Diffusion tensor tractography-based analysis of the cingulum: clinical utility and findings in traumatic brain injury with chronic sequels

Association of cognitive-linguistic deficits to diffusion tensor imaging parameters in moderate to severe traumatic diffuse axonal injury

Cognitive-linguistic functions are an essential part of adequate communication competence. Cognitive-linguistic deficits are common after traumatic diffuse axonal injury (DAI). We aimed to examine the integrity of perisylvian white matter tracts known to be associated with linguistic functions in individuals with DAI and their eventual association with poor cognitive-linguistic outcomes. Diffusion tensor imaging (DTI) results of 44 adults with moderate-to-severe DAI were compared with those of 67 controls. Fractional anisotropy (FA) values of the superior longitudinal fasciculus (SLF), arcuate fasciculus (AF), SLF with frontal connections to the lower parietal cortex, and AF with temporal connections to the lower parietal cortex were measured using tractography. The associations between white matter integrity FA values and cognitive-linguistic deficits were studied in the DAI group. Cognitive-linguistic deficits were determined based on our earlier study using the novel KAT test. No previous studies have examined the associations between white matter integrity and cognitive-linguistic deficits determined using the KAT test. Patients with DAI showed lower FA values in all left-side tracts than the controls. Unexpectedly, the poor cognitive-linguistic outcome in the language comprehension and production domains was associated with high FA values of several tracts. After excluding five cases with the poorest cognitive-linguistic performance, but with the highest values in the DTI variables, no significant associations with DTI metrics were found. The association between white matter integrity and cognitive-linguistic functioning is complex in patients with DAI of traumatic origin, probably reflecting the heterogeneity of TBI.

Fixel-based analysis of the diffusion properties of the patients with brain injury and chronic health symptoms

The diffusion properties from diffusion tensor imaging (DTI) are sensitive to white matter (WM) abnormalities and could serve as indicators of diffuse axonal damages incurred during a traumatic brain injury (TBI). Analyses of diffusion metrics in the regions of interest (ROIs) were used to compare the differences in the 18 major fiber tracts in 46 participants, between TBI participants with (n = 17) or without (n = 16) chronic symptoms (CS) and a control group (CG, n = 13). In addition to the widely used diffusion metrics, such as fractional anisotropy (FA), mean (MD), axial (AD) and radial (RD) diffusivities, apparent fiber density (AFD), complexity (CX) and fixel number (FN) derived from Mrtrix3 software package were used to characterize WM tracts and compare between participant groups in the ROIs defined by the fixel numbers. Significant differences were found in FA, AFD, MD, RD and CX in ROIs with different FNs in the corpus callosum forceps minor, left and right inferior longitudinal fasciculus, and left and right uncinate fasciculus for both TBI groups compared to controls. Diffusion properties in ROIs with different FNs can serve as detailed biomarkers of WM abnormalities, especially for individuals with chronic TBI related symptoms.

A patient with Korsakoff syndrome of psychiatric and alcoholic etiology presenting as DSM-5 mild neurocognitive disorder

Background: Wernicke's encephalopathy (WE) and Korsakoff syndrome (KS) are underdiagnosed. The DSM-5 has raised the diagnostic threshold by including KS in the major neurocognitive disorders, which requires that the patient needs help in everyday activities. Methods: We report clinical, neuropsychological, and radiological findings from a patient who developed Wernicke-Korsakoff syndrome as a result of alcohol use and weight loss due to major depression. We assess the diagnosis in the context of the scientific literature on KS and according to the DSM-IV and the DSM-5. Results: The patient developed ataxia during a period of weight loss, thus fulfilling current diagnostic criteria of WE. WE was not diagnosed, but the patient partially improved after parenteral thiamine treatment. However, memory problems became evident, and KS was considered. In neuropsychological examination, the Logical Memory test and the Word List test were abnormal, but the Verbal Pair Associates test was normal (Wechsler Memory Scale-III). There were intrusions in the memory testing. The Wisconsin Card Sorting Test was broadly impaired, but the other test of executive functions (difference between Trail Making B and Trail Making A tests) was normal. There was atrophy of the mammillary bodies, the thalamus, the cerebellum, and in the basal ganglia but not in the frontal lobes. Diffusion tensor imaging showed damage in several tracts, including the uncinate fasciculi, the cinguli, the fornix, and the corona radiata. The patient remained independent in everyday activities. The patient can be diagnosed with KS according to the DSM-IV. According to the DSM-5, the patient has major neurocognitive disorders. Conclusions: Extensive memory testing is essential in the assessment of KS. Patients with a history of WE and typical clinical, neuropsychological, and radiological KS findings may be independent in everyday activities. Strict use of the DSM-5 may worsen the problem of Wernicke-Korsakoff syndrome underdiagnosis by excluding clear KS cases that do not have very severe functional impairment.

Traumatic axonal injury of the cingulum in patients with mild traumatic brain injury: a diffusion tensor tractography study

The cingulum, connecting the orbitofrontal cortex to the medial temporal lobe, involves in diverse cognition functions including attention, memory, and motivation. To investigate the relationship between the cingulum injury and cognitive impairment in patients with chronic mild traumatic brain injury, we evaluated the integrity between the anterior cingulum and the basal forebrain using diffusion tensor tractography in 73 patients with chronic mild traumatic brain injury (39 males, 34 females, age 43.29 ± 11.42 years) and 40 healthy controls (22 males, 18 females, age 40.11 ± 16.81 years). The patients were divided into three subgroups based on the integrity between the anterior cingulum and the basal forebrain on diffusion tensor tractography: subgroup A (n = 19 patients) - both sides of the anterior cingulum were intact; subgroup B (n = 36 patients) - either side of the anterior cingulum was intact; and subgroup C (18 patients) - both sides of the anterior cingulum were discontinued. There were significant differences in total Memory Assessment Scale score between subgroups A and B and between subgroups A and C. There were no significant differences in diffusion tensor tractography parameters (fractional anisotropy, apparent diffusion coefficient, and fiber volume) between patients and controls. These findings suggest that the integrity between the anterior cingulum and the basal forebrain, but not diffusion tensor tractography parameter, can be used to predict the cognitive function of patients with chronic mild traumatic brain injury. This study was approved by Yeungnam University Hospital Institutional Review Board (approval No. YUMC-2014-01-425-010) on August 16, 2017.

Structural networks analysis for depression combined with graph theory and the properties of fiber tracts via diffusion tensor imaging

Previous studies have suggested that major depressive disorder was associated with topological properties of impaired white matter. However, most related studies only use one property of nerve fibers to construct whole-brain structural brain network. Considering white matter changes variously, We hypothesized whether the alternations of white matter topological properties could reflect different impairment of white matter integrity. In addition, it is still unknown whether impaired integrity of the white matter fiber tracts has relationship with abnormal topological properties in MDD. This study investigated the impaired white matter by using graph theoretic analyses in a cohort of 37 MDD patients and 38 matched control subjects. In addition, we further investigated fiber tracts differences in three interregional connectivity matrixes of significant different topological regions in MDD. Our graph theoretic analyses demonstrated that 7 different regions were observed for the local measures in patients with MDD compared with control groups. These regions were the central nodes of cortical-limbic network, frontal-cingulate network, default mode network (DMN), cognitive control network(CCN)and affective network (AN). In addition, two impaired white matter pathways which included inferior longitudinal fasciculus (ILF) and cingulum were observed in MDD using fiber tracts analysis. We speculate impaired integrity of ILF is due to the alternations in the number of axons or myelination. The results further demonstrated that the number of fiber tracts of anterior cingulum was associated with the depression scores in MDD.

Diffusion parameters of the core of cingulum are associated with age-related ventricular enlargement: a diffusion tensor tractography study

PURPOSE

To evaluate the influence of the size of lateral ventricles on diffusion parameters of the normal cingulate bundle.

METHODS

Eighty normal subjects (17-55 years) underwent MRI at 3 T including diffusion tensor imaging. Superior (SC) and inferior (IC) cingulum were analyzed separately. Mean diffusivity (MD_0.30) and fractional anisotropy (FA_0.30) were measured by tractography at FA threshold 0.30; further diffusion parameters were analyzed by tractography-based core analysis in volumes of 3.0 cm³/1.5 cm³. The diffusion parameters were correlated with corresponding cross-sectional coronal areas of lateral ventricles. The analysis was performed also separately for young (17-34) and middle-aged (35-55) subjects.

RESULTS

FA_0.30 values did not correlate with ventricular size, but there was a weak negative correlation (r = - 0.225) between MD_0.30 of SC and ventricular size. In all controls and in the older age group, ventricular size correlated positively with core FA of SC (r = 0.262/r = 0.391) and negatively with mean diffusivity (r = - 0.324/r = - 0.303) and radial diffusivity (λ₂: r = - 0.238/r = - 0.277; λ₃: r = - 0.353/r = - 0.424) of the core of SC. In the younger age group, only the mean diffusivity of SC correlated with ventricular size (r = - 0.273). Ventricular size was not associated with axial diffusivity. The core parameters of IC did not correlate with ventricular size.

CONCLUSION

Radial diffusivity of the core of cingulum decreases in age-dependent ventricular enlargement, which can be related to tissue compaction with stretching of axons and diminution of extracellular spaces. The phenomenon, which is reverse to the assumed effect of age-related myelin loss, can influence on DTI parameters in middle-aged subjects.

Mechanism of cognitive impairment in chronic patients with putaminal hemorrhage: A diffusion tensor tractography

It is not clear whether the fornix and cingulum are involved in cognition after putaminal hemorrhage (PH). We investigated structural changes and differences of the neural tracts, and the relationship between the integrity of the neural tracts and cognition not only at the affected but also at the unaffected side.Sixteen patients with left chronic putaminal hemorrhage and 20 healthy volunteers were enrolled. Using diffusion tensor tractography (DTT), we compared fiber number (FN), fractional anisotropy (FA), and apparent diffusion coefficient (ADC) of the neural tracts between patient and control groups. The relationship between the neural tract parameters and neuropsychological results was also analyzed.The left fornix FN was significantly lower than the right fornix FN in the patient group. Except for the cingulum FA, the neural tracts parameters for both the affected and unaffected hemispheres differed significantly between the groups. The fornix FA and ADC at the affected side were significantly correlated with intelligence quotient (IQ), mini-mental status examination (MMSE), and short-term memory. Interestingly, the fornix ADC at the unaffected side was significantly correlated with MMSE. However, none of the cingulum parameters was correlated with neuropsychological results.The fornix integrity is critical for cognitive impairment after putaminal hemorrhage.

Korsakoff Syndrome in Non-alcoholic Psychiatric Patients. Variable Cognitive Presentation and Impaired Frontotemporal Connectivity

Background: Non-alcoholic Wernicke's encephalopathy and Korsakoff syndrome are greatly underdiagnosed. There are very few reported cases of neuropsychologically documented non-alcoholic Korsakoff syndrome, and diffusion tensor imaging (DTI) data are scarce. Methods: We report clinical characteristics and neuropsychological as well as radiological findings from three psychiatric patients (one woman and two men) with a history of probable undiagnosed non-alcoholic Wernicke's encephalopathy and subsequent chronic memory problems. Results: All patients had abnormal neuropsychological test results, predominantly in memory. Thus, the neuropsychological findings were compatible with Korsakoff syndrome. However, the neuropsychological findings were not uniform. The impairment of delayed verbal memory of the first patient was evident only when the results of the memory tests were compared to her general cognitive level. In addition, the logical memory test and the verbal working memory test were abnormal, but the word list memory test was normal. The second patient had impaired attention and psychomotor speed in addition to impaired memory. In the third patient, the word list memory test was abnormal, but the logical memory test was normal. All patients had intrusions in the neuropsychological examination. Executive functions were preserved, except for planning and foresight, which were impaired in two patients. Conventional MRI examination was normal. DTI showed reduced fractional anisotropy values in the uncinate fasciculus in two patients, and in the corpus callosum and in the subgenual cingulum in one patient. Conclusions: Non-alcoholic Korsakoff syndrome can have diverse neuropsychological findings. This may partly explain its marked underdiagnosis. Therefore, a strong index of suspicion is needed. The presence of intrusions in the neuropsychological examination supports the diagnosis. Damage in frontotemporal white matter tracts, particularly in the uncinate fasciculus, may be a feature of non-alcoholic Korsakoff syndrome in psychiatric patients.

Minimally Invasive Surgery for Evacuating the Intracerebral Hematoma in Early Stages Decreased Secondary Damages to the Internal Capsule in Dog Model of ICH Observed by Diffusion Tensor Imaging

BACKGROUND

Diffusion tensor imaging was used to observe the effects of performing early minimally invasive surgery (MIS) on internal capsule in dog model of intracerebral hemorrhage (ICH).

METHODS

Twenty-five male dogs were selected to prepare an ICH model, and then they were randomly distributed into a model control (MC) group (5 dogs) or an MIS group (20 dogs). In the MIS group, the intracerebral hematoma was evacuated by stereotactic minimally invasive procedures over 6 hours (5 dogs), 12 hours (5 dogs), 18 hours (5 dogs), or 24 hours (5 dogs) after successful induction of ICH. The same procedure was performed in the MC group but without evacuating the hematoma. All the animals were sacrificed within 2 weeks after the hematoma was surgically evacuated. The neurologic deficit score and diffusion tensor imaging (DTI) were observed before and after the MIS. The perihematomal blood-brain barrier (BBB) permeability and the brain water content (BWC) were measured 2 weeks after the hematoma was surgically evacuated.

RESULTS

The DTI demonstrated that integrity of the internal capsule restored largely after surgery and the fractional anisotropy (FA) values of the internal capsule on the hematoma side increased significantly as compared with those in the MC group or those before surgery in the same group. The postoperative ratios of FA values of each MIS subgroup increased compared with the MC group and those before surgery in the same subgroup before operation. The neurologic deficit score, the perihematomal BBB permeability, and the BWC of each MIS subgroup decreased significantly compared with those of the MC group. The 6-12-hour group displayed a more favorable result.

CONCLUSIONS

Performing the MIS in the early stage (6-12 hours) after ICH could decrease the secondary damages to the internal capsule so as to promote the recovery of motor function. The optimal time window for MIS should be within 6-12 hours after onset of ICH.

Non-alcoholic Korsakoff syndrome in psychiatric patients with a history of undiagnosed Wernicke's encephalopathy

Wernicke's encephalopathy is often undiagnosed, particularly in non-alcoholics. There are very few reports of non-alcoholic patients diagnosed with Korsakoff syndrome in the absence of a prior diagnosis of Wernicke's encephalopathy and no studies of diffusion tensor imaging in non-alcoholic Korsakoff syndrome. We report on three non-alcoholic psychiatric patients (all women) with long-term non-progressive memory impairment that developed after malnutrition accompanied by at least one of the three Wernicke's encephalopathy manifestations: ocular abnormalities, ataxia or unsteadiness, and an altered mental state or mild memory impairment. In neuropsychological examination, all patients had memory impairment, including intrusions. One patient had mild cerebellar vermis atrophy in MRI taken after the second episode of Wernicke's encephalopathy. The same patient had mild hypometabolism in the lateral cortex of the temporal lobes. Another patient had mild symmetrical atrophy and hypometabolism of the superior frontal lobes. Two patients were examined with diffusion tensor imaging. Reduced fractional anisotropy values were found in the corona radiata in two patients, and the uncinate fasciculus and the inferior longitudinal fasciculus in one patient. Our results suggest that non-alcoholic Korsakoff syndrome is underdiagnosed. Psychiatric patients with long-term memory impairment may have Korsakoff syndrome and, therefore, they should be evaluated for a history of previously undiagnosed Wernicke's encephalopathy.

Progesterone neuroprotection: The background of clinical trial failure

Since the first pioneering studies in the 1990s, a large number of experimental animal studies have demonstrated the neuroprotective efficacy of progesterone for brain disorders, including traumatic brain injury (TBI). In addition, this steroid has major assets: it easily crosses the blood-brain-barrier, rapidly diffuses throughout the brain and exerts multiple beneficial effects by acting on many molecular and cellular targets. Moreover, progesterone therapies are well tolerated. Notably, increased brain levels of progesterone are part of endogenous neuroprotective responses to injury. The hormone thus emerged as a particularly promising protective candidate for TBI and stroke patients. The positive outcomes of small Phase 2 trials aimed at testing the safety and potential protective efficacy of progesterone in TBI patients then provided support and guidance for two large, multicenter, randomized and placebo-controlled Phase 3 trials, with more than 2000 TBI patients enrolled. The negative outcomes of both trials, named ProTECT III and SyNAPSE, came as a big disappointment. If these trials were successful, progesterone would have become the first efficient neuroprotective drug for brain-injured patients. Thus, progesterone has joined the numerous neuroprotective candidates that have failed in clinical trials. The aim of this review is a reappraisal of the preclinical animal studies, which provided the proof of concept for the clinical trials, and we critically examine the design of the clinical studies. We made efforts to present a balanced view of the strengths and limitations of the translational studies and of some serious issues with the clinical trials. We place particular emphasis on the translational value of animal studies and the relevance of TBI biomarkers. The probability of failure of ProTECT III and SyNAPSE was very high, and we present them within the broader context of other unsuccessful trials.