In the chronically demented patient, there are usually a number of “frontal release” signs, such as picking at the bedsheets and clothes, grasping, groping, sucking, and paratonic rigidity of the limbs. However, some demented patients are as bewildered as those with confusional psychosis, and the two conditions are distinguishable only by differences in their mode of onset and chronicity. This suggests that the affected parts of the nervous system may be the same in both conditions.
At times, a left hemispheral lesion causing a mild Wernicke’s aphasia resembles a confusional state in that the stream of speech and thought are incoherent. The prominence of paraphasias and neologisms in spontaneous speech, difficulties in auditory comprehension, and normal nonverbal behavior mark the disorder as aphasic in nature. However, a problem with naming may be more common in nonaphasic global confusional states, as alluded to earlier in the chapter and emphasized in a brief piece by Geschwind. Spontaneous speech in these circumstances is unaffected.
The distinction between an acute confusional state and dementia is difficult at times, particularly if the mode of onset and the course of the mental decline are not known. The patient with an acute confusional state is said to have a “clouded sensorium” (an ambiguous term referring to a symptom complex of inattention, disorientation, perhaps drowsiness, and an inclination to inaccurate perceptions and sometimes to hallucinations and delusions), whereas the patient with dementia usually has a clear sensorium.
As indicated earlier, schizophrenia and bipolar psychosis, particularly with mania can usually be separated from the confusional states by the presence of a clear sensorium and relatively intact memory function.
A thorough medical and neurologic examination, CT or MRI, and—in cases with fever or with no other apparent cause—blood count, chest x-ray, and lumbar puncture should be performed. The medical, neurologic, and laboratory findings (including measurements of Na, Ca, CO2, blood urea nitrogen [BUN], NH3, calcium, glucose, Pao2, Pco2, “toxic screen”) determine the underlying disease and its treatment, and they also give information concerning prognosis. An approach to the laboratory tests that are useful in revealing the common conditions that give rise to the confusional state, when the cause is not self-evident from the history and physical examination, is given in
Table 19-2; but as always, the choice of tests is governed by the clinical circumstances.
These details are of the utmost importance. It has been estimated that 20 to 25 percent of medically ill hospital inpatients will experience some degree of confusion; moreover, elderly patients who are delirious have a significant level of mortality, variously estimated at 22 to 76 percent according to Weber and colleagues. Optimal care begins with the identification of individuals at risk for delirium, including those who have an underlying dementia, preexisting medical illnesses, or a history of alcoholism or serious depression. Furthermore, delirium is more common in males and, not surprisingly, is more likely when sensory function is already impaired (loss of vision and hearing) (Burns et al; Weber et al).