Neuroanatomical Heterogeneity of Tremor Propranolol

There were no significant differences in demographic characteristics, general cognition, or results of detailed neuropsychological tests between the groups. Data suggest that patients with ET have heterogeneous cortical thinning and WM alteration with respect to responsiveness to propranolol, suggesting that propranolol responsiveness may be a predictive factor to determine ET subtypes in terms of neuroanatomical heterogeneity.

TBSS analysis of fractional anisotropy (FA) in comparison of responder and non-responder groups.

Higher FA values of the non-responders compared with the responders were found in the bilateral frontal, corpus callosal (genu), and right parieto-temporal WM (FWE-corrected P<0.05). 

A schematic illustration of the neuroanatomy in the pathophysiology of essential tremor (ET).

(A) The locus coeruleus (LC) and its related structure, a major cortical glutamatergic afferent from orbitofrontal cortex (OFC) [a], may play a role in the pathogenesis of ET through the coerulo-cerebellar pathway [b]. (B) The cerebello–thalamo–cortical loop [c] is also an important pathway implicated in ET. These two distinct structures are consistent with heterogeneous neuro-pathologies (Changes in the brainstem and cerebellum, respectively) demonstrated in previous postmortem studies. Beta blockers seem to act centrally via Renshaw cells [d], and the LC is a strong candidate for mediating the beta-adrenergic effects to this pathway correlation analysis indicated that the parameters of tremor severity and disease duration were not significantly correlated with regional cortical thinning or WM alterations. These observations further support the role of propranolol responsiveness as an important factor for ET heterogeneity.