Dialysis dementia -- the Chicago experience

Advances in dialysis encephalopathy research: a review

Dialysis encephalopathy (DE) is a progressive, fatal disease with a high mortality rate. Understanding the causes of this disease and the efforts to prevent and treat it would help improve the prognosis and quality of life of affected patients. This paper reviews the etiology, clinical features, methods of examining accessory features, diagnosis, treatment, and prevention of DE. We found that DE is likely to be related to aluminum poisoning. The clinical manifestations of DE include language disorders, mental and behavioral disorders, cognitive decline, and movement disorders. Electroencephalogram (EEG) findings mainly consist of an abundance of low waves, intermittent bilateral synchronous high-amplitude spikes, and ridge waves. Assessing the clinical features and obtaining an EEG are of great value in diagnosis, and DE is treated by both reducing aluminum intake and increasing aluminum excretion. Deferoxamine (DFO) is an effective treatment for DE.

Toxin-Induced Movement Disorders

Toxins can be cited as a cause of several movement disorders, but this association is rare and the resultant syndromes usually include additional signs that are not typical for the idiopathic movement disorders. Most instances of confirmed toxin-induced movement disorders show lesions on CT and MRI scans of cortical or subcortical structures. A common underlying element in these toxin-induced syndromes is the development of lesions primarily in the pallidum and striatum. Because many toxins result in lesions affecting these structures, a selective vulnerability to hypoxic or metabolic insults has long been postulated. The susceptibility of these structures may relate to a number of factors, including the pattern of oxidative metabolism, heavy metal concentration, vascular perfusion, and neuronal innervation. Finally, in addition to causing disability, certain neurotoxins have led to a better understanding of human disease through the development of research models. As an example, the MPTP model has not only provided an animal model to study therapeutic strategies in PD but has also contributed important insights into the mechanism of neuronal degeneration.

Characterization and extracorporeal application of a new phosphate-binding agent

A new phosphate-binding agent which does not cause any severe side effects in vivo was developed by modifying a crosslinked dextran with polynuclear iron(III)oxide-hydroxide. Its particle size ranges from 150 to 300 microns, and the iron content was about 18% by dry weight. The oxidation state of iron was characterized by ESCA and Mössbauer spectroscopy. The maximum phosphate binding capacity of the iron(III)oxide-hydroxide-modified dextran was determined with respect to aqueous phosphate solutions, human serum and whole blood. The effects on whole blood count, haemolysis, protein concentration and enzyme activities were examined. In addition, the influence of phosphate concentration, pH and temperature on the phosphate uptake of the material was determined. The results show that this new adsorbent might provide an alternative to conventional phosphate-binding agents. This paper also describes the first experiments on the therapeutic application of the material in an extracorporeal blood perfusion system for the treatment of hyperphosphataemia during haemodialysis.

In vitro simulation of biocompatibility of Ti-Al-V

The presented data are the result of a reappraisal of the biocompatibility properties of titanium alloys. An in vitro study has been conducted using Hanks' solution with four different additional compounds (EDTA, l-leucine, Na-citrate, and 8-hydroxyquinoline). A measurable dissolution rate was observed for Ti and Al in a solution containing EDTA and for Ti, Al, and V for a solution containing Na-citrate. The dissolution kinetics are discussed and explained in terms of the composition of the surface layers. The results contain useful introductory information for an extended study of media allowing representative in vitro simulation of the in vivo behavior of titanium alloys.

Dialysis encephalopathy: neuropathologic aspects

The clinical, epidemiologic, electroencephalographic, and toxicologic features of dialysis encephalopathy (DE) have been clarified, but the neuropathologic and clinicopathologic aspects of the disease have remained obscure. In three cases of DE associated with a dialysate of high aluminum content, spongy change restricted to the upper layers of the cerebral cortex was found. The spongy change was distributed through the cerebral cortex bilaterally and diffusely, but the left hemisphere was involved more severely and extensively than the right hemisphere, and the opercular portions of the frontal and temporal lobes were affected more than the remainder of those lobes. This topographic distribution correlated with the clinical defects in higher cortical functions, including aphasia. The spongy change consisted of vacuoles in the neuropil and inside nerve cell bodies. The vacuoles in the neuropil were located in dendrites, astrocytic processes, and, possibly, other structures. Thus, DE is a disease of neurons and astrocytes of the cerebral cortex. Although spongy change of the upper layers of the cerebral cortex is a nonspecific abnormality, when it occurs in the distribution described and in the absence of other diffuse cerebral diseases, it is characteristic of DE.

Aluminum associated bone disease: clinico-pathologic correlation

A chemical, aurine tricarboxylic acid was used to identify aluminum in bone in a group of chronic renal failure patients with severe osteomalacia. Thirteen out of 49 (26%) patients had a positive stain at the bone-osteoid junction. The presence of aluminum at the staining site was confirmed by electron dispersion x-ray analysis. The patients' biopsies staining negative with this clinical, although having high bone aluminum levels, had more significant features of hyperparathyroidism, both biochemically and histologically than those having a positive stain. The usefulness of this technique to diagnose presymptomatic aluminum related osteomalacia is emphasized.

The clinical biochemistry of aluminum

The methods for aluminum analysis vary from the simple and often nonspecific chemical and physical procedures to the highly sophisticated types such as neutron activation and atomic absorption spectrometry. Atomic absorption procedures are the techniques of choice for most routine hospital laboratories. The wide distribution of aluminum in nature can create severe contamination problems in aluminum analysis. Procedures to avoid contamination are discussed. In recent years aluminum has been implicated as a possible etiological agent in DES and in Alzheimer's Disease. A common finding in these two conditions is an elevated brain aluminum content. The patients with Alzheimer's Disease develop characteristic neurofibrillary tangles which lead to the degeneration of the affected neurons. Similar tangles can be induced in laboratory animals injected intracerebrally with aluminum salts. Even though the laboratory animals develop tangles resembling those seen in patients with Alzheimer's Disease, no evidence has been published to show that the tangles seen in Alzheimer's Disease are induced by the elevated brain aluminum content. Although there are some similar clinical symptoms in both Alzheimer's Disease and DES, the hemodialysis patients with DES do not develop neurofibrillary tangles despite an elevated brain aluminum content. The significance of this difference is not understood. The sources of the increase in tissue aluminum levels found in hemodialysis patients are from the gastrointestinal absorption of aluminum in aluminum containing phosphate-binding gels and by transfer from the dialyzate to the blood during the hemodialysis procedure. Plasma aluminum values may be reduced by the administration of a minimum dosage of phosphate-binding gels and by the use of purified water to make up the dialysate. The incidence of DES is reduced by the use of these procedures to maintain the hemodialysis patients' plasma aluminum at a low concentration. The increased brain aluminum content of patients with Alzheimer's Disease is derived from the environment. Because of the ubiquitous occurrence of aluminum, we are exposed to it daily in our food, water, and in the air. The low levels of aluminum absorbed from the environment may explain why susceptible patients do not develop Alzheimer's Disease until after many years of exposure, if indeed aluminum is the etiological agent in Alzheimer's Disease. The many papers that have been published concerning aluminum, DES, and Alzheimer's Disease make a strong case for linking elevated tissue aluminum content with these conditions. However, conclusive evidence to support this theory has not been published. Until the effect of aluminum on cellular chemistry is more fully understood, the possibility that DES and Alzheimer's Disease may result from other causes or from aluminum and another agent acting concomitantly must be considered.