Impaired sleep quality and cognition in patients of Parkinson's disease with REM sleep behavior disorder: a comparative study.

OBJECTIVES: The present study was undertaken to evaluate the cognitive profile of Parkinson's disease (PD) patients with REM sleep behavior disorder (RBD) and to correlate with the clinical stage and polysomnographic variables. METHODS: The study included 25 PD patients who had RBD and 25 PD patients who based on two questionnaires were determined as not having RBD. These patients underwent overnight polysomnography (PSG) and neuropsychological assessment using a defined battery of tests. RESULTS: The mean age of the patients with clinically probable RBD (RBD+) was 60.4 ± 8.2 years and PD patients without RBD (RBD-) was 57.3 ± 6.6 years (p = 0.14). The mean age at onset of the disease was 53.7 ± 9.4 years for RBD+ and 49.8 ± 7.8 years for RBD-patients (p = 0.12). The mean Unified Parkinson Disease Rating Scale (UPDRS) part III OFF score was 27.4 ± 11.1 for RBD+ and 32.7 ± 8.2 for RBD- (p = 0.06). The total sleep time of the patients was 4.3 ± 1.7 h with sleep efficiency of 53.8 ± 21.0%. Patients with RBD+ were found to have significant impairment in many neuropsychological tests compared to RBD-. CONCLUSIONS: RBD + patients had significant impairment in MMSE, category fluency test (FAS test), frontal assessment battery, attention (digit span backwards, Corsi span), verbal memory (story recall) and Rey's auditory verbal learning test. These patients also had poor sleep quality.

Evaluation of Cognition and Cortical Excitability in Huntington's Disease.

BACKGROUND: Recent advances in neurophysiological techniques have contributed to our understanding of the pathophysiology of Huntington's disease (HD). Studies of the motor cortical excitability and central motor pathways have shown variable results. OBJECTIVES: Our aims were to evaluate the cortical excitability changes in HD using transcranial magnetic stimulation (TMS) and correlate the changes with cognitive impairment. METHODS: The study included 32 HD patients and 30 age- and gender-matched controls. The demographic and clinical profiles of the patients were recorded. All subjects were evaluated by TMS and resting motor threshold (RMT), central motor conduction time (CMCT), silent period (SP), short-interval intracortical inhibition (SICI), and intracortical facilitation were determined. A battery of neuropsychological tests was administered to all subjects. RESULTS: The mean age of the patients was 42.1±14.1 years, and that of controls 39.4±12.4 years (p=0.61). There was no significant difference in RMT and CMCT between the two groups. There was a mild prolongation of the contralateral SP in HD, but it was not significant. SICI was significantly reduced in HD (p<0.0001). A significant impairment in attention, verbal fluency, executive function, visuospatial function, learning, and memory was observed in HD patients. However, there was no correlation between cortical excitability changes and cognitive impairment. CONCLUSIONS: TMS is a valuable method of evaluating cortical excitability changes in HD. These patients have reduced SICI and significant impairment of cognition in multiple domains.

Long Loop Reflex 2 in Patients with Cortical Dementias: A Pilot Study.

INTRODUCTION: Dementia is a major public health problem and it appears to be a global epidemic. The prevalence is doubling every 5 years and it is expected that 70% of persons above 60 years will live in developing countries by 2020 and 15% of them are likely to suffer from dementia. Disease modifying treatments work only if initiated very early; however, diagnostic tools are not always able to clearly differentiate the different types in very early stage. Therefore, inexpensive and easily available biomarkers are needed to know if collectively they will improve the sensitivity of specific diagnosis. Therefore, in this pilot study, we have tried to analyze if long loop reflex (LLR2) is differentially affected in these two conditions early in the course of Alzheimer's dementia (AD) and frontotemporal dementia (FTD) based on hypothesis taking into account the anatomical substrates involved. PATIENTS AND METHODS: Mild cases of clinically probable AD and FTD after appropriate inclusion criteria were subjected for LLR testing in the upper limb at median nerve. The presence or absence of LLR was assessed and also the latency, amplitude, and duration assessed. RESULTS AND CONCLUSION: LLR 2 is differentially affected in both these conditions. Absence of LLR2 was consistently seen in FTD which can be explained by early break down of frontal subcortical circuits in this condition as against AD. This is likely to serve as a very cheap and very early biomarker to differentiate the two common types of cortical dementias.

Re-emergent tremor in Parkinson's disease: A clinical and electromyographic study.

BACKGROUND: Re-emergent tremor (ReT) in Parkinson's disease (PD) is the tremor that re-emerges after a variable period of latency while maintaining posture. The phenomenology and electrophysiological aspects of ReT have not been well characterized. The aims of this study were to characterize ReT clinically and electrophysiologically. METHODS: Sixty three patients with tremor dominant PD were recruited and subjected to clinical and electrophysiological evaluations. Group 1 consisted of 26 patients with rest tremor (RT) and ReT and group 2 consisted of 37 patients with RT and postural tremor (PT). The presence of silent period of ReT was determined clinically and confirmed electrophysiologically. RESULTS: The duration of illness was significantly shorter in patients with ReT as compared to patients without ReT (5.2±4.4years vs 7.4±4.5years, p=0.03). ReT was similar to RT in terms of both frequency (4.8±0.7Hz vs 4.7±0.6Hz, p=0.1) and pattern of contraction. The frequency of RT was not significantly different in the 2 groups (p=0.5). The mean duration of silent period was 8.1±8.7s. CONCLUSIONS: A significantly shorter duration of illness was found in patients with ReT as compared to patients without ReT. ReT is similar to RT in terms of frequency and pattern of contraction. However, the presence of silent period may imply additional pathophysiological mechanisms.

A Study of Cortical Excitability, Central Motor Conduction, and Cortical Inhibition Using Single Pulse Transcranial Magnetic Stimulation in Patients with Early Frontotemporal and Alzheimer's Dementia.

INTRODUCTION: Degenerative cortical dementias affect several million people worldwide. Early diagnosis and categorization are essential for initiating appropriate pharmacological and nonpharmacological treatment so that deterioration can be postponed, and disability adjusted life years can be saved both for the patient and for the caregiver. Therefore, an early, simple, noninvasive biomarker will serve as a boon. PATIENTS AND METHODS: Patients who satisfied probable Alzheimer's disease (AD) or frontotemporal dementia (FTD) using international consensus criteria for FTD and National Institute of Neurological Disorders and Stroke-AD and Related Disorders Association criteria for AD were evaluated using single pulse transcranial magnetic stimulation with figure of eight coil and motor evoked potential from right first dorsal interossei. Resting threshold (MT), central motor conduction time (CMCT), and silent period (SP) were evaluated. RESULTS: Resting MT and SP are reduced in patients with Alzheimer's disease whereas CMCT is prolonged in patients with FTD and SP is in the lower limit of normal in both conditions. CONCLUSION: The patterns of central motor conduction and MT are distinctly different in patients with early Alzheimer's disease (AD) and FTD.

Transcranial Magnetic Stimulation (TMS) as a Tool for Early Diagnosis and Prognostication in Cortico-Basal Ganglia Degeneration (CBD) Syndromes: Review of Literature and Case Report.

BACKGROUND: Cortico basal degeneration (CBD) of the brain is a rare progressive neurodegenerative disease which encompasses unique neuropsychiatric manifestations. Early diagnosis is essential for initiating proper treatment and favorable outcome. Transcranial Magnetic Stimulation (TMS), a well-known technique for assessment of cortical excitatory and inhibitory properties. It was suggested that in a degenerative disease like CBD which involves the cortex as well as the subcortical structures, comparing both hemispheres, a differential pattern in TMS can be obtained which would help in early identification, prognostication and early therapeutic intervention. CASE REPORT: We describe a case of CBD with corroborative clinical and imaging picture wherein single pulse TMS was used over both the hemispheres measuring the following parameters of interest which included: Motor Threshold (MT), Central Motor Conduction Time (CMCT) and Silent Period (SP). RESULTS AND CONCLUSION: Differential patterns of MT, CMCT and SP was obtained by stimulating over both the hemispheres with the affected hemisphere showing significantly reduced MT and prolonged CMCT implying early impairment of cortical and subcortical structures thereby revealing the potential application of TMS being utilized in a novel way for early detection and prognostication in CBD syndromes.

Transcranial magnetic stimulation in patients with early cortical dementia: A pilot study.

CONTEXT: The diagnostic accuracy of the currently available tools carries poor sensitivity resulting in significant delay in specific diagnosis of cortical dementias. Considering the properties of default mode networking of the brain it is highly probable that specific changes may be seen in frontotemporal dementias (FTDs) and Alzheimer's disease sufficiently early. AIM: The aim of this study is to look for changes in Transcranial Magnetic Stimulation (TMS) in cortical dementia. MATERIALS AND METHODS: Evaluated with a single pulse TMS with the figure of eight coil and recorded from right first dorsal interossei (FDI). Resting Motor Threshold (RMT) was estimated on the opposite motor cortex (T1). Second site of stimulation was cervical spine at C7-T2. Central motor conduction time (CMCT) is equal toT1-T2. Silent Period (SP) identified by applying TMS pulse to contracting FDI. CONCLUSIONS: RMT was reduced in seven out of eight Alzheimer's dementias. CMCT was in the upper limit of normal in both patients with FTD. The most consistent observation was that SP was reduced and there were escape discharges noticed during the SP suggesting increased cortical excitability and decreased cortical inhibition. This suggests probable early asymptomatic changes in the gamma-aminobutyric acid (GABA) nergic and cholinergic system is taking place. This if confirmed may give some insight into early diagnosis and therapeutic role of GABA agonists in these disorders.

Alterations of cortical excitability and central motor conduction time in Wilson's disease.

Wilson's disease (WD) leads to widespread structural alterations of central nervous system and our objectives were to determine the cortical excitability changes in WD by using transcranial magnetic stimulation (TMS). Thirteen patients with WD, diagnosed by the presence of Kayser-Fleischer ring and biochemical tests, were studied. TMS was performed using a figure-of-eight coil attached to Magstim 200 stimulator. Motor evoked potentials (MEP) were recorded from right first dorsal interosseous at rest. Resting motor threshold (RMT) was determined using standard techniques and central motor conduction time (CMCT) by 'F' wave method. Comparison was made with control data of our laboratory. Dysarthria was the presenting symptom in 5 patients (38.5%) and chorea, tremors, dystonia and abnormal gait in 2 patients each (15.4%). RMT was recordable in 10 patients and not recordable in 3. Compared to controls, patients in whom RMT was recordable, had significantly higher mean RMT (80.9 ± 14.8 vs. 41.1 ± 7, p<0.0001) and CMCT (6.7 ± 0.5 ms vs. 4.8 ± 0.6 ms; p<0.0001). In 2 of the 3 patients with non-recordable RMT, MEP could be obtained with active contraction. CMCT in these 2 patients was also prolonged. Patients with WD have reduced cortical excitability and prolonged CMCT which may be due to the intracortical presynaptic motor dysfunction.