Clinical outcome and intraoperative neurophysiology for focal limb dystonic tremor without generalized dystonia treated with deep brain stimulation.
OBJECTIVE
Dystonic tremor (DT) is defined as a postural/kinetic tremor occurring in the body region affected by dystonia. DT is typically characterized by focal tremors with irregular amplitudes and variable frequencies typically below 7Hz. Pharmacological treatment is generally unsuccessful and guidelines for deep brain stimulation (DBS) targeting and indications are scarce. In this article, we present the outcome and neurophysiologic data of two patients with refractory, focal limb DT treated with Globus Pallidus interna (Gpi) DBS and critically review the current literature regarding surgical treatment of DT discussing stereotactic targets and treatment considerations.


METHODS
A search of literature concerning treatment of DT was conducted. Additionally, Gpi DBS was performed in two patients with DT and microelectrode recordings for multi unit analysis (MUAs) and local field potentials (LFPs) were obtained.


RESULTS
The mean percentage improvement in tremor severity was 80.5% at 3 years follow up. MUAs and LFPs did not show significant differences in DT patients compared with other forms of dystonia or PD except for higher interspikes bursting indices. LFP recordings in DT demonstrated high power at low frequencies with action (<3.5Hz).


CONCLUSIONS
Gpi DBS is an effective treatment in patients with focal limb DT without associated generalized dystonia. Intraoperative neurophysiologic findings suggest that DT is part of phenotypic motor manifestations in dystonia.
Department of Neurology, Albany Medical College, Albany, NY, United States. Electronic address: RamireA@mail.amc.edu.
Adolfo
A
Ramirez-Zamora
Center for Neuroscience and Neuropharmacology, Albany, NY, United States.
Brian
B
Kaszuba
Center for Neuroscience and Neuropharmacology, Albany, NY, United States.
Lucy
L
Gee
Department of Neurosurgery, Albany Medical Center, Albany, NY, United States.
Julia
J
Prusik
Department of Neurology, Albany Medical College, Albany, NY, United States.
Eric
E
Molho
Department of Neurosurgery, Albany Medical Center, Albany, NY, United States.
Meghan
M
Wilock
Center for Neuroscience and Neuropharmacology, Albany, NY, United States.
Damian
D
Shin
Center for Neuroscience and Neuropharmacology, Albany, NY, United States; Department of Neurosurgery, Albany Medical Center, Albany, NY, United States. Electronic address: RamireA@mail.amc.edu.
Julie G
JG
Pilitsis
D046690:Deep Brain Stimulation / Q000379:methods*; D004421:Dystonia / Q000150:complications*; D005260:Female; D005917:Globus Pallidus; D006801:Humans; D064795:Intraoperative Neurophysiological Monitoring / Q000379:methods*; D008875:Middle Aged; D016896:Treatment Outcome; D014202:Tremor / Q000209:etiology / Q000628:therapy*
Deep brain stimulation; Dystonia neurophysiology; Dystonic tremor; Globus pallidus interna; Local field potentials; Tremor