Subcortical Arteriosclerotic Encephalopathy (SAE)

Subcortical arteriosclerotic encephalopathy (SAE), or Binswanger’s disease, is one of the forms of vascular dementia. In SAE arteriosclerotic changes affect subcortical arteries and arteroles. Atherosclerosis of large cerebral arteries is common among SAE patients. As dyslipoproteinemias are risk factors for atherosclerosis we studied blood lipids and lipoproteins in patients with clinical diagnosis of SAE.

In 11 patients diagnosis of the disease was established on the basis of CT scans and clinical course consistent with SAE. In the studied group a tendency to increased total cholesterol and apolipoprotein B and to decreased HDL cholesterol (HDL‐CH) were found. The levels of LDL cholesterol (LDL‐CH) and the CH/HDL‐CH and HDL phospholipides/HDL‐CH ratios were significantly higher in SAE patients when compared to controls.

Binswanger’s encephalopathy is reviewed in respect to history, computed tomography, magnetic resonance imaging, epidemiology, pathology, clinical picture, laboratory findings, differential diagnosis, and treatment. The various viewpoints on the pathogenesis of the process are discussed, in particular the role of ischemia, vascular disease, high blood pressure, lacunar infarction, hypoxia, edema, and hydrocephalus. The white matter hypomyelination of congophilic angiopathy and Alzheimer’s disease should provide clues. A unifying hypothesis has not been attained.

Subcortical arteriosclerotic encephalopathy (SAE), also known as Binswanger disease or small vessel dementia, refers to slowly progressive exclusively white-matter multi-infarct dementia.

A genetically transmitted form of the disease is known as familial arteriopathic leukoencephalopathy or CADASIL (cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy).

Clinical presentation

Patients usually present with subcortical dementia symptoms including forgetfulness, personality and emotional changes.

Clinical criteria for the diagnosis are as follows:

marked subcortical microangiopathic lesions at MR imaging

a negative family history for strokes, early cognitive impairment, or psychiatric disorders in first- and second-degree relatives

documented arterial hypertension: systolic values higher than 160 mm Hg, diastolic values higher than 95 mm Hg, or both, measured on several occasions 5

Pathology

Pathologically, relatively symmetrical and diffuse bilateral deep periventricular white matter lesions are associated with severe arteriosclerosis of the small penetrating arteries which are thickened, lipohyalinised, stenotic, or even occluded. In most patients, multiple lacunar infarcts are also present in the basal ganglia, thalami, and pons 3.

Radiographic features:

CT

Diffuse, incompletely symmetrical hypodensities are present in deep white matter, especially prominent in the frontal lobes and centrum semiovale 3.

MRI

MRI changes are much more striking, consisting of subcortical and periventricular hyperintense lesions visible on FLAIR, T2-weighted, and proton-density sequences.

The white matter lesions are usually small, commonly grouped around the frontal and occipital horns and in the centrum semiovale.

Moderate diffuse cerebral atrophy is invariably present, and lacunar infarcts in the basal ganglia and thalami are common 3.

History and etymology

It was first described in 1894 by Otto Ludwig Binswanger (1852-1929), a Swiss psychiatrist and neurologist 4.

Differential diagnosis

CADASIL: classically, lesions involve anterior temporal and superior frontal lobes which are uncommonly involved in SAE. Also, arcuate fibers are more likely to be affected in CADASIL. Low signal intensity of the basal ganglia and dentate nuclei of the cerebellum are more pronounced in CADASIL than in SAE 5.