Highlights
- •Cerebellar features including imbalance are increasingly recognized symptoms in ET
- •The effects of thalamic DBS on imbalance in ET are contradictory
- •Reduction in DBS frequency to the lowest effective settings for tremor, provided benefit in disequilibrium in our patients
- •Larger, prospective, well conducted clinical trials are warranted to validate these initial results
Abstract
Essential tremor (ET) is a syndrome characterized by the presence of symmetric, moderate
to high frequency postural and action tremors of the limbs. Additionally, increasing
evidence indicates the occurrence of associated cerebellar features in ET patients
including impaired gait and balance. Deep brain stimulation (DBS) of the ventralis
intermedius (VIM) nucleus of the thalamus has been shown to be an effective treatment
for medically-refractory ET tremor but its effects on balance remain unclear with
conflicting results reported. In this article, we report the effects of frequency
modification in four patients with disequilibrium after DBS and review available literature
regarding the effects of neurostimulation on balance in ET. Reduction in DBS frequency
(10–20 Hz reduction intervals) to the lowest effective settings for tremor control was conducted
followed by immediate and 4-week assessment of disequilibrium. All patients reported
improvement in balance ranging from mild to marked benefit on clinical global impression
scale and in the posture and gait disturbance sub-scores of the International Cooperative
Ataxia Rating Scale (ICARS). There was no significant difference in tremor control
with DBS frequency adjustments. Our results suggest a relationship between the effects
of high-frequency stimulation and disequilibrium in ET patients treated with bilateral
or unilateral DBS. Additional larger, prospective studies are warranted to validate
these results and discern the relationship between DBS stimulation settings and cerebellar
findings in ET.
Keywords
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Article info
Publication history
Published online: June 02, 2016
Accepted:
June 1,
2016
Received in revised form:
May 23,
2016
Received:
May 4,
2015
Identification
Copyright
© 2016 Elsevier B.V. All rights reserved.
