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Abstract
Assessment of dementia should be done via a comprehensive evaluation. This approach will aim to diagnose dementia early, assess for complications of dementia and establish the cause of the dementia (Brandt and Munro, 2002).
Dementia is not a single disease, but a heterogeneous complex of disorders with the common finding of impairment in multiple cognitive domains. Determining the etiology of the dementia can be difficult. Fortunately, clues leading to a correct diagnosis can be obtained in the physical and mental status examination (Brandt and Munro, 2002).
Cortical and subcortical dementias can be distinguished satisfactorily on pathology is primarily cortical or subcortical, but it is interesting that they are characterized by different clinical syndromes (Flaherty and Rost , 2007).
In cortical dementias, cognitive deficits were reported to include impairments in language and memory, agnosia, and apraxia, whereas subcortical dementias were considered to be associated with a relatively greater general slowness of thought processes and impaired manipulation of acquired knowledge, such as deficits in abstracting abilities, retrieval of information, and visuospatial functions (Starkstein and Merello, 2004).
The cardinal clinical features of subcortical dementia are apathy, inattention and psychomotor slowing. Patients
with subcortical dementia typically appear apathetic. They have a blunted affect, poor personal hygiene and sloppy appearance. The patients are often aware of their cognitive deficit but appear unconcerned. In contrast, patients in the early stages of AD typically have normal affect, grooming and dress. Patients with AD who are aware of their deficit are typically quite concerned (Flaherty and Rost, 2007).
The disorders causing subcortical dementia include disorders of brainstem nuclei (Parkinson’s disease and progressive supranuclear palsy), disorders of the basal ganglia (Huntington’s disease, Wilson’s disease, basal ganglia calcification and neuroacanthocytosis), disorders of thalamic nuclei (thalamic degeneration), disorders of cerebral white matter (ischemic vascular disease, multiple sclerosis, normal pressure hydrocephalus and HIV-related dementia) and disorders of the cerebellum (spinocerebellar ataxias) (Brandt and Munro, 2002).
It is useful when assessing a patient with cognitive impairment in the clinic to consider the following straightforward questions:
- Is the patient demented?
- If so, does the loss of function conform to a characteristic
pattern?
- Does the pattern of dementia conform to a particular
pattern?
- What is the likely disease process responsible for the
dementia? (Cooper and Greene, 2005).
The aim of determining the etiology of dementia is to rule out potentially reversible causes of dementia and
selecting appropriate treatment strategies for the irreversible dementias. This is done via clinical history and
physical examination, followed by laboratory investigations and neuroimaging (Sian et al., 2007).
Screening and early detection included:
1)Clinical presentation (Medical history and Physical
examination):
It is useful to interview the patient and the accompanying person separately. Interviewing the patient separately enables the cooperation and language skills to be assessed without being masked by interruptions or assistance from a third party. Inquiries should also be made regarding:
- Symptoms at onset
- The tempo of evolution of symptoms
- The impact on work and family life
- Issues of safety
- About risk factors for dementias
- Past medical history
- Review medications
- Family history
Examine the neurological system in any patient with possible cognitive impairment and other systems is also useful in looking for evidence of multisystem disease (Calabrese, 2008).
2) Neuropsychological testing :
Neuropsychological testing is usually administered by clinical psychologists. It is useful in detecting subtle cognitive difficulties which are not picked up by the brief
screening instruments. They should be performed on subjects:
- who have memory complaints but do not yet satisfy
criteria for dementia.
- Depressed subjects who present with memory complaints
to help in determining whether the memory complaints
are due solely to the depression or whether they have
concomitant dementia.
- Subjects in whom decision-making capacity is being
assessed.
- They are also useful in etiologic differentiation of
dementia (Calabrese, 2008).
Assessing complications of dementia:
Behavioral problems
Behavioral problems occur frequently in dementia patients; they affect 10% to 75% of all patients at some stage of their dementia. They can present severe problems to all who interact with them (Sian et al., 2007).
Functional difficulties
Functional difficulties can be assessed at three levels: community functioning, home functioning and self-care (Sian et al., 2007).
Social problems
As a result of dementia, there is also loss of social role of the patient as a parent, spouse, friend and member
of the larger society and these often result in caregivers’ coping difficulties (Sian et al., 2007).
3) Laboratory assessment:
Laboratory assessment help us to diagnose MS, Wilson’s disease and HIV antibody and Western blot testing. Some memory disorder specialists perform cerebrospinal fluid examination in every patient with AIDS, suspected cases with Multiple Sclerosis, Huntington disease dementia and atypical dementia (Barrett, 2008).
4) Electrophysiologic studies:
Electroencephalography evaluation.
EEG may be helpful in the evaluation of dementia;
-First, it may confirm that an abnormality of cerebral
function exists.
-Second, it may indicate that a focal process is present,
rather than a diffuse process.
-Third, it may find that a previously unidentified seizure
disorder is present (Fenton, 2002).
Event-Related Potentials in dementia.
Event-related or evoked potentials (ERPs or EPs) consist of transient voltage changes that occur in response to a sensory stimulus. These take the form of a series of negative and positive EEG waves, which last a number of milliseconds (ms) and measure a few micro volts (mV) in amplitude. Some work suggests that auditory ERP patterns may be useful in distinguishing cortical from subcortical
dementia (Fenton, 2002). Evoked potential testing in Multiple sclerosis(MS) is especially helpful in detecting
clinically silent lesions and documenting an organic basis for vague complaints (Dangond,2009).
5) Neuroimaging techniques:
The rationale for the use of magnetic resonance imaging/computed tomography (MRI/CT) scans in the work-up of dementia includes the following:
(a) Neuroimaging contributes to increased diagnostic
accuracy and may detect occult lesions not evident on
clinical examination.
(b) CT or MRI may identify potentially treatable causes of
dementia missed by clinical evaluation.
(c) Imaging protects against possible malpractice suits
(Burns and Pearlson, 2002).
Computed Tomography Scan (CT scan)
In addition to measures of global cerebral atrophy and ventricular enlargement, CT scans can provide other information of clinical interest. Regional cerebral atrophy has been shown to be related to certain behavioral disturbances. Demented patients with affective symptomatology have less severe CT scan changes, including relative preservation of the interhemispheric fissure (Burns and Pearlson, 2002).
Magnetic Resonance Imaging (MRI)
The application of MRI in geriatric psychiatry has been extensive. There are two broad areas to which MR
techniques have been applied. One is to evaluate the presence of gross pathology and the other is to evaluate
morphemetric changes in a variety of disorders in the elderly (Krishnan, 2002).
The modern MRI techniques such as FLAIR, fast spino-echo, short inversion imaging recovery(STIR), magnetization transfer ratio(MTR), MR spectroscopy (MRS) and suspect ability weighted imaging(SWI) have increased the ability to detect and characterize early lesions. They increase the sensitivity of prediction for diagnostic and prognostic purposes (Dangond, 2009).
Functional Magnetic Resonance Imaging (fMRI )
It allows for the measurement of brain activity during cognitive tasks without any radiation exposure to the patient(Krishnan, 2002).
Single Photon Emission Computerized Tomography
The introduction of single-photon emission computed tomography (SPECT) has markedly enhanced the study of brain function (Abou-Saleh and Geaney, 2002).
Positron emission tomography (PET)
It provides quantitative images of the function of the brain in life. It generates an image of the distribution of a radioactively-labeled tracer substance that is distributed in the brain according to its pattern of physiological activity(Grady et al., 2002).
6) Other Tests:
Genetic studies
The use of genetic testing can provide unequivocal confirmation of Wilson`s disease(Carter, 2007) and genetic testing can be done to find out whether or not a person has inherited the repeat expansion or gene mutation for Spinocerebellar ataxias (SCA) types 1, 2, 3, 6, 7, 8, 10, 12, 14, and 17 (Smith et al.,2004). In patients with CADASIL genetic testing is commercially available to detect mutations in notch 3 (Behrous and Benbadis, 2008).
Sleep studies
Sleep patterns are often abnormal in individuals with PSP. Polysomnograms show diminished total sleep time, increased awakenings, progressive loss of rapid eye movement (REM) sleep, and decreased REM–to–non-REM (NREM) quotient (Eggenberger and Vanek, 2009).
Liver biopsy
Is the criterion standard for the diagnosis of Wilson`s disease. A hepatic copper content of more than 250 mcg dry weight of the liver confirms the diagnosis (Shah and Piper, 2009).
Skin biopsy
In CADASIL skin biopsy typically shows ultrastructural alterations of skin vessels similar to those of brain arteries (Behrouz and Benbadis, 2008).
Treatment of Subcortical Dementia
1)Disease prevention
A) Disease elimination
Disease elimination suits diseases with single known causes.
B) Disease postponement
Disease postponement may be an adequate prevention measure for the foreseeable future. While postponement does not prevent disease, the period of time involved may still have a dramatic effect. Delaying the onset of dementia could allow a person to enjoy a longer period of healthy life.
2)Management behavioral and psychological symptoms of dementia
More than 50% of people with dementia experience behavioral and psychological symptoms of dementia (BPSD). BPSD are distressing for patients and their caregivers, and are often the reason for placement into residential care (Fairbairn, 2007).
A) Non-pharmacologic therapy
Non-pharmacologic interventions should be the first line of treatment. There increasing number of non-pharmacological therapies are now available for people with dementia. It is therefore important for a clinician to have some knowledge of a number of these approaches,
enabling a combination of treatments tailored to the individual requirements of the patient (Kozman et al., 2006).
B) Pharmacologic management
Although there are multiple classes of drugs in use for neuropsychological symptoms,including antipsychotics, anticonvulsants,antidepressants,anxiolytics, cholinesterase inhibitors and NMDA modulators, there is no consensus nor clear standard of care, and treatment is often based on local pharmacotherapy customs (Sink et al., 2005).
3) Specific treatment
According to diseases causing Subcortical Dementia.
4) Provide Education and Support to Patients and Families
A)Educate the patient and family about the illness and
available treatments
B) Refer the family to appropriate sources of care and
support.
C) Watch for signs of caregiver distress.
D) Support families during taking decisions about
institutionalization (Rabins et al., 2007).