Binswanger's Disease (Subcortical arteriosclerotic encephalopathy)

Background Neuroimaging Gross Pathology Histopathology & Immunohistochemistry Differential Diagnosis Reference

BACKGROUND AND CLINICAL INFORMATION: Head

Clinical features: Binswanger's disease is a form of vascular dementia frequently present with hypertension, dementia, a pseudobulbar state, a gait disorder often of Parkinsonian type, transient ischemic attack, and multiple strokes. Patients with hypercoagulatory state have also been described recently.

Clinical diagnostic criteria: [Bennett DA et al.]

Dementia must be established by clinical examination and confirmed by neuropsychological tests.

One finding from two of the following three groups must be present:

the presence of a vascular risk factor or evidence of systemic vascular disease
evidence of focal cerebrovascular disease
evidence of "subcortical" cerebral dysfunction

Bilateral leukoaraiosis on CT or subcortical T2 weighed lesions larger than 2 X 2 mm on MRI

These criteria lose their validity in the presence of multiple or bilateral cortical lesions on imaging or severe dementia (e.g. MMS <10).

Comment: clearly, these criteria do not exclude CADASIL!

Diagnosis: Binswanger's disease is a clinicopathologic diagnosis. A clinical diagnosis can be made with these criteria. For pathologic diagnosis, typical histology must be present and a clinical history of dementia must be established before a definitive diagnosis of Binswanger's disease is made. Cases without a well established clinical history of dementia are only "consistent with Binswanger's disease".

Genetics: can be sporadic or familial.

Possible etiologies:

Hypertension.
Ischemia.
Vasculopathy including abnormal blood brain barrier and degeneration of the media associated with depositions of collagens type I, III, IV, V and possibly type VI, and other components of extracellular matrix.
Hypercoagulation: significant elevation in levels of thrombin-antithrombin complex, prothrombin fragment 1+2, and cross-linked D-dimer have been reported in patients with Binswanger's disease.

NEUROIMAGING: Head

Binswanger disease has been associated with a particular radiologic appearance that reflects the confluence of areas of white matter changes. Leukoareosis is a term used to described the less intense appearance of periventricular tissues in chronically hypertensive patients. Although frequently seen in Binswanger's disease; leukoareosis, however, is not sufficient to make the diagnosis.

GROSS PATHOLOGY: Head

Brain weight is usually within normal limits.

Marked atherosclerosis of the major cerebral arteries, enlarged lateral ventricles, and shrunken white matter are usually the most prominent features.

Extensive softening of white matter extending from the ventricles to the subcortical white matter. The hemispheric white matter are discoloured, rubbery and firm, sprinkled with foci of infarction. The cerebral hemispheres are affected and show frontal or parieto-occipital accentuation in some cases. The cerebellum is usually not affected. A sponge like cut surface can be seen.

Cribiform changes: White matter shows ‚tat cribl‚ and gray matter show ‚tat lucanaire. These changes are not specific for Binswanger's disease and can be seen in brains of eldery hypertensive patients, vascular dementia with multiple infarcts and in dementia with evidence of both Alzheimer's disease and vascular disease.

HISTOPATHOLOGY AND IMMUNOHISTOCHEMISTRY: Head

Myelin loss is marked, extensive, diffuse, and often symmetrical. The subcortical U-fibers are characteristically preserved. There is a variable amount of reactive astrocytosis. The number of oligodendrocytes is reduced. Except in the recetly infarcted areas, macrophages are uncommon.

Multiple small infarcts are noted in white and deep gray matter.

Cerebral cortex is usually preserved.

Axonal disruption: The most severely demyelinated zones shade into areas of frank necrosis with axonal disruption best demonstrated by immunostaining for neurofilament and silver stains. Reduction in axonal density is also noted outside the areas of infarction.

Blood vessels: there is show marked narrowing and hyalinization of small arterioles (obliterative microangiopathy) in damaged areas with loss of smooth muscle but usually without vascular occlusion. There is also enlarged perivascular space surrounded by gliotic, attentuated gray or white matter.

DIFFERENTIAL DIAGNOSIS: Head

CADASIL (See the chapter on CADASIL).

MELAS: clinical presentation, in particular age of onset and muscle pathology, and genetic studies are very helpful.

REFERENCES: Head

Bennett DA et al. J Neurol Neurosurg Psychiat 1990 53:961.

NeuroLearn NeuroHelp Vascular For Comment: KarMing-Fung@ouhsc.edu

Background Neuroimaging Gross Pathology Histopathology & Immunohistochemistry Differential Diagnosis Reference