Plasticity in language cortex and white matter tracts after resection of dominant inferior parietal lobule arteriovenous malformations: a combined fMRI and DTI study

Abstract

<jats:sec><jats:title>OBJECTIVE</jats:title><jats:p>The dominant inferior parietal lobe (IPL) contains cortical and subcortical structures that serve language processing. A high incidence of postoperative short-term aphasia and good potential for language reorganization have been observed. The authors’ goal was to study the plasticity of the language cortex and language-related fibers in patients with brain arteriovenous malformations (BAVMs) located in the IPL.</jats:p></jats:sec><jats:sec><jats:title>METHODS</jats:title><jats:p>A total of 6 patients who underwent microsurgical treatment of an IPL BAVM were prospectively recruited between September 2016 and May 2018. Blood oxygen level–dependent functional MRI (BOLD-fMRI) and diffusion tensor imaging (DTI) were performed within 1 week before and 6 months after microsurgery. Language-related white matter (WM) eloquent fiber tracts and their contralateral homologous fiber tracts were tracked. The Western Aphasia Battery was administered to assess language function. The authors determined the total number of fibers and mean fractional anisotropy (FA) indices for each individual tract. In addition, they calculated the laterality index (LI) between the activated language cortex voxels in the lesional and contralesional hemispheres and compared these indices between the preoperative and postoperative fMR and DT images.</jats:p></jats:sec><jats:sec><jats:title>RESULTS</jats:title><jats:p>Of the 6 patients with IPL BAVMs, all experienced postoperative short-term language deficits, and 5 (83.3%) recovered completely at 6 months after surgery. Five patients (83.3%) had right homologous reorganization of BOLD signal activations in both Broca’s and Wernicke’s areas. More fibers were observed in the arcuate fasciculus (AF) in the lesional hemisphere than in the contralesional hemisphere (1905 vs 254 fibers, p = 0.035). Six months after surgery, a significantly increased number of fibers was seen in the right hemispheric AF (249 fibers preoperatively vs 485 postoperatively, p = 0.026). There were significantly more nerve fibers in the postoperative left inferior frontooccipital fasciculus (IFOF) (874 fibers preoperatively vs 1186 postoperatively, p = 0.010). A statistically significant increase in right hemispheric dominance of Wernicke’s area was observed. The overall functional LI showed functional lateralization of Wernicke’s area in the right hemisphere (LI ≤ −0.20) in all patients.</jats:p></jats:sec><jats:sec><jats:title>CONCLUSIONS</jats:title><jats:p>The authors’ findings provide evidence for the functional reorganization by recruiting the right hemispheric homologous region of Broca’s and Wernicke’s areas, right hemispheric AFs, and left hemispheric IFOFs following resection of IPL BAVMs.</jats:p><jats:p>Clinical trial registration no.: NCT02868008 (clinicaltrials.gov)</jats:p></jats:sec>

Altered Topological Patterns of Gray Matter Networks in Tinnitus: A Graph-Theoretical-Based Study

“…Combining the above, results in this study should be interpreted with caution, and future studies investigating causal relations in the network dynamics are strongly suggested. For instance, resting-state fMRI could be combined with structural MRI to investigate the possible topographical changes in the functional network (Salvador et al, 2005;Achard et al, 2006), building a weighted network with multi-modality approaches such as fMRI and DTI (Jiao et al, 2020), or using combined volume-based and tract-based approaches (Husain et al, 2011) along with graphtheoretical analyses to investigate the causal relationship between duration/severity and brain network topology.…”

The structural connectivity of the human angular gyrus as revealed by microdissection and diffusion tractography

“…9). These local (short-range) cortical connections (involving both Wernicke and Geschwind territories and the convexity of the occipital cortex) play a role in the integration of visual stimuli in the verbal semantic processing and could play a role in the local plasticity phenomena supporting language recovery after restricted damage at the temporo-parieto-occipital junction in the left hemisphere (Sarubbo et al 2012;Jiao et al 2020).…”

Diffusion tensor imaging, intra-operative neurophysiological monitoring and small craniotomy: Results in a consecutive series of 103 gliomas

“…Moreover, it has been shown that cortical areas can undergo brain plasticity phenomena, much more relevant than white matter tracts ( 6 , 49 ). Based on these considerations, it becomes clear that the possibility to know in advance the location of the main white matter tracts and their relationships with a brain tumor constitutes a fundamental help for neurosurgeons approaching a brain tumor resection ( 50 – 53 ). DTI allows to reconstruct and visualize the most important white matter tracts on anatomical MR images of patients, permitting to build a personalized and complete surgical planning.…”