The spatial patterns of pathological brain lesions in 12 patients with corticobasal degeneration

Staging disease severity in movement disorder tauopathies: Brain atrophy separates progressive supranuclear palsy from corticobasal degeneration

The movement disorders progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD) both deposit tau in degenerating neurons and are considered to be tauopathies. The recently developed scheme for staging tissue degeneration in another tauopathy, frontotemporal dementia [Broe et al., Neurology 2003;60:1005-1011] was applied to pathologically confirmed PSP (n = 24) and CBD (n = 9) cases and correlated with clinical indices. In contrast to frontotemporal dementia, the majority of PSP cases had limited or no visible atrophy, while the pattern of atrophy in CBD cases conformed to the existing staging scheme (all but one case exhibiting substantial visible tissue atrophy). Despite similar clinical severity and disease duration between groups, there was a marked difference between the PSP and CBD cases in pathological disease stage (chi(2) = 8.86; P = 0.03). The degree of global atrophy in PSP appears to be distinct from other tauopathies, while CBD fits the same pattern as other pathological forms of frontotemporal dementia.

Coherence analysis in the myoclonus of corticobasal degeneration

We investigated whether myoclonus in corticobasal degeneration (CBD) is cortical or subcortical in origin. Many authors have suggested that the myoclonus in CBD is a subtype of cortical myoclonus, despite the fact that back-averaging fails to detect a cortical correlate to spontaneous or action induced jerks and giant sensory evoked potentials are seldom found. Electroencephalographic-electromyographic (EEG-EMG) and EMG-EMG frequency analysis may be more sensitive to cortical drives when EMG bursts occur at a high frequency and at low amplitudes as in CBD. We evaluated EEG-EMG and EMG-EMG coherence and phase in 5 patients with clinically probable CBD and unilateral, action-induced and stimulus-sensitive myoclonus. We found negligible corticomuscular coherence despite a dramatically exaggerated EMG-EMG coherence. We conclude that an inflated EMG-EMG coherence is found in some patients with CBD and that this is unlikely to be due to an exaggerated cortical drive.