Objective: To identify a common structural network for stimulation-induced dysarthria (SID) in thalamic deep brain stimulation (DBS) and DBS of the Nucleus subthalamicus (STN).
Background: DBS is an established treatment option for people with essential tremor (ET) and Parkinson’s Disease (PD). However, DBS can induce troublesome and potentially therapy-limiting side-effects, such as SID. Previously we separately investigated structural networks associated with SID in thalamic DBS (ET) and in STN-DBS (PD), each pointing towards an involvement of cerebello-thalamic fibers as well as the internal capsule [1, 2].
Method: Here we retrospectively combined the results of two previous studies where SID thresholds were determined in steps of 0.5 mA at each contact level for 15 ET patients with thalamic DBS and 25 PD patients with STN-DBS [1, 2]. Than, DBS leads were reconstructed and stimulation volumes were calculated with LEAD-DBS. A well-established normative structural connectome (HCP 985 subjects) was employed to calculate fiber-wise Odds Ratios (OR) for thalamic DBS and STN-DBS respectively and the resulting models were combined in an agreement map, calculated following Horn et al . A cross-validation of the target-specific models, as well as a leave-one-out validation of the agreement map was conducted using ROC-analyses. All analysis were pooled on the left hemisphere.
Results: A total of 2913 stimulation volumes were included in the analysis (ET: N = 1299, PD: N = 1614). SID was provoked at contact levels (ET: N = 51, PD: N = 128). In the agreement map, fibers with higher OR were located lateral to the STN and postero-medial to the STN, emanating from the Nucleus ruber. ROC analysis resulted in an AUC of 0.737 (Train dataset: thalamic DBS, Validation dataset: STN-DBS), 0.745 (Train dataset: STN-DBS, Validation dataset: thalamic DBS, and 0.739 (leave-one-out validation of the agreement map) respectively.
Conclusion: Our results point towards a common structural network of SID in thalamic and STN-DBS involving both, cerebello-thalamic fibers and the internal capsule. Although further validation in independent datasets is needed, the present study might guide future individual imaging-based programming strategies.
References:  Petry‐Schmelzer JN, Jergas H, Thies T, et al. Network Fingerprint of Stimulation‐Induced Speech Impairment in Essential Tremor. Ann Neurol 2021;89(2):315–326.
 Jergas H, Petry-Schmelzer JN, Hannemann JG, et al. Network Fingerprint of Stimulation-Induced Speech Impairment in Parkinson’s disease. In: MOVEMENT DISORDERS. WILEY 111 RIVER ST, HOBOKEN 07030-5774, NJ USA; 2022 p. S167–S168.
 Sobesky L, Goede L, Odekerken VJJ, et al. Subthalamic and pallidal deep brain stimulation: are we modulating the same network? Brain 2022;145(1):251–262.
To cite this abstract in AMA style:JN. Petry-Schmelzer, H. Jergas, T. Thies, JC. Baldermann, V. Visser-Vandewalle, TA. Dembek, MT. Barbe. Is there a common structural network for stimulation-induced dysarthria in subthalamic and thalamic deep brain stimulation? [abstract]. Mov Disord. 2023; 38 (suppl 1). https://www.mdsabstracts.org/abstract/is-there-a-common-structural-network-for-stimulation-induced-dysarthria-in-subthalamic-and-thalamic-deep-brain-stimulation/. Accessed September 21, 2023.
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