White matter microstructural changes using ultra-strong diffusion gradient MRI in adult-onset idiopathic focal cervical dystonia

Background and Objectives Adult-onset idiopathic focal cervical dystonia (AOIFCD) involves abnormal posturing of the cervical musculature and, in some individuals, an associated head tremor. Existing neuroimaging studies have implicated key motor networks. However, measures used to date lack specificity toward underlying pathophysiologic differences. We aim to assess white matter motor pathways for localized, microstructural differences, which may aid in understanding underlying mechanisms. Methods Individuals diagnosed with AOIFCD and an age- and sex-matched control group were prospectively recruited through the Welsh Movement Disorders Research Network. All participants underwent in-depth clinical phenotyping and MRI (structural and diffusion sequences) using ultra-strong diffusion gradients. Tractography (whole-tract median values) and tractometry (along tract profiling) were performed for key white matter motor pathways assessing diffusion kurtosis imaging (DKI), neurite orientation dispersion and density imaging (NODDI), and standard model parameters. Groups were compared using linear model analysis with Bonferroni multiple comparison correction. Results Fifty participants with AOIFCD and 30 healthy control participants were recruited, with 46 with AOIFCD and 30 healthy controls included for analysis (33 without head tremor, 13 with head tremor). Significant differences were observed in the anterior thalamic radiations (lower mid-tract fractional anisotropy [estimate = −0.046, p = 3.07 × 10−3], radial kurtosis [estimate = −0.165, p = 1.42 × 10−4], f–intra-axonal signal fraction [estimate = −0.044, p = 2.78 × 10−3], p2 orientation coherence [estimate = −0.043, p = 1.64 × 10−3], higher Orientation Dispersion Index [ODI, estimate = 0.023, p = 2.22 × 10−3]) and thalamopremotor tracts (higher mid-tract mean kurtosis [estimate = 0.064, p = 7.56 × 10−4], lower Neurite Density Index [estimate = 0.062, p = 2.1 × 10−3], higher distal tract ODI [estimate = 0.062, p = 3.1 × 10−3], lower f [estimate = −0.1, p = 2.3 × 10−3], and striatopremotor tracts [proximal lower f: estimate = −0.075, p = 1.06 × 10−3]). These measures correlated with clinical measures: dystonia duration (right thalamopremotor distal ODI: r = −0.9, p = 1.29 × 10−14), psychiatric symptoms (obsessive compulsive symptoms: left anterior thalamic radiation p2 r = 0.92, p = 2.797 × 10−11), sleep quality (Sleep Disorders Questionnaire Score: left anterior thalamic radiation ODI: r = −0.84, p = 4.84 × 10−11), pain (left anterior thalamic radiation ODI: r = −0.89, p = 1.4 × 10−13), and cognitive functioning (paired associated learning task p2, r = 0.94, p = 6.68 × 10−20)

White Matter Microstructural Changes Using Ultra-Strong Diffusion Gradient MRI in Adult-Onset Idiopathic Focal Cervical Dystonia

Background and Objectives Adult-onset idiopathic focal cervical dystonia (AOIFCD) involves abnormal posturing of the cervical musculature and, in some individuals, an associated head tremor. Existing neuroimaging studies have implicated key motor networks. However, measures used to date lack specificity toward underlying pathophysiologic differences. We aim to assess white matter motor pathways for localized, microstructural differences, which may aid in understanding underlying mechanisms. Methods Individuals diagnosed with AOIFCD and an age- and sex-matched control group were prospectively recruited through the Welsh Movement Disorders Research Network. All participants underwent in-depth clinical phenotyping and MRI (structural and diffusion sequences) using ultra-strong diffusion gradients. Tractography (whole-tract median values) and tractometry (along tract profiling) were performed for key white matter motor pathways assessing diffusion kurtosis imaging (DKI), neurite orientation dispersion and density imaging (NODDI), and standard model parameters. Groups were compared using linear model analysis with Bonferroni multiple comparison correction. Results Fifty participants with AOIFCD and 30 healthy control participants were recruited, with 46 with AOIFCD and 30 healthy controls included for analysis (33 without head tremor, 13 with head tremor). Significant differences were observed in the anterior thalamic radiations (lower mid-tract fractional anisotropy [estimate = −0.046, p = 3.07 × 10−3], radial kurtosis [estimate = −0.165, p = 1.42 × 10−4], f–intra-axonal signal fraction [estimate = −0.044, p = 2.78 × 10−3], p2 orientation coherence [estimate = −0.043, p = 1.64 × 10−3], higher Orientation Dispersion Index [ODI, estimate = 0.023, p = 2.22 × 10−3]) and thalamopremotor tracts (higher mid-tract mean kurtosis [estimate = 0.064, p = 7.56 × 10−4], lower Neurite Density Index [estimate = 0.062, p = 2.1 × 10−3], higher distal tract ODI [estimate = 0.062, p = 3.1 × 10−3], lower f [estimate = −0.1, p = 2.3 × 10−3], and striatopremotor tracts [proximal lower f: estimate = −0.075, p = 1.06 × 10−3]). These measures correlated with clinical measures: dystonia duration (right thalamopremotor distal ODI: r = −0.9, p = 1.29 × 10−14), psychiatric symptoms (obsessive compulsive symptoms: left anterior thalamic radiation p2 r = 0.92, p = 2.797 × 10−11), sleep quality (Sleep Disorders Questionnaire Score: left anterior thalamic radiation ODI: r = −0.84, p = 4.84 × 10−11), pain (left anterior thalamic radiation ODI: r = −0.89, p = 1.4 × 10−13), and cognitive functioning (paired associated learning task p2, r = 0.94, p = 6.68 × 10−20)

Clinical and imaging characteristics of early Parkinson's disease

Background. Pathological processes in Parkinson’s disease (PD) start long before the first symptoms appear and by the time the disease is clinically established the results of neurodegeneration may be irreversible. Efforts to prevent or stem disease progression need to start in early disease and good characterization and new markers of early PD are urgently needed. Objectives. This thesis aims to characterize early disease stages in three projects. Firstly, clinical features of PD within 3 years of diagnosis will be explored in an incident cohort of patients and controls, using a range of tools to cover the whole breadth of clinical presentation of PD. Secondly, functional imaging studies in PD published so far will be examined through a meta-analysis to identify the most robust functional imaging markers. Thirdly, a functional MRI resting-state study in early PD will be performed to identify reproducible differences between patients and matched control subjects. Results. The cohort analysis found that age was a strong predictor of disease severity, independent of disease duration, while gender was seen to affect disease severity depending on the body region. A meta-analysis of all published functional imaging studies across all disease stages showed abnormal activations in the Basal Ganglia but also in a wide range of motor and non-motor brain areas. Dopamine supplementation normalized activations in the Basal Ganglia and some other areas, while other circuits remained resistant to medication suggesting non-dopaminergic abnormality. In the resting-state study, the Basal Ganglia Network showed greatly reduced connectivity in early PD compared to controls, which normalized on administration of dopaminergic medication. Reduced BGN connectivity was also validated on a separate group of PD subjects achieving very good separation of patients from controls. Conclusions. The effect of gender and age on early presentation of PD has potential significance for early diagnosis and choice of outcome measures for clinical trials. Within the realm of imaging, traditional task-based fMRI studies fail to show a clear and reproducible pattern of activations making this method unfeasible for early diagnostic testing. In contrast, resting-state fMRI connectivity in the Basal Ganglia Network appears to be a promising and reliable method even in the early stages of PD. Clinical profiling and resting imaging changes offer avenues for developing future biomarkers in early PD

Use of remote monitoring and integrated platform for the evaluation of sleep quality in adult-onset idiopathic cervical dystonia

Background Up to 70% of individuals diagnosed with adult-onset idiopathic focal cervical dystonia (AOIFCD) report difficulties with sleep. Larger cohort studies using wrist-worn accelerometer devices have emerged as an alternative to smaller polysomnography studies, in order to evaluate sleep architecture. Methods To measure activity during the sleep/wake cycle, individuals wore a consumer-grade wrist device (Garmin vivosmart 4) continuously over 7 days on their non-dominant wrist, while completing a daily sleep diary and standardised sleep and non-motor questionnaires via a dedicated app. Sleep measures were derived from the captured raw triaxial acceleration and heart rate values using previously published validated algorithms. Results Data were collected from 50 individuals diagnosed with AOIFCD and 47 age- and sex-matched controls. Those with AOIFCD self-reported significantly higher levels of excessive daytime sleepiness (p = 0.04) and impaired sleep quality (p = 0.03), while accelerometer measurements found the AOIFCD cohort to have significantly longer total sleep times (p = 0.004) and time spent in NREM sleep (p = 0.009), compared to controls. Overall, there was limited agreement between wearable-derived sleep parameters, and self-reported sleep diary and visual analogue scale records. Discussion This study shows the potential feasibility of using consumer-grade wearable devices in estimating sleep measures at scale in dystonia cohorts. Those diagnosed with AOIFCD were observed to have altered sleep architecture, notably longer total sleep time and NREM sleep, compared to controls. These findings suggest that previously reported disruptions to brainstem circuitry and serotonin neurotransmission may contribute to both motor and sleep pathophysiology

REM sleep behaviour disorder is associated with worse quality of life and other non-motor features in early Parkinson's disease

BACKGROUND: Concomitant REM sleep behaviour disorder (RBD) is commonly observed in patients with Parkinson's disease (PD). Although the brainstem structures responsible for the symptoms of RBD correspond to the premotor stages of PD, the association of RBD with motor and non-motor features in early PD remains unclear. METHODS: The study evaluated 475 patients with PD within 3.5 years of diagnosis for the presence of probable RBD (pRBD) using the REM Sleep Behaviour Disorder Screening Questionnaire (RBDSQ). A neurologist and a trained research nurse carried out evaluation of each participant blinded to the results of the RBDSQ. Standardised rating scales for motor and non-motor features of PD, as well as health-related quality of life measures, were assessed. Multiple linear and logistic regression analyses were used to determine the relationship between pRBD and a variety of outcomes, controlling for confounding factors. RESULTS: The overall frequency of pRBD was 47.2% (95% CI 42.7% to 51.9%). None of the patients had a previous diagnosis of RBD. Patients with PD and concomitant pRBD did not differ on motor phenotype and scored comparably on the objective motor scales, but reported problems with motor aspects of daily living more frequently. Adjusted for age, sex, disease duration and smoking history, pRBD was associated with greater sleepiness (p=0.001), depression (p=0.001) and cognitive impairment (p=0.006). CONCLUSIONS: pRBD is common and under-recognised in early PD. It is associated with increased severity and frequency of non-motor features, poorer subjective motor performance and a greater impact on health-related quality of life

New-onset refractory status epilepticus (NORSE) in a 23-year-old female

Highlights Mitochondrial disease is a rare cause of new-onset refractory status epilepticus (NORSE) We present a case NORSE caused by POLG-related mitochondrial disease This case is illustrated with MRI brain and EEG typical of POLG<br/

Aberrant functional connectivity within the basal ganglia of patients with Parkinson's disease

Resting state functional MRI (rs-fMRI) has been previously shown to be a promising tool for the assessment of early Parkinson's disease (PD). In order to assess whether changes within the basal ganglia network (BGN) are disease specific or relate to neurodegeneration generally, BGN connectivity was assessed in 32 patients with early PD, 19 healthy controls and 31 patients with Alzheimer's disease (AD). Voxel-wise comparisons demonstrated decreased connectivity within the basal ganglia of patients with PD, when compared to patients with AD and healthy controls. No significant changes within the BGN were seen in AD, when compared to healthy controls. Moreover, measures of functional connectivity extracted from regions within the basal ganglia were significantly lower in the PD group. Consistent with previous radiotracer studies, the greatest change when compared to the healthy control group was seen in the posterior putamen of PD subjects. When combined into a single component score, this method differentiated PD from AD and healthy control subjects, with a diagnostic accuracy of 81%. Rs-fMRI can be used to demonstrate the aberrant functional connectivity within the basal ganglia of patients with early PD. These changes are likely to be representative of patho-physiological basal ganglia dysfunction and are not associated with generalised neurodegeneration seen in AD. Further studies are necessary to ascertain whether this method is sensitive enough to detect basal ganglia dysfunction in prodromal PD, and its utility as a potential diagnostic biomarker for premotor and early motoric disease