Finely-tuned gamma (FTG) oscillations can be recorded from cortex or the subthalamic nucleus (STN) in patients with Parkinson's disease (PD) on dopaminergic medication, and have been associated with ...dyskinesias. When recorded during deep brain stimulation (DBS) on medication the FTG is entrained to half the stimulation frequency. We investigated whether these characteristics are shared off medication by recording local field potentials (LFP) from the STN from externalised DBS leads in 14 PD patients after overnight withdrawal of medication. FTG was induced de-novo by DBS in the absence of dyskinesias in a third of our cohort. The FTG could outlast stimulation or arise only after DBS ceased. FTG frequencies decreased during and across consecutive DBS blocks, but did not shift with changing stimulation frequency off medication. Together with the sustained after-effects this argues against simple entrainment by DBS in the off medication state. We also found significant coherence between STN-LFP and electroencephalogram (EEG) signals at FTG frequencies. We conclude that FTG is a network phenomenon that behaves differently in the off medication state, when it is neither associated with dyskinesias nor susceptible to entrainment.
•DBS induces de-novo finely-tuned gamma (FTG) oscillations in the subthalamic LFP•Induced FTG appears off levodopa and without dyskinesias•FTG frequencies change within and across consecutive stimulation periods•STN-LFP and cortical activities are coherent at FTG frequencies
Gamma oscillations comprise a loosely defined, heterogeneous group of functionally different activities between 30 and 100 Hz in the cortical and subcortical local field potential (LFP) of the motor ...network. Two distinct patterns seem to emerge which are easily conflated: Finely-tuned gamma (FTG) oscillations – a narrowband activity with peaks between 60 and 90 Hz – have been observed in multiple movement disorders and are induced by dopaminergic medication or deep brain stimulation (DBS). FTG has been linked with levodopa or DBS-induced dyskinesias, which makes it a putative biomarker for adaptive DBS. On the other hand, gamma activity can also present as a broad phenomenon (30–100 Hz) in the context of motor activation and dynamic processing. Here, we contrast FTG, either levodopa-induced or DBS-induced, from movement-related broadband gamma synchronisation and further elaborate on the functional role of FTG and its potential implications for adaptive DBS. Given the unclear distinction of FTG and broad gamma in literature, we appeal for more careful separation of the two. To better characterise cortical and subcortical FTG as biomarkers for dyskinesia, their sensitivity and specificity need to be investigated in a large clinical trial.
Dystonia is characterized by excessive muscle contractions giving rise to abnormal posture and involuntary twisting movements. Although dystonia syndromes are a heterogeneous group of disorders, ...certain pathophysiological mechanisms have been consistently identified across different forms. These pathophysiological mechanisms have subsequently been exploited for the development of non‐invasive brain stimulation (NIBS) techniques able to modulate neural activity in one or more nodes of the putative network that is altered in dystonia, and the therapeutic role of NIBS has hence been suggested. Here all studies that applied such techniques as a therapeutic intervention in any forms of dystonia, including the few works performed in children, are reviewed and emerging concepts and pitfalls of NIBS are discussed.
Background and purpose
There is large variability in the diagnostic approach and clinical management in functional movement disorders (FMD). This study aimed to examine whether opinions and clinical ...practices related to FMD have changed over the past decade.
Methods
Adapted from a 2008 version, we repeated the survey to members of the International Parkinson and Movement Disorder Society (MDS).
Results
In all, 864/7689 responses (denominator includes non‐neurologists) were received from 92 countries. Respondents were more often male (55%), younger than 45 (65%) and from academic practices (85%). Although the likelihood of ordering neurological investigations prior to delivering a diagnosis of FMD was nearly as high as in 2008 (47% vs. 51%), the percentage of respondents communicating the diagnosis without requesting additional tests increased (27% vs. 19%; P = 0.003), with most envisioning their role as providing a diagnosis and coordinating management (57% vs. 40%; P < 0.001). Compared to patients with other disorders, 64% of respondents were more concerned about missing a diagnosis of another neurological disorder. Avoiding iatrogenic harm (58%) and educating patients about the diagnosis (53%) were again rated as the most effective therapeutic options. Frequent treatment barriers included lack of physician knowledge and training (32%), lack of treatment guidelines (39%), limited availability of referral services (48%) and cultural beliefs about psychological illnesses (50%). The preferred term for communication favored ‘functional’ over ‘psychogenic’ (P < 0.001).
Conclusions
Attitudes and management of FMDs have changed over the past decade. Important gaps remain in access to treatment and in the education of neurologists about the inclusionary approach to FMD diagnosis.
Background and purpose
Hypomimia is a prominent clinical feature in people with Parkinson’s disease (PD), but it remains under‐investigated. We aimed to examine the clinical correlates of hypomimia ...in PD and to determine whether this is a levodopa‐responsive sign.
Methods
We included 89 people with PD. Hypomimia was assessed from digital video recordings by movement disorder specialists. Clinical evaluation included use of the Unified Parkinson’s Disease Rating Scale part III (UPDRS‐III), and assessment of motor and non‐motor symptoms using standardized clinical scales. The relationships between hypomimia and other clinical data were analysed using Mann–Whitney U‐tests and regression analysis.
Results
Hypomimia occurred in up to 70% of patients with PD. Patients with hypomimia had worse UPDRS‐III 'off‐medication' scores, mainly driven by bradykinesia and rigidity subscores. Patients with hypomimia also had worse apathy than patients without hypomimia. Finally, we found that hypomimia was levodopa‐responsive and its improvement mirrored the change by levodopa in axial motor symptoms.
Conclusion
Our study provides novel information regarding the clinical correlates of hypomimia in people with PD. A better understanding of hypomimia may be relevant for improving treatment and quality of life in PD.
•VoA – DBS is effective on both dystonia and tremor.•VoA – DBS benefits are not impaired by tolerance or side effects.•The variable VoA-DBS outcome previously reported were not proven by VTA ...simulation.•Application of new consensus on tremor classification may improve patient selection.
This study was designed to examine whether corticocortical paired associative stimulation (cc-PAS) can modulate interhemispheric inhibition (IHI) in the human brain. Twelve healthy right-handed ...volunteers received 90 paired transcranial stimuli to the right and left primary motor hand area (M1HAND) at an interstimulus interval (ISI) of 8 ms. Left-to-right cc-PAS (first pulse given to left M1HAND) attenuated left-to-right IHI for one hour after cc-PAS. Left-to-right cc-PAS also increased corticospinal excitability in the conditioned right M1HAND. These effects were not seen in an asymptomatic individual with callosal agenesis. Additional experiments showed no changes in left-to-right IHI or corticospinal excitability when left-to-right cc-PAS was given at an ISI of 1 ms or at multiple ISIs in random order. At the behavioral level, left-to-right cc-PAS speeded responses with the left but not right index finger during a simple reaction time task. Right-to-left cc-PAS (first pulse given to right M1HAND) reduced right-to-left IHI without increasing corticospinal excitability in left M1HAND. These results provide a proof of principle that cc-PAS can induce associative plasticity in connections between the targeted cortical areas. The efficacy of cc-PAS to induce lasting changes in excitability depends on the exact timing of the stimulus pairs suggesting an underlying Hebbian mechanism.
Dystonia is characterized by two main pathophysiological abnormalities: ‘reduced’ excitability of inhibitory systems at many levels of the sensorimotor system, and ‘increased’ plasticity of neural ...connections in sensorimotor circuits at a brainstem and spinal level. A surprising finding in two recent papers has been the fact that abnormalities of inhibition similar to those in organic dystonia are also seen in patients who have psychogenic dystonia. To try to determine the critical feature that might separate organic and psychogenic conditions, we investigated cortical plasticity in a group of 10 patients with psychogenic dystonia and compared the results with those obtained in a matched group of 10 patients with organic dystonia and 10 healthy individuals. We confirmed the presence of abnormal motor cortical inhibition (short-interval intracortical inhibition) in both organic and psychogenic groups. However, we found that plasticity (paired associative stimulation) was abnormally high only in the organic group, while there was no difference between the plasticity measured in psychogenic patients and healthy controls. We conclude that abnormal plasticity is a hallmark of organic dystonia; furthermore it is not a consequence of reduced inhibition since the latter is seen in psychogenic patients who have normal plasticity.
Abstract
Introduction
Unintentional dural puncture (UDP) occurs in 0.5–1.5% of labour epidural analgesia cases. To date, little is known about evidence of UDP-related complications. This work aimed ...to assess the incidence of intrapartum and postpartum complications in parturients who experienced UDP.
Methods
This is a 10-year retrospective observational study on parturients admitted to our centre who presented UDP. Data collection gathered UDP-related complications during labour and postpartum. All women who displayed UDP received medical therapy and bed rest. An epidural blood patch (EBP) was not used in this population. Once asymptomatic, patients were discharged from the hospital.
Results
Out of 7718 neuraxial analgesia cases, 97 cases of UDP occurred (1.25%). During labour, complications appeared in a small percentage of analgesia procedures performed, including total spinal anaesthesia (1.0%), extended motor block (3%), hypotension (4.1%), abnormal foetal heart rate (2%), inadequate analgesia (14.4%), and general anaesthesia following neuraxial anaesthesia failure (33.3% of emergency caesarean sections). During the postpartum period, 53.6% of parturients exhibited a postdural puncture headache, 13.4% showed neurological symptoms, and 14.4% required neurological consultation and neuroimaging. No patient developed subdural hematoma or cerebral venous sinus thrombosis; one woman presented posterior reversible encephalopathy syndrome associated with eclampsia. Overall, 82.5% of women experienced an extension of hospital stay.
Conclusion
Major complications occurred in a small percentage of patients during labour. However, since they represent high-risk maternal and neonatal health events, a dedicated anaesthesiologist and a trained obstetric team are essential.
No major neurological complications were registered postpartum, and EBP was not performed. Nevertheless, all patients with UDP were carefully monitored and treated until complete recovery before discharge, leading to an extension of their hospitalization.
Obsessive–compulsive disorder (OCD) is a clinically heterogeneous condition. Although its pathophysiology is not completely understood, neurophysiologic and neuroimaging data have disclosed ...functional abnormalities in the networks linking frontal cortex, supplementary motor and premotor areas, striatum, globus pallidus, and thalamus (CSPT circuits). By means of transcranial magnetic stimulation (TMS) it is possible to test inhibitory and excitatory circuits within motor cortex.
Previous studies on OCD patients under medication have demonstrated altered cortical inhibitory circuits as tested by TMS. On the other hand there is growing evidence suggesting an alteration of sensory-motor integration. Therefore, the aim of the present study was to evaluate sensory-motor integration (SAI and LAI), intracortical inhibition, and facilitation in drug-naïve OCD patients, using TMS. In our sample, we have demonstrated a significant SAI reduction in OCD patients when compared to a cohort of healthy individuals. SAI abnormalities may be related to a dysfunction of CSPT circuits which are involved in sensory-motor integration processes. Thus, it can be speculated that hypofunctioning of such system might impair the ability of OCD patients to suppress internally triggered intrusive and repetitive movements and thoughts. In conclusion, our data suggest that OCD may be considered as a sensory motor disorder where a dysfunction of sensory-motor integration may play an important role in the release of motor compulsions.
•In OCD there're functional abnormalities in the CSPT circuits.•CSPT circuits are involved in sensory-motor integration processes.•SAI abnormalities reflect impaired sensory-motor integration and sensory gating.
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