This problem has attracted increasing attention in the past decades as a cause of otherwise obscure confusional states. It is discussed in Chaps. 15 and 16, but here we only comment that the process may be portrayed clinically only because of small myoclonic twitches or eyelid fluttering. The only certain way to arrive at, or exclude the diagnosis is with EEG monitoring for more than the usual 30 min recording if possible. One suspects nonconvulsive seizures particularly in known epileptics, septic patients, and in certain medical diseases such as TTP.
A small proportion of psychoses of schizophrenic or bipolar type first become manifest during an acute medical illness or following an operation or parturition and need to be distinguished from an acute confusional state. The manic state in particular can produce an overtly confusional state but the patient sleeps little, is prone to excessive writing and, unlike the patient with a global confusional state, flits from one topic to the next in a vaguely pertinent way, makes bizarre or unusual misidentifications of people, and is reluctant to let the examiner out of the room or the opposite, is rude and requests that the physician or an entourage leave immediately. Rarely, a catatonic state will make its first appearance in these circumstances. A causal relationship between the psychosis and medical illness is sought but cannot be established. The psychosis may have preceded the medical illness but was not recognized. The diagnostic study of the psychiatric illness must then proceed along the lines suggested in Chap. 48. Close observation will usually disclose a clear sensorium and relatively intact memory, features that permit differentiation from an acute confusional or delirious state or dementia.
The syndromes themselves and their main clinical causes are the only satisfactory basis for classification until such time as their actual causes and pathophysiology are discovered (see Table 19-1).
The first step in diagnosis is to recognize that the patient is confused. This is obvious in most cases but, as pointed out earlier, the mildest forms, particularly when some other alteration of personality is prominent, may be overlooked. Sometimes, the patient’s attention can be best engaged by speaking softly or whispering rather than shouting or using a conversational amplitude of voice. A subtle disorder of orientation may be betrayed by an incorrect response regarding dates (off by more than one day of the month or day of the week), or in misnaming the hospital. The ability to retain a span of digits forward (normally 7) and backward (normally 5), spelling a word such as “world” or “earth” forward and then backward, reciting the months of the year in their reverse order, and serial subtraction of 3s from 30 or 7s from 100 are useful bedside tests of the patient’s capacity for attentiveness and sustained mental activity, though some of these presuppose that the patient is literate or has a knowledge of mathematics. Another is the efficiency in performing dual tasks such as tapping alternately with each hand while reading aloud. Memory of recent events is one of the most delicate tests of adequate mental function and is readily accomplished by having the patient relate the details of entry to the hospital; examinations undertaken in the previous days; naming the president, vice president; and summarizing major current events, as outlined in Chap. 21. Errors in performance should not be minimized or attributed to age, for they may presage serious upcoming problems during the hospitalization.
Once it is established that the patient is confused, the differential diagnosis must be made between an acute confusional state associated with psychomotor underactivity, delirium, a beclouded dementia, and a confusional state that complicates focal cerebral disease. This is done by taking into account the degree of the patient’s alertness, wakefulness, psychomotor and hallucinatory activity, and disturbances of memory and impulse, as well as the presence or absence of asterixis or myoclonus or signs of overactivity of the autonomic nervous system and of generalized or focal cerebral disease. In the neurologic examination, particular attention should be given to the presence or absence of focal neurologic signs and to asterixis, myoclonus, and seizures.