Treatment of Chronic Pain: Diffusion Tensor Imaging Identification of the Ventroposterolateral Nucleus Confirmed with Successful Deep Brain Stimulation

Abstract

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.

Diffusion Tensor Imaging-Based Thalamic Segmentation in Deep Brain Stimulation for Chronic Pain Conditions

“…Studies in non-human primates have shown that the thalamic ventrobasal complex (the caudal division of the VPL nucleus and the large-celled portion of the ventroposteromedial nucleus) project to primary and secondary somatosensory areas (S1 and S2) [23–31]. In humans, the ventroposterior nuclei (VPL and VPM) have the strongest probability of primary somatosensory cortical connectivity.…”

Deep Brain Stimulation for the Treatment of Dejerine-Roussy Syndrome

“…Current theory broadly postulates that DBS modulates fiber pathways in the pain network in order to treat chronic pain, although the exact mechanism is not understood [2,21,43,44,45,46]. DBS of the nucleus accumbens (NAcc) in control rats prompted a decreased metabolism in the basal ganglia and periaqueductal gray, while metabolism increased in the subiculum [47].…”

“…It is currently believed to constitute components of the lateral pain system, and as such the area became a major target of interest in the earliest studies of DBS for DRS [38,43,44,45]. Contemporary practice is to specifically target the VPM for facial pain, while the VPL can be a target for arm and leg pain [45].…”

DBSproc: An open source process for DBS electrode localization and tractographic analysis

“…Case studies characterizing optimal DBS targets using DTI have isolated specific relevant white‐matter targets [Anthofer et al, ; Kovanlikaya et al, ; Riva‐Posse et al, ; Schlaier et al, ; Sweet et al, ]. However, these studies have been limited to small sample sizes, and tractography measures have been based on deterministic rather than probabilistic tractography, whereas the latter has been demonstrated to provide more robust estimates of underlying white‐matter structures [Descoteaux et al, ].…”