Left Superior Cerebellar Peduncle Research Articles

Analysis of diffusion changes in cerebral tissues of Parki̇nson's patients who underwent subthalamic nucleus deep brain stimulation: Correlation of improvements in motor and neuropsychiatric symptoms

ObjectiveParkinson's disease (PD) as a neurodegenerative disorder characterized by a reduction in both the quantity and functionality of dopaminergic neurons. This succinctly highlights the central pathological feature of PD and its association with dopaminergic neuron degeneration, which underlies the motor and non-motor symptoms of the disease.This study aims to elucidate the nuances of apparent diffusion coefficient (ADC) changes in different cerebral regions by after the bilateral subthalamic nucleus (STN) deep brain stimulation (DBS) surgery of PD, as well as to investigate their potential interactions with the motor and neuropsychiatric spectrum. MethodsPatients who underwent STN-DBS surgery for PD between 2017 and 2019 were included in this study. The results of diffusion magnetic resonance imaging (MRI), Unified Parkinson Disease Rating Scale (UPDRS) III scores, Beck and Hamilton depression tests were recorded before and at the 3rd month of postoperative stimulation. The data obtained were evaluated with the Wilcoxon signed rank test. Result of the statistical tests were within the 95 % confidence interval and p values were significant below 0.05. ResultsOur study was conducted with a total of 13 patients, 8 men and 5 women. As a result of measurements made in a total of 32 different regions, especially in the motor and neuropsychiatric areas of the brain, an increase in ADC values was found in all areas. ADC changes of eight localizations such as left corpus callosum, right corona radiata, left corona radiata, hippocampus, right insula, left superior cerebellar peduncle, left caudate nucleus and left putamen were statistically significant. UPDRS III scores improved by 57 % (p <0.05), and Beck and Hamilton depression scores by 25 % and 33 %, respectively (p> 0.05). ConclusionsThis article implicate that bilateral STN-DBS surgery potentially exerts beneficial effects on both motor and neuropsychiatric symptomatology in individuals with PD. We believe that this therapeutic mechanism is hypothesized to involve modulation of diffusion alterations within distinct cerebral tissues.

Posterior Interhemispheric-Transtentorial Approach for Resection of an Arteriovenous Malformation of the Superior Medullary Velum and Fourth Ventricle: 2-Dimensional Operative Video.

Brain arteriovenous malformations (AVMs) of the fourth ventricle represent a rare subtype associated with an aggressive natural course.1,2 In this case, a woman in her early 50s presented with dizziness. An AVM was diagnosed in the left superior cerebellar peduncle extending into the fourth ventricle. The AVM was supplied by superior cerebellar artery branches and classified as a Spetzler-Martin grade III and a Lawton-Young grade III, with a supplemented grade of 6.3,4 Being a single case report, institutional review board approval was not needed. Patient consent was obtained. The lesion was accessed through a torcular craniotomy and posterior interhemispheric-transtentorial approach, employing gravity to naturally retract the parietooccipital lobe.5-7 Dissection continued into the quadrigeminal and ambient cisterns, where the tentorium was incised parallelling the straight sinus to reach the superior vermis. Partial resection of the lingual and central lobules of the vermis facilitated access to the superior medullary velum. The superior cerebellar artery feeders were divided and followed to the superior cerebellar peduncle and through the superior medullary vellum. A vertical incision in the superior medullary velum facilitated entry into the fourth ventricle, where the AVM nidus was dissected circumferentially and resected en bloc. Intraoperative indocyanine green videoangiography and postoperative digital subtraction angiography confirmed complete obliteration of the AVM. After surgery, the patient experienced mild ataxia, but motor symptoms greatly improved during 3-month follow-up. This video illustrates resection of a complex fourth ventricular AVM through a posterior interhemispheric-transtentorial approach, highlighting pivotal considerations of patient positioning and approach selection to optimize treatment outcome for complex posterior fossa AVM resection.

Based on white matter microstructure to early identify bipolar disorder from patients with depressive episode

ObjectiveBecause of similar clinical manifestations, bipolar disorder (BD) patients are often misdiagnosed as major depressive disorder (MDD). This study aimed to compare the difference between depressed patients later converting to BD and unipolar depression (UD) according to diffusion tensor imaging (DTI). MethodPatients with MDD (562 participants) in depressive episode states and healthy controls (HCs) (145 participants) were recruited over 10 years. Demographic and magnetic resonance imaging (MRI) data were collected at the time of recruitment. All patients with MDD were followed up for 5 years and classified into the transfer to BD (tBD) group (83 participants) and UD group (160 participants) according to the follow-up results. DTI and functional magnetic resonance imaging at baseline were compared. ResultsCommon abnormalities were found in both tBD and UD groups, including left superior cerebellar peduncle (SCP.L), right anterior limb of the internal capsule (ALIC.R), right superior fronto-occipital fasciculus (SFOF.R), and right inferior fronto-occipital fasciculus (IFOF.R). The tBD showed more extensive abnormalities than the UD in the body of corpus callosum, fornix, left superior corona radiata, left posterior corona radiata, left superior longitudinal fasciculus, and left superior fronto-occipital fasciculus. ConclusionThe study demonstrated the common and distinct abnormalities of tBD and UD when compared to HC. The tBD group showed more extensive disruptions of white matter integrity, which could be a potential biomarker for the early identification of BD.

Multishell diffusion MRI reveals whole-brain white matter changes in HIV.

Diffusion tensor imaging (DTI) and diffusion kurtosis imaging (DKI) have been previously used to explore white matter related to human immunodeficiency virus (HIV) infection. While DTI and DKI suffer from low specificity, the Combined Hindered and Restricted Model of Diffusion (CHARMED) provides additional microstructural specificity. We used these three models to evaluate microstructural differences between 35 HIV-positive patients without neurological impairment and 20 healthy controls who underwent diffusion-weighted imaging using three b-values. While significant group effects were found in all diffusion metrics, CHARMED and DKI analyses uncovered wider involvement (80% vs. 20%) of all white matter tracts in HIV infection compared with DTI. In restricted fraction (FR) analysis, we found significant differences in the left corticospinal tract, middle cerebellar peduncle, right inferior cerebellar peduncle, right corticospinal tract, splenium of the corpus callosum, left superior cerebellar peduncle, left superior cerebellar peduncle, pontine crossing tract, left posterior limb of the internal capsule, and left/right medial lemniscus. These are involved in language, motor, equilibrium, behavior, and proprioception, supporting the functional integration that is frequently impaired in HIV-positivity. Additionally, we employed a machine learning algorithm (XGBoost) to discriminate HIV-positive patients from healthy controls using DTI and CHARMED metrics on an ROIwise basis, and unique contributions to this discrimination were examined using Shapley Explanation values. The CHARMED and DKI estimates produced the best performance. Our results suggest that biophysical multishell imaging, combining additional sensitivity and built-in specificity, provides further information about the brain microstructural changes in multimodal areas involved in attentive, emotional and memory networks often impaired in HIV patients.

A Pilot Study of Adolescents with Psychotic Experiences: Potential Cerebellar Circuitry Disruption Early Along the Psychosis Spectrum.

A berrant connectivity in the cerebellum has been found in psychotic conditions such as schizophrenia corresponding with cognitive and motor deficits found in these conditions. Diffusion differences in the superior cerebellar peduncles, the white matter connecting the cerebellar circuitry to the rest of the brain, have also been found in schizophrenia and high-risk states. However, white matter diffusivity in the peduncles in individuals with sub-threshold psychotic experiences (PEs) but not reaching the threshold for a definitive diagnosis remains unstudied. This study investigates the cerebellar peduncles in adolescents with PEs but no formal psychiatric diagnosis.Sixteen adolescents with PEs and 17 age-matched controls recruited from schools underwent High-Angular-Resolution-Diffusion neuroimaging. Following constrained spherical deconvolution whole-brain tractography, the superior, inferior and middle peduncles were isolated and virtually dissected out using ExploreDTI. Differences for macroscopic and microscopic tract metrics were calculated using one-way between-group analyses of covariance controlling for age, sex and estimated Total Intracranial Volume (eTIV). Multiple comparisons were corrected using Bonferroni correction.A decrease in fractional anisotropy was identified in the right (p = 0.045) and left (p = 0.058) superior cerebellar peduncle; however, this did not survive strict Bonferroni multiple comparison correction. There were no differences in volumes or other diffusion metrics in either the middle or inferior peduncles.Our trend level changes in the superior cerebellar peduncle in a non-clinical sample exhibiting psychotic experiences complement similar but more profound changes previously found in ultra-high-risk individuals and those with psychotic disorders. This suggests that superior cerebellar peduncle circuitry perturbations may occur early along in the psychosis spectrum.

IMMU-19. NIVOLUMAB-INDUCED CNS DEMYELINATION IN A 15-YEAR-OLD WITH CLASSIC HODGKIN LYMPHOMA

Abstract INTRODUCTION Nivolumab associated neurologic immune-related adverse events (irAEs) have been reported in less than 1% of patients and mainly in the adult population. Here we present a pediatric case of nivolumab related CNS demyelination. Case description: 15-year-old male with nodular sclerosis stage III classic Hodgkin lymphoma was enrolled to receive chemotherapy following SWOG S1826 protocol. Eight weeks after the first dose of nivolumab, he had a single episode of seizure. Prolonged EEG showed no epileptiform discharges. Levetiracetam was initiated. Initial MRI showed a non-enhancing T2 hyperintense focal cortical thickening in the left primary motor cortex. CSF studies were significant for mild lymphocytic pleocytosis. One dose of nivolumab was held with subsequent doses given. Levetiracetam was continued and follow-up EEGs were normal. Repeat MRI done three months later showed multiple new parenchymal hyperintense lesions including in the anterior temporal lobe with central curvilinear enhancement, and faintly enhancing lesions in the left fusiform gyrus, juxtacortical white matter of the right middle temporal gyrus, and left superior cerebellar peduncle, findings consistent with CNS demyelination. At this time, CSF showed 9 WBCs (94% lymphocytes) and oligoclonal bands with negative cytology and flow cytometry making CNS lymphoma highly unlikely. The last two doses of nivolumab were held and he was started on methylprednisolone. The most recent MRI ten weeks after the last dose of nivolumab showed resolution of the abnormal findings. DISCUSSION There is limited published literature about neurologic complications of immune checkpoint inhibitors (ICPis) in the pediatric population. CNS demyelination and other neurologic irAEs should be suspected in patients presenting with new neurologic symptoms who started any ICPi within the past three months and after other causes including disease progression, metastasis, metabolic or infectious disorders have been ruled out. Treatment varies depending on severity but includes discontinuation of the ICPi and steroids.

Causal relationships between migraine and microstructural white matter: a Mendelian randomization study

BackgroundMigraine is a disabling neurological disorder with the pathophysiology yet to be understood. The microstructural alteration in brain white matter (WM) has been suggested to be related to migraine in recent studies, but these evidence are observational essentially and cannot infer a causal relationship. The present study aims to reveal the causal relationship between migraine and microstructural WM using genetic data and Mendelian randomization (MR).MethodsWe collected the Genome-wide association study (GWAS) summary statistics of migraine (48,975 cases / 550,381 controls) and 360 WM imaging-derived phenotypes (IDPs) (31,356 samples) that were used to measure microstructural WM. Based on instrumental variables (IVs) selected from the GWAS summary statistics, we conducted bidirectional two-sample MR analyses to infer bidirectional causal associations between migraine and microstructural WM. In forward MR analysis, we inferred the causal effect of microstructural WM on migraine by reporting the odds ratio (OR) that quantified the risk change of migraine for per 1 standard deviation (SD) increase of IDPs. In reverse MR analysis, we inferred the causal effect of migraine on microstructural WM by reporting the β value that represented SDs of changes in IDPs were caused by migraine.ResultsThree WM IDPs showed significant causal associations (p < 3.29 × 10− 4, Bonferroni correction) with migraine and were proved to be reliable via sensitivity analysis. The mode of anisotropy (MO) of left inferior fronto-occipital fasciculus (OR = 1.76, p = 6.46 × 10− 5) and orientation dispersion index (OD) of right posterior thalamic radiation (OR = 0.78, p = 1.86 × 10− 4) exerted significant causal effects on migraine. Migraine exerted a significant causal effect on the OD of left superior cerebellar peduncle (β = − 0.09, p = 2.78 × 10− 4).ConclusionsOur findings provided genetic evidence for the causal relationships between migraine and microstructural WM, bringing new insights into brain structure for the development and experience of migraine.

Disruption of specificwhite matter tracts is associated with neurogenic lower urinary tract dysfunction in women with multiple sclerosis.

To identify specific white matter tracts (WMTs) whose disruption is associated with the severity of neurogenic lower urinary tract dysfunction (NLUTD) in two independent cohorts of women with multiple sclerosis(MS) and NLUTD. Cohort 1 consisted of twenty-eight women with MS and NLUTD. The validation cohort consisted of 10women with MS and NLUTD. Eleven healthy women served as controls. Participants of both MS cohorts had the same inclusion and exclusion criteria. Both MS cohorts and the healthy controls underwent the same clinical assessment and functional MRI(fMRI) protocol, except that the validation MS cohort underwent 7-Tesla fMRI scan. Fifteen WMTs (six coursing to relevant brainstem areas) involved in bladder control were a priori regions of interest (ROI). Spearman's correlation test was performed between each the Fractional Anisotropy (FA) and mean diffusivity (MD) of each WMT and the clinical parameters. Overall, we found a very high degree of overlap (100% of a priori ROI) in the tracts identified by our correlation analysis as having the greatest contribution to NLUTD symptoms in MS women. The right inferior cerebellar peduncle, left posterior limb of internal capsule, and left superior cerebellar peduncle displayed significant associations to the greatest number of clinical parameters. Our correlation analysis supports the role of specific WMT disruptions in the contribution of symptoms in women with MS and NLUTD, as confirmed in two independent MS cohorts.

Spatiotemporal changes in along-tract profilometry of cerebellar peduncles in cerebellar mutism syndrome

Cerebellar mutism syndrome, characterised by mutism, emotional lability and cerebellar motor signs, occurs in up to 39% of children following resection of medulloblastoma, the most common malignant posterior fossa tumour of childhood. Its pathophysiology remains unclear, but prior studies have implicated damage to the superior cerebellar peduncles. In this study, the objective was to conduct high-resolution spatial profilometry of the cerebellar peduncles and identify anatomic biomarkers of cerebellar mutism syndrome.In this retrospective study, twenty-eight children with medulloblastoma (mean age 8.8 ± 3.8 years) underwent diffusion MRI at four timepoints over one year. Forty-nine healthy children (9.0 ± 4.2 years), scanned at a single timepoint, served as age- and sex-matched controls. Automated Fibre Quantification was used to segment cerebellar peduncles and compute fractional anisotropy (FA) at 30 nodes along each tract.Thirteen patients developed cerebellar mutism syndrome. FA was significantly lower in the distal third of the left superior cerebellar peduncle pre-operatively in all patients compared to controls (FA in proximal third 0.228, middle and distal thirds 0.270, p = 0.01, Cohen’s d = 0.927). Pre-operative differences in FA did not predict cerebellar mutism syndrome. However, post-operative reductions in FA were highly specific to the distal left superior cerebellar peduncle, and were most pronounced in children with cerebellar mutism syndrome compared to those without at the 1–4 month follow up (0.325 vs 0.512, p = 0.042, d = 1.36) and at the 1-year follow up (0.342, vs 0.484, p = 0.038, d = 1.12).High spatial resolution cerebellar profilometry indicated a site-specific alteration of the distal segment of the superior cerebellar peduncle seen in cerebellar mutism syndrome which may have important surgical implications in the treatment of these devastating tumours of childhood.

Continuous Unilateral Eye Blinking Related to Cerebellar Epilepsy in a Neonate.

A 4-month-old baby girl with continuous left eye blinking associated with ipsilateral head rotation since birth was submitted to epilepsy workup (Video 1). MRI revealed a mass in the left superior cerebellar peduncle (Figure, A) and PET/CT showed hypermetabolism in the lesion and occipital lobes. Superficial EEG was normal. During surgical resection, an electrode was placed directly in the lesion and seizure activity was registered originating from it (Figure, C). Histopathology confirmed the diagnosis of cerebellar gangliomatous hamartoma (Figure, D). She was seizure-free after surgery. Cerebellar lesions can rarely cause epilepsy presenting with hemifacial spasm; possible mechanisms are interruption of the dentorubrothalamic tract and facial nucleus compression.1,2

Spatiotemporal changes in along-tract profilometry of cerebellar peduncles in cerebellar mutism syndrome

Abstract Aims Cerebellar mutism syndrome occurs in 25% of children following resection of posterior fossa tumours. Characterised by mutism, emotional lability and cerebellar motor signs, the syndrome is usually reversible over weeks to months. Its pathophysiology remains unclear, but evidence from diffusion MRI studies has implicated damage to the superior cerebellar peduncles in the development of this condition. The objective of this study was to describe the application of automated tractography of the cerebellar peduncles to provide a high-resolution spatiotemporal profile of diffusion MRI changes in cerebellar mutism syndrome. Method A retrospective case-control study was performed at Lucille Packard Children’s Hospital, Stanford University. Thirty children with midline medulloblastoma (mean age ± standard deviation 8.8 ± 3.8 years) underwent volumetric T1-weighted and diffusion MRI at four timepoints over one year. Forty-nine healthy children (9.0 ± 4.2 years), scanned at a single timepoint, were included as age- and sex-matched controls. Cerebellar mutism syndrome status was determined by contemporaneous casenote review. Automated Fibre Quantification was used to segment each subject’s cerebellar peduncles (Figure 1), and fractional anisotropy was computed at 30 nodes along each tract. A non-parametric permutation-based method was used to generate a critical cluster size and p-value for by-node ANOVA group comparisons. Z-scores for patients’ fractional anisotropy at each node were calculated based on values from controls’ corresponding nodes; these were analysed using mixed ANOVA with post-hoc false discovery rate-corrected pairwise t-tests. Results 13 patients developed cerebellar mutism syndrome. Automated fibre segmentation successfully identified the cerebellar peduncles in the majority of participants, but was more robust at follow-up timepoints (78.7% vs. 44.7% pre-operatively). Fractional anisotropy was significantly lower in the distal regions of the left superior cerebellar peduncle pre-operatively (p=0.0137) in patients compared to controls, although patients could not be distinguished pre-operatively with respect to cerebellar mutism syndrome status (Figure 2). Post-operative reductions in fractional anisotropy in children with cerebellar mutism syndrome were highly specific to the distal left superior cerebellar peduncle, and were most pronounced at follow-up timepoints (p=0.006; Figure 3). There were no significant differences in other cerebellar peduncles, either in along-tract fractional anisotropy or Z-scores, with respect to cerebellar mutism syndrome status. Conclusion A novel application of an automated tool to extract diffusion MRI data along the length of the cerebellar peduncles is described in a longitudinal retrospective cohort of paediatric medulloblastoma. Changes in fractional anisotropy in the cerebellar peduncles following tumour resection are described in a heretofore unprecedented level of spatiotemporal detail. In particular, children with post-operative cerebellar mutism syndrome show changes in the distal regions of the left superior cerebellar peduncle, and these changes persist up to a year post-operatively. These findings will have direct clinical implications for neurosurgeons performing resection of midline paediatric posterior fossa tumours.

Relationship between post-traumatic amnesia and white matter integrity in traumatic brain injury using tract-based spatial statistics

This study used tract-based spatial statistics to examine the relationship between post-traumatic amnesia (PTA) and white matter integrity in patients with a traumatic brain injury (TBI). Forty-seven patients with TBI in the chronic stage and 47 age- and sex-matched normal control subjects were recruited to the study. Correlation coefficients were calculated to observe the relationships among the PTA duration, white matter fractional anisotropy (FA) values, and mini-mental state examination (MMSE) results in the patient group. Both before and after Benjamini–Hochberg (BH) corrections, FA values of 46 of the 48 regions of interests of the patient group were lower than those of the control group. The FA values of column and body of fornix, left crus of fornix, left uncinate fasciculus, right hippocampus part of cingulum, left medial lemniscus, right superior cerebellar peduncle, left superior cerebellar peduncle, and left posterior thalamic radiation (after BH correction: the uncinate fasciculus and right hippocampus part of cingulum) in the patient group were negatively correlated with PTA duration. PTA duration was related to the injury severity of eight neural structures, each of which is involved in the cognitive functioning of patients with TBI. Therefore, PTA duration can indicate injury severity of the above neural structures in TBI patients.

Peribuccal and pharyngeal myorhythmia as a presenting symptom of hypertrophic olivary degeneration

A 58-year-old woman underwent to a successful surgical treatment of a left cerebellar paravermian cavernous malformation. Seven months later she progressively developed involuntary contractions of the left peribuccal region. Neurological examination revealed repetitive, rhythmic, slow frequency jerks of the left corner of the mouth (Video, segment-1). She did not report swallowing difficulties, saliva pooling or ear clicks. However, a careful examination of the oral cavity revealed the presence of synchronous contractions of left pharyngeal muscles (Video, segment-2). The involuntary movements occurred at rest and were suppressed neither by voluntary activity nor by distractions manoeuvres with motor tasks, disappearing during sleep. No palatal or ocular movement abnormalities were observed. Surface electromyography recorded to the left orbicularis oris at rest showed repetitive synchronous 3-Hz rhythmic bursts with a mean duration of 130 msec (Fig. 1D and E), without any electroencephalographic correlation. 3T-brain MRI revealed FLAIR hyperintensity and hypertrophy of right inferior olivary nucleus (ION) consistent with hypertrophic olivary degeneration (HOD), associated with T2-hyperintensity and thinning of left superior cerebellar peduncle (Fig. 1A and B). DTI-based fiber direction failed in demonstrating the normal appearance of decussation of superior cerebellar peduncles, probably as a result of axonal degeneration processes of dentatorubral tract (Fig. 1, C). A diagnosis of isolated peribuccal and pharyngeal myorhythmia due to HOD was made. Clonazepam and pregabalin did not entail any benefit. Botulinum toxin type A injections was started and repeated every three months with 8 Xeomin® units injected into the left orbicularis oris and depressor anguli oris muscles, leading to persistent reduction of involuntary peribuccal contractions. To date, 24 months after surgery patient's conditions are stable with no palatal involvement.

Diffusion tensor imaging in orthostatic tremor: a tract-based spatial statistics study.

ObjectiveThe pathogenesis of orthostatic tremor (OT) is unknown. We investigated OT‐related white matter changes and their correlations with scores from a neuropsychological testing battery.MethodsDiffusion tensor imaging measures were compared between 14 OT patients and 14 age‐ and education‐matched healthy controls, using whole‐brain tract‐based spatial statistics analysis. Correlations between altered diffusion metrics and cognitive performance in OT group were assessed.ResultsIn all cognitive domains (attention, executive function, visuospatial ability, verbal memory, visual memory, and language), OT patients’ cognitive performance was significantly worse than that of healthy controls. OT patients demonstrated altered diffusivity metrics not only in the posterior lobe of the cerebellum (left cerebellar lobule VI) and in its efferent cerebellar fibers (left superior cerebellar peduncle), but also in medial lemniscus bilaterally (pontine tegmentum), anterior limb of the internal capsule bilaterally, right posterior limb of the internal capsule, left anterior corona radiata, right insula, and the splenium of corpus callosum. No relationship was found between diffusion measures and disease duration in OT patients. Diffusion white matter changes, mainly those located in right anterior limb of the internal capsule, were correlated with poor performance on tests of executive function, visuospatial ability, verbal memory, and visual memory in OT patients.InterpretationWhite matter changes were preferentially located in the cerebellum, its efferent pathways, as well as in the pontine tegmentum and key components of the frontal–thalamic–cerebellar circuit. Further work needs to be done to understand the evolution of these white matter changes and their functional consequences.

Reduced Fractional Anisotropy of Superior Cerebellar Peduncle is Associated With Persistent Ataxia in Children Undergoing Resection of Posterior Fossa Tumors

Abstract INTRODUCTION Persistent neurological deficits are seen in over 60% of children after resection of posterior fossa tumors. The goal of this study was to determine if these deficits are associated with persistent structural injury to white matter tracts. METHODS Demographic, clinical, and imaging data were reviewed for children undergoing resection of posterior fossa tumors at a tertiary care pediatric hospital. Preoperative, early postoperative (within 48 h of injury) and follow-up diffusion tensor imaging (DTI) were analyzed. Fractional anisotropy (FA) of the middle and superior cerebellar peduncles (SCP) were measured using manual regions of interest. Mean FA values before and after surgery were compared using paired sample T-test. Preoperative, postoperative and follow-up FA values were compared between patients with and without persistent neurological deficits. Statistical significance was set at P &lt; .05. RESULTS A toal of 20 patients (12 male, mean age 6.1 ± 4.1 yr) were included in this study. A total of Twelve patients (60%) underwent a trans-vermian approach and 15 patients (75%) underwent gross total resection. All patients had preoperative DTI scans, and follow-up DTI scans were available for 18 patients at a median duration of 19.7 mo (range 4-57.9 mo). Compared to preoperative DTI, FA of the left SCP was significantly reduced on early postoperative DTI scans (0.44 ± 0.07 vs 0.53 ± 0.1, P = .003). Significant reduction in left SCP FA on follow-up DTI was seen in patients with persistent ataxia at follow-up (0.43 ± 0.1 vs 0.55 ± 0.1, P = .016). Patients with persistent ataxia at follow-up (n = 10) had significantly lower FA of the left SCP at follow-up compared to patients who recovered from early postoperative ataxia (n = 4) (0.43 ± 0.1 vs 0.55 ± 0.04, P = .04). CONCLUSION Reduced FA of the SCP is associated with persistent ataxia at follow-up in children undergoing resection of posterior fossa tumors.

Association between postoperative DTI metrics and neurological deficits after posterior fossa tumor resection in children.

Resection of posterior fossa tumors in children may be associated with persistent neurological deficits. It is unclear if these neurological deficits are associated with persistent structural damage to the cerebellar pathways. The purpose of this research was to define longitudinal changes in diffusion tensor imaging (DTI) metrics in white matter cerebellar tracts and the clinical correlates of these metrics in children undergoing resection of posterior fossa tumors. Longitudinal brain DTI was performed in a cohort of pediatric patients who underwent resection of posterior fossa tumors. Fractional anisotropy (FA) of the superior cerebellar peduncles (SCPs) and middle cerebellar peduncles (MCPs) was measured on preoperative, postoperative, and follow-up DTI. Early postoperative (< 48 hours) and longer-term follow-up neurological deficits (mutism, ataxia, and extraocular movement dysfunction) were documented. Statistical analysis was performed to determine differences in FA values based on presence or absence of neurological deficits. Statistical significance was set at p < 0.05. Twenty children (mean age 6.1 ± 4.1 years [SD], 12 males and 8 females) were included in this study. Follow-up DTI was performed at a median duration of 14.3 months after surgery, and the median duration of follow-up was 19.7 months. FA of the left SCP was significantly reduced on postoperative DTI in comparison with preoperative DTI (0.44 ± 0.07 vs 0.53 ± 0.1, p = 0.003). Presence of ataxia at follow-up was associated with a persistent reduction in the left SCP FA on follow-up DTI (0.43 ± 0.1 vs 0.55 ± 0.1, p = 0.016). Patients with early postoperative mutism who did not recover at follow-up had significantly decreased FA of the left SCP on early postoperative DTI in comparison with those who recovered (0.38 ± 0.05 vs 0.48 ± 0.06, p = 0.04). DTI after resection of posterior fossa tumors in children shows that persistent reduction of SCP FA is associated with ataxia at follow-up.

Diffusion tensor imaging reveals diffuse white matter injuries in locked-in syndrome patients.

Locked-in syndrome (LIS) is a state of quadriplegia and anarthria with preserved consciousness, which is generally triggered by a disruption of specific white matter fiber tracts, following a lesion in the ventral part of the pons. However, the impact of focal lesions on the whole brain white matter microstructure and structural connectivity pathways remains unknown. We used diffusion tensor magnetic resonance imaging (DT-MRI) and tract-based statistics to characterise the whole white matter tracts in seven consecutive LIS patients, with ventral pontine injuries but no significant supratentorial lesions detected with morphological MRI. The imaging was performed in the acute phase of the disease (26 ± 13 days after the accident). DT-MRI-derived metrics were used to quantitatively assess global white matter alterations. All diffusion coefficient Z-scores were decreased for almost all fiber tracts in all LIS patients, with diffuse white matter alterations in both infratentorial and supratentorial areas. A mixture model of two multidimensional Gaussian distributions was fitted to cluster the white matter fiber tracts studied in two groups: the least (group 1) and most injured white matter fiber tracts (group 2). The greatest injuries were revealed along pathways crossing the lesion responsible for the LIS: left and right medial lemniscus (98.4% and 97.9% probability of belonging to group 2, respectively), left and right superior cerebellar peduncles (69.3% and 45.7% probability) and left and right corticospinal tract (20.6% and 46.5% probability). This approach demonstrated globally compromised white matter tracts in the acute phase of LIS, potentially underlying cognitive deficits.

Functional and Structural Connectivity of the Cerebellar Nuclei With the Striatum and Cerebral Cortex in First-Episode Psychosis.

Evidence suggests that the cortico-striatal-thalamo-cortical circuitry plays an important role in schizophrenia pathophysiology. Cerebellar contribution from deep cerebellar nuclei to the circuitry has not yet been examined. The authors investigated resting-state functional connectivity (RSFC) of cerebellar output nuclei with striatal-thalamic-cortical regions in relation to white-matter integrity and regional gray-matter volumes in first-episode psychosis (FEP). Methods: Forty FEP patients and 40 age- and gender-matched healthy control subjects (HCs) participated. RSFC between cerebellar nuclei and striatal-thalamic-cortical regions was examined. Diffusion tensor imaging and volumetric scans were examined for possible structural constraints on RSFC. The authors also examined relationships between neuroimaging variables and cognitive and clinical measures. Results: FEP patients, compared with HCs, exhibited decreased RSFC between the left fastigial nucleus and right putamen, which was associated with poor letter fluency performance and lower global assessment of functioning scores. By contrast, patients showed widespread increased accumbens network connectivity in the left nucleus. The authors further observed both hypo- and hyper-RSFC between the cerebellar nuclei and fronto-parietal areas in patients, independent of striatal activity. Finally, the authors found impaired integrity of the left superior cerebellar peduncle and decreased bilateral putamen volume in patients, whereas structural-functional relationships found in HCs were absent in patients. Conclusions: This study provides evidence of disordered RSFC of cerebellar output nuclei to the striatum and neocortex at the early stage of schizophrenia. Furthermore, dysfunctional cerebellar influences on fronto-parietal areas that are independent of striatal dysfunction in patients with FEP were observed. The results suggest that cortico-striatal abnormalities in patients with FEP are produced by abnormal cerebellar influences.

Brain white matter microstructural alterations in children of type I Gaucher disease characterized with diffusion tensor MR imaging

ObjectivesTo investigate white matter (WM) microstructural alterations in type I Gaucher disease (type I GD) pediatric patients and explore the correlation between the disease duration and WM changes. MethodsTwenty-two GD patients and twenty-two sex- and age-matched typical development (TD) children were recruited. Changes in WM were investigated using diffusion tensor imaging (DTI) and applying atlas-based tract analysis. For all DTI measurements, independent-samples t-test was applied to report significant differences between type I GD and TD. Partial correlation was applied to determine whether the disease duration was correlated with DTI measurements. ResultsBidirectional fractional anisotropy (FA) changes were found in the bilateral superior cerebellar peduncle, right posterior limb of the internal capsule, right posterior corona radiata, and right posterior thalamic radiation (p < 0.05). Higher mean diffusivity (MD)was found in the right superior corona radiata, middle cerebellar peduncle, right posterior thalamic radiation and right superior longitudinal fasciculus (p < 0.05) in type I GD. And higher radial diffusivity (RD) was also found in the left superior cerebellar peduncle (p < 0.05) in type I GD. The disease duration of type I GD patients is positively correlated with axial diffusivity and MD in multiple major WM tracts. ConclusionDTI findings supported the microstructural alterations of multiple WM tracts in type I GD patients.

Microstructural Alterations in Asymptomatic and Symptomatic Patients with Spinocerebellar Ataxia Type 3: A Tract-Based Spatial Statistics Study.

Spinocerebellar ataxia type 3 (SCA3) is the most commonly occurring type of autosomal dominant spinocerebellar ataxia. The present study aims to investigate progressive changes in white matter (WM) fiber in asymptomatic and symptomatic patients with SCA3. A total of 62 participants were included in this study. Among them, 16 were asymptomatic mutation carriers (pre-SCA3), 22 were SCA3 patients with clinical symptoms, and 24 were normal controls (NC). Group comparison of tract-based spatial statistics was performed to identify microstructural abnormalities at different SCA3 disease stages. Decreased fractional anisotropy (FA) and increased mean diffusivity (MD) were found in the left inferior cerebellar peduncle and superior cerebellar peduncle (SCP) in the pre-SCA3 group compared with NC. The symptomatic SCA3 group showed brain-wide WM tracts impairment in both supratentorial and infratentorial networks, and the mean FA value of the WM skeleton showed a significantly negative correlation with the International Cooperative Ataxia Rating Scale (ICARS) scores. Specifically, FA of the bilateral posterior limb of the internal capsule negatively correlated with SCA3 disease duration. We also found that FA values in the right medial lemniscus and SCP negatively correlated with ICARS scores, whereas FA in the right posterior thalamic radiation positively correlated with Montreal Cognitive Assessment scores. In addition, MD in the middle cerebellar peduncle, left anterior limb of internal capsule, external capsule, and superior corona radiate positively correlated with ICARS scores in SCA3 patients. WM microstructural changes are present even in the asymptomatic stages of SCA3. In individuals in which the disease has progressed to the symptomatic stage, the integrity of WM fibers across the whole brain is affected. Furthermore, abnormalities in WM tracts are closely related to SCA3 disease severity, including movement disorder and cognitive dysfunction. These findings can deepen our understanding of the neural basis of SCA3 dysfunction.