Probabilistic diagnosis of normal pressure hydrocephalus and other treatable cerebral lesions in dementia.

Clinical profiles of dementia patients, differing with respect to age, presence of gait abnormalities and urinary incontinence are discussed. Epidemiological data, subjective probabilities and clinical reasoning are used to predict a treatable cerebral lesion, i.e., an intracranial space occupying lesion or normal pressure hydrocephalus (NPH). Our calculations help in distinguishing clinically between demented patients who are, and who are not likely to benefit from computed tomography (CT) investigation for treatable lesions and, eventually, from cerebrospinal fluid shunting for NPH. Utility calculations show that shunting can be recommended only for a patient with the full triad of symptoms of NPH, and CT evidence of NPH, when no other prognostic information is available. Future clinical research should address the long-term prognosis of (treated) NPH patients, and the mortality of shunting, because these two factors are critical to the shunting decision.