Treatment of chronic pain: diffusion tensor imaging identification of the ventroposterolateral nucleus confirmed with successful deep brain stimulation.

BACKGROUND/AIMS: A variety of pain syndromes have been treated successfully with deep brain stimulation (DBS) by targeting the thalamic ventroposterolateral (VPL) nucleus. The purpose of this study was to preoperatively identify the thalamic VPL nucleus by diffusion tensor imaging (DTI) fiber tractography (FT) and confirm it intraoperatively.

METHODS AND RESULTS: FT was performed to identify the thalamic VPL nucleus in 6 healthy volunteers and a patient with intractable chronic pain. The patient had preoperative DTI followed by DBS with the electrode placed by conventional stereotactic methods. Postoperative CT images of the DBS electrode tip were fused with the preoperative DTI and the electrode was noted to be in the position of the VPL nucleus predicted preoperatively by FT. The electrode was then used as a seed region of interest (ROI) to confirm FT back to the somatosensory cortex. Clinical confirmation was also achieved with the patient's pain relief. In all volunteers, VPL nuclei were identified in similar locations in both thalami, although slight inter- and intrasubject differences were observed.

CONCLUSION: DTI has the potential to identify the thalamic nuclei in individuals, which would be more accurate than anatomical localization and likely identical to intraoperative physiological testing. Postoperative DBS electrode placement and the affected cortical areas can be confirmed with coregistration of CT and FT using the electrode as a seed ROI.