[Neurology]. / Neurologie.

Aducanumab reduces the burden of amyloid plaques in Alzheimer's disease, with significant improvement of clinical scores. Endovascular thrombectomy is recommended in patients with acute stroke with proximal occlusion of the anterior circulation. CGRP antagonists and botulinum toxin are effective in migraine. ZIKA virus infection has been linked to the Guillain-Barré syndrome. Edaravone has been approved for amyotrophic lateral sclerosis. Two monoclonal antibodies (ocrelizumab and daclizumab) and siponimod show positive results in multiple sclerosis. Thalamotomy of ventral intermediate nucleus (by gamma-knife or by magnetic resonance-guided focused ultrasound) is effective in drug-resistant essential tremor. The dose-dependent risk of foetal malformations associated with valproate and topiramate is confirmed.

L'aducanumab réduit la présence de plaques amyloïdes dans la maladie d'Alzheimer, avec amélioration significative des scores cliniques. Dans l'AVC aigu, la thrombectomie endovasculaire est recommandée en présence d'une occlusion proximale de la circulation antérieure. La toxine botulinique est efficace dans la migraine chronique. L'infection à virus Zika est associée au syndrome de Guillain-Barré. L'édaravone a été approuvé pour la sclérose latérale amyotrophique. Deux anticorps monoclonaux (ocrélizumab et daclizumab) et le siponimod montrent des résultats positifs dans la sclérose en plaques. La thalamotomie du noyau ventral intermédiaire par gamma-knife et par ultrasons focalisés guidés par résonance magnétique est efficace dans le tremblement pharmaco-résistant. Le risque dose-dépendant de malformations fœtales liées au valproate et au topiramate est confirmé.

Investigation of memory, executive functions, and anatomic correlates in asymptomatic FMR1 premutation carriers.

Fragile X-associated tremor/ataxia syndrome (FXTAS) is a late-onset movement disorder associated with FMR1 premutation alleles. Asymptomatic premutation (aPM) carriers have preserved cognitive functions, but they present subtle executive deficits. Current efforts are focusing on the identification of specific cognitive markers that can detect aPM carriers at higher risk of developing FXTAS. This study aims at evaluating verbal memory and executive functions as early markers of disease progression while exploring associated brain structure changes using diffusion tensor imaging. We assessed 30 aPM men and 38 intrafamilial controls. The groups perform similarly in the executive domain except for decreased performance in motor planning in aPM carriers. In the memory domain, aPM carriers present a significant decrease in verbal encoding and retrieval. Retrieval is associated with microstructural changes of the white matter (WM) of the left hippocampal fimbria. Encoding is associated with changes in the WM under the right dorsolateral prefrontal cortex, a region implicated in relational memory encoding. These associations were found in the aPM group only and did not show age-related decline. This may be interpreted as a neurodevelopmental effect of the premutation, and longitudinal studies are required to better understand these mechanisms.

Brain structure in asymptomatic FMR1 premutation carriers at risk for fragile X-associated tremor/ataxia syndrome.

Fragile X-associated tremor/ataxia syndrome (FXTAS), a late-onset movement disorder affecting FMR1 premutation carriers, is associated with cerebral and cerebellar lesions. The aim of this study was to test whether computational anatomy can detect similar patterns in asymptomatic FMR1 premutation carriers (mean age 46.7 years) with qualitatively normal -appearing grey and white matter on brain MRI. We used a multimodal imaging protocol to characterize brain anatomy by automated assessment of gray matter volume and white matter properties. Structural changes in the hippocampus and in the cerebellar motor network with decreased gray matter volume in lobule VI and white matter alterations of the corresponding afferent projections through the middle cerebellar peduncles are demonstrated. Diffuse subcortical white matter changes in both hemispheres, without corresponding gray matter alterations, are only identified through age × group interactions. We interpret the hippocampal fimbria and cerebellar changes as early alterations with a possible neurodevelopmental origin. In contrast, progression of the diffuse cerebral hemispheric white matter changes suggests a neurodegenerative process, leading to late-onset lesions, which may mark the imminent onset of FXTAS.

On-shoe wearable sensors for gait and turning assessment of patients with Parkinson's disease.

Assessment of locomotion through simple tests such as timed up and go (TUG) or walking trials can provide valuable information for the evaluation of treatment and the early diagnosis of people with Parkinson's disease (PD). Common methods used in clinics are either based on complex motion laboratory settings or simple timing outcomes using stop watches. The goal of this paper is to present an innovative technology based on wearable sensors on-shoe and processing algorithm, which provides outcome measures characterizing PD motor symptoms during TUG and gait tests. Our results on ten PD patients and ten age-matched elderly subjects indicate an accuracy ± precision of 2.8 ± 2.4 cm/s and 1.3 ± 3.0 cm for stride velocity and stride length estimation compared to optical motion capture, with the advantage of being practical to use in home or clinics without any discomfort for the subject. In addition, the use of novel spatio-temporal parameters, including turning, swing width, path length, and their intercycle variability, was also validated and showed interesting tendencies for discriminating patients in ON and OFF states and control subjects.

A novel approach to reducing number of sensing units for wearable gait analysis systems.

Gait analysis methods to estimate spatiotemporal measures, based on two, three or four gyroscopes attached on lower limbs have been discussed in the literature. The most common approach to reduce the number of sensing units is to simplify the underlying biomechanical gait model. In this study, we propose a novel method based on prediction of movements of thighs from movements of shanks. Datasets from three previous studies were used. Data from the first study (ten healthy subjects and ten with Parkinson's disease) were used to develop and calibrate a system with only two gyroscopes attached on shanks. Data from two other studies (36 subjects with hip replacement, seven subjects with coxarthrosis, and eight control subjects) were used for comparison with the other methods and for assessment of error compared to a motion capture system. Results show that the error of estimation of stride length compared to motion capture with the system with four gyroscopes and our new method based on two gyroscopes was close ( -0.8 ±6.6 versus 3.8 ±6.6 cm). An alternative with three sensing units did not show better results (error: -0.2 ±8.4 cm). Finally, a fourth that also used two units but with a simpler gait model had the highest bias compared to the reference (error: -25.6 ±7.6 cm). We concluded that it is feasible to estimate movements of thighs from movements of shanks to reduce number of needed sensing units from 4 to 2 in context of ambulatory gait analysis.

[Resistance to treatment in movement disorders]. / Résistances thérapeutiques dans les mouvements anormaux.

Therapeutic strategies for essential tremor (ET) and Parkinson's disease (PD) can be divided into two successive steps, one based on oral medications and the other, more invasive, using pumps or functional neurosurgery. When ET becomes refractory to propranolol, primidone and other, second-choice compounds, deep brain stimulation of the VIM nucleus of the thalamus can be considered. When PD becomes resistant to dopamine replacement therapy using various combinations of dopaminergic agents, then three options can be discussed: first, a subcutaneous apomorphine mini-pump, second, a jejunal levodopa-delivery system by means of percutaneous gastrostomy, and third, bilateral deep brain stimulation of the subthalamic nucleus. The above interventions are successful in about 80% of cases.

Tremor revisited: treatment of PD tremor.

Parkinsonian tremor is among the most emblematic medical signs and is one of the cardinal manifestations of Parkinson's disease (PD). Its semiology has been extensively addressed by ancient and contemporary medical literature, but more attention has been dedicated to its medical treatment in the past than nowadays. Among the hundreds of studies performed to determine the value of medical and surgical approaches on motor and non motor signs of PD, only a minority specifically considered effect on tremor as an efficacy outcome. Current available guidelines for PD treatment include attempts to specifically address tremor treatment but stress the low level of evidences available. In these conditions, with its still poorly understood pathophysiological basis and variable clinical expression PD tremor treatment is a clinical challenge. Only surgery (lesion or high frequency stimulation) of discrete deep brain targets consistently provides symptomatic long lasting alleviation. Through revision of contemporary scientific evidence, the purpose of this paper is to offer a systematic pragmatic approach to symptomatic management of tremor as one of the distinctive signs of PD that may generate substantial disability.

Hippocampal atrophy predicts conversion to dementia after STN-DBS in Parkinson's disease.

BACKGROUND: Hippocampal atrophy (HA) is a known predictor of dementia in Alzheimer's disease. HA has been found in advanced Parkinson's disease (PD), but no predicting value has been demonstrated yet. The identification of such a predictor in candidates for subthalamic deep brain stimulation (STN-DBS) would be of value. Our objective was to compare preoperative hippocampal volumes (HV) between PD patients who subsequently converted to dementia (PDD) after STN-DBS and those who did not (PDnD). METHODS: From a cohort of 70 consecutive STN-DBS treated PD patients, 14 converted to dementia over 25.6+/-20.2 months (PDD). They were compared to 14 matched controls (PDnD) who did not convert to dementia after 43.9+/-11.7 months. On the preoperative 3D MPRAGE MRI images, HV and total brain volumes (TBV) were measured by a blinded investigator using manual and automatic segmentation respectively. RESULTS: PDD had smaller preoperative HV than PDnD (1.95+/-0.29 ml; 2.28+/-0.33 ml; p<0.01). This difference reinforced after normalization for TBV (3.28+/-0.48, 3.93+/-0.60; p<0.01). Every 0.1 ml decrease of HV increased the likelihood to develop dementia by 24.6%. A large overlap was found between PD and PDnD HVs, precluding the identification of a cut-off score. CONCLUSIONS: As in Alzheimer's disease, HA may be a predictor of the conversion to dementia in PD. This preoperative predictor suggests that the development of dementia after STN-DBS is related to the disease progression, rather then the procedure. Further studies are needed to define a cut-off score for HA, in order to affine its predictive value for an individual patient.

Rapid resolution of dopamine dysregulation syndrome (DDS) after subthalamic DBS for Parkinson disease (PD): a case report.

OBJECTIVE: To describe how subthalamic deep brain stimulation (STN-DBS) and reduction in dopamine replacement therapy (DRT) allowed rapid resolution of dopamine dysregulation syndrome (DDS) with severe behavioral disorder in a patient with late stage Parkinson disease (PD). BACKGROUND: DDS was recently defined as compulsive use of dopaminergic drugs, associated with severe behavioral symptoms, and impaired social functioning, occurring in about 4% of PD patients under DRT. STN-DBS is an effective treatment for late stage PD with treatment resistant motor fluctuations, which frequently allows also to reduce DRT. METHODS: A late stage PD patient referred to our center for STN-DBS, suffering from severe DDS necessitating in-ward psychiatric management, was comprehensively assessed preoperatively and postoperatively for motor, cognitive, and psychiatric status. RESULTS: Following subthalamic DBS procedure and medication reduction, we observed a rapid and dramatic resolution of DDS and associated psychiatric symptoms, allowing discharge from a 2-year stay in a psychiatric institution. CONCLUSIONS: DDS occurring in late stage PD patients may be dramatically improved by STN-DBS, possibly in relation with the reduction of dopaminergic medication. In contrast to other psychiatric symptoms, DDS should not be considered as an obstacle to DBS procedure in late stage PD patients.

Ambulatory monitoring of physical activities in patients with Parkinson's disease.

A new ambulatory method of monitoring physical activities in Parkinson's disease (PD) patients is proposed based on a portable data-logger with three body-fixed inertial sensors. A group of ten PD patients treated with subthalamic nucleus deep brain stimulation (STN-DBS) and ten normal control subjects followed a protocol of typical daily activities and the whole period of the measurement was recorded by video. Walking periods were recognized using two sensors on shanks and lying periods were detected using a sensor on trunk. By calculating kinematics features of the trunk movements during the transitions between sitting and standing postures and using a statistical classifier, sit-to-stand (SiSt) and stand-to-sit (StSi) transitions were detected and separated from other body movements. Finally, a fuzzy classifier used this information to detect periods of sitting and standing. The proposed method showed a high sensitivity and specificity for the detection of basic body postures allocations: sitting, standing, lying, and walking periods, both in PD patients and healthy subjects. We found significant differences in parameters related to SiSt and StSi transitions between PD patients and controls and also between PD patients with and without STN-DBS turned on. We concluded that our method provides a simple, accurate, and effective means to objectively quantify physical activities in both normal and PD patients and may prove useful to assess the level of motor functions in the latter.

Long-term cognitive profile and incidence of dementia after STN-DBS in Parkinson's disease.

An effect of subthalamic nucleus deep brain stimulation (STN-DBS) on cognition has been suspected but long-term observations are lacking. The aim of this study was to evaluate the long-term cognitive profile and the incidence of dementia in a cohort of Parkinson's disease (PD) patients treated by STN-DBS. 57 consecutive patients were prospectively assessed by the mean of a neuropsychological battery over 3 years after surgery. Dementia (DSM-IV) and UPDRS I to IV were recorded. 24.5% of patients converted to dementia over 3 years (incidence of 89 of 1,000 per year). This group of patients cognitively continuously worsened over 3 years up to fulfilling dementia criteria (PDD). The rest of the cohort remained cognitively stable (PD) over the whole follow-up. Preoperative differences between PDD and PD included older age (69.2 +/- 5.8 years; 62.6 +/- 8 years), presence of hallucinations and poorer executive score (10.1 +/- 5.9; 5.5 +/- 4.4). The incidence of dementia over 3 years after STN-DBS is similar to the one reported in medically treated patients. The PDD presented preoperative risk factors of developing dementia similar to those described in medically treated patients. These observations suggest dementia being secondary to the natural evolution of PD rather than a direct effect of STN-DBS.

Long-duration response to levodopa in patients with advanced Parkinson disease treated with subthalamic deep brain stimulation.

BACKGROUND: Long-duration response (LDR) to levodopa is supposed to decrease with Parkinson disease (PD) progression, but direct observation of this response in advanced PD has never been performed. OBJECTIVE: To study the LDR to levodopa in patients with advanced PD treated with subthalamic deep brain stimulation (DBS). DESIGN AND SETTING: We studied 30 consecutive patients with PD who underwent subthalamic DBS. One group had no antiparkinsonian treatment since surgery (no-levodopa group), whereas medical treatment had to be reinitiated in the other group (levodopa group). MAIN OUTCOME MEASURE: Motor subscale score of the Unified Parkinson's Disease Rating Scale. RESULTS: Compared with preoperative assessment, evaluation 6 months postoperatively with DBS turned off for 3 hours found a worsening of the motor subscale score of the Unified Parkinson's Disease Rating Scale in the no-levodopa group. This worsening being absent in the levodopa group, it probably reflected the loss of the LDR to levodopa in the no-levodopa group. When DBS was turned on, postoperative motor subscale scores of the Unifid Parkinson's Disease Rating Scale in both groups were similar to preoperative scores while receiving medication, suggesting that subthalamic DBS compensated for the short-duration response and LDR to levodopa. CONCLUSIONS: Our results suggest that the LDR to levodopa remains significant even in advanced PD, and that subthalamic DBS compensates for the short-duration response and LDR to levodopa.

Gait assessment in Parkinson's disease: toward an ambulatory system for long-term monitoring.

An ambulatory gait analysis method using body-attached gyroscopes to estimate spatio-temporal parameters of gait has been proposed and validated against a reference system for normal and pathologic gait. Later, ten Parkinson's disease (PD) patients with subthalamic nucleus deep brain stimulation (STN-DBS) implantation participated in gait measurements using our device. They walked one to three times on a 20-m walkway. Patients did the test twice: once STN-DBS was ON and once 180 min after turning it OFF. A group of ten age-matched normal subjects were also measured as controls. For each gait cycle, spatio-temporal parameters such as stride length (SL), stride velocity (SV), stance (ST), double support (DS), and gait cycle time (GC) were calculated. We found that PD patients had significantly different gait parameters comparing to controls. They had 52% less SV, 60% less SL, and 40% longer GC. Also they had significantly longer ST and DS (11% and 59% more, respectively) than controls. STN-DBS significantly improved gait parameters. During the stim ON period, PD patients had 31% faster SV, 26% longer SL, 6% shorter ST, and 26% shorter DS. GC, however, was not significantly different. Some of the gait parameters had high correlation with Unified Parkinson's Disease Rating Scale (UPDRS) subscores including SL with a significant correlation (r = -0.90) with UPDRS gait subscore. We concluded that our method provides a simple yet effective way of ambulatory gait analysis in PD patients with results confirming those obtained from much more complex and expensive methods used in gait labs.

Subthalamic DBS replaces levodopa in Parkinson's disease: two-year follow-up.

BACKGROUND: Subthalamic nucleus (STN) deep brain stimulation (DBS) of patients with PD allows reduction of antiparkinsonian medication but has only a mild direct effect on dyskinesia. Since antiparkinsonian medication has short- and long-term effects that may prevent an estimate of the maximal possible impact of STN DBS, such medication was used at the lowest possible dosage after DBS implantation. OBJECTIVE: To study the maximal and long-term effects of STN DBS using the lowest dose of medication. METHODS: Twenty consecutive patients with PD with motor fluctuations and dyskinesia underwent bilateral implantation under stereotactic guidance, microrecording, and clinical control. All medications were stopped before implantation and reintroduced, at the lowest dosage needed, only if the postoperative motor score did not reach the baseline level. Unified PD Rating Scale (UPDRS) motor (subscale III) scores were measured at baseline and after 3, 6, 12, and 24 months. RESULTS: After 21 plus minus 8 months, the UPDRS III "off-medication" score was decreased by 45% and was similar to the preoperative UPDRS III "on" score. Overall, medication was reduced by 79%, being completely withdrawn in 10 patients. Fluctuations and dyskinesia showed an overall reduction of >90%, disappearing completely in patients without medication. These improvements were maintained for 2 years. CONCLUSIONS: These results show that STN DBS could replace levodopa and allowed all antiparkinsonian medication to be discontinued in 50% of patients with PD. Fluctuations and dyskinesia disappeared completely in these patients but persisted in those still on medication. These improvements were maintained for 2 years.