Widespread gray matter abnormalities in patients with TN. (A) CT analysis revealed several cortical gray matter abnormalities in TN patients. Compared to controls, patients had thinner cortex (red clusters) in the pgACC bilaterally, the right ins including the dorsal posterior insula and the ventral anterior insula (vAI), and the ventral OFC bilaterally. TN patients had thicker cortex (blue clusters) in the bilateral FP and M1, and left S1 (putative face area, contralateral to their side of pain). (B) Patients also had several subcortical gray matter abnormalities as determined using voxel-based morphometry. Compared to controls, TN patient had larger volumes (blue clusters) in the sensory thalamus, including the MD and VPM thalamus bilaterally, the right amygdala, the posterior putamen bilaterally, PAG (green box shows magnified region), and regions of the right NAc, anterior putamen, and caudate. (C) Prior to surgery, CT abnormalities (compared to healthy controls) in the pgACC, the OFC and M1, were more pronounced in the TN patients who had significant pain relief after effective Tx (blue bars) compared to those in which treatment was ineffective (red bars). These pre-treatment baseline CT levels were significantly different between the groups of patients that achieved effective vs. ineffective effects of surgery. While it remains unknown as to whether these abnormalities are a consequence of the pain or are pre-existing and contribute to the development of TN, these preliminary data suggest that certain abnormalities may have predictive value to identify patients that will benefit from treatment. Abbreviations: LH, left hemisphere; RH, right hemisphere; R, right; L, left; pgACC, pregenual anterior cingulate cortex; PCC, posterior cingulate cortex; ins, insular cortex; OFC, orbitofrontal cortex; FP, frontal pole; M1, primary motor cortex; S1, primary somatosensory cortex. MD, medial dorsal nucleus (thalamus); VPM, ventral posterior medial nucleus (thalamus); NAc, nucleus accumbens; PAG, periaqueductal gray. CT, cortical thickness; Tx, treatment. Panels (A,B) have been reproduced from DeSouza et al. (2013); © 2013 DeSouza et al.