TY - JOUR
T1 - Bilateral cerebellar activation in unilaterally challenged essential tremor
AU - Broersma, Marja
AU - van der Stouwe, Anna M. M.
AU - Buijink, Arthur W. G.
AU - de Jong, Bauke M.
AU - Groot, Paul F. C.
AU - Speelman, Johannes D.
AU - Tijssen, Marina A. J.
AU - van Rootselaar, Anne-Fleur
AU - Maurits, Natasha M.
PY - 2016
Y1 - 2016
N2 - Essential tremor (ET) is one of the most common hyperkinetic movement disorders. Previous research into the pathophysiology of ET suggested underlying cerebellar abnormalities. In this study, we added electromyography as an index of tremor intensity to functional Magnetic Resonance Imaging (EMG-fMRI) to study a group of ET patients selected according to strict criteria to achieve maximal homogeneity. With this approach we expected to improve upon the localization of the bilateral cerebellar abnormalities found in earlier fMRI studies. We included 21 propranolol sensitive patients, who were not using other tremor medication, with a definite diagnosis of ET defined by the Tremor Investigation Group. Simultaneous EMG-fMRI recordings were performed while patients were off tremor medication. Patients performed unilateral right hand and arm extension, inducing tremor, alternated with relaxation (rest). Twenty-one healthy, age- and sex-matched participants mimicked tremor during right arm extension. EMG power variability at the individual tremor frequency as a measure of tremor intensity variability was used as a regressor, mathematically independent of the block regressor, in the general linear model used for fMRI analysis, to find specific tremor-related activations. Block-related activations were found in the classical upper-limb motor network, both for ET patients and healthy participants in motor, premotor and supplementary motor areas. In ET patients, we found tremor-related activations bilaterally in the cerebellum: in left lobules V, VI, VIIb and IX and in right lobules V, VI, VIIIa and b, and in the brainstem. In healthy controls we found simulated tremor-related activations in right cerebellar lobule V. Our results expand on previous findings of bilateral cerebellar involvement in ET. We have identified specific areas in the bilateral somatomotor regions of the cerebellum: lobules V, VI and VIII. •We added EMG as an index of tremor intensity to fMRI to study essential tremor.•Block- and tremor-related activations during a unilateral motor task were separated.•Block-related activations were found in the classical motor network.•Tremor-related activations were found in bilateral cerebellar lobules V, VI and VIII
AB - Essential tremor (ET) is one of the most common hyperkinetic movement disorders. Previous research into the pathophysiology of ET suggested underlying cerebellar abnormalities. In this study, we added electromyography as an index of tremor intensity to functional Magnetic Resonance Imaging (EMG-fMRI) to study a group of ET patients selected according to strict criteria to achieve maximal homogeneity. With this approach we expected to improve upon the localization of the bilateral cerebellar abnormalities found in earlier fMRI studies. We included 21 propranolol sensitive patients, who were not using other tremor medication, with a definite diagnosis of ET defined by the Tremor Investigation Group. Simultaneous EMG-fMRI recordings were performed while patients were off tremor medication. Patients performed unilateral right hand and arm extension, inducing tremor, alternated with relaxation (rest). Twenty-one healthy, age- and sex-matched participants mimicked tremor during right arm extension. EMG power variability at the individual tremor frequency as a measure of tremor intensity variability was used as a regressor, mathematically independent of the block regressor, in the general linear model used for fMRI analysis, to find specific tremor-related activations. Block-related activations were found in the classical upper-limb motor network, both for ET patients and healthy participants in motor, premotor and supplementary motor areas. In ET patients, we found tremor-related activations bilaterally in the cerebellum: in left lobules V, VI, VIIb and IX and in right lobules V, VI, VIIIa and b, and in the brainstem. In healthy controls we found simulated tremor-related activations in right cerebellar lobule V. Our results expand on previous findings of bilateral cerebellar involvement in ET. We have identified specific areas in the bilateral somatomotor regions of the cerebellum: lobules V, VI and VIII. •We added EMG as an index of tremor intensity to fMRI to study essential tremor.•Block- and tremor-related activations during a unilateral motor task were separated.•Block-related activations were found in the classical motor network.•Tremor-related activations were found in bilateral cerebellar lobules V, VI and VIII
U2 - https://doi.org/10.1016/j.nicl.2015.12.011
DO - https://doi.org/10.1016/j.nicl.2015.12.011
M3 - Article
C2 - 26909321
SN - 2213-1582
VL - 11
SP - 1
EP - 9
JO - NeuroImage. Clinical
JF - NeuroImage. Clinical
ER -