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Binswanger's disease

Leukoencephalopathy, Subcortical leukoencephalopathy

Overview

Binswanger's disease (BD), also called subcortical vascular dementia, is a type of dementia caused by widespread, microscopic areas of damage to the deep layers of white matter in the brain. The damage is the result of the thickening and narrowing (atherosclerosis) of arteries that feed the subcortical areas of the brain. Atherosclerosis (commonly known as "hardening of the arteries") is a systemic process that affects blood vessels throughout the body. It begins late in the fourth decade of life and increases in severity with age. As the arteries become more and more narrowed, the blood supplied by those arteries decreases and brain tissue dies.

White matter atrophy can be caused by many circumstances including chronic hypertension as well as old age. This disease is characterized by loss of memory and intellectual function and by changes in mood. These changes encompass what are known as executive functions of the brain. It usually presents between 54 and 66 years of age, and the first symptoms are usually mental deterioration or stroke.

It was described by Otto Binswanger in 1894, and Alois Alzheimer first used the phrase "Binswanger's disease" in 1902. However, Olszewski is credited with much of the modern-day investigation of this disease which began in 1962.

A characteristic pattern of BD-damaged brain tissue can be seen with modern brain imaging techniques such as CT scans or magnetic resonance imaging (MRI). The symptoms associated with BD are related to the disruption of subcortical neural circuits that control what neuroscientists callexecutive cognitive functioning: short-term memory, organization, mood, the regulation of attention, the ability to act or make decisions, and appropriate behavior. The most characteristic feature of BD is psychomotor slowness - an increase in the length of time it takes, for example, for the fingers to turn the thought of a letter into the shape of a letter on a piece of paper. Other symptoms include forgetfulness (but not as severe as the forgetfulness of Alzheimer's disease), changes in speech, an unsteady gait, clumsiness or frequent falls, changes in personality or mood (most likely in the form of apathy, irritability, and depression), and urinary symptoms that aren't caused by urological disease. Brain imaging, which reveals the characteristic brain lesions of BD, is essential for a positive diagnosis.

Symptoms - Binswanger's disease

Symptoms include mental deterioration, language disorder, transient ischemic attack, muscle ataxia, and impaired movements including change of walk, slowness of movements, and change in posture. These symptoms usually coincide with multiple falls, epilepsy, fainting, and uncontrollable bladder.

Because Binswanger’s disease affects flow processing speed and causes impaired concentration, the ability to do everyday tasks such as managing finances, preparing a meal and driving may become very difficult.

Neural presentation

Binswanger's disease is a type of subcortical vascular dementia caused by white matter atrophy to the brain. However, white matter atrophy alone is not sufficient for this disease; evidence of subcortical dementia is also necessary.

The histologic findings are diffuse, irregular loss of axons and myelin accompanied by widespread gliosis, tissue death due to an infarction or loss of blood supply to the brain, and changes in the plasticity of the arteries. The pathologic mechanism may be damage caused by severe atherosclerosis. The onset of this disease is typically between 54 – 66 years of age and the first symptoms are usually mental deterioration or stroke.

The vessels that supply the subcortical white matter come from the vessels that support basal ganglia, internal capsule, and thalamus. It is described as its own zone by and susceptible to injury. Chronic hypertension is known to cause changes in the tension of the smooth wall vessels and changes in the vessel diameter. Arterioles can become permeable resulting in compromise of the blood brain barrier. It has been shown that Binswanger’s disease targets the vessels in this zone of the subcortex, but spares the microcirculation's vessels and capillaries which may be attributed to a difference between Alzheimer’s and Binswanger’s disease.

Mental presentation

There is a difference between cortical and subcortical dementia. Cortical dementia is atrophy of the cortex which affects ‘higher’ functions such as memory, language, and semantic knowledge whereas subcortical dementia affects mental manipulation, forgetfulness, and personality/emotional changes. Binswanger’s Disease has shown correlations with impairment in executive functions, but have normal episodic or declarative memory. Executive functions are brain processes that are responsible for planning, cognitive flexibility, abstract thinking, rule acquisition, initiating appropriate actions and inhibiting inappropriate actions, and selecting relevant sensory information. There have been many studies done comparing the mental deterioration of Binswanger patients and Alzheimer patients. It has been found in the Graphical Sequence Test that Binswanger patients have hyperkinetic perseveration errors which cause the patients to repeat motion even when not asked whereas Alzheimer patients have semantic perseveration because when asked to write a word they will instead draw the object of the word.

Causes - Binswanger's disease

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Prevention - Binswanger's disease

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Diagnosis - Binswanger's disease

Binswanger's disease can usually be diagnosed with a CT scan, MRI, and a proton MR spectrography in addition to clinical examination. Indications include infarctions, lesions, or loss of intensity of central white matter and enlargement of ventricles, and leukoaraiosis. Recently a Mini Mental Test (MMT) has been created to accurately and quickly assess cognitive impairment due to vascular dementia across different cultures.

Imaging

Leukoaraiosis (LA) refers to the imaging finding of white matter changes that are common in Binswanger disease. However, LA can be found in many different diseases and even in normal patients, especially in people older than 65 years of age.

There is controversy whether LA and mental deterioration actually have a cause and effect relationship. Recent research is showing that different types of LA can affect the brain differently, and that proton MR spectroscopy would be able to distinguish the different types more effectively and better diagnosis and treat the issue. Because of this information, white matter changes indicated by an MRI or CT cannot alone diagnose Binswanger disease, but can aid to a bigger picture in the diagnosis process. There are many diseases similar to Binswanger's disease including CADASIL syndrome and Alzheimer's disease, which makes this specific type of white matter damage hard to diagnose. Binswanger disease is best when diagnosed of a team by experts including a neurologist and psychiatrist to rule out other psychological or neurological problems. Because doctors must successfully detect enough white matter alterations to accompany dementia as well as an appropriate level of dementia, two separate technological systems are needed in the diagnosing process.

Much of the major research today is done on finding better and more efficient ways to diagnose this disease. Many researchers have divided the MRIs of the brain into different sections or quadrants. A score is given to each section depending on how severe the white matter atrophy or leukoaraiosis is. Research has shown that the higher these scores, the more of a decrease in processing speed, executive functions, and motor learning tasks. Other researchers have begun using computers to calculate the percentage of white matter atrophy by counting the hyper-intense pixels of the MRI. These and similar reports show a correlation between the amount of white matter alterations and the decline of psychomotor functions, reduced performance on attention and executive control. One recent type of technology is called susceptibility weighted imaging (SWI) which is a magnetic resonance technique which has an unusually high degree of sensitivity and can better detect white matter alternations.

Prognosis - Binswanger's disease

Binswanger's disease is a progressive disease; there is no cure. Changes may be sudden or gradual and then progress in a stepwise manner. Binswanger's disease can often coexist with Alzheimer's disease. Behaviors that slow the progression of high blood pressure, diabetes, and atherosclerosis -- such as eating a healthy diet and keeping healthy wake/sleep schedules, exercising, and not smoking or drinking too much alcohol -- can also slow the progression of Binswanger's disease.

Treatment - Binswanger's disease

There is no specific course of treatment for BD. Treatment is symptomatic. People with depression or anxiety may require antidepressant medications such as the serotonin-specific reuptake inhibitors (SSRI) sertraline or citalopram. Atypical antipsychotic drugs, such as risperidone and olanzapine, can be useful in individuals with agitation and disruptive behavior. Recent drug trials with the drug memantine have shown improved cognition and stabilization of global functioning and behavior. The successful management of hypertension and diabetes can slow the progression of atherosclerosis, and subsequently slow the progress of BD. Because there is no cure, the best treatment is preventive, early in the adult years, by controlling risk factors such as hypertension, diabetes, and smoking.

The best way to manage the vascular risk factors that contribute to poor perfusion in the brain is to treat the cause, such as chronic hypertension or diabetes. It has been shown that current Alzheimer’s medication, donepezil (trade name Aricept), may help Binswanger’s Disease patients as well. Donepezil increases the acetylcholine in the brain through a choline esterase inhibitor which deactivates the enzyme that breaks down acetylcholine. Alzheimer as well as Binswanger patients have low levels of acetylcholine and this helps to restore the normal levels of neurotransmitters in the brain. This drug may improve memory, awareness, and the ability to function. If no medical interception of the disease is performed then the disease will continue to worsen as the patient ages due to the continuing atrophy of the white matter from whatever was its original cause.

Resources - Binswanger's disease

  • NIH
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