M. Munneke

Prevalence of oropharyngeal dysphagia in Parkinson's disease: a meta-analysis.

Dysphagia is a potentially harmful feature, also in Parkinsons disease (PD). As published prevalence rates vary widely, we aimed to estimate the prevalence of oropharyngeal dysphagia in PD in a meta-analysis. We conducted a systematic literature search in February 2011 and two independent reviewers selected the papers. We computed the estimates of the pooled prevalence weighted by sample size. Twelve studies were suitable for calculating prevalence rates. Ten studies provided an estimate based on subjective outcomes, which proved statistically heterogeneous (p < 0.001), with a pooled prevalence estimate with random effect analysis of 35% (95% CI 28-41). Four studies provided an estimate based on objective measurements, which were statistically homogeneous (p = 0.23), with a pooled prevalence estimate of 82% (95% CI 77-87). In controls the pooled subjective prevalence was 9% (95% CI 2-17), while the pooled objective prevalence was 23% (95% CI 13-32). The pooled relative risk was 3.2 for both subjective outcomes (95% CI 2.32-4.41) and objective outcomes (95% CI 2.08-4.98). Clinical heterogeneity between studies was chiefly explained by differences in disease severity. Subjective dysphagia occurs in one third of community-dwelling PD patients. Objectively measured dysphagia rates were much higher, with 4 out of 5 patients being affected. This suggests that dysphagia is common in PD, but patients do not always report swallowing difficulties unless asked. This underreporting calls for a proactive clinical approach to dysphagia, particularly in light of the serious clinical consequences.

Endogenous control of waking brain rhythms induces neuroplasticity in humans

This study explores the possibility of noninvasively inducing long‐term changes in human corticomotor excitability by means of a brain–computer interface, which enables users to exert internal control over the cortical rhythms recorded from the scalp. We demonstrate that self‐regulation of electroencephalogram rhythms in quietly sitting, naive humans significantly affects the subsequent corticomotor response to transcranial magnetic stimulation, producing durable and correlated changes in neurotransmission. Specifically, we show that the intrinsic suppression of alpha cortical rhythms can in itself produce robust increases in corticospinal excitability and decreases in intracortical inhibition of up to 150%, which last for at least 20 min. Our observations may have important implications for therapies of brain disorders associated with abnormal cortical rhythms, and support the use of electroencephalogram‐based neurofeedback as a noninvasive tool for establishing a causal link between rhythmic cortical activities and their functions.

CSF analysis differentiates multiple-system atrophy from idiopathic late-onset cerebellar ataxia

Background: Differentiating idiopathic late-onset cerebellar ataxia (ILOCA) from ataxia due to the cerebellar subtype of multiple-system atrophy (MSA-C) can be difficult in the early stages of the disease Methods: The authors analyzed the levels of various CSF biomarkers in 27 patients with MSA-C and 18 patients with ILOCA and obtained cut-off points for each potential biomarker to differentiate MSA-C from ILOCA. Results: Increased levels of neurofilament light chain (NFL) and neurofilament heavy chain (NFHp35) and decreased levels of the neurotransmitter metabolites homovanillic acid (HVA), 5-hydroxyindoleaceticacid (5-HIAA), and 3-methoxy-4-hydroxyphenylethyleneglycol (MHPG) were observed in MSA-C compared with ILOCA patients. Receiver operating characteristic analysis showed high sensitivity and specificity levels for NFL, NFHp35, and MHPG analysis. At a cut-off of 24.4 ng/L for the NFL analysis, a sensitivity of 79% and a specificity of 94% were obtained for differentiating MSA-C from ILOCA. At a cut-off point for NFHp35 of 129.5 ng/L, sensitivity was 87% and specificity 83%. Analysis of MHPG levels (cut-off 42.5 nM) resulted in a sensitivity of 86% with a specificity of 75%. A multivariate logistic regression model selected NFL, MHPG, and tau as independent predictive biomarkers that separated the MSA-C and ILOCA groups. Conclusions: Increased levels of neurofilament light chain and tau and decreased levels of 3-methoxy-4-hydroxyphenylethyleneglycol were associated with high accuracy levels in differentiating the cerebellar subtype of multiple-system atrophy from idiopathic late-onset cerebellar ataxia (LOCA). CSF analysis may thus serve as a useful tool in early diagnostic differentiation of LOCA.

Allied health care interventions and complementary therapies in Parkinson's disease

Allied health care and complementary therapies are used by many patients with Parkinsons disease (PD). For allied health care, supportive scientific evidence is gradually beginning to emerge, and interventions are increasingly integrated in the treatment programs for PD patients. To evaluate whether such multidisciplinary programs are justifiable, we review the literature of allied health care and complementary therapies in PD. According to the level of available evidence, we provide recommendations for clinical practice. Finally, we discuss the need for an improved organization of allied health care, and identify topics for future research to further underpin the pros and cons of allied health care and complementary therapies in PD.

Assessing the interplay between cognition and gait in the clinical setting

Summary.In this review, we outline how the influence of cognitive processes on gait or balance can be appreciated in a clinical setting. Careful history taking of the patient or direct carer provides information about multiple task problems in daily life and the presence of cognitive impairment, depression or fear of falling. Physical examination may reveal abnormalities such as an inappropriately high walking speed or an inability to handle secondary tasks while walking. Assessment of frontal executive function helps to understand the nature of these multiple task problems and to detect “risky” behaviour caused by frontal disinhibition. Examples of clinically useable techniques include pressure-sensitive insoles or an electronic walkway (to record strides) or accelerometers (to measure body motion while walking). Combining these assessments may lead to a better appreciation of the fascinating but complex interplay between cognition and gait.

Improving community healthcare for patients with Parkinson's disease: the dutch model.

Because of the complex nature of Parkinsons disease, a wide variety of health professionals are involved in care. Stepwise, we have addressed the challenges in the provision of multidisciplinary care for this patient group. As a starting point, we have gained detailed insight into the current delivery of allied healthcare, as well as the barriers and facilitators for optimal care. To overcome the identified barriers, a tertiary referral centre was founded; evidence-based guidelines were developed and cost-effectively implemented within regional community networks of specifically trained allied health professionals (the ParkinsonNet concept). We increasingly use ICT to bind these professional networks together and also to empower and engage patients in making decisions about their health. This comprehensive approach is likely to be feasible for other countries as well, so we currently collaborate in a European collaboration to improve community care for persons with Parkinsons disease.

Subcortical Structures in Humans Can Be Facilitated by Transcranial Direct Current Stimulation

Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique that alters cortical excitability. Interestingly, in recent animal studies facilitatory effects of tDCS have also been observed on subcortical structures. Here, we sought to provide evidence for the potential of tDCS to facilitate subcortical structures in humans as well. Subjects received anodal-tDCS and sham-tDCS on two separate testing days in a counterbalanced order. After stimulation, we assessed the effect of tDCS on two responses that arise from subcortical structures; (1) wrist and ankle responses to an imperative stimulus combined with a startling acoustic stimulus (SAS), and (2) automatic postural responses to external balance perturbations with and without a concurrent SAS. During all tasks, response onsets were significantly faster following anodal-tDCS compared to sham-tDCS, both in trials with and without a SAS. The effect of tDCS was similar for the dominant and non-dominant leg. The SAS accelerated the onsets of ankle and wrist movements and the responses to backward, but not forward perturbations. The faster onsets of SAS-induced wrist and ankle movements and automatic postural responses following stimulation provide strong evidence that, in humans, subcortical structures - in particular the reticular formation - can be facilitated by tDCS. This effect may be explained by two mechanisms that are not mutually exclusive. First, subcortical facilitation may have resulted from enhanced cortico-reticular drive. Second, the applied current may have directly stimulated the reticular formation. Strengthening reticulospinal output by tDCS may be of interest to neurorehabilitation, as there is evidence for reticulospinal compensation after corticospinal lesions.

Clinimetric analyses of the Modified Parkinson Activity Scale.

OBJECTIVE The Parkinson Activity Scale (PAS) is designed for functional assessment in Parkinsons disease (PD), but the scale has - in its current form - several drawbacks. The objectives of the present study are to (a) introduce a Modified PAS, with unambiguous scoring options and without ceiling effect; (b) evaluate the inter-rater agreement, using physiotherapists with and without PD-specific expertise; and (c) examine the concurrent validity with the VAS-Global Functioning and the UPDRS-III. METHODS The Modified PAS was developed based on the results of a recent pilot feasibility study [Keus SHJ, Bloem BR, van Hilten JJ, Ashburn A, Munneke M. Effectiveness of physiotherapy in Parkinsons disease: The feasibility of a randomised controlled trial. Parkinsonism Relat Disord 2007; 13(2):115-21.]. To evaluate inter-rater agreement, the Modified PAS was scored by a large number of raters (n=13) in 15 patients (Hoehn and Yahr stage 2-4), thus yielding a high number of observations (n=195) and creating adequate power. To ascertain broad applicability of the results, both physiotherapists with and without PD-specific expertise participated. RESULTS The interquartile range of the Modified PAS total scores was 40-51, within a possible range of 0 (optimal performance) to 56 (worst performance), suggesting lack of ceiling effect. The precision of these scores was 2.6 points, with an inter-rater error of 1.3 and a patient-induced error of 2.3. There were no differences between experts and non-experts. Correlation to Global Functioning (0.79) and UPDRS-III (0.64) was good. CONCLUSION The Modified PAS showed no ceiling effect, good concurrent validity, good inter-rater agreement and no differences between experts and non-experts.

Dissociated small hand muscle atrophy in aging: the ‘senile hand’ is a split hand

The term ‘split hand’ refers to a pattern of dissociated atrophy of hand muscles and was first described in ALS. We hypothesize that this phenomenon also occurs in ‘normal’ aging. We investigated healthy subjects of different ages and found a progressive dissociation in atrophy of the hand muscles, as measured with compound muscle action potential amplitudes, with increasing age. Different possible causes of this progressive dissociation are discussed. It might be related to preferential use of thenar muscles in humans, which render these muscles and their motor neurons more susceptible to oxidative stress. In addition, a difference in intrinsic susceptibility to oxidative stress might be involved. The relation between normal age‐related muscle loss (sarcopenia) and the pathologic loss in motor neuron disease is discussed.

Monitoring of walking in Parkinson's disease: validation of an ambulatory activity monitor

Nearly all patients with Parkinson’s disease (PD) experience gait problems, often already in early disease stages, with clear worsening as the disease progresses. It would be helpful to have a simple and objective tool to quantify gait, both in the laboratory setting and in the patient’s own home environment. This could facilitate clinical decision making, or can be used as outcome measure in clinical trials. It is currently possible to provide very detailed assessments in the gait laboratory, for example using motion analysis systems. While accurate, such evaluations are also expensive, and not necessarily reflective of real-life performance. Moreover, the gait laboratory only documents walking impairments, but does not investigate the subject’s actual walking behavior. To address these limitations, ambulatory gait monitors have been introduced to quantify movements of the limbs or trunk during a prolonged time in daily life. In healthy subjects, ambulatory monitors can record spatiotemporal gait parameters such as stride cycles, numbers of left and right steps, step length and walking speed over ground walking [1]. Later work also concentrated on applying activity monitors in patients with PD [2–4]. However, none of these studies evaluated the ability of activity monitors to estimate walking distances in patients with PD. We therefore evaluated the ability of a simple activity monitor (based on tri-axial accelerometers) to estimate walking distance in PD.