Mohammed T. Abou-Saleh

THE PHYSICIAN’S ROLE 129The reliability of subtle focal signs, such as asymmetry intendon reflexes, should also be regarded with scepticism, given theextent of inter-observer variation in the assessment of the patientwith obvious hemiplegic stroke 30,31 . The most reliable signs arethose that can be easily reproduced and particularly those that arereflected in the patient’s behaviour, such as dysphasia or unilateralneglect. This raises the more general point that the diagnosticassessment does not end with the formal physical examination butmust include careful observation of the patient over the next fewdays. A host of signs that might otherwise have been missed, fromepisodes of fever, syncope, or fits to a craving for alcohol oropiates, may be revealed. Assessment of vision and hearing areparticularly important, as the presence of sensory deficits mayincrease the risk of developing delirium, and a recent studyshowed that attention to and correction of sensory deficits mayreduce the severity and duration of delirium 32 . Impairments ofvision or hearing may also only become clear after a period ofobservation.The choice of laboratory tests tends to be determined more byinstitutional tradition and by habits and attitudes of the clinicianthan by scientific evidence. The value of any tests depends largelyon the prior probability of finding treatable disease. Thus, theurine should always be tested but a computed tomography (CT)scan comes low on the list of priorities. Whilst CT head scans mayfrequently show minor abnormalities, such as cerebral atrophy, acause for delirium is rarely found unless there are other features inthe history and examination to point to an intracerebral cause,such as new onset of focal neurological signs 33 . Similarly, whilstelectroencephalography (EEG) is frequently abnormal in delirium,showing diffuse slow-wave activity 34–36 , it is rarely useful as adiagnostic tool unless there is clinical suspicion of epilepsy.Indeed, the very non-specific nature of the EEG changes seen indelirium raises interesting (although under-researched) questionsabout the pathogenesis of the disorder. Other invasive tests, suchas lumbar puncture (LP), have been used in research andnumerous abnormalities of neurotransmitters have been identifiedin delirium, but as a diagnostic test in clinical circumstances, LP isagain only useful in those with features of meningism 37,38 .The range of diagnostic possibilities is almost always wide andthere may be few clinical clues. This has led to the erroneous andderogatory use of the expression ‘‘geriatric screening’’ to describethe laboratory investigation of elderly patients presenting withnon-specific symptoms or functional problems. Screening testsalways have a low yield, since the vast majority of subjects havenothing wrong with them, whereas tests done in order to trackdown the cause of delirium have a high probability of showing anabnormality, and serum calcium, urea and electrolytes, full bloodcount and glucose should virtually always be done.DEMENTIADelirium and dementia commonly occur together; indeed, the preexistenceof dementia is a major risk factor for the development ofdelirium 39 and up to 70% of patients presenting with an episode ofdelirium will have some degree of chronic brain failure as well 40 .There is a clear relationship between the degree of vulnerability ofa patient and the size of the insult required to precipitatedelirium 39 . The principles of assessing a patient with ‘‘decompensateddementia’’ are similar to those outlined above, withsome slight changes in emphasis. A psychological upset ordisruption of the normal protective social environment may beenough to precipitate a crisis in a mentally frail person. Whetheror not such an episode of decompensation actually constitutesdelirium is debatable 41 but it can only be a short step away, asphysical complication such as exhaustion, dehydration orhypothermia may quickly supervene. Whether or not the initialevent was some kind of social or psychological trauma, it shouldnot prevent a careful search for physical disease, for in such frailindividuals, relatively minor remediable disorders can havedramatic functional consequences.The distinction between decompensated dementia and deliriumis also of practical importance because of the special problemsinvolved in admitting the former group to hospital. A balancemust be struck between the patient’s need for a stable, familiarand reassuring environment and the availability of facilities forinvestigation and treatment. The former may be the overridingconsideration in the case of decompensated dementia, while in thepreviously well person with delirium the latter is the mainconcern. In some (but not all) cases, day hospital facilities mayprovide a useful compromise.Physical illness in a person with dementia may also present adecline in physical rather than mental function, with developmentof non-specific symptoms or signs such as unsteadiness, falls,immobility or incontinence. Again, the sudden appearance of suchproblems should not be assumed to be due to the progression ofdementia or put down to ‘‘another stroke’’ but must beinvestigated, since timely intervention may prevent irreversibledeterioration or even unnecessary institutionalization.Recent research has highlighted the associations betweenphysical illness and dementia, particularly vascular pathologyand risk factors for such conditions. Dementia is thus significantlyassociated with the presence of atrial fibrillation 42 , ischaemic heartdisease 43,44 , cerebrovascular disease 43,44 , hypertension 44,45 anddiabetes 46,47 . Moreover, there is suggestive evidence that poorcontrol in some of these conditions may result in acceleratedcognitive decline 45 . Therefore, whilst evidence from large-scaleprospective studies is not yet available, it would seem sensible forthe physician to actively treat such coexisting physical illness inthe presence of dementia. Whilst high blood pressure appears tobe a risk factor for the development of dementia, the prevalence oflow blood pressure and orthostatic hypotension (OH) is also morecommon in dementia and may have an aetiological role 48,49 , andthe physician should be alert to the presence of OH and considerappropriate intervention.Involving physicians in the assessment of patients withdementia is important to help rule out a treatable cause. Clearlyno-one can afford to miss ‘‘reversible dementia’’ but unfortunatelywe have no idea of its true prevalence. Estimates of the frequencyof reversibility in series of hospital patients has been reported tobe as high as 40% 50 , but older studies are hopelessly biased byconcentrating on younger ‘‘pre-senile’’ patients from secondary ortertiary referral centres. In the few community-based studies thathave been reported, the frequency of ‘‘reversible’’ cases was lessthan 10% 51 . More recent studies have estimated the prevalence ofpotentially reversible dementia in the region of 7.2% 52 to 23% 53 ,although only at best 3% were actually reversed 52,53 . An analogymay be drawn with the frequency of space-occupying lesions inpatients presenting with ‘‘acute stroke’’, which was estimated at15% in a study based at a neurological centre 54 , compared to1.5% in a series of patients admitted to an acute geriatric unit 55and a similar figure in a community stroke survey 56 . There is anurgent need for equivalent community-based studies of dementiain which all cases are thoroughly investigated. Until then, practicemust be based on questionable and possibly ageist assumptionsabout the likelihood of finding treatable disease in particulargroups of patients. Thus, few clinicians would disagree thatyounger patients should be fully investigated, as well as those ofany age whose symptoms are of recent onset or rapidlyprogressing.As emphasized above, a careful drug history is of overridingimportance, since it is bad enough to miss a treatable disorder butunforgivable to be responsible for causing it or making it worse.As in the case of delirium, all drugs should come under suspicion,