Descriptive Psychopathology: The Signs and Symptoms of ...

104 Section 2: The neuropsychiatric evaluationdelirium, and that the parsimonious diagnosis was psychotic depressionwith catatonia. A course of bilateral ECT quickly resolved the patient’s melancholiaand she returned home.Although Patient 4.14 had several infections and likely medication overdose, herdepressive features, psychosis, malignant catatonia, agitation and self-injuriousbehavior are all consistent with severe melancholia. A corollary to all the rules ofdiagnosis is: “If there is no likely harm, make the diagnosis with the bestprognosis and the one for which there are good treatments.”Eliminating the possibilities to find the probable diagnosisThe Duck Principle, Sutton’s Law and The Rule of Parsimony each indicate thatclinical diagnosis is basically “betting the odds” on the “favorite”: “Of all theconditions that afflict humans, which one is most likely affecting my patient?”The process of elimination occurs rapidly, and much of it is automatic. Ifthe patient is male, pregnancy, uterine and ovarian problems and all otherfemale gender-specific conditions are immediately eliminated. If the patient isprepubescent, the differential diagnostic list is markedly different from that of aperson over age 65, even if both patients have many common symptoms. Anxiety,tremor, and muscle stiffness are consistent with basal ganglia disease, butwhile Parkinson’s disease immediately comes to mind if the patient is age 65, ina 14-year-old patient Wilson’s disease and illicit drug use must be considered first.An onset over a few hours evokes a different set of diagnostic choices(e.g. stroke, intoxication) than onsets developing over days, weeks, or months.For some behavioral conditions, laboratory tests are helpful (e.g. waking and sleepEEG, structural and functional neuroimaging, assessments of the hypothalamic–pituitary axis functioning), and some tests are definitive (e.g. genetic testing forHuntington’s disease, serologic testing for HIV and syphilis), but testing shouldnot be random. Tests should be linked to the differential diagnostic list generatedby the principles of clinical diagnosis. Patient 4.15 illustrates.Patient 4.15 29A 14-year-old girl was admitted to a psychiatric inpatient unit complaining ofhearing voices telling her to kill people she didn’t like. She recently brought aknife to school to kill a boy, and a month before tried to stab a girl. The voices,keeping her awake at night, had been experienced intermittently over theprevious 14 months. She reported feeling “sad, irritable, and angry”, and saidshe worried constantly, but denied other features of melancholia or mania.A previous hospitalization two years before led to the diagnosis of conduct