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

• A clear directionality of somatosensory evoked potentials recorded from segmented DBS leads in the sensory thalamus is observed. • This directional effect provides further evidence in support of the somatotopy of the sensory thalamus. • This may help identify the neurophysiological sweet spot in the possibly reorganized sensory thalamus in chronic pain patients. 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. 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. 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. SEP recordings from directional DBS leads offer additional information about the neurophysiological (re)organization of the sensory thalamus. Directional recordings of thalamic SEPs bear the potential to assist clinical decision-making in DBS for pain. [ABSTRACT FROM AUTHOR]