Imagerie morphologique des démences

Dementia refers to all pathological processes affecting mental health causing progressive deterioration of cognitive and non-cognitive functioning and leading to a loss of autonomy in daily life. The diagnosis of any such process requires not only clinical and neuropsychological tests, but also morphological imaging, an indispensable exploration in all cases of recent onset dementia. The article was designed to recall the role of imaging in the diagnosis of primary and secondary dementia and to illustrate each situation with the mainstay morphological diagnostic criteria. The first step is to distinguish between primary degenerative dementias and secondary dementias in order to rule out dementia resulting from neurosurgical, vascular, inflammatory, infectious, metabolic or toxic events. The morphological diagnosis is the second step and requires good knowledge of the signs of normal brain aging. MRI is the most contributive examination for the exploration of dementia. Computed tomography has a limited role and should be reserved for situations where MRI is not available. On conclusion, appropriate management of dementia begins with the elimination of a secondary dementia. Then, the objective is to establish the diagnosis of the type of dementia. This requires extensive knowledge of all imaging manifestations of dementias, notably on MRI.