Differential vulnerability of white matter structures to experimental infantile hydrocephalus detected by diffusion tensor imaging

Purpose

The differential vulnerability of white matter (WM) to acute and chronic infantile hydrocephalus and the related effects of early and late reservoir treatment are unknown, but diffusion tensor imaging (DTI) could provide this information. Thus, we characterized WM integrity using DTI in a clinically relevant model.

Methods

Obstructive hydrocephalus was induced in 2-week-old felines by intracisternal kaolin injection. Ventricular reservoirs were placed 1 (early) or 2 (late) weeks post-kaolin and tapped frequently based solely on neurological deficit. Hydrocephalic and age-matched control animals were sacrificed 12 weeks postreservoir. WM integrity was evaluated in the optic system, corpus callosum, and internal capsule prereservoir and every 3 weeks using DTI. Analyses were grouped as acute (<6 weeks) or chronic (≥6 weeks).

Results

In the corpus callosum during acute stages, fractional anisotropy (FA) decreased significantly with early and late reservoir placement (p?=?0.0008 and 0.0008, respectively), and diffusivity increased significantly in early (axial, radial, and mean diffusivity, p?=?0.0026, 0.0012, and 0.0002, respectively) and late (radial and mean diffusivity, p?=?0.01 and 0.0038, respectively) groups. Chronically, the corpus callosum was thinned and not detectable by DTI. FA was significantly lower in the optic chiasm and tracts (p?=?0.0496 and 0.0052, respectively) with late but not early reservoir placement. In the internal capsule, FA in both reservoir groups increased significantly with age (p?Conclusions All hydrocephalic animals treated with intermittent ventricular reservoir tapping demonstrated progressive ventriculomegaly. Both reservoir groups demonstrated WM integrity loss, with the CC the most vulnerable and the optic system the most resilient.     

Palliative epilepsy surgery in Aicardi syndrome: a case series and review of literature

Purpose

Aicardi syndrome (AS) is a severe neurodevelopmental disorder characterized by the triad of seizures, agenesis of corpus callosum, and chorioretinal lacunae. Seizures in AS are typically frequent, of various types, and refractory to medical therapy. Optimal treatment of seizures in AS remains undetermined.

Methods

We report a series of four patients with Aicardi syndrome who underwent surgical management of their epilepsy including two with corpus callosotomy (CC) of a partial corpus callosum and three with vagus nerve stimulator implantation.

Results

Seizure outcome was variable and ranged from near complete resolution of seizures to worsening of seizure profile. The most favorable seizure outcome was seen in a patient with partial agenesis of the corpus callosum treated with CC.

Conclusions

Seizure outcome following CC or vagus nerve stimulation in patients with Aicardi syndrome is variable. Although palliative epilepsy surgery may result in improvement in the seizure profile in some patients, studies on larger patient cohorts are needed to identify the precise role that surgery may play in the multidisciplinary approach to controlling seizures in Aicardi syndrome.     

An investigation of factors associated with psychiatric hospital admission despite the presence of crisis resolution teams

Background

Evidence suggests that white matter integrity may play an underlying pathophysiological role in schizophrenia. N-acetylaspartate (NAA), as measured by Magnetic Resonance Spectroscopy (MRS), is a neuronal marker and is decreased in white matter lesions and regions of axonal loss. It has also been found to be reduced in the prefrontal and temporal regions in patients with schizophrenia. Diffusion Tensor Imaging (DTI) allows one to measure the orientations of axonal tracts as well as the coherence of axonal bundles. DTI is thus sensitive to demyelination and other structural abnormalities. DTI has also shown abnormalities in these regions.

Methods

MRS and DTI were obtained on 42 healthy subjects and 40 subjects with schizophrenia. The data was analyzed using regions of interests in the Dorso-Lateral Prefrontal white matter, Medial Temporal white matter and Occipital white matter using both imaging modalities.

Results

NAA was significantly reduced in the patient population in the Medial Temporal regions. DTI anisotropy indices were also reduced in the same Medial Temporal regions. NAA and DTI-anisotropy indices were also correlated in the left medial temporal region.

Conclusion

Our results implicate defects in the medial temporal white matter in patients with schizophrenia. Moreover, MRS and DTI are complementary modalities for the study of white matter disruptions in patients with schizophrenia.     

Complementary diffusion tensor imaging study of the corpus callosum in patients with first-episode and chronic schizophrenia

Background

Abnormalities in the corpus callosum have long been implicated in schizophrenia. Previous diffusion tensor imaging (DTI) studies in patients with different durations of schizophrenia yielded inconsistent results. By comparing patients with different durations of schizophrenia, we investigated if white matter abnormalities of the corpus callosum emerge at an early stage in the illness or result from pathological progression.

Methods

We recruited patients with first-episode schizophrenia, patients with chronic schizophrenia and age-, sex-and handedness-matched healthy controls. We used 2 DTI techniques (voxel-based and fibre-tracking DTI) to investigate differences in corpus callosum integrity among the 3 groups.

Results

With both DTI techniques, significantly decreased fractional anisotropy values were identified in the genu of corpus callosum in patients with chronic schizophrenia, but not first-episode schizophrenia, compared with healthy controls.

Limitations

This study was cross-sectional, and the sample size was relatively small.

Conclusion

Abnormalities in the genu of the corpus callosum might be a progressive process in schizophrenia, perhaps related to disease severity and prognosis.     

Combined analysis of grey matter voxel-based morphometry and white matter tract-based spatial statistics in late-life bipolar disorder

Background

Previous magnetic resonance imaging (MRI) studies in young patients with bipolar disorder indicated the presence of grey matter concentration changes as well as microstructural alterations in white matter in various neocortical areas and the corpus callosum. Whether these structural changes are also present in elderly patients with bipolar disorder with long-lasting clinical evolution remains unclear.

Methods

We performed a prospective MRI study of consecutive elderly, euthymic patients with bipolar disorder and healthy, elderly controls. We conducted a voxel-based morphometry (VBM) analysis and a tract-based spatial statistics (TBSS) analysis to assess fractional anisotropy and longitudinal, radial and mean diffusivity derived by diffusion tensor imaging (DTI).

Results

We included 19 patients with bipolar disorder and 47 controls in our study. Fractional anisotropy was the most sensitive DTI marker and decreased significantly in the ventral part of the corpus callosum in patients with bipolar disorder. Longitudinal, radial and mean diffusivity showed no significant between-group differences. Grey matter concentration was reduced in patients with bipolar disorder in the right anterior insula, head of the caudate nucleus, nucleus accumbens, ventral putamen and frontal orbital cortex. Conversely, there was no grey matter concentration or fractional anisotropy increase in any brain region in patients with bipolar disorder compared with controls.

Limitations

The major limitation of our study is the small number of patients with bipolar disorder.

Conclusion

Our data document the concomitant presence of grey matter concentration decreases in the anterior limbic areas and the reduced fibre tract coherence in the corpus callosum of elderly patients with long-lasting bipolar disorder.     

Diffusion tensor imaging of pyramidal tract reorganization after pediatric stroke

Background

Plasticity of the developing motor tracts is a contributor to recovery of motor function after pediatric stroke. The mechanism of these plastic changes may be functional and/or structural in nature. The corticospinal tract (CST) represents the major pathway responsible for voluntary movement. Stroke-induced damage to the CST as well as to other motor tracts leads to motor deficits which may show favorable functional recovery particularly in the pediatric population.

Methods

We report the case of a 3-year-old girl demonstrating reorganization of the pyramidal tracts after an extensive left MCA territory stroke secondary to head trauma. Reorganization is characterized using serial diffusion tensor imaging (DTI) of the pyramidal tracts which contain the CST.

Results

Imaging shows decreased ipsi-lesional fractional anisotropy (FA) suggestive of Wallerian degeneration and increased contralesional FA.

Conclusions

These results point to plastic reorganization of the pyramidal tract post-stroke and the utility of DTI in recognizing these changes.     

Longitudinal changes of fractional anisotropy in Alzheimer’s disease patients treated with galantamine: a 12-month randomized, placebo-controlled, double-blinded study

Diffusion tensor imaging (DTI) demonstrates decline of fractional anisotropy (FA) as a marker of fiber tract integrity in Alzheimer's disease (AD). We aimed to assess the longitudinal course of white matter microstructural changes in AD and healthy elderly control (HC) subjects and to evaluate the effects of treatment with the cholinesterase inhibitor galantamine on white matter microstructure in AD patients. We enrolled 28 AD patients and 11 healthy elderly control subjects (HC). AD patients were randomly assigned to 6-month double-blind galantamine treatment or placebo, with a 6-month open-label extension phase. DTI was performed at baseline, as well as at 6 and 12-month follow-up in AD patients. The HC subjects underwent DTI at baseline and 12-month follow-up without treatment. We measured FA in regions of interest covering the posterior cingulate and corpus callosum. At 6-month follow-up, the AD group showed significant FA decline in the left posterior cingulate. FA decline was significantly preserved in the posterior body of the corpus callosum in AD group with treatment compared to placebo. At 12-month follow-up, the AD patients showed no differences in FA decline between initial treatment and placebo groups after the 6-month open-label extension phase. A significant FA decline occurred in the left posterior cingulate across the AD and HC groups without between-group differences. DTI demonstrated FA decline in intracortically projecting fiber tracts in aging and AD over 1 year. Galantamine had limited impact on regional FA decline, which was not preserved after additional 6-month open-label treatment.     

Preliminary experience with diffusion tensor imaging before and after re-irradiation treatments in children with progressive diffuse pontine glioma

Purpose

The purpose of this study is to evaluate quantitative changes in diffusion tensor imaging (DTI) tractography and fractional anisotropy (FA) of the pons along with clinical correlation, in patients who receive re-irradiation for progressive diffuse intrinsic pontine glioma (DIPG).

Methods

A retrospective case review of children with progressive DIPG who received re-irradiation at our institution from 2007 to 2011 after approval from the Institutional Review Board was performed. Tractography analysis and FA were analyzed pre and post-re-irradiation, and correlation with clinical features and MR imaging was performed.

Results

DTI analysis showed reduced values of FA on tumor progression. Increase in the FA values was noted after re-irradiation in these patients. This correlated with clinical improvement. These changes were concordant with the 3D tractography analysis which showed better visualization of the corticospinal tracts as they course through brainstem and posterior transverse pontine fibers following re-irradiation.

Conclusion

Serial changes in the FA values using DTI could provide clinically more correlative information in patients with progressive DIPG, who receive re-irradiation. Though the use and results of this modality has been reported in the newly diagnosed DIPG before, evaluation of DTI in children who receive re-irradiation for progressive DIPG has not been reported earlier. Though limited by the small sample size and treatment variability, this study for the first time shows the preliminary experience, potential, and likely efficacy of complementing DTI analysis to routine neuroimaging also in patients re-irradiated for progressive DIPG to better assess treatment response.     

Altered white matter integrity in temporal lobe epilepsy: Association with cognitive and clinical profiles

Purpose: Diffusion tensor imaging (DTI) studies have reported substantial white matter abnormalities in patients with temporal lobe epilepsy (TLE). However, limited data exist regarding the extent of white matter tract abnormalities, cognitive effects of these abnormalities, and relationship to clinical factors. The current study examined these issues in subjects with chronic TLE. Methods: DTI data were obtained in 12 TLE subjects and 10 age‐matched healthy controls. Voxel‐wise statistical analysis of fractional anisotropy (FA) was carried out using tract‐based spatial statistics (TBSS). White matter integrity was correlated with cognitive performance and epilepsy‐related clinical parameters. Results: Subjects with TLE, as compared to healthy controls, demonstrated four clusters of reduced FA, in anterior temporal lobe, mesial temporal lobe, and cerebellum ipsilateral, as well as frontoparietal lobe contralateral to the side of seizure onset. Mean FA was positively correlated with delayed memory, in anterior temporal lobe; and immediate memory, in mesial temporal lobe. Lower FA values in the posterior region of corpus callosum were related to earlier age of seizure onset. Conclusion: TLE is associated with widespread disturbances in white matter tracts and these changes have important cognitive and clinical consequences.     

Time-varying inter-hemispheric coherence during corpus callosotomy

Objective

Corpus callosotomy limits the bilateral synchrony of epileptic discharges. However, the instantaneous changes in bilateral synchrony during corpus callosotomy are unclear. The present study investigated how and when bilateral synchrony is suppressed in the anterior and then posterior steps of corpus callosotomy.

Methods

Intra-operative scalp electroencephalography (EEG) was recorded simultaneously with surgical video for six patients who underwent total corpus callosotomy for medically intractable drop attacks. The time-varying EEG inter-hemispheric coherence was quantified by wavelet transform coherence and trend analysis.

Results

The 4–13 Hz coherence decreased after corpus callosotomy in five patients. Significant decrease in coherence was observed only during the posterior step of callosal sectioning in three patients, but throughout both steps in two patients.

Conclusions

Decrease in inter-hemispheric coherence is not always correlated with the stages of callosal sectioning. Inter-hemispheric coherence is decreased during the final stage of corpus callosotomy and the effect is maximized after sectioning is completed.

Significance

Various patterns of coherence decrease suggest individual variations in the participation of the corpus callosum in the genesis of bilateral synchrony. Time-varying inter-hemispheric EEG coherence is useful to monitor the physiological completeness of corpus callosotomy.     

精神发育迟滞脑白质磁共振弥散张量成像研究

目的:通过检查精神发育迟滞(MR)患者脑白质磁共振弥散张量成像(DTI)来了解该病患者脑白质发育情况,以寻找MR患者新的诊断手段,并探讨发病机制中脑白质纤维束发育障碍的根据.方法:用DTI扫描技术对45例MR患者作了皮质脊髓束、枕额束、扣带束、胼胝体束的检查.结果:45例患者中仅4例未发现异常,枕额束有异常为27例,皮...     

Altered white matter integrity of forebrain in treatment-resistant depression: a diffusion tensor imaging study with tract-based spatial statistics

Background

The association between alterations of the white matter (WM) integrity in brain regions and mood dysregulation has been reported in major depressive disorder (MDD). However, there has never been a neuroimaging study in patients who have treatment-resistant depression (TRD) and are in a current treatment-resistant state. In the present study, we used diffusion tensor imaging (DTI) with tract-based spatial statistics (TBSS) method to investigate the WM integrity of different brain regions in patients who had TRD and were in a current treatment-resistant state.

Methods

Twenty-three patients with TRD and Hamilton Rating Scale total score of ≥ 18 and 19 healthy controls matched with age, gender, and education level to patients were scanned with DTI. Thirty 4 mm thick, no gap, contiguous axial slices were acquired and fractional anisotropy (FA) images were generated for each participant. An automated TBSS approach was used to analyze the data.

Results

Voxel-wise statistics revealed that patients with TRD had lower FA values in the right anterior limb of internal capsule, the body of corpus callosum, and bilateral external capsule compared to healthy subjects. Patients with TRD did not have increased FA values in any brain regions compared to healthy subjects. There was no correlation between the FA values in any brain region and patients' demographics and the severity of illness.

Conclusions

Our findings suggest the abnormalities of the WM integrity of neuronal tracts connecting cortical and subcortical nuclei and two brain hemispheres may play a key role in the pathogenesis of TRD.     

Neurofibromatosis type 1 (NF1) associated with tumor of the corpus callosum

Introduction

Neurofibromatosis type 1 (NF1), one of the most common neurocutaneous disorders, is a multisystemic disease associated with tumors in any organ of the body, especially in the central nervous system and also the peripheral nervous system. Pilocytic astrocytomas have been described in almost all intracranial regions in patients with NF1. However, only a few patients with NF1 and tumor of the corpus callosum have been reported to date.

Material and methods

An 11-year-old white Spanish boy was evaluated due to a family history of NF1 and low performance test scores in school. He was studied from the neurological and intellectual level points of view.

Results

Magnetic resonance (MR) study revealed a tumor in the anterior-middle portion of the corpus callosum and a Wechsler Intelligence Scale for Children-Revised showed verbal IQ of 92, a performance IQ of 108, and a total IQ of 100. In addition, he showed attention deficit and hyperactivity disorder.

Conclusions

Tumors of corpus callosum in patients with NF1 are very uncommon. The patient presented in this paper consulted due to family history of NF1, progressive hyperactivity, and below average school performance. The MR study showed tumor in the corpus callosum. Tumor histology was not investigated.     

Longitudinal Diffusion Tensor Imaging Detects Recovery of Fractional Anisotropy Within Traumatic Axonal Injury Lesions

Background

Traumatic axonal injury (TAI) may be reversible, yet there are currently no clinical imaging tools to detect axonal recovery in patients with traumatic brain injury (TBI). We used diffusion tensor imaging (DTI) to characterize serial changes in fractional anisotropy (FA) within TAI lesions of the corpus callosum (CC). We hypothesized that recovery of FA within a TAI lesion correlates with better functional outcome.

Methods

Patients who underwent both an acute DTI scan (≤day 7) and a subacute DTI scan (day 14 to inpatient rehabilitation discharge) at a single institution were retrospectively analyzed. TAI lesions were manually traced on the acute diffusion-weighted images. Fractional anisotropy (FA), apparent diffusion coefficient (ADC), axial diffusivity (AD), and radial diffusivity (RD) were measured within the TAI lesions at each time point. FA recovery was defined by a longitudinal increase in CC FA that exceeded the coefficient of variation for FA based on values from healthy controls. Acute FA, ADC, AD, and RD were compared in lesions with and without FA recovery, and correlations were tested between lesional FA recovery and functional recovery, as determined by disability rating scale score at discharge from inpatient rehabilitation.

Results

Eleven TAI lesions were identified in 7 patients. DTI detected FA recovery within 2 of 11 TAI lesions. Acute FA, ADC, AD, and RD did not differ between lesions with and without FA recovery. Lesional FA recovery did not correlate with disability rating scale scores.

Conclusions

In this retrospective longitudinal study, we provide initial evidence that FA can recover within TAI lesions. However, FA recovery did not correlate with improved functional outcomes. Prospective histopathological and clinical studies are needed to further elucidate whether lesional FA recovery indicates axonal healing and has prognostic significance.

     

Boomerang Sign on MRI

Introduction

Altered mental status and more subtle cognitive and personality changes after traumatic brain injury (TBI) are pervasive problems in patients who survive initial injury. MRI is not necessarily part of the diagnostic evaluation of these patients.

Methods

Case report with relevant image and review of the literature.

Results

Injury to the corpus callosum is commonly described in traumatic brain injury; however, extensive lesions in the splenium are not well described. This image shows an important pattern of brain injury and demonstrates a common clinical syndrome seen in patients with corpus callosum pathology.

Conclusion

Injury to the splenium of the corpus callosum due to trauma may be extensive and can cause significant neurologic deficits. MRI is important in the diagnostic evaluation of patients with cognitive changes after TBI.     

Evidence for white matter disruption in traumatic brain injury without macroscopic lesions

Background

Non‐missile traumatic brain injury (nmTBI) without macroscopically detectable lesions often results in cognitive impairments that negatively affect daily life.

Aim

To identify abnormal white matter projections in patients with nmTBI with cognitive impairments using diffusion tensor magnetic resonance imaging (DTI).

Methods

DTI scans of healthy controls were compared with those of 23 patients with nmTBI who manifested cognitive impairments but no obvious neuroradiological lesions. DTI was comprised of fractional anisotropy analysis, which included voxel‐based analysis and confirmatory study using regions of interest (ROI) techniques, and magnetic resonance tractography of the corpus callosum and fornix.

Results

A decline in fractional anisotropy around the genu, stem and splenium of the corpus callosum was shown by voxel‐based analysis. Fractional anisotropy values of the genu (0.47), stem (0.48), and splenium of the corpus callosum (0.52), and the column of the fornix (0.51) were lower in patients with nmTBI than in healthy controls (0.58, 0.61, 0.62 and 0.61, respectively) according to the confirmatory study of ROIs. The white matter architecture in the corpus callosum and fornix of patients with nmTBI were seen to be coarser than in the controls in the individual magnetic resonance tractography.

Conclusions

Disruption of the corpus callosum and fornix in patients with nmTBI without macroscopically detectable lesions is shown. DTI is sensitive enough to detect abnormal neural fibres related to cognitive dysfunction after nmTBI.Cognitive and vocational sequelae are common complications after non‐missile traumatic brain injury (nmTBI) without obvious neuroradiological lesions.^1,2 They may present as memory disturbance, impairments in multitask execution and loss of self‐awareness.³ These symptoms have been attributed to diffuse brain injury and the diffuse loss of white matter or neural networks in the brain.^4,5,6 Currently no accurate method is available for diagnosing and assessing the distribution and severity of diffuse axonal injury. As computed tomography and magnetic resonance imaging (MRI) findings underestimate the extent of diffuse axonal injury and correlate poorly with the final neuropsychological outcome,^7,8 this dysfunction tends to be clinically underdiagnosed or overlooked. Indirect evidence for loss of functional connectivity after nmTBI has been provided by both morphometric and functional neuroimaging studies. Morphometric analysis of nmTBI has shown the relationship between atrophy of the corpus callosum and fornix and the neuropsychological outcome.⁹ Most functional neuroimaging studies conducted after nmTBI have shown that cognitive and behavioural disorders are correlated, with some degree of secondary hypometabolism or hypoperfusion in regions of the cortex.⁵ To date, however, there has been no direct in vivo demonstration of structural disconnections without macroscopically detectable lesions in patients with nmTBI.Diffusion tensor magnetic resonance imaging (DTI), which measures diffusion anisotropy in vivo, is a promising method for the non‐invasive detection of the degree of fibre damage in various disease processes affecting the white matter.^10,11 In biological systems, the diffusional motion of water is impeded by tissue structures, such as cell membranes, myelin sheaths, intracellular microtubules and associated proteins. Motion parallel to axons or myelin sheaths is inhibited to a lesser degree than perpendicular motion, a phenomenon known as diffusion anisotropy.¹² Fractional anisotropy was applied to evaluation of post‐traumatic diffuse axonal injury¹³ and its clinical usefulness described. In a previous study,¹⁴ fractional anisotropy score in the acute stage as an index of injury to white matter showed promise in predicting outcome in patients with traumatic brain injury, by using the regions of interest (ROIs) techniques. MRI voxel‐based analysis, a statistical normalising method, has been developed to reduce interindividual variability and to evaluate the whole brain objectively.^15,16,17 We investigated the regions in the whole brain that are commonly injured in patients having nmTBI with cognitive impairments but no macroscopic lesions, using voxel‐based analysis of fractional anisotropy, referred to as diffusion anisotropy. The advent of DTI has allowed inter‐regional fibre tracking, called magnetic resonance tractography, which reconstructs the three‐dimensional trajectories of white matter tracts.^11,18,19 We also investigated whether magnetic resonance tractography sensitively recognises degeneration of the corpus callosum and fornix in individual patients with nmTBI.     

Increased white matter integrity in the corpus callosum in subjects with high genetic loading for schizophrenia

Objective

White matter abnormalities in the corpus callosum (CC) of schizophrenia have been reported to predate the illness onset. This study aimed to investigate the effect of genetic predisposition on the white matter integrity of the CC, in subjects at genetically high risk for schizophrenia (GHR) and schizophrenia patients.

Method

Fractional anisotropy (FA) of the mid-sagittal CC in 22 young GHR, 15 schizophrenia, and 26 control subjects were examined. GHR subjects were defined as non-prodromal individuals who had more than two relatives with schizophrenia within third-degree relatives, one of whom must be a first-degree relative.

Results

ANCOVA with age and gender as covariates revealed overall difference of FA in the genu and splenium among the three groups. Post-hoc analysis found significantly increased FA in the genu of GHR subjects compared to controls (corrected p < 0.01), whereas schizophrenia patients showed significantly decreased FA in the splenium.

Conclusion

The white matter change of the CC in young GHR subjects was the opposite of that in schizophrenia. To consider previous reports on FA decrease in the CC in schizophrenia and the impaired frontal functioning in GHR group, the increased FA may be an indicator of compensatory alteration in white matter integrity in young GHR people.     

Unexpected Recovery of Function After Severe Traumatic Brain Injury: The Limits of Early Neuroimaging-Based Outcome Prediction

Background

Prognostication in the early stage of traumatic coma is a common challenge in the neuro-intensive care unit. We report the unexpected recovery of functional milestones (i.e., consciousness, communication, and community reintegration) in a 19-year-old man who sustained a severe traumatic brain injury. The early magnetic resonance imaging (MRI) findings, at the time, suggested a poor prognosis.

Methods

During the first year of the patient’s recovery, MRI with diffusion tensor imaging and T2*-weighted imaging was performed on day 8 (coma), day 44 (minimally conscious state), day 198 (post-traumatic confusional state), and day 366 (community reintegration). Mean apparent diffusion coefficient (ADC) and fractional anisotropy values in the corpus callosum, cerebral hemispheric white matter, and thalamus were compared with clinical assessments using the Disability Rating Scale (DRS).

Results

Extensive diffusion restriction in the corpus callosum and bihemispheric white matter was observed on day 8, with ADC values in a range typically associated with neurotoxic injury (230–400 × 10^?6 mm²/s). T2*-weighted MRI revealed widespread hemorrhagic axonal injury in the cerebral hemispheres, corpus callosum, and brainstem. Despite the presence of severe axonal injury on early MRI, the patient regained the ability to communicate and perform activities of daily living independently at 1 year post-injury (DRS = 8).

Conclusions

MRI data should be interpreted with caution when prognosticating for patients in traumatic coma. Recovery of consciousness and community reintegration are possible even when extensive traumatic axonal injury is demonstrated by early MRI.     

Hemispheric lateralization of microstructural white matter abnormalities in children with active benign childhood epilepsy with centrotemporal spikes (BECTS): A preliminary DTI study

PurposeThe deficit of white matter is reported to be involved during the disease progression in patients with benign childhood epilepsy with centrotemporal spikes (BECTS). The aim of this study is to investigate patterns of white matter damage in children with BECTS with left- or right-hemispheric focus by using diffusion tensor imaging (DTI), and its relationship with the cofactors such duration, seizure frequency and handedness.MethodsDiffusion tensor imaging (DTI) was performed in twenty-eight children with BECTS and eighteen healthy controls. The data were analyzed using both tract-based spatial statistics (TBSS) and region of interest (ROI) analyses. Correlations were investigated between the fractional anisotropy (FA) values of the identified altered regions and clinical features such as age, age of onset and seizure frequency.ResultsThe TBSS analysis revealed that white matter impairment in children with rolandic spikes on the ipsilateral hemisphere was much wider. The FA value was significantly lower in the body of the corpus callosum and forceps minor in BECTS patients with spikes on the ipsilateral hemisphere. The seizure frequency correlated positively with the FA values of body of corpus callosum (CC), bilateral cingulate gyrus and left uncinate fasciculi (UA).ConclusionThe impaired WM integrity in patients with BECTS was greater in patients with spikes on the dominant hemisphere, possibly due to the greater vulnerability of the left hemisphere and excitotoxic effects of seizures.     

Fibre tract analysis using diffusion tensor imaging reveals aberrant connectivity in a rat model of depression

Objectives: Abnormal brain connectivity has been described in depressive disorder. However, these studies are correlational or cross-sectional and their design does not examine causal relationships. We aimed to investigate structural connectivity in a genetic rat model of depression.

Methods: Using diffusion tensor imaging (DTI), we reconstructed white matter tracts and analysed fractional anisotropy (FA) and diffusivity indices (mean, axial and radial) to investigate structural connectivity in fibre tracts implicated in major depression: the corpus callosum, fornix, cingulum and anterior commissures.

Results: Tractography-based analysis revealed that, compared to Wistar control rats, the Wistar–Kyoto strain (WKY) rat model of depression exhibited decreased connectivity, manifested by decreased FA in the corpus callosum, right and left anterior commissures. A statistical trend of decreased FA was observed in both the right and left cingulum. Increased diffusivity (mean diffusion) was detected in both the corpus callosum and the fornix of WKY rats compared to controls. Voxel-based analysis confirmed differences between WKY and controls in the regions investigated.

Conclusions: Decreased connectivity in a genetic rat model of depression corroborates the findings in patients suffering from major depression suggesting that the vulnerability for developing depression is mainly polygenic and less likely to be due to childhood adversity per se.