Lija George

Repetitive transcranial magnetic stimulation induced modulations of resting state motor connectivity in writer's cramp.

Writers cramp (WC) is a focal task‐specific dystonia of the hand which is increasingly being accepted as a network disorder. Non‐invasive cortical stimulation using repetitive transcranial magnetic stimulation (rTMS) has produced therapeutic benefits in some of these patients. This study aimed to visualize the motor network abnormalities in WC and also its rTMS induced modulations using resting state functional magnetic resonance imaging (rsfMRI).

Utility of resting fMRI and connectivity in patients with brain tumor

BACKGROUND Resting state (task independent) Functional Magnetic Resonance Imaging (fMRI) has opened a new avenue in cognitive studies and has found practical clinical applications. MATERIALS AND METHODS Resting fMRI analysis was performed in six patients with brain tumor in the motor cortex. For comparison, task-related mapping of the motor cortex was done. Connectivity analysis to study the connections and strength of the connections between the primary motor cortex, premotor cortex, and primary somatosensory cortex on the affected side was also performed and compared with the contralateral normal side and the controls. RESULTS Resting fMRI in patients with brain tumor in the motor cortex mapped the motor cortex in a task-free state and the results were comparable to the motor task paradigm. Decreased connectivity on the tumor-affected side was observed, as compared to the unaffected side. CONCLUSION Resting fMRI and connectivity analysis are useful in the presurgical evaluation of patients with brain tumors and may help in uncooperative or pediatric patients. They can also prognosticate the postoperative outcome. This method also has significant applications due to the ease of image acquisition.

Understanding the pathophysiology of reflex epilepsy using simultaneous EEG-fMRI

Measuring neuro-haemodynamic correlates in the brain of epilepsy patients using EEG-fMRI has opened new avenues in clinical neuroscience, as these are two complementary methods for understanding brain function. In this study, we investigated three patients with drug-resistant reflex epilepsy using EEG-fMRI. Different types of reflex epilepsy such as eating, startle myoclonus, and hot water epilepsy were included in the study. The analysis of EEG-fMRI data was based on the visual identification of interictal epileptiform discharges on scalp EEG. The convolution of onset time and duration of these epilepsy spikes was estimated, and using these condition-specific effects in a general linear model approach, we evaluated activation of fMRI. Patients with startle myoclonus epilepsy experienced epilepsy in response to sudden sound or touch, in association with increased delta and theta activity with a spike-and-slow-wave pattern of interictal epileptiform discharges on EEG and fronto-parietal network activation pattern on SPECT and EEG-fMRI. Eating epilepsy was triggered by sight or smell of food and fronto-temporal discharges were noted on video-EEG (VEEG). Similarly, fronto-temporo-parietal involvement was noted on SPECT and EEG-fMRI. Hot water epilepsy was triggered by contact with hot water either in the bath or by hand immersion, and VEEG showed fronto-parietal involvement. SPECT and EEG fMRI revealed a similar fronto-parietal-occipital involvement. From these results, we conclude that continuous EEG recording can improve the modelling of BOLD changes related to interictal epileptic activity and this can thus be used to understand the neuro-haemodynamic substrates involved in reflex epilepsy.

Unraveling Brain Functional Connectivity of encoding and retrieval in the context of education

Human memory is an enigmatic component of cognition which many researchers have attempted to comprehend. Accumulating studies on functional connectivity see brain as a complex dynamic unit with positively and negatively correlated networks in perfect coherence during a task. We aimed to examine coherence of network connectivity during visual memory encoding and retrieval in the context of education. School Educated (SE) and College Educated (CE) healthy volunteers (n=60) were recruited and assessed for visual encoding and retrieval. Functional connectivity using seed to voxel based connectivity analysis of the posterior cingulate cortex (PCC) was evaluated. We noticed that there were reciprocal dynamic changes in both dorsolateral prefrontal cortex (DLPFC) region and PCC regions during working memory encoding and retrieval. In agreement with the previous studies, there were more positively correlated regions during retrieval compared to encoding. The default mode network (DMN) networks showed greater negative correlations during more attentive task of visual encoding. In tune with the recent studies on cognitive reserve we also found that number of years of education was a significant factor influencing working memory connectivity. SE had higher positive correlation to DLPFC region and lower negative correlation to DMN in comparison with CE during encoding and retrieval.

Three‐dimensional neuromelanin‐sensitive magnetic resonance imaging of the substantia nigra in Parkinson's disease

The aim was to investigate the diagnostic utility of signal intensity measurement of the substantia nigra pars compacta (SNc) using three‐dimensional (3D) neuromelanin‐sensitive magnetic resonance imaging (MRI), for discrimination of patients with Parkinsons disease (PD) from healthy controls.

Abnormalities of white and grey matter in early multiple system atrophy: comparison of parkinsonian and cerebellar variants

ObjectiveMultiple system atrophy (MSA) is a neurodegenerative disorder with progressive motor and autonomic dysfunction. There is a paucity of information on the early neurostructural changes in MSA, especially its subtypes, MSA-P (patients with predominant parkinsonism) and MSA-C (patients with predominant cerebellar signs). This study investigates the abnormalities of grey matter (GM) and white matter (WM) in early MSA and its subtypes using multi-modal voxel-based analysis.Materials and methodsTwenty-six patients with MSA with duration of symptoms ≤ 2.5 years (mean duration: 1.6 ±0.9 years) were assessed clinically and with 3T MRI. Voxel-based morphometry (VBM) and diffusion tensor imaging (DTI) were performed to identify the structural changes in MSA and its subtypes. The GM changes and diffusion parameters of WM tracts were correlated with the clinical scores. The results were compared with MRI of 25 age- and gender-matched healthy controls.ResultsThe early structural changes in MSA included GM loss of the cerebellum and subcallosal gyrus with widespread involvement of supratentorial and infratentorial WM fibres. In MSA-C, GM loss was limited to the cerebellum with WM changes predominantly affecting the infratentorial WM and association tracts. In contrast, MSA-P did not demonstrate any GM loss and the WM involvement was mainly supratentorial. There was no significant correlation between structural changes and clinical severity score.ConclusionIn early MSA, WM microstructure was more affected than GM. These changes were greater in MSA-C than in MSA-P, suggesting variable deterioration in the subtypes of MSA.Key Points• Structural changes in early multiple system atrophy were evaluated using multi-modal neuroimaging.• White matter was more affected than grey matter in early MSA.• Clinical variables did not correlate with early structural changes.

Role of Corpus Callosum Volumetry in Differentiating the Subtypes of Progressive Supranuclear Palsy and Early Parkinson's Disease

Progressive supranuclear palsy (PSP) is a progressive neurodegenerative disorder. Classic PSP or Richardson‐Steele phenotype (PSP‐RS) and parkinsonian phenotype (PSP‐P) are the common subtypes of PSP. At the early stage, differentiating the subtypes of PSP as well as differentiating PSP from other parkinsonian disorders, especially Parkinsons disease (PD) is challenging. Microstructural abnormalities of corpus callosum (CC) have been reported both in PSP and PD. The objective of this study was to compare the volumes of various segments of CC between patients with PSP‐P, PSP‐RS, and early PD.

Impaired frontal lobe functions in patients with Parkinson’s disease and psychosis

INTRODUCTION Patients with Parkinsons disease (PD) may develop several non-motor symptoms (NMS). Psychosis is one of the debilitating NMS of PD. The neurobiology of psychosis is not fully understood. This study aims to compare the frontal lobe functions of PD patients with and without psychosis using the Frontal Assessment Battery (FAB). METHODOLOGY This study included 69 patients with PD; 34 with psychosis (PD-P) and 35 without psychosis (PD-NP). Mini Mental Status Examination (MMSE) was used to screen for cognitive impairment. Unified Parkinsons disease Rating scale part-III (UPDRS-III) was used to measure the severity and Hoehn and Yahr score (H&Y) was used to measure the stage of PD. Frontal lobe functions were assessed by FAB. RESULTS The PD-P and PD-NP groups were comparable for age (58.7±8.4 vs 55.7±8.2, p=0.14), age at onset of symptoms (51.4±8.1 vs 50.0±8.8, p=0.48), gender distribution (men: 88%vs 80%, p=0.51), MMSE (28.2±1.9 vs 28.7±1.2 p=0.12), levodopa equivalent dose/day (736.0±376.3 vs 625.2±332.2, p=0.19), UPDRS-III OFF-score (36.7±8.8 vs 35.4±13.2, p=0.64), UPDRS-III ON-score (13.2±5.4 vs 12.4±6.6, p=0.44) and H&Y stage (2.3±0.3 vs 2.3±0.3, p=0.07). PD-P group had lower total FAB score compared to PD-NP group (13.9±2.2 vs 16.5±1.8, p<0.01). On the FAB, PD-P group had lower scores compared to PD-NP in lexical fluency (FAB-2), programming (FAB-3), sensitivity to interference (FAB-4) and inhibitory control (FAB-5). CONCLUSION Patients with PD-P had significant frontal lobe dysfunction compared to PD-NP. FAB may be a simple and useful bedside tool to assess frontal dysfunction in patients with PD in a busy neurological set up.