Directional recordings of somatosensory evoked potentials from the sensory thalamus in chronic poststroke pain patients

Nowacki A, Zhang D, Wermelinger J, Abel Alvarez Abut P, Rosner J, Pollo C, Seidel K.

Clin Neurophysiol. 2023 Jul;151:50-58. doi: 10.1016/j.clinph.2023.03.359. Epub 2023 Apr 14. PMID: 37156120.

Abstract

Objective: The aim of this feasibility study was to investigate the properties of median nerve somatosensory evoked potential (SEPs) recorded from segmented Deep Brain Stimulation (DBS) leads in the sensory thalamus (VP) and how they relate to clinical and anatomical findings.

Methods: We analyzed four patients with central post-stroke pain and DBS electrodes placed in the VP. Median nerve SEPs were recorded with referential and bipolar montages. Electrode positions were correlated with thalamus anatomy and tractography-based medial lemniscus. Early postoperative clinical paresthesia mapping was performed by an independent pain nurse. Finally, we performed frequency and time-frequency analyses of the signals.

Results: We observed differences of SEP amplitudes recorded along different directions in the VP. SEP amplitudes did not clearly correlate to both atlas-based anatomical position and fiber-tracking results of the medial lemniscus. However, the contacts of highest SEP amplitude correlated with the contacts of lowest effect-threshold to induce paraesthesia.

Conclusions: SEP recordings from directional DBS leads offer additional information about the neurophysiological (re)organization of the sensory thalamus.

Significance: Directional recordings of thalamic SEPs bear the potential to assist clinical decision-making in DBS for pain.

Keywords: Deep Brain Stimulation; High frequency components; Neuropathic pain; Somatosensory evoked potentials; Time–frequency analysis.