Neurological Disorders: Vascular Dementia

Introduction

Vascular Dementia (VD - unofficial abbreviation) is the term used for dementing illness caused by vascular factors. Vascular is the medical adjective used for blood vessels, example - stroke or similar ischemic pathologies of the brain. Ischemia is the term used for total or partial arrest of blood supply to an organ.

A stoke can be due to ischemia or bleeding in the brain, and both can case dementia.

Types of VD & Classification

There are few different types of VDs as below;

• Related with bleeding type strokes

* Single large bleed
* Multiple bleeds

• Related with ischemic type strokes (infarcts)

* Single large infarct
* Multiple large or small infarcts (multi infarct dementia)
* Binswanger’s Dementia

A single small stroke (bleed or infarct) may not always produce dementia, and even a single large stroke depending upon its location may-not always precipitate dementia. So the location of the stroke/strokes is also important. Involvement of the frontal, parietal, temporal lobes, white matter, thalamus etc are important for dementia development. A single stroke (some times even multiple) involving areas like internal capsule, occipital lobes etc may not produce dementias most of the times.

Clinical presentation

Strokes are rapid in onset agree? And these dementias too. In fact such a rapid onset dementia should raise the suspicion of VD, of course there are other causes for rapid onset dementia like head injuries, encephalitis, CJD (crutzfeldt Jacob disease), MS (multiple Sclerosis) etc but history will help in differentiating them.

Focal neurological deficits are characteristic for this dementia. Patients may present with aphasias (speech difficulties), limb paralysis, facial droop etc.

But rapid onset and focal deficits are not the rule, for example in Binswanger dementia there is usually a slow onset and progression of dementia and focal features my be subtle or absent.

Diagnosis

A CT or MRI of the brain is a must for any dementia evaluation. In case of vascular-dementia these imaging studies might confirm the diagnosis. Of course there could be mixed dementias (Alzheimer’s dementia and vascular-dementia) so careful history is required to separate them.

If history is consistent with VD and CT and/or MRI is confirming it to then other investigations are not necessary. But if there is ambiguity with the history or radiological features then additional test are necessary as below on case to case basis;

• Thyroid tests (TSH to start wit)
• B12
• Folate
• ESR
• Blood calcium
• HIV
• ANA etc.

Treatment

There is no curative treatment for dementias including VD so the treatment is preventive/symptomatic/supportive type. To prevent future strokes antiplatelet agents (e.g. aspirin), anticoaguants (e.g. warfarin) etc are tried. Carotid endarterecomy needed for some patients if there is moderate to severe carotid artery atherothrombosis.

Risk factors for stroke like high blood pressure, diabetes mellitus, high cholesterol etc are treated.

The symptomatic dementia medications like cholinesterase inhibitors (e.g. donepezil), NMDA antagonist like memantine are less useful and so less often used for VD as compared to Alzheimer’s dementia.

A neurologist is frequently involved in the care of patients with Vascular Dementia.



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