title: Hypokinesia upon Pallidal Deep Brain Stimulation of Dystonia: Support of a GABAergic Mechanism.
abstract: In the past, many studies have documented the beneficial effects of deep brain stimulation (DBS) in the globus pallidus internus for treatment of primary segmental or generalized dystonia. Recently however, several reports focused on DBS-induced hypokinesia or freezing of gait (FOG) as a side effect in these patients. Here we report on two patients suffering from FOG after successful treatment of their dystonic movement disorder with pallidal high frequency stimulation (HFS). Several attempts to reduce the FOG resulted in worsening of the control of dystonia. In one patient levodopa treatment was initialized which was somewhat successful to relieve FOG. We discuss the possible mechanisms of hypokinetic side effects of pallidal DBS which can be explained by the hypothesis of selective GABA release as the mode of action of HFS. Pallidal HFS is also effective in treating idiopathic Parkinson's disease as a hypokinetic disorder which at first sight seems to be a paradox. In our view, however, the GABAergic hypothesis can explain this and other clinical observations.
authors.affiliation: Department of Neurology, University Medical Center Freiburg , Freiburg , Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Amtage
authors.affiliation: Section of Clinical Neuropharmacology, Department of Neurosurgery, University Medical Center Freiburg , Freiburg , Germany.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Feuerstein
authors.affiliation: Department of Neurology, University Medical Center Freiburg , Freiburg , Germany.
authors.forename: Simone
authors.initials: S
authors.lastname: Meier
authors.affiliation: Department of Stereotactic and Functional Neurosurgery, University Medical Center Freiburg , Freiburg , Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Prokop
authors.affiliation: Department of Neurology, University Medical Center Freiburg , Freiburg , Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Piroth
authors.affiliation: Department of Stereotactic and Functional Neurosurgery, University Medical Center Freiburg , Freiburg , Germany.
authors.forename: Marcus O
authors.initials: MO
authors.lastname: Pinsker
keywords: deep brain stimulation; dystonia; globus pallidus internus; idiopathic Parkinson’s disease; subthalamic nucleus