Vascular Dementia - Diagnosis

Diagnostic criteria for vascular dementia

A. Development of multiple cognitive deficits that manifest simultaneously

1. Memory impairment (impaired ability to remember new or recall previously learned information)
2. One (or more) of the following cognitive disorders:
   • aphasia (speech disorder)
   • apraxia (impaired ability to perform actions despite the preservation of basic motor functions)
   • agnosia (impaired ability to recognize or identify objects despite the preservation of basic sensory functions)
   • disorder of regulatory (executive) functions (planning, organization, step-by-step implementation, abstraction)

B. Each of the cognitive impairments specified in criteria A1 and A2 causes significant impairment in functioning in the social or occupational spheres and represents a significant decline in relation to the previous level of functioning

B. Focal neurologic symptoms (eg, brisk deep tendon reflexes, extensor plantar signs, pseudobulbar palsy, gait disturbances, limb weakness) or paraclinical signs of cerebrovascular disease (eg, multiple infarcts involving the cortex and underlying white matter) that can be etiologically related to cognitive impairment

D. Cognitive impairment does not occur exclusively during delirium.

Diagnostic criteria for vascular dementia ADDTC

I. Possible vascular dementia

A. - Dementia

• Two (or more) strokes or a single stroke with a clear temporal relationship to the onset of dementia
• At least one extracerebellar infarction documented by neuroimaging

B. The diagnosis of possible vascular dementia is also confirmed by:

• Indications of multiple infarctions in areas where damage may lead to dementia
• History of multiple TIAs
• Presence of vascular risk factors (arterial hypertension, heart disease, diabetes mellitus)
• High score on the Khachinsky scale.

C. Clinical features that are considered to be manifestations of vascular dementia, but require further study:

• Relatively early onset of gait disturbances and urinary incontinence
• Changes in the periventricular and deep white matter in the T2 mode are more pronounced than the corresponding age-related changes.
• Focal changes according to electrophysiological studies (EEG, EP) or neuroimaging methods.

D. Clinical signs that do not have strict diagnostic significance (neither “for” nor “against” the diagnosis of possible vascular dementia:

• Presence of periods of slow progression of symptoms.
• Illusions, psychoses, hallucinations
• Epileptic seizures

E. Clinical features that make the diagnosis of possible vascular dementia questionable:

• Transortical sensory aphasia in the absence of corresponding focal lesions on neuroimaging
• Absence of focal neurological symptoms (other than cognitive impairment)

II. Probable vascular dementia.

• Dementia plus one (or more) of the following:
  • History or clinical evidence of a single stroke (but not multiple strokes) without a clear temporal relationship to the onset of dementia.
  • Or Binswanger's syndrome (without multiple strokes), which includes all of the following manifestations: The appearance of urinary incontinence in the early stages of the disease (which is not associated with urological pathology) or gait disorders (parkinsonian, apraxic, "senile") that cannot be explained by peripheral causes.
  • Vascular risk factors
  • Extensive white matter changes on neuroimaging

III. Definite vascular dementia

A definite diagnosis of vascular dementia requires histopathological examination of the brain, as well as:

• A - the presence of clinical dementia syndrome
• B - morphological confirmation of multiple infarctions, including outside the cerebellum.

With the progression of vascular (and degenerative) dementia, signs of brain atrophy appear in the form of expansion of the lateral ventricles and convexital subarachnoid space, which reflects the loss of a significant portion of the brain volume. The occurrence of any dementia is determined either by the critical volume of lost brain matter (from 50 to 100 ml), or by the localization of the lesion, strategically important for the development of dementia (associative areas of the cortex, anterior parts of the brain, temporal, limbic, thalamic structures, corpus callosum).

The clinical picture of dementia itself in Alzheimer's disease and vascular encephalopathy is almost identical. But since degenerative and vascular dementias constitute the absolute majority of all possible causes of dementia, differential diagnosis between them is of primary importance. In this regard, the Khachinsky scale has become widely popular, which is based on clear clinical signs, is easy to use and has a high diagnostic resolution: in about 70% of cases, the diagnosis based on the Khachinsky scale coincides with CT or MRI data. Sudden onset of dementia, its fluctuating course, the presence of arterial hypertension, a history of stroke and focal neurological symptoms indicate the vascular nature of dementia, which is confirmed by high scores (7 points or more) on the Khachinsky scale. The absence of the above-mentioned manifestations gives a total of 4 points or less on this scale, which indicates primary degenerative dementia, mainly Alzheimer's disease or senile dementia of the Alzheimer's type.

It is important, however, to consider that both Alygheimer's disease and vascular dementia are age-related diseases and therefore often coexist in the same patient. Such mixed degenerative-vascular dementia is difficult to diagnose and is quite common (according to some data - about 10% of dementia). Therefore, the share of other etiological forms of dementia ("other" dementias), associated with intoxications, metabolic disorders, tumors, infections, craniocerebral trauma, hydrocephalus, etc., accounts for only about 10% of all cases of dementia. Dementia in HIV infection (the so-called "AIDS-dementia complex") is becoming increasingly relevant.

An important achievement of neurology in recent years is the development of the concept of so-called reversible and irreversible forms of dementia. Reversible dementias occur in many diseases, such as intoxications, infections, nutritional disorders (nutritional dementias), metabolic and vascular disorders, volumetric intracranial processes, and normotensive hydrocephalus.

It is useful to remember that intoxications can be the result of the use of drugs, administered intentionally or accidentally. It is necessary to register each of the drugs taken, including the seemingly most trivial ones. The list of drugs that can cause dementia is gradually expanding. These include opiate analgesics, corticosteroids, anticholinergics, antihypertensives, digitalis and its derivatives. Finally, combinations of drugs can have such a destructive effect in the end. In addition, virtually all chemicals used as drugs from heroin to glue can cause dementia. Other chemicals can also have the same final effect: carbon monoxide, lead, mercury, manganese.

Any infections capable of affecting the brain can lead to reversible dementia: bacterial, fungal or viral encephalitis. Among nutritional disorders, as a possible cause of reversible dementia, such conditions as vitamin B1 deficiency; persistent vomiting during pregnancy; pernicious anemia; folate deficiency; pellagra have been described.

Metabolic disorders as a cause of reversible dementia include diseases of the thyroid and parathyroid glands, adrenal glands and pituitary gland. Lung diseases can cause reversible dementia due to hypoxia or hypercapnia. The prognosis and course of encephalopathy and dementia in renal or hepatic failure depend on the underlying cause.

Shunt surgery for normal pressure hydrocephalus often has a dramatic effect, causing reversal of dementia.

Irreversible dementias are characteristic of such progressive degenerative diseases of the nervous system as Alzheimer's disease, Pick's disease, Parkinson's disease, Huntington's chorea, multiple system atrophy, some forms of amyotrophic lateral sclerosis, progressive supranuclear palsy, corticobasal degeneration, diffuse Lewy body disease, Creutzfeldt-Jakob disease. Almost all of the above-mentioned diseases are recognized by the characteristic neurological manifestations accompanying dementia. Among the latter, Parkinsonism is the most common.

The ischemic scale of Khachinsky is traditionally used for the diagnosis of vascular dementia. However, if this scale is used in isolation from other data, then, as clinical and pathomorphological comparisons show, its accuracy, sensitivity and specificity are quite low. The Khachinsky scale differentiates well patients with clinically manifested infarctions of medium and large sizes and patients with other very heterogeneous changes: lacunar infarctions, subclinical infarctions, chronic ischemic damage of white matter, Binswanger's disease, a combination of vascular dementia and Alzheimer's disease - that is, variants of vascular dementia that differ from multi-infarction dementia.

Vascular dementia is a heterogeneous group of conditions that have in common the presence of dementia, some degree of cerebral blood flow disorder, and a cause-and-effect relationship between them. The diagnosis is confirmed by a carefully collected anamnesis, examination data, and neuropsychological testing.

Among the frequently used criteria are the vascular dementia criteria developed by the international working group NINDS-AIREN (National Institute of Neurological Disorders and Stroke - Association Internationale pour la Recherche et l'Enseignement en Neurosciences). According to the NINDS-AIREN criteria, the diagnosis of vascular dementia is confirmed by the acute development of cognitive impairment, the presence of gait disorders or frequent falls, frequent urination or urinary incontinence, focal neurological symptoms (hemiparesis, weakness of the facial muscles of the lower half of the face, sensory impairment, visual field defects, pseudobulbar syndrome, extrapyramidal manifestations), depression, affective lability and other mental changes. According to the NINDS-AIREN criteria, dementia is defined as a memory impairment combined with a deficit in two other cognitive areas (orientation, attention, speech, visual-spatial and executive functions, motor control and praxis). Cognitive impairment should interfere with daily activities, regardless of the impact of the stroke-related physical impairment. Cases with impaired consciousness, delirium, sensorimotor impairment, severe aphasia, and psychosis should be excluded if they prevent a full neuropsychological assessment. According to the NINDS-AIREN criteria, focal signs and symptoms consistent with stroke should be detected during neurological examination. The criteria identify several types of ischemic brain damage that can lead to vascular dementia, including: extensive infarcts associated with damage to large cerebral arteries, single infarcts in strategic areas (with cognitive impairment corresponding to their location), lacunar infarcts in deep white and gray matter, extensive ischemic damage to white matter, or a combination of these changes. Dementia must manifest within 3 months after a documented stroke or be characterized by episodes of sudden deterioration in cognitive function or a fluctuating course with a stepwise progression of cognitive impairment.

Differential diagnosis of vascular dementia and Alzheimer's disease is important because the treatment approaches for these conditions differ; in the case of vascular dementia, effective primary and secondary preventive therapy is possible. According to the NINCDS-ADRDA criteria for Alzheimer's disease, the diagnosis of dementia requires the recognition of cognitive impairment in only two areas, including those outside the memory area.