PMC9795845_01
MRI scan before DBS implantation. At age 47 years, MRI showed no signs of cerebellar or supratentorial atrophy. The middle cerebellar peduncles (MCP) were normally developed according to the patient's age. The images presented in the sagittal and axial plane were acquired as T2-weighted sequences.
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The cerebellum was developed according to the patient's age including the middle cerebellar peduncles (MCP) thereby not revealing any evidence for FXTAS (Figure 1).
Timeline of the patient's history, diagnostic and therapeutic work-up. The patient was initially diagnosed with essential tremor (ET) due to early-onset postural arm tremor at the age of 7 years and implanted with VIM-DBS at the age of 47 years. Slowly emerging ataxia led to the diagnosis of spinocerebellar ataxia 27 (SCA 27) at the age of 49 years. Programming of deep brain stimulation (DBS) following a monopolar review showed relevant tremor attenuation by high-frequency stimulation of the 2nd lowermost contacts. The patient was randomized to follow-up stimulation settings meaning high-frequency stimulation at daytime and either StimOFF or 30 Hz stimulation of subthalamic fiber tracts (lowermost contacts) at night. Both stimulation paradigms were activated for 5 weeks in a randomized order followed by clinical examinations blinded to the settings of the previous interval.
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PMC9795845_02
Reconstruction of DBS electrode placement. (A) Electrode placement in the VIM with the lowest contacts (0, 5) reaching beyond the thalamus border. (B) Topographic vicinity of the dentato-thalamic tract (DTT) and the volume of tissue activated (VTA) during low-frequency stimulation of the lowest contacts (30 Hz, 4 mA). The electrode position in relation to the DTT is shown from both a lateral and a superior perspective. The right side of the patient is marked with "R". (C) Electrode placement and MNI coordinates of the active contacts for the high-frequency stimulation programme (contacts 1, 6: 3.5 mA, 30 Hz, 60 mus) and the low-frequency stimulation programme (contacts 0, 5: 4 mA, 30 Hz, 60 mus) are displayed. Electrode placement was reconstructed by co-registration of preoperative MRI and postoperative CT images and normalization into the MNI_ICBM_2009b_NLIN_ASYM space and anatomic atlases using the Lead-DBS toolbox.
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Reconstruction of electrode placement indicated spatial vicinity between the DTT and the lowermost contacts (Figure 3). Simulation of the volume of tissue activated (VTA) by the 30 Hz-stimulation programme revealed a partial overlap of the VTA and the DTT (Figure 3B).
Clinical tremor and ataxia scores assessed with different stimulation paradigms. (A) In the immediate assessment, TRS and SARA were scored with StimOFF, 180 Hz-stimulation of the 2nd-lowermost (VIM) contacts and 30 Hz stimulation of the lowermost (subthalamic) contacts with increasing amplitudes from 1 to 7 mA in a randomized order. (B) The first follow-up examination was scheduled 5 weeks from baseline with preceding 180 Hz-stimulation (3.5 mA) at daytime and 30 Hz stimulation (4 mA) at night. (C) The second follow-up was scheduled 10 weeks from baseline with preceding 180 Hz-stimulation (3.5 mA) at daytime and StimOFF at night. For all assessments, the rater and patient were blinded to the respective previous stimulation settings.
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Tremor in the StimOFF condition (TRS: 12) improved to a TRS of 7 by activating the 180 Hz-programme (Figure 4B). After the second interval during which the patient adopted StimOFF at night, the baseline TRS was higher in the StimOFF condition (TRS: 23) and slightly improved (TRS: 17) when using 180 Hz-stimulation (Figure 4C).
PMC9795845_03
Clinical tremor and ataxia scores assessed with different stimulation paradigms. (A) In the immediate assessment, TRS and SARA were scored with StimOFF, 180 Hz-stimulation of the 2nd-lowermost (VIM) contacts and 30 Hz stimulation of the lowermost (subthalamic) contacts with increasing amplitudes from 1 to 7 mA in a randomized order. (B) The first follow-up examination was scheduled 5 weeks from baseline with preceding 180 Hz-stimulation (3.5 mA) at daytime and 30 Hz stimulation (4 mA) at night. (C) The second follow-up was scheduled 10 weeks from baseline with preceding 180 Hz-stimulation (3.5 mA) at daytime and StimOFF at night. For all assessments, the rater and patient were blinded to the respective previous stimulation settings.
fneur-13-1048530-g0004.jpg
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F4
Tremor in the StimOFF condition (TRS: 12) improved to a TRS of 7 by activating the 180 Hz-programme (Figure 4B). After the second interval during which the patient adopted StimOFF at night, the baseline TRS was higher in the StimOFF condition (TRS: 23) and slightly improved (TRS: 17) when using 180 Hz-stimulation (Figure 4C).