Neuroimaging of Rapidly Progressive Dementias, Part 2: Prion, Inflammatory, Neoplastic, and Other Etiologies

Abstract

SUMMARY:Most dementias begin insidiously, developing slowly and generally occurring in the elderly age group. The so-called rapidly progressive dementias constitute a different, diverse collection of conditions, many of which are reversible or treatable. For this reason, accurate identification and assessment of acute and subacute forms of dementia are critical to effective treatment; neuroimaging aids greatly in narrowing the diagnosis of these conditions. This second installment of a 2-part review of rapidly progressive dementias examines the use of imaging in an assortment of other etiologies in the differential diagnosis, from prion disease and neoplastic-related conditions to rare metabolic and other conditions such as Wernicke encephalopathy. In these clinical conditions, MR imaging has the potential to narrow this broad differential diagnosis and, at times, can definitively aid in the diagnosis of certain conditions on the basis of typical imaging patterns. ABBREVIATIONS:CJD ϭ Creutzfeldt-Jakob disease; LG ϭ lymphomatoid granulomatosis; SREAT ϭ steroid-responsive encephalopathy with autoimmune thyroid-

Autoimmune Encephalitis: Pathophysiology and Imaging Review of an Overlooked Diagnosis

“…[3][4][5] Despite its growing recognition as a rare cause of altered mental status, autoimmune encephalitis remains a diagnosis of exclusion with more common causes often identified during the standard diagnostic evaluation. 16,17 However, more complex presentations of altered mental status may display atypical features without a clear etiology identified after routine testing. 16,17 In these situations, recognition of potential cases of autoimmune encephalitis by the radiologist can be the first step to optimizing clinical outcomes through ensuring that a prompt and appropriate clinical work-up is performed, including the use of specialized serum/CSF antibody panels, with the ultimate goal of establishing an effective treatment regimen before the onset of devastating complications.…”

“…16,17 However, more complex presentations of altered mental status may display atypical features without a clear etiology identified after routine testing. 16,17 In these situations, recognition of potential cases of autoimmune encephalitis by the radiologist can be the first step to optimizing clinical outcomes through ensuring that a prompt and appropriate clinical work-up is performed, including the use of specialized serum/CSF antibody panels, with the ultimate goal of establishing an effective treatment regimen before the onset of devastating complications. 3,5,8,18 The purpose of this article is to discuss the subset of immunemediated CNS conditions with features of autoimmune encephalitis (ie, antibody-mediated inflammation of the brain), provide a framework for radiologists to understand the relevant neuroimmunology, review the major antibody subtypes, and describe the constellation of clinical and imaging features that are most suggestive of this diagnosis.…”

When Dementia Progresses Quickly: A Practical Approach to the Diagnosis and Management of Rapidly Progressive Dementia

“…MRI of the brain with and without gadolinium is indispensable in the evaluation of patients with RPD, and is critical to screen for structural (neoplastic, infectious and hemorrhagic), demyelinating/inflammatory, vascular, neurodegenerative or metabolic causes (Figure 4) [6,7,60,61]. Whenever possible, imaging should be completed under protocols providing sagittal views of the corpus callosum and juxtacortical structures (commonly involved in demyelinating disease), and coronal views of medial temporal lobes (commonly involved in limbic encephalitis and neurodegenerative diseases).…”

Herpes simplex encephalitis: unusual imaging appearances

“…Lesions affecting this region can be broadly classified into the following: neoplastic (primary and secondary), developmental, inflammatory/granulomatous diseases and lesions arising from the adjacent brain parenchyma 4. Wernicke encephalopathy is an acute neurological condition resulting from a dietary Vitamin B1 (thiamine) deficiency and characteristically symmetrically involves the mamillary bodies, dorsomedial thalami, tectal plate, periaqueductal area and the grey matter around the third and fourth ventricle 5 6. It usually happens in a background of alcoholism or GI resection.…”