“…The authors, as well as others,19 found that the most accurate prediction rule was that of Dietch,20 requiring imaging in patients with recent onset (less than 1 month) of cognitive symptoms, fluctuations or acute changes (within 48 hours) of cognitive function, focal signs or symptoms, papilloedema or visual field deficits, headache, history of recent head trauma or malignant tumour, seizures, history of stroke, urinary incontinence, or gait ataxia or apraxia. However, even Dietch's rule could not attain 100% sensitivity1—the benchmark figure that most clinical neurologists and psychiatrists consider acceptable in the detection of reversible causes 16. The bottom line is that, although the vast majority of scans carried out in patients with cognitive deterioration are negative, no combination of first line (clinical and laboratory) signs can identify cases of reversible or treatable causes with 100% sensitivity and reasonably high specificity 17…”