Individualized current-shaping reduces DBS-induced dysarthria in patients with essential tremor.
OBJECTIVE
To investigate in patients with essential tremor (ET) treated with thalamic/subthalamic deep brain stimulation (DBS) whether stimulation-induced dysarthria (SID) can be diminished by individualized current-shaping with interleaving stimulation (cs-ILS) while maintaining tremor suppression (TS).


METHODS
Of 26 patients screened, 10 reported SID and were invited for testing. TS was assessed by the Tremor Rating Scale and kinematic analysis of postural and action tremor. SID was assessed by phonetic and logopedic means. Additionally, patients rated their dysarthria on a visual analog scale.


RESULTS
In 6 of the 10 patients with ET, DBS-ON (relative to DBS-OFF) led to SID while tremor was successfully reduced. When comparing individualized cs-ILS with a non-current-shaped interleaving stimulation (ILS) in these patients, there was no difference in TS while 4 of the 6 patients showed subjective improvement of speech during cs-ILS. Phonetic analysis (ILS vs cs-ILS) revealed that during cs-ILS there was a reduction of voicing during the production of voiceless stop consonants and also a trend toward an improvement in oral diadochokinetic rate, reflecting less dysarthria. Logopedic rating showed a trend toward deterioration in the diadochokinesis task when comparing ON with OFF but no difference between ILS and cs-ILS.


CONCLUSIONS
This is a proof-of-principle evaluation of current-shaping in patients with ET treated with thalamic/subthalamic DBS and experiencing SID. Data suggest a benefit on SID from individual shaping of current spread while TS is preserved.


METHODS
This study provides Class IV evidence that in patients with ET treated with DBS with SID, individualized cs-ILS reduces dysarthria while maintaining tremor control.
From the Departments of Neurology (M.T.B., T.A.D., J.B., I.G.M., G.R.F., L.T.) and Stereotaxy and Functional Neurosurgery (M.R., M.M.), University Hospital Cologne; Cognitive Neuroscience (INM3) (M.T.B., G.R.F.), Institute of Neuroscience and Medicine, Research Centre Jülich; Department of Neurology (J.R.), University Hospital Kiel; and IB-Hochschule Berlin (M.H.), Germany.
Michael T
MT
Barbe
Till A
TA
Dembek
Johannes
J
Becker
Jan
J
Raethjen
Mariam
M
Hartinger
Ingo G
IG
Meister
Matthias
M
Runge
Mohammad
M
Maarouf
Gereon R
GR
Fink
Lars
L
Timmermann
D000368:Aged; D001696:Biomechanical Phenomena / Q000502:physiology; D046690:Deep Brain Stimulation / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods*; D004401:Dysarthria / Q000209:etiology* / Q000517:prevention & control; D004567:Electrodes, Implanted; D055590:Electromagnetic Phenomena; D020329:Essential Tremor / Q000628:therapy*; D005260:Female; D006801:Humans; D007807:Language Tests; D008297:Male; D008875:Middle Aged; D057285:Precision Medicine / Q000379:methods; D020530:Subthalamus / Q000502:physiology* / Q000503:physiopathology / Q000601:surgery; D013788:Thalamus / Q000502:physiology* / Q000503:physiopathology / Q000601:surgery; D016896:Treatment Outcome