Corticobasal syndrome: neuroimaging and neurophysiological advances

Abstract

Corticobasal degeneration (CBD) is a neurodegenerative condition characterized by 4R tau protein deposition in several brain regions that clinically manifests itself as a heterogeneous atypical parkinsonism typically expressed in adulthood. The prototypical clinical phenotype of CBD is corticobasal syndrome (CBS). Important insights into the pathophysiological mechanisms underlying motor and higher cortical symptoms in CBS have been gained by using advanced neuroimaging and neurophysiological techniques. Structural and functional neuroimaging studies often show asymmetric cortical and subcortical abnormalities, mainly involving perirolandic and parietal regions and basal ganglia structures. Neurophysiological investigations including electroencephalography and somatosensory evoked potentials provide useful information on the origin of myoclonus and on cortical sensory loss. Transcranial magnetic stimulation demonstrates heterogeneous and asymmetric changes in the excitability and plasticity of primary motor cortex and abnormal hemispheric connectivity. Neuroimaging and neurophysiological abnormalities in multiple brain areas reflect asymmetric neurodegeneration, leading to asymmetric motor and higher cortical symptoms in CBS.

Corticobasal syndrome: a practical guide

“…12 13 29 Electrophysiology studies suggest the myoclonus is cortical or subcortical in origin. [31][32][33]…”

“…Brain imaging has three roles in the assessment of patients with corticobasal syndrome-ruling out mimics/structural causes (see below), providing support for the clinical diagnosis of a corticobasal syndrome, and providing clues to the underlying pathology. 33…”

“…53 Such measures will be increasingly relevant as protein-specific treatments hopefully emerge over the coming years. 33 Ultimately their utility will depend on their ability to distinguish between pathologies at individual rather than at group level.…”

Degeneración corticobasal

“…En etapas más tardías suele haber un declinar de la unión estriatal de DaT (transportador de la dopamina) con ligera o moderada asimetría, similar a la observada en los pacientes con EP [34][35][36] . En los últimos años se han desarrollado ligandos de PET sobre agregados de tau, con buena afinidad por los filamentos helicoidales pareados 3R/4R de la DTA, pero con menor afinidad por los filamentos rectos 4R y alta unión no específica 16,30 . El nuevo trazador de PET tau NEUROIMAGEN La mayoría de los hallazgos de neuroimagen en la DCB se correlacionan con la localización de la patología, y por tanto con los hallazgos clínicos, pero no con la naturaleza específica del proceso neurodegenerativo 5 .…”

The Significance of Vascular Pathogenesis in the Examination of Corticobasal Syndrome

“…Among the typical features of CBS there is also an asymmetric distribution of the motor symptoms. According to Di Stasio et al (2019) this kind of typical pattern corresponds with decreased glucose metabolism and cerebral blood flow in positron emission tomography (PET) and single photon emission computed tomography (SPECT), as the affected side of frontoparietal cortex, caudate, putamen, thalamus, pons, and cerebellum is often contralateral to the clinically more symptomatic side ( Abe et al, 2016 ).…”