scholarly journals Perspectives on (A)symmetry of Arcuate Fasciculus. A Short Review About Anatomy, Tractography and TMS for Arcuate Fasciculus Reconstruction in Planning Surgery for Gliomas in Language Areas

2021 ◽  
Vol 12 ◽  
Author(s):  
Andrea Di Cristofori ◽  
Gianpaolo Basso ◽  
Camilla de Laurentis ◽  
Ilaria Mauri ◽  
Martina Andrea Sirtori ◽  
...  
Keyword(s):  
Diffusion Tensor ◽  
Preoperative Evaluation ◽  
Brain Magnetic Resonance Imaging ◽  
Connectionist Model ◽  
Arcuate Fasciculus ◽  
Human Beings ◽  
Dominant Hemisphere ◽  
Language Functions ◽  
Dti Tractography ◽  
Language Areas

Gliomas are brain tumors that are treated with surgical resection. Prognosis is influenced by the extent of resection and postoperative neurological status. As consequence, given the extreme interindividual and interhemispheric variability of subcortical white matter (WM) surgical planning requires to be patient's tailored. According to the “connectionist model,” there is a huge variability among both cortical areas and subcortical WM in all human beings, and it is known that brain is able to reorganize itself and to adapt to WM lesions. Brain magnetic resonance imaging diffusion tensor imaging (DTI) tractography allows visualization of WM bundles. Nowadays DTI tractography is widely available in the clinical setting for presurgical planning. Arcuate fasciculus (AF) is a long WM bundle that connects the Broca's and Wernicke's regions with a complex anatomical architecture and important role in language functions. Thus, its preservation is important for the postoperative outcome, and DTI tractography is usually performed for planning surgery within the language-dominant hemisphere. High variability among individuals and an asymmetrical pattern has been reported for this WM bundle. However, the functional relevance of AF in the contralateral non-dominant hemisphere in case of tumoral or surgical lesion of the language-dominant AF is unclear. This review focuses on AF anatomy with special attention to its asymmetry in both normal and pathological conditions and how it may be explored with preoperative tools for planning surgery on gliomas in language areas. Based on the findings available in literature, we finally speculate about the potential role of preoperative evaluation of the WM contralateral to the surgical site.

Correlation between language function and the left arcuate fasciculus detected by diffusion tensor imaging tractography after brain tumor surgery

2012 ◽  
Vol 117 (5) ◽  
pp. 839-843 ◽  
Author(s):  
Yutaka Hayashi ◽  
Masashi Kinoshita ◽  
Mitsutoshi Nakada ◽  
Jun-ichiro Hamada
Keyword(s):  
Brain Tumor ◽  
Diffusion Tensor ◽  
Tumor Surgery ◽  
Language Function ◽  
Arcuate Fasciculus ◽  
Brain Tumor Surgery ◽  
Language Functions ◽  
Postoperative Changes ◽  
Dti Tractography

Object Disturbance of the arcuate fasciculus in the dominant hemisphere is thought to be associated with language-processing disorders, including conduction aphasia. Although the arcuate fasciculus can be visualized in vivo with diffusion tensor imaging (DTI) tractography, its involvement in functional processes associated with language has not been shown dynamically using DTI tractography. In the present study, to clarify the participation of the arcuate fasciculus in language functions, postoperative changes in the arcuate fasciculus detected by DTI tractography were evaluated chronologically in relation to postoperative changes in language function after brain tumor surgery. Methods Preoperative and postoperative arcuate fasciculus area and language function were examined in 7 right-handed patients with a brain tumor in the left hemisphere located in proximity to part of the arcuate fasciculus. The arcuate fasciculus was depicted, and its area was calculated using DTI tractography. Language functions were measured using the Western Aphasia Battery (WAB). Results After tumor resection, visualization of the arcuate fasciculus was increased in 5 of the 7 patients, and the total WAB score improved in 6 of the 7 patients. The relative ratio of postoperative visualized area of the arcuate fasciculus to preoperative visualized area of the arcuate fasciculus was increased in association with an improvement in postoperative language function (p = 0.0039). Conclusions The role of the left arcuate fasciculus in language functions can be evaluated chronologically in vivo by DTI tractography after brain tumor surgery. Because increased postoperative visualization of the fasciculus was significantly associated with postoperative improvement in language functions, the arcuate fasciculus may play an important role in language function, as previously thought. In addition, postoperative changes in the arcuate fasciculus detected by DTI tractography could represent a predicting factor for postoperative language-dependent functional outcomes in patients with brain tumor.

scholarly journals Positive relation between arcuate fasciculus white matter fiber structure and severity of auditory hallucinations: A DTI tractography study

2019 ◽  
Author(s):  
Liv E. Falkenberg ◽  
René Westerhausen ◽  
Erik Johnsen ◽  
Rune Kroken ◽  
Else-Marie Løberg ◽  
...  
Keyword(s):  
White Matter ◽  
Diffusion Tensor ◽  
Control Group ◽  
Arcuate Fasciculus ◽  
Auditory Verbal Hallucinations ◽  
Syndrome Scale ◽  
Healthy Control ◽  
Dti Tractography ◽  
Positive Correlations ◽  
Language Areas

AbstractThe arcuate fasciculus (AF) has been implicated in the pathology behind schizophrenia and auditory verbal hallucinations (AVHs). White matter tracts forming the arcuate fasciculus can be quantified and visualized using diffusion tensor imaging (DTI) tractography. Although there have been a number of studies on this topic, the results have been conflicting. Studying the underlying white matter structure of the AF could shed light on functional connectivity between temporal and frontal language areas in AVHs. The participants were 66 patients with a schizophrenia diagnosis, where AVHs were defined from the Positive and Negative Syndrome Scale (PANSS), and compared with a healthy control group. DTI was performed on a 3T MR scanner, and tensor estimation was done using deterministic streamline tractography. Statistical analysis of the data showed significantly longer tracts along the AF in patients with severe and frequent AVHs, as well as an overall significant asymmetry with longer fibers on the left side. In addition, there were significant positive correlations between PANSS scores and tract length, tract volume, and number of streamlines for the posterior AF segment on the left side. It is concluded that the present structural results complement previous functional findings of fronto-temporal connectivity in AVH patients.

Impairment and Plasticity of Language-Related White Matter in Patients With Brain Arteriovenous Malformations

Stroke ◽  
2021 ◽  
Author(s):  
Xiaofeng Deng ◽  
Hu Yin ◽  
Yan Zhang ◽  
Dong Zhang ◽  
Shuo Wang ◽  
...  
Keyword(s):  
White Matter ◽  
Diffusion Tensor ◽  
Disease Model ◽  
Control Group ◽  
Language Functions ◽  
Traditional Language ◽  
The Difference ◽  
Uncinate Fascicle ◽  
Myelin Deficits ◽  
Language Areas

Background and Purpose: Language dysfunction is rarely seen in patients with unruptured brain arteriovenous malformation (AVM) albeit the AVM nidus involving language areas, which provides a unique disease model to study language reorganization. The objective of this study was to investigate the impairment and reorganization patterns and characteristics of language-related white matter in AVMs located at different brain areas. Methods: Thirty-three patients with AVMs involving language areas were prospectively enrolled. Patients were categorized into 3 groups according to the lesion locations: the frontal (14 patients), temporal (15 patients), and parietal groups (4 patients). Thirty age- and sex-matched healthy controls were enrolled as comparison. All participants underwent diffusion tensor imaging scans, and automated fiber quantification method was applied to quantitatively study the difference of segmented language-related white matter connectivity between 3 AVM groups and control group. Results: Language functions were normal in all subjects according to Western Aphasia Battery test. In the frontal group, fractional anisotropy (FA) value decreased in the left arcuate fascicle and increased in left superior longitudinal fasciculus and uncinate fascicle; in the temporal group, FA values decreased in left inferior fronto-occipital fascicle and inferior longitudinal fascicle and increased in right anterior thalamic radiation and uncinate fascicle; in the parietal group, FA values decreased in left arcuate fascicle and inferior longitudinal fascicle and increased in bilateral anterior thalamic radiations and uncinate fascicles and right inferior fronto-occipital fascicle. In fascicles with decreased FA values, the increase of radial diffusivity was common, and fascicles with increased FA values usually presented along with increased axial diffusivity values. Conclusions: Remodeling of language-related white matter occurs when traditional language areas are involved by AVM nidus, and its reorganization patterns vary with locations of AVM nidus. Fascicle impairment is mainly caused by the myelin deficits, and its plasticity may be dominated by the axon remodeling procedure.

Visualization of the frontotemporal language fibers by tractography combined with functional magnetic resonance imaging and magnetoencephalography

2007 ◽  
Vol 106 (1) ◽  
pp. 90-98 ◽  
Author(s):  
Kyousuke Kamada ◽  
Tomoki Todo ◽  
Yoshitaka Masutani ◽  
Shigeki Aoki ◽  
Kenji Ino ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Diffusion Tensor ◽  
Tumor Resection ◽  
Awake Surgery ◽  
Hemispheric Dominance ◽  
Dominant Hemisphere ◽  
Functional Magnetic Resonance ◽  
Accurate Identification ◽  
Generation Task ◽  
Language Functions

Object There is continuous interest in the monitoring of language function during tumor resection around the fron-totemporal regions of the dominant hemisphere. The aim of this study was to visualize language-related subcortical connections, such as the arcuate fasciculus (AF) by diffusion tensor (DT) imaging–based tractography. Methods Twenty-two patients with brain lesions adjacent to the AF in the frontotemporal regions of the dominant hemisphere were studied. The AF tractography was accomplished by placing initiation and termination sites (seed and target points) in the frontal and temporal regions, which were functionally identified by using functional magnetic resonance (fMR) imaging in conjunction with a verb generation task and magnetoencephalography (MEG) in conjunction with a reading task. The combination of fMR imaging and MEG data clearly demonstrated the hemispheric dominance of language functions, which was confirmed by an intracranial amobarbital test (Wada procedure). In all 22 patients, the authors were able to consistently visualize the AF by DT imaging–based tractography, using the functionally identified seed and target points and a fractional anisotropy value of 0.16. In two of 22 cases investigated, the functional information, including the results of AF tractography, fMR imaging, and MEG, was imported to a neuronavigation system and was validated by bipolar electric stimulation of the cortical and subcortical areas during awake surgery. The cortical stimulation to the gyrus that included the area of activation identified in fMR imaging with the language task evoked speech arrest, while the subcortical stimulation close to the AF reproducibly caused paranomia without speech arrest. Postoperative AF tractography showed that the distances between the stimulus points and the AF were within 6 mm. Conclusions The combination of these techniques facilitated accurate identification of the location of the AF and verification of the language fibers.

scholarly journals Delayed development of aphasia related to degeneration of the arcuate fasciculus in the dominant hemisphere nine years after the onset in a patient with intracerebral hemorrhage: a case report

BMC Neurology ◽  
2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Min Jye Cho ◽  
Sung Ho Jang
Keyword(s):  
Intracerebral Hemorrhage ◽  
Diffusion Tensor ◽  
Mean Diffusivity ◽  
Magnetic Resonance Images ◽  
Arcuate Fasciculus ◽  
Dominant Hemisphere ◽  
Neural Degeneration ◽  
Delayed Development ◽  
Hemosiderin Deposits ◽  
Post Onset

Abstract Background We report on a patient with an intracerebral hemorrhage (ICH), who showed delayed development of aphasia, which was demonstrated via follow up diffusion tensor tractography (DTT) to be related to neural degeneration of the arcuate fasciculus (AF). Case presentation A 51-year-old, right-handed male presented with right hemiparesis, which occurred at the onset of a spontaneous ICH in the left corona radiata and basal ganglia. Brain magnetic resonance images showed a hematoma in the left subcortical area at one month after onset and hemosiderin deposits in the left subcortical area at nine years after onset. At four weeks after onset, he exhibited severe aphasia, and Western Aphasia Battery (WAB) testing revealed an aphasia quotient in the 39.6 percentile (%ile). However, his aphasia improved to nearly a normal state, and at three months after onset, his aphasia quotient was in the 90.5 %ile. At approximately eight years after onset, he began to show aphasia, and his aphasia increased slowly with time resulting in a WAB aphasia quotient in the 12.5 %ile at nine years after onset. The integrity of the left AF over the hematoma was preserved on 1-month post-onset DTT. However, the middle portion of the left AF in the middle of the hemosiderin deposits showed discontinuation on 9-year post-onset DTT. The fractional anisotropy value of the left AF was higher on the 9-year post-onset DTT (0.48) than that on the 1-month post-onset DTT (0.35), whereas the mean diffusivity value was lower on the 9-year post-onset DTT (0.10) than that on the 1-month post-onset DTT (0.32). The fiber number of the left AF was decreased to 175 on the 9-year post-onset DTT from 239 on the 1-month post-onset DTT. Conclusions We report on a patient with ICH who showed delayed development of aphasia, which appeared to be related to degeneration of the AF in the dominant hemisphere. Our results suggest that DTT would be useful in ruling out neural degeneration of the AF.

scholarly journals Language hemispheric dominance analyzed with magnetic resonance DTI: correlation with the Wada test

2020 ◽  
pp. 1-8
Author(s):  
Juan Delgado-Fernández ◽  
Maria Ángeles García-Pallero ◽  
Rafael Manzanares-Soler ◽  
Pilar Martín-Plasencia ◽  
Guillermo Blasco ◽  
...  
Keyword(s):  
Epilepsy Surgery ◽  
Diffusion Tensor ◽  
Hemispheric Dominance ◽  
Uncinate Fasciculus ◽  
Arcuate Fasciculus ◽  
Dominant Hemisphere ◽  
Wada Test ◽  
Pharmacoresistant Epilepsy ◽  
Linear Discriminant ◽  
Dominance Testing

OBJECTIVELanguage lateralization is a major concern in some patients with pharmacoresistant epilepsy who will face surgery; in these patients, hemispheric dominance testing is essential to avoid further complications. The Wada test is considered the gold standard examination for language localization, but is invasive and requires many human and material resources. Functional MRI and tractography with diffusion tensor imaging (DTI) have demonstrated that they could be useful for locating language in epilepsy surgery, but there is no evidence of the correlation between the Wada test and DTI MRI in language dominance.METHODSThe authors performed a retrospective review of patients who underwent a Wada test before epilepsy surgery at their institution from 2012 to 2017. The authors retrospectively analyzed fractional anisotropy (FA), number and length of fibers, and volume of the arcuate fasciculus and uncinate fasciculus, comparing dominant and nondominant hemispheres.RESULTSTen patients with temporal lobe epilepsy were reviewed. Statistical analysis showed that the mean FA of the arcuate fasciculus in the dominant hemisphere was higher than in the nondominant hemisphere (0.369 vs 0.329, p = 0.049). Also, the number of fibers in the arcuate fasciculus was greater in the dominant hemisphere (881.5 vs 305.4, p = 0.003). However, no differences were found in the FA of the uncinate fasciculus or number of fibers between hemispheres. The length of fibers of the uncinate fasciculus was longer in the dominant side (74.4 vs 50.1 mm, p = 0.05). Volume in both bundles was more prominent in the dominant hemisphere (12.12 vs 6.48 cm3, p = 0.004, in the arcuate fasciculus, and 8.41 vs 4.16 cm3, p = 0.018, in the uncinate fasciculus). Finally, these parameters were compared in patients in whom the seizure focus was situated in the dominant hemisphere: FA (0.37 vs 0.30, p = 0.05), number of fibers (114.4 vs 315.6, p = 0.014), and volume (12.58 vs 5.88 cm3, p = 0.035) in the arcuate fasciculus were found to be statistically significantly higher in the dominant hemispheres. Linear discriminant analysis of FA, number of fibers, and volume of the arcuate fasciculus showed a correct discrimination in 80% of patients (p = 0.024).CONCLUSIONSThe analysis of the arcuate fasciculus and other tract bundles by DTI could be a useful tool for language location testing in the preoperative study of patients with refractory epilepsy.

scholarly journals The utility of diffusion tractography for speech preservation in laser ablation of the dominant insula: illustrative case

2021 ◽  
Vol 1 (19) ◽  
Author(s):  
Timothy J. Kaufmann ◽  
Vance T. Lehman ◽  
Lily C. Wong-Kisiel ◽  
Panagiotis Kerezoudis ◽  
Kai J. Miller
Keyword(s):  
Laser Ablation ◽  
White Matter ◽  
Diffusion Tensor ◽  
Neurological Deficits ◽  
Illustrative Case ◽  
Dominant Hemisphere ◽  
White Matter Tracts ◽  
Dti Tractography ◽  
Magnetic Resonance Imaging Mri ◽  
Open Surgical Treatment

BACKGROUND Open surgical treatment of insular epilepsy holds particular risk of injury to middle cerebral artery branches, the operculum (through retraction), and adjacent language-related white matter tracts in the language-dominant hemisphere. Magnetic resonance imaging (MRI)-guided laser interstitial thermal therapy (LITT) is a surgical alternative that allows precise lesioning with potentially less operative risk. The authors presented the case of a 13-year-old girl with intractable, MRI-negative, left (dominant hemisphere) insular epilepsy that was treated with LITT. Diffusion tensor imaging (DTI) tractography was used to aid full posterior insular lesioning in the region of stereo electroencephalography–determined seizure onset while avoiding thermal injury to the language-related superior longitudinal fasciculus (SLF)/arcuate fasciculus (AF) and inferior fronto-occipital fasciculus (IFOF). OBSERVATIONS DTI tractography was used successfully in planning insular LITT and facilitated a robust insular ablation with sharp margins at the interfaces with the SLF/AF and IFOF. These tracts were spared, and no neurological deficits were induced through LITT. LESSONS Although it is technically demanding and has important limitations that must be understood, clinically available DTI tractography adds precision and confidence to insular laser ablation when used to protect important language-related white matter tracts.

Changes in the corticospinal tract after wearing prosthesis in bilateral transtibial amputation

2017 ◽  
Vol 41 (5) ◽  
pp. 507-511
Author(s):  
Sang Yoon Lee ◽  
Si Hyun Kang ◽  
Don-Kyu Kim ◽  
Kyung Mook Seo ◽  
Hee Joon Ro ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Diffusion Tensor Imaging ◽  
Magnetic Resonance ◽  
Primary Motor Cortex ◽  
Corticospinal Tract ◽  
Diffusion Tensor ◽  
Brain Magnetic Resonance Imaging ◽  
Resonance Imaging ◽  
Transtibial Amputation

Background:After amputation, the brain is known to be reorganized especially in the primary motor cortex. We report a case to show changes in the corticospinal tract in a patient with serial bilateral transtibial amputations using diffusion tensor imaging.Case Description and Methods:A 78-year-old man had a transtibial amputation on his left side in 2008 and he underwent a right transtibial amputation in 2011. An initial brain magnetic resonance imaging with a diffusion tensor imaging was performed before starting rehabilitation on his right transtibial prosthesis, and a follow-up magnetic resonance imaging with diffusion tensor imaging was performed 2 years after this.Findings and Outcomes:In the initial diffusion tensor imaging, the number of fiber lines in his right corticospinal tract was larger than that in his left corticospinal tract. At follow-up diffusion tensor imaging, there was no definite difference in the number of fiber lines between both corticospinal tracts.Conclusion:We found that side-to-side corticospinal tract differences were equalized after using bilateral prostheses.Clinical relevanceThis case report suggests that diffusion tensor imaging tractography could be a useful method to understand corticomotor reorganization after using prosthesis in transtibial amputation.

Abstract 14258: Modulation of Kynurenine Pathway to Prevent Brain Injury After Cardiac Arrest and Cardiopulmonary Resuscitation in Mice

Circulation ◽  
2021 ◽  
Vol 144 (Suppl_2) ◽  
Author(s):  
Aurora Magliocca ◽  
Carlo Perego ◽  
Francesca Motta ◽  
Giulia Merigo ◽  
Francesca M Fumagalli ◽  
...  
Keyword(s):  
Cardiac Arrest ◽  
Neurological Outcome ◽  
Diffusion Tensor ◽  
Neuroprotective Effect ◽  
Brain Mri ◽  
Brain Magnetic Resonance Imaging ◽  
Kynurenine Pathway ◽  
Baseline Heart Rate ◽  
Brain White Matter ◽  
Fluoro Jade B

Introduction: Kynurenine pathway (KP) is emerging as one of the potential components affecting cardiac arrest (CA) outcomes. The aim of this study is to evaluate the effects of KP inhibition through genetic deletion of the rate-limiting enzyme of the KP, indoleamine-2,3-dyoxygenase (IDO) on survival and neurological outcome after CA. Methods and Results: Sixteen adult male wild-type (WT) and IDO-deleted (IDO -/- ) mice were subjected to 8 min untreated CA followed by resuscitation. At baseline heart rate and mean arterial pressure (MAP) did not differ among groups. At the time of return of spontaneous circulation, 30 and 60 min later, MAP was higher in the IDO -/- group compared to the WT one (p=0.0005). IDO -/- mice showed higher survival compared to WT at 7 days after CA (68.5% in IDO -/- vs 37.5% in WT; log rank p=0.036). Neurological function was higher in IDO -/- than in WT mice during the 7 days following CA (p=0.0124). IDO -/- mice also showed an improved locomotor function compared to WT mice (p=0.037). Brain magnetic resonance imaging (MRI) with diffusion tensor imaging (DTI) sequences showed a reduction in fractional anisotropy in the external capsule of the corpus callosum in WT mice compared to IDO -/- mice at 7 days after resuscitation (p=0.015). We then treated additional IDO -/- mice with L-kyn 15 min before CA, to revert the IDO -/- phenotype. Brain MRI with diffusion-weighted imaging (DWI) sequences and histological analysis were performed 24h after CA in WT, IDO -/- , and IDO -/- +L-Kyn mice. Brain MRI revealed restriction of water diffusivity 24h after CA in WT mice. IDO-deletion reduced water diffusion abnormalities while the beneficial effect was reverted in the L-kyn group (p=0.01). Degenerating neurons in the frontal cortex, represented as Fluoro-Jade B positive cells, were more numerous in WT compared to IDO -/- mice; L-kyn halted this IDO deletion-induced reduction in degenerating cells (p=0.05). Conclusion: KP inhibition improves survival and neurological outcome after CA. The neuroprotective effect of IDO-deletion was associated with preservation of brain white matter microintegrity and with reduction of cerebral cytotoxic edema. Reversal of these beneficial effects by L-kyn administration in IDO -/- mice further confirm the KP role in CA outcome.

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