study on experimental animals.

Entry of plasma proteins into damaged neurons has previously been demonstrated in various pathological conditions, but little is known about brain infarcts in this respect. In the present study, focal ischemic lesions were produced in rats by permanent occlusion of the middle cerebral artery (MCA). The animals were killed from 1 to 48 h postlesion. Leakage of plasma proteins across the blood-brain barrier into the infarcted area was visualized with immunostaining 2-3 h after the occlusion. This is earlier than in most previous reports. Entry of plasma proteins into ischemic neurons was seen 3 h after permanent occlusion of the MCA, while reliable changes were not seen until 12-24 h in sections stained with hematoxylin and eosin (H & E). Ischemic neurons stained for plasma proteins irrespective of their morphological appearance. Even cells that appeared normal with H & E staining were positively labeled. The technique may be used to diagnose very early ischemic lesions.

Toxicity of metrizamide and meglumine iocarmate in the spinal subarachnoid space. An experimental study in rats with special reference to long-term effects.

The toxic effects of metrizamide, a new non-ionic contrast medium, and of meglumine iocarmate (Dimer-X), were investigated after injection into the spinal subarachnoid space of rats. Convulsions were seen in 8 of 11 animals with meglumine iocarmate. No such irritative effects seen with metrizamide. Histologic examiniation of the spinal cord was carried out here 4 months. No changes were seen which could be ascribed to toxic effects of the contrast media.

Air-filled ultrasound contrast agents do not damage the cerebral microvasculature or brain tissue in rats.

RATIONALE AND OBJECTIVES: Air microemboli may damage the cerebral microvasculature. The aim of this study was to evaluate the safety of ultrasound contrast agents composed of air microspheres with regard to cerebral damage when administered into the arterial system (ie, when not filtered by the capillary system of the lungs). METHODS: Three experimental methods were used in 75 rats after injection of either Albunex, Echovist, or Levovist into the left heart ventricle. The alkaline phosphatase (ALP) method to demonstrate small segmental brain capillary and arteriolar dilatations (SCADs), intravenous injections of Evans blue and fluorescence microscopy to detect increased vascular permeability (blood-brain barrier damage), and histologic examination of the brain to detect microinfarction. Intracardiac injections of saline, air, and corn oil were used as controls. RESULTS: Brain microinfarcts and SCADs formation of the brain microvasculature occurred only after control injections with corn oil. None of the brains from animals that received ultrasound contrast agent showed gross discoloration, as an indication of increased vascular permeability, with the Evans blue/fluorescence microscopy method. Definite leakage of Evans blue occurred only after large doses (150 microL) of air. CONCLUSIONS: This study indicates that ultrasound contrast media composed of air microspheres do not cause lesions of the brain microvasculature or parenchyma.

The perineuronal glial reaction after axotomy.

The perineuronal glial reaction after axotomy of the facial nerve was examined in adult mice and rats and in newborn rabbits. The facial nerve was damaged in two ways: by crush lesions, which were followed by complete neuronal regeneration, and by transection (in mice) or evulsion (in rats and rabbits), which caused extensive nerve cell disintegration. After nerve lesions which caused irreversible damage the microglial cells encircled the degenerating neurons and ultimately phagocytosed them. After crush lesions there were great species variations in the glial reaction: the neurons of rats and rabbits showed considerable and reversible separation of the synaptic terminals by glial cells, while mice showed no significant synaptic separation. It is suggested that the main function of the microglial cells may be to serve as potential phagocytes for disintegrating neurons, and that the reversible glial changes around regenerating neurons possibly represent abortive glial reactions.

On the pathology of experimental hydrocephalus.

Acute hydrocephalus was produced in newborn rabbits by injection of kaolin into the cisterna magna. The light microscopic changes which occurred in the ependyma and periventricular brain tissue were studied. Some animals also received intraventricular injection of Evans blue albumin (EBA) at various times after the kaolin injection to study the permeability of the ependyma. There was a progressive dilatation of the lateral ventricles from the second day after the kaolin injection. Marked hydrocephalus was seen after 2 weeks. The white matter of the cerebral hemispheres showed increasing reduction in volume with the degree of hydrocephalus. Neither destruction of brain tissue nor macrophage response or inflammation were seen. The ependyma adapted remarkably well to the increased intraventricular pressure by extensive flattening and stretching. No convincing breaks or ruptures were seen. There was a patchy spongy zone beneath the ependyma, probably indicating oedema of the periventricular white matter due to transventricular absorption of the cerebrospinal fluid (CSF). Denudement of the ependymal lining is not necessary for the concept of transventricular flow of CSF. No difference was seen in the penetration of EBA into the periventricular tissue between hydrocephalic and control animals. The reduction of the cerebral mantle thickness was probably caused by simple pressure atrophy. This indicates that the morphological changes may to a large extent be reversible if the hydrocephalus is properly treated within reasonable time. The role of morphological changes in the pathophysiology of hydrocephalus if briefly commented upon in relation to certain aspects of human hydrocephalus.

Effect of apolipoprotein E genotype on Alzheimer's disease neuropathology in a cohort of elderly Norwegians.

A cohort of elderly Norwegians dying in nursing homes in the Oslo region have been genotyped for the Apolipoprotein E (ApoE) gene. Alzheimer's disease (AD) cortical neuropathology and clinical evidence of dementia were used to assign cases without evidence of other confounding neuropathology. Senile plaque (SP) and neurofibrillary tangle (NFT) densities in frontal, temporal and parietal cortex were then correlated with ApoE genotype to determine any relationship between ApoE genotype and AD pathology. Comparisons with ApoE epsilon 3, epsilon 4 and epsilon 2 allele dosage failed to show any significant effect on cortical SP densities in any cortical area. NFT densities were increased by epsilon 4 allele dosage in the frontal cortex but not in other cortical regions. A reduction was seen in cortical NFT densities with epsilon 2 allele, though again this was not consistently significant in any of the groups. The epsilon 3 allele failed to show any consistent effect on cortical NFT densities. Assessment by individual genotypes showed epsilon 2/3 < epsilon 2/4 < epsilon 3/3 < epsilon 3/4 < epsilon 4/4 which had highest cortical NFT densities in all areas. By genotype, SP densities were generally of the order epsilon 2/4 < epsilon 2/3 < epsilon 3/3 < epsilon 4/4 < epsilon 3/4 though in none of the groups was this significant. Duration of disease showed no consistent effect on neuropathological burden. ApoE genotype may have an effect on determining whether individuals suffer from AD and the age at onset of disease but may only have a minimal effect on pathology burden.

A case of chronic demyelinating polyneuropathy resembling the Guillain-Barré syndrome.

A case of demyelinating polyneuropathy is reported which was clinically and pathologically indistinguishable from the Guillain-Barré syndrome, with the exception that the symptoms progressed steadily for 7 months. Pathologically, the peripheral nerves and intraspinal roots showed selective demyelination with axonal sparing and patchy mononuclear inflammation. The posterior columns of the spinal cord also showed selective demyelination with axonal sparing. The simultaneous destruction of central and peripheral myelin is discussed in relation to the immune theory for the Guillain-Barré syndrome. Numerous anterior horn cells showed severe chromatolysis although there was little axon loss. It is suggested that chromatolysis may occur after severe and longstanding demyelination.

The prevalence of alcoholic cerebellar atrophy. A morphometric and histological study of an autopsy material.

The Purkinje cell densities in the cerebellar vermis were determined in 31 male alcoholics and 34 non-alcoholic controls under 70 years of age. In addition, all cases were examined histologically for atrophy of the superior vermis. All analyses were performed independently of each other and on randomized slides. The alcoholics had significantly lower Purkinje cell densities than the controls in the superior and middle segments of the vermis. Histologically verified atrophy of the superior vermis was found in 13 of the alcoholics (42%) and in 3 of the controls (9%). There was a good accordance between the morphometric data and the histologic diagnoses. The cause of the cerebellar atrophy in the 3 control cases is uncertain. It could be due to hidden alcoholism or to premature ageing. In a series of non-alcoholic control cases above 70 years, one third of the cases showed atrophy of the superior vermis similar to that of alcoholics. The diagnosis alcoholic cerebellar atrophy should therefore be made with great caution in cases over 70 years. From previous morphometric data on symptomatic cases (Victor et al. 1959), it can be assumed that the majority of the present cases with histologically verified atrophy had overt clinical symptoms. It is concluded that almost one half of all severe alcoholics have atrophy of the superior vermis which can be recognized morphologically and probably also clinically.

Atrophy of the cerebellar vermis in ageing. A morphometric and histologic study.

Morphometric analysis of the cerebellar vermis in 67 non-alcoholic men between 36 and 94 years of age showed a significant decline in Purkinje cell densities with increasing age in all parts of the cerebellar vermis. However, the nerve cell loss was much more severe in the superior than in the inferior part. There were large individual variations and one-half of the subjects over 80 years showed densities similar to those in the sixties. By independent evaluation, atrophy of the superior vermis was diagnosed histologically in 16 cases, 13 of whom were over 70 years of age. There was a good correspondence between the histologic diagnoses and the morphometric findings. The atrophy involved all 3 cortical layers and the changes were identical to those seen in alcoholics. The diagnosis of alcoholic cerebellar atrophy must therefore be made with great caution in subjects over 70 years of age. Cases with malignant tumours had significantly lower Purkinje cell densities in the superior vermis than those without tumours but the decline with age was of the same magnitude in the 2 groups. The age-dependent atrophy of the superior vermis seemed to be correlated to age alone and not to other known conditions. It probably was sufficiently severe to be recognized radiologically and clinically in a considerable number of the cases.

Brain lesions in alcoholics. A neuropathological study with clinical correlations.

Among 8735 autopsies performed during a 5-year period at Ullevål Hospital in Oslo there were 70 cases of Wernicke's encephalopathy (0.8%) and 152 cases of alcoholic cerebellar atrophy (1.7%). Cerebellar atrophy was found in 26.8% of all examined alcoholics. Twenty-two of the cases with Wernicke's encephalopathy were active (acute and subacute) and 48 were inactive (chronic). Examination of the clinical records showed that stupor and coma were the dominating symptoms in active cases. A pure Korsakoff's psychosis with a selective memory defect was present in about one-third of the cases with inactive encephalopathy while the remaining had more or less pronounced global dementia ("alcoholic dementia"). It is suggested that inactive Wernicke's encephalopathy is the main underlying lesion both in Korsakoff's psychosis and "alcoholic dementia" but that additional lesions are present in the latter group. The brain weight in 545 male alcoholics was compared with that of 586 controls. Cases with non-alcoholic brain lesions were excluded from both groups. In alcoholics the brain weight was significantly lower than in controls in all age groups below 70 years. The mean weight difference was 31 g. The study thus confirmed the existence of a generalized alcoholic brain atrophy.

Infantile Refsum's disease: a generalized peroxisomal disorder. Case report with postmortem examination.

Infantile Refsum's disease (IRD) is a peroxisomal deficiency disease which is closely related to neonatal adrenoleukodystrophy (NALD) and the Zellweger syndrome (ZS). Recent observations suggest that NALD and ZS are separate genetic disorders but the delimitation towards IRD remains uncertain. We present here the first autopsy report of a patient who was clinically and biochemically diagnosed as having IRD, and we compare the findings with those from NALD and ZS. The main gross and microscopic findings comprised micronodular liver cirrhosis, small hypoplastic adrenals without degenerative changes, and large groups of lipid macrophages in liver, lymph nodes and certain areas of the cerebral white matter. The brain showed no malformations except for a severe hypoplasia of the cerebellar granule layer and ectopic location of the Purkinje cells in the molecular layer. A mild and diffuse reduction of axons and myelin was found in the corpus callosum and periventricular white matter, the corticospinal tracts, and the optic nerves. Large numbers of perivascular macrophages were present in the same areas but there was no active demyelination. The retina and cochlea showed severe degenerative changes. Peripheral nerves, skeletal system and kidneys were normal. Electron microscopy showed characteristic cytoplasmic inclusions with bilamellar profiles in macrophages in the liver, lymph nodes and brain but not in the adrenals. Similar inclusions were found in liver cells and astrocytes. The findings differ from ZS which shows cortical renal cysts, skeletal changes, liver changes, cerebral micropolygyria, neuronal heterotopias, and demyelination of the white matter. Cases with NALD show mild cerebral malformations, active demyelination, degenerative changes of the adrenals, liver changes, and bilamellar electromicroscopic inclusions in macrophages. Our cases thus resembled NALD but lacked active demyelination, cerebral cortical malformations and adrenal degenerative changes. Further autopsy studies will be necessary to determine whether these changes are consistent findings in IRD.

Clivus epidural hematoma: a case report.

An acute traumatic epidural hematoma extending from the odontoid process to the dorsum sella is described. The mechanism for the formation of an extradural hematoma in this unusual location seems to be related to age and a severe hyperflexion injury.

The spinal cord central canal in kaolin-induced hydrocephalus.

In order to study the cause of the great individual variations in kaolin-induced hydrocephalus, the lower brain stem and upper spinal cord were examined histologically in a series of young rabbits that had received injections of kaolin into the cisterna magna. Animals with complete occlusion of the outlets from the fourth ventricle into the subarachnoid space showed only a moderate ventricular dilatation, while cases with marked hydrocephalus also plugs of kaolin in the caudal part of the fourth ventricle. The intraventricular kaolin was adherent to the roof of the fourth ventricle by strands of connective tissue and it is suggested that the plugs served as valves that initially occluded the opening of the central canal and were then lifted away as the ventricle dilated and the roof moved posteriorly. The animals with marked hydrocephalus also had extensive dilatation of the central canal with cleft formation in the posterior columns. The observations support the concept that in hydrocephalus the central canal may serve as an alternative resorption route for the cerebrospinal fluid through communication with the spinal subarachnoid space.

Subarachnoid hemorrhage and cerebrovascular spasm. Morphological study of intracranial arteries based on animal experiments and human autopsies.

Artificial subarachnoid hemorrhage (SAH) produced by injection of autologous blood into the cisterna magna in dogs gave rise to considerable narrowing or spasm of the basilar artery and its branches, including the posterior cerebral arteries, as demonstrated by cerebral angiography. Repeated cisternal injections of blood at various intervals produced more severe spasm than a single injection. After perfusion-fixation of the brain, the cerebral arteries were examined by light and electron microscopy. None of the animals showed abnormalities in the intima or media of the vessel walls. Previously reported findings of morphological changes due to spasm could not be confirmed. Postmortem examination of brain vessels from nine patients with SAH and arterial spasm showed no specific changes that could be ascribed to spasm.

Topographic distribution and severity of brain lesions in Wernicke's encephalopathy.

The distribution and severity of the brain lesions were studied in 45 cases (age range: 26-84 years) of Wernicke's encephalopathy. The process was acute or subacute (active) in 24 cases and chronic (inactive) in 21. Cases with acute and subacute disease had more extensive and severe lesions than the chronic ones. The majority of the acute cases had lesions involving the mammillary bodies and thalamus and the subependymal structures along the third and fourth ventricles and the aqueduct. Only three acute cases had lesions restricted to the mammillary bodies. Among the chronic cases, the majority of the lesions were restricted to the mammillary bodies and the thalamus. Only two lesions extended as far down as the inferior collicles. Eleven out of 21 chronic cases has isolated lesions of the mammillary bodies. The affection of the mammillary bodies in chronic cases varied from barely visible to subtotal destruction of the tissue. Similarly, the lesions in the thalamus varied from slight gliosis in the dorsomedial nucleus to extensive nerve cell loss in several nuclei. There were similar variations in the severity of the clinical picture. Memory loss was recorded in three cases with isolated lesions of the mammillary bodies.

Watershed infarcts in the brain caused by microemboli.

Multiple vascular occlusions are frequently found in the leptomeningeal arteries over watershed infarcts in the brain. These occlusions have largely been interpreted as thrombi secondary to slowing of the blood flow. This report suggests that most of the occlusions are microemboli, which may lodge preferentially in these areas, and that they are the cause of the infarcts rather than secondary events. These suggestions are based upon the analysis of three groups of patients. The first group consists of four cases, two of which had atheromatous masses and the other two, tumor emboli in the overlying leptomeningeal arteries. These cases prove beyond doubt that microemboli can lodge preferentially in the watershed areas and cause infarcts in the brain. The second group consists of the cases of watershed infarcts that were precipitated by hypotensive episodes. Only one of these showed occlusion of the overlying arteries, although all of them obviously had slowing of the blood flow during the acute phase. These cases thus discredit the concept that stagnation thrombosis is a frequent event. Finally, three cases with watershed infarcts and vascular occlusions interpreted as platelet microemboli are presented to demonstrate different pathogenetic mechanisms effective in the process of embolization.