The corticobasal syndrome–Alzheimer’s disease conundrum

Abstract

Corticobasal syndrome (CBS), once thought to be pathognomonic for corticobasal degeneration pathology, is increasingly reported with various underlying pathologies. Alzheimer’s disease is one such pathology, also once believed to be unique for its clinical syndrome of dementia of the Alzheimer’s type. CBS is believed to result from topography of asymmetric parietofrontal cortical lesion involvement, rather than lesion subtype. However, this topographical pattern is strikingly different to that typically associated with AD for unclear reasons. This article will focus on CBS with underlying AD pathology (CBS-AD), and will review associated clinical, imaging and demographic factors. Predicting AD pathology is of marked interest as disease-modifying therapies loom on the horizon, with biomarkers and imaging research underway. By reviewing the literature for CBS-AD case reports and series and contrasting them with CBS with underlying corticobasal degeneration pathology cases, the article aims to examine factors that may predict AD pathology. How AD pathology may produce this clinical phenotype, rather than the prototype dementia of the Alzheimer’s type, will also be reviewed.

Keywords::

• alien limb
• Alzheimer’s disease
• apraxia
• corticobasal degeneration
• corticobasal syndrome
• dementia
• myoclonus
• rigidity
• tau
• voxel-based morphometry

Financial & competing interests disclosure

Jennifer L Whitwell and Keith A Josephs are supported by NIH grants R01 DC10367, R01 AG37491, R21 AG38736 and the Dana Foundation. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.

Notes

Aβ: Amyloid β; CBD: Corticobasal degeneration; FDG: Fluorodeoxyglucose; MMSE: Mini-Mental State Examination; PiB: Pittsburgh compound B ([N-methyl-¹¹C]2-(4´-methylaminophenyl)-6-hydroxybenzothiazole).