Rapidly Progressive Dementia - Clinical Aspects and Management

Abstract

Although no precise definition for rapidly progressive dementia (RPD) exists, this term is generally used to refer to cases with significant and progressive cognitive impairment that occurs over weeks or months. RPD represents an unusual but severe condition that causes distress not only for patients and their relatives but also for the clinicians involved, as multiple investigations and decisions about management must be made urgently to avoid misdiagnosing a treatable condition and to preserve as much of the neural tissue as possible from definite damage. While Creutzfeldt-Jacob disease (CJD) has for a long period of time been regarded as the prototype of RPD, this infrequent but severe condition can be produced by an extensive variety of causes such as various endocrine, metabolic or toxic disorders, central nervous system (CNS) infections, primary or secondary CNS neoplasms, various CNS vasculitides and various autoimmune conditions in which autoantibodies against neural tissue are produced, whether in the presence of a neoplasm or not. However, even in the more common and usually slowly progressive dementias such as Alzheimer’s disease, frontotemporal lobar degeneration, dementia with Lewy bodies and other degenerative dementias, as well as vascular dementia, establishment and progression of the disease is occasionally surprisingly accelerated, leading to a clinical presentation of RPD. The few published case series of RPD have shown that the relative frequency of underlying diseases depends mainly on the clinical setting. Thus, CJD has been found to be the most prevalent cause in referral centres for spongiform encephalopathies, while secondary causes are more prevalent in general referral centres for dementia diagnosis. In clinical practice, for the cases presenting with RPD, the diagnostic procedure must be exhaustive, starting with a detailed clinical evaluation and proceeding to a complete laboratory work-up and sophisticated neuroimaging studies. There has been recent enormous progress in imaging, with sensitive new sequences of magnetic resonance imaging and immunology; as a result, a plethora of antibodies against the CNS can now be detected in cases of autoimmune dementias, which has dramatically changed the diagnostic approach and early management of cases of RPD. The same favourable effect in clinical practice comes from the accumulated knowledge of the complex clinical picture of various causes of RPD, associated specific neurological features (pyramidal signs, ataxia, myoclonus) and systematic features (weight loss, hyponatraemia, hepatic disorders) and their mode of progression.