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DEMENTIA : A CLINICAL APPROACH
HN PAREKH
Senior Registrar, Department of Neurology, Bombay Hospital Institute of Medical Sciences, 12, New Marine Lines, Mumbai 400 020. India.
This article is focusing on the clinical approach to the dementia. It includes basic classification and imcstig,ations for dementia. It gives brief summary of clinical presentation and management of common dcruenlias likr Alzheimer's Disease and Vascular dementia. It also gives some details of Crcutzfeldt-Jakob (I'rion) disease.DEFINITION
The dementia is a broad term. It includes a group of diseases. By definition[1] The cognitive impairment should be acquired[2].The impairment should involve multiple domains of cognitive function rather than a discrete neuropsy-chological deficit[3].The patient should not have impairment of arousal in contrast to delirium, in which this is a prominent feature.
Bedside classification of Dementia.[7]
1.Diseases in which dementia is associated with signs of other medical disease.
a.Alzheimer's disease.
b. Pick 's disease.
c.Frontal lobe dementia.
2. Diseases in which dementia is associated with signs of other medical diseases.
a. Acquired immune deficiency syndrome.
b. Endocrine disorder like hypothyroidism,cushing's disease.
c. Heavy metal or toxins like arsenic, bismuth,gold, manganese and mercury.
d. Paraneoplastic syndromes.
3. Diseases in which dementia is associated with other neurological signs but not with other obvious medical disease.
a.With other neurologocal signs.Choreo-athetosis : Huntington's disease.
Myclonic dementia : Creutzfeldt-jakob disease.
Extrapyramidal : Parkinson's disease.b.Often associated with other neurological signs.
1.Multiple thrombotic infarctions.
2.Brain tumours.[7]
Alzheimers Disease . 50% Multiple Infarct Dementia. 10% Miscellaneous Diseases(Hyperthyroidism,Neurosyphilis,Creuzfeldt-jakob Disease etc). 7-10% Alcoholic Dementia*. 5-10% Pseudodementias. 7% Normal pressure hydrocephalus. 6% Intracranial tumours. 5% Chronic drug intoxications 3% huntington's chorea 3% Undiagnosed types. 3% * Frequency varies with incidence of alcoholism in the population studied.
The clinical examination include detail higher functions including lobe functions, Mini-mental status examination[2] and ischaemtic score[1] are used.
The main aim to investigate the patient is to rule out any treatable or reversible cause of dementia.The treatable causes are chronic central nervous system infection like tuberculosis, syphilis, cryptococcus, hypothyroidism, hypercalcemia,intoxication, third ventricular or pineal tumours, callosal and vitamin B 12 deficiency states.[2]
Routine tests Optional focused tests Occasionally helpful Complete blood count HIV EEG Electrolytes CSF Parathyroid functions VDRL Liver function Urine heavy metals. CT/MRI Renal function Thyroid function Vit. B12. Urine toxic screen CT/MRI brain : To rule out space occupying lesions, hydrocephalus and sub-dural haematomas. EEG : To look for characteristic periodic complexes in Creutzfeldt-Jakob disease. CSF study : To rule out neurosyphilis, tuberculous meningitis and other inflammatory causes. Brain biopsy .is necessary to exclude granulomatous angiitis or (in rare case). Creutzfeldt-Jakob disease. [3]
Alzheimer's Disease. [4]
It generally presents in three stages.
Stage I : (Duration of disease 1 to 3 years). Memory-new learning defects, remote recall impaired. Visuo-spatial skills topographic disorientation, poor concentration.
Stage 2 : (Duration of disease 2 to 10 years).Language - Fluent aphasia. They also have acalcu- lia and ideomotor apraxias. Personality changes Indifference and apathy.
Stage 3 : (Duration of disease 8 to 12 years). Intellectual functions severely disoriented. Sphincter control : Urinary and faecal incontinence.
Management[5] : Rivastigmine improves behaviour and reduces the tranquilizer usages. It is a cholinesterase inhibitor for the treatment of Alzheimer's disease. It is a new generation G1 isoform specific acetylcholine inhibitor.It slows the pro gression of Alzeimer's disease. Tacrine[10] (Tetra-hydro-acridinamide) acetyl-choline esterase inhibitor produces statistically significant improvement on cognitive function tests.
Vascular Dementia
It is mainly of two types:
1. Multi-Infarct Dementia : This is a most com- mon type of dementia in hospital base study in India. The clinical course is progressive with a variable survival of 5 to 7 years[12] . The clinical diagnosis of multi-infarct dementia in a demented patient is based on presence of signs and symptoms of cerebrovascular disease.
It depends on ischaernic score.[1]
If the score is < 4 suggestive of primary degenerative dementia.
It is score is > 7 suggestive of multi-infarct dementia. disease.
The main goal of management is secondary prevention of athero-thrombotic strokes by treatment of hypertension, anticoagulants in cardiac embolic disease and aspirin.
2. Binswanger's Disease (Subcortical Arterio- sclerotic Encephalopathy) : The diagnosis of - Binswanger's Disease should only be made in pa- tients with leukoaraiosis who are demented and have no other obvious cause for dementia. Three pathological proven cases are reported from India.[22]
Creutzfeldt-Jakob Disease [6],[1]
It is a prototype of human prion disease. The classical clinical tetrad of Creutzfeldt-Jakob diseases is a sub-acute progressive dementia,myoclonus, typical periodic complexes on electro-encephalography and normal cerebro-spinal fluid. In classic case, illness presents with increasing impairment of memory, spatial disorientation and behaviour disturbances that include depression and emotion lability. Typical EEG shows one to two cycles/sec typical sharp waves which are generally superimposed on a depressed background.
REFERENCES
1. Walter G Bradley, et al. Editor : Neurology in clinical practice. Second edition, Butterworth-Heinemann. 2 : 1583.
2. Antony S Fauci, et al. Editor : Harrison's principles of Internal Medicine. 14th edition. McGraw Hill. 1 : 148.
3. Perkin GD, et al. Editor : Diagnostic tests in Neurology. Chapman and Hall-London. 79.
4. Jaffrey L Cummings, et al. Editor : Dementia - A clinical approach Butterworths. 1983;38.
5. Keith R. Edwards, American Psychiatric association.Annual meeting.Washington. Effects of Rivastigmine in the treatment of Alzeimer's disease. 1999.
6. Poser S, et al. How to improve the clinical diagnosis of Creutzfeldt-Jakob disease. Brain Dec. 1999; 122 (12) 2345-51.
7. Raymond D Adams, et al. Editor : Principles of Neurology, 6th edition. Mcgraw Hill. 1997; 425.
8. William J Weiner, et al. Editor : Neurology for the Non Neurologist. 2nd edition. JB Lippincott company. Philadelphia. 1989; 205.
9. Hachinski VC, et al. Cerebral blood flow in dementia. Arch Neurology 1975; 32 : 632-37.
10. Gifford DR, et al. Tacrine use in nursing homes : Implications for prescribing new cholinesterase inhibitor. Neurology 1999; 52 (2) : 238-43.
11. Mckhann G, et al. Clinical diagnosis of Alzeimer's disease, report of the NINCDS-ADRDA work group under the auspices of Department of health and Human services Task Force on Alzheimer's Disease. Neurology 1984; 34 939-44.
12. Chopra JS, et al. Editor : Neurology in Tropics. BI Churchill Livingstone Pvt. Ltd, New Delhi, India. 1999; 594- 609.
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