gms | German Medical Science

64th Annual Meeting of the German Society of Neurosurgery (DGNC)

German Society of Neurosurgery (DGNC)

26 - 29 May 2013, Düsseldorf

Evaluation of thalamo-cortical networks using electrical stimulation and electrophysiological recordings during deep brain stimulation

Meeting Abstract

  • Georgios Naros - Universitätsklinik für Neurochirurgie, Eberhard Karls Universität Tübingen
  • Florian Grimm - Universitätsklinik für Neurochirurgie, Eberhard Karls Universität Tübingen
  • Sorin Breit - Universitätsklinik für Neurologie, Eberhard Karls Universität Tübingen
  • Rejko Krüger - Universitätsklinik für Neurologie, Eberhard Karls Universität Tübingen
  • Alireza Gharabaghi - Universitätsklinik für Neurochirurgie, Eberhard Karls Universität Tübingen

Deutsche Gesellschaft für Neurochirurgie. 64. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC). Düsseldorf, 26.-29.05.2013. Düsseldorf: German Medical Science GMS Publishing House; 2013. DocP 049

doi: 10.3205/13dgnc466, urn:nbn:de:0183-13dgnc4664

Published: May 21, 2013

© 2013 Naros et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.



Objective: During Deep Brain Stimulation (DBS) electrophysiological recordings are used for intraoperative targeting. At the same time, they enable insights into complicated subcortical-cortical networks. Further knowledge about these loops will improve targeting in DBS. In this study we present our findings using intraoperative electrical stimulation and cortical/subcortical electrophysiological recordings in evaluation of thalamus-cortical networks.

Method: 13 patients with Essential Tremor or Holmes Tremor, who were selected for DBS of the ventral intermediate (VIM) nucleus of the thalamus, participated in the study resulting in 23 examined hemispheres. After insertion of 1–4 microelectrodes, nucleo-cortical evoked potentials (NCEP) were elicited by subcortical electrical stimulation in 1–2 mm steps until reaching target depth. Multi-channel electroencephalography (EEG) and local field potentials (LFP) were recorded. Cortical effects of subcortical stimulation was assessed in the time series and frequency domain. In a subgroup of patients , functional connectivity between subcortical (LFP) and cortical (EEG) signals (nucleo-cortical coherence, NCC) was calculated by magnitude squared coherence (MSC).

Results: After VIM stimulation, NCEPs are found over the ipsilateral motor cortex consistent with the anatomical connections. Transferring the post-stimulation cortical signals into the frequency domain, a synchronization in the beta (15–25Hz) band frequencies was observed for the ispilateral hemisphere after thalamic stimulation. In subcortical recordings, we found a power increase for beta (15–25Hz) frequencies close to the target depth. This increase of power correlates with a high nucleo-cortical coherence in the beta (15–20Hz) and gamma (70–80Hz) frequencies (r=0.877 and r=0.856). Notably, there was a good correlation between the depths associated with the strongest ipsilateral NCEP and the depths with highest NCC (r=0.77).

Conclusions: We conclude, there is a interaction between the VIM and the ipsilateral motor cortex in the beta and gamma frequencies. Functional connected areas are characterized by an increase of spectral beta power in subcortical LFP recordings. Cortical responses on subcortical electrical stimulation elicit functional connections and provide new insights in the physiology of thalamo-cortical networks. Such multimodal intraoperative electrophysiological monitoring will improve intraoperative targeting in DBS.