Growing evidence suggests an increasing significance for the extent of gastrointestinal tract (GIT) dysfunction in Parkinson’s disease (PD). Most patients suffer from GIT symptoms, including dysphagia, sialorrhea, bloating, nausea, vomiting, gastroparesis, and constipation during the disease course. The underlying pathomechanisms of this α-synucleinopathy play an important role in disease development and progression, i.e., early accumulation of Lewy pathology in the enteric and central nervous systems is implicated in pharyngeal discoordination, esophageal and gastric motility/peristalsis impairment, chronic pain, altered intestinal permeability and autonomic dysfunction of the colon, with subsequent constipation. Severe complications, including malnutrition, dehydration, insufficient drug effects, aspiration pneumonia, intestinal obstruction, and megacolon, frequently result in hospitalization. Sophisticated diagnostic tools are now available that permit more detailed examination of specific GIT impairment patterns. Furthermore, novel treatment approaches have been evaluated, although high-level evidence trials are often missing. Finally, the burgeoning literature devoted to the GIT microbiome reveals its importance for neurologists. We review current knowledge about GIT pathoanatomy, pathophysiology, diagnosis, and treatment in PD and provide recommendations for management in daily practice.

Objective This pivotal phase III study, SIAXI, investigated the efficacy and safety of incobotulinumtoxinA for the treatment of chronic sialorrhea due to Parkinson disease (PD), atypical parkinsonism, stroke, or traumatic brain injury (TBI). Methods Adult patients with PD (70.7%), atypical parkinsonism (8.7%), stroke (19.0%), or TBI (2.7%) were randomized (2:2:1) to double-blind treatment with placebo (n = 36), or total doses of incobotulinumtoxinA 75 U (n = 74) or 100 U (n = 74), in a single treatment cycle. The coprimary endpoints were change in unstimulated salivary flow rate from baseline to week 4, and patients9 Global Impression of Change Scale score at week 4. Adverse events were recorded throughout. Results A total of 184 patients were randomized. Both incobotulinumtoxinA dose groups showed reductions in mean unstimulated salivary flow rate at week 4, with a significant difference vs placebo in the incobotulinumtoxinA 100 U group (p = 0.004). Patients9 Global Impression of Change Scale scores also improved at week 4, with a significant difference vs placebo in the incobotulinumtoxinA 100 U group (p = 0.002). A lasting effect was observed at week 16 post injection. The most frequent treatment-related adverse events in the incobotulinumtoxinA 75 U and 100 U groups were dry mouth (5.4% and 2.7% of patients) and dysphagia (2.7% and 0.0% of patients). Conclusions IncobotulinumtoxinA 100 U is an effective and well-tolerated treatment of chronic sialorrhea in adults. ClinicalTrials.gov identifier NCT02091739. Classification of evidence This study provides Class I evidence that incobotulinumtoxinA reduces salivary flow rates in patients with chronic sialorrhea due to PD, atypical parkinsonism, stroke, or TBI.

Since the 1980s, the MAO-B inhibitors have gained considerable status in the therapy of the Parkinson’s disease. In addition to the symptomatic effect in mono- and combination therapies, a neuroprotective effect has repeatedly been a matter of some discussion, which has unfortunately led to a good many misunderstandings. Due to potential interactions, selegiline has declined in significance in the field. For the MAO-B inhibitor safinamide, recently introduced to the market, an additional inhibition of pathological release of glutamate has been postulated. At present, rasagiline and selegiline are being administered in early therapy as well as in combination with levodopa. Safinamide has been approved only for combination therapy with levodopa when motor fluctuations have occurred. MAO-B inhibitors are a significant therapeutic option for Parkinson’s disease, an option which is too often not appreciated properly.

Inhibitors of monoamine oxidase B (MAO-B) and catechol-O-methyltransferase (COMT) are major strategies to reduce levodopa degradation and thus to increase and prolong its effect in striatal dopaminergic neurotransmission in Parkinson’s disease patients. While selegiline/rasagiline and tolcapone/entacapone have been available on the market for more than one decade, safinamide and opicapone have been approved in 2015 and 2016, respectively. Meanwhile, comprehensive data from several post-authorization studies have described the use and specific characteristics of the individual substances in clinical practice under real-life conditions. Here, we summarize current knowledge on both medication classes, with a focus on the added clinical value in Parkinson’s disease. Furthermore, we outline practical considerations in the treatment of motor fluctuations and provide an outlook on ongoing studies with MAO-B and COMT inhibitors.

Continuous medical progress is significantly improving the quality of health care. As a result, people are living longer than during the past century, but this has also caused an increase of the prevalence of many neurological disorders. Parkinson’s disease (PD) is the fastest growing neurological condition, with a doubling of cases reported between 1995 and 2015 and a further doubling projected by 2030. Parkinson’s disease is generally associated with characteristic motor symptoms (resting tremor, rigidity, bradykinesia and postural instability). However, patients with PD also experience many non-motor symptoms that might be at least as debilitating as the motor symptoms and which significantly impact patients’ quality of life (QoL). Pain is a frequent yet underrecognized symptom; the incidence in PD is much higher than in the general population and constitutes a silent disability that significantly contributes to a deterioration in QoL. Accurate identification of parkinsonian pain is important for its diagnosis and effective treatment. In this review, we provide an overview of the pathophysiology, classification, and management of pain in PD. We define the various modalities of chronic PD pain, suggesting possible explanations for its relationship with PD pathology, and discuss its management and currently recommended therapies.

Glutamate is the major excitatory neurotransmitter in the central nervous system and, as such, many brain regions, including the basal ganglia, are rich in glutamatergic neurons. The importance of the basal ganglia in the control of voluntary movement has long been recognised, with the effect of dysfunction of the region exemplified by the motor symptoms seen in Parkinson's disease (PD). However, the basal ganglia and the associated glutamatergic system also play a role in the modulation of emotion, nociception and cognition, dysregulation of which result in some of the non-motor symptoms of PD (depression/anxiety, pain and cognitive deficits). Thus, while the treatment of PD has traditionally been approached from the perspective of dopaminergic replacement, using agents such as levodopa and dopamine receptor agonists, the glutamatergic system offers a novel treatment target for the disease. Safinamide has been approved in over 20 countries globally for fluctuating PD as add-on therapy to levodopa regimens for the management of 'off' episodes. The drug has both dopaminergic and non-dopaminergic pharmacological effects, the latter including inhibition of abnormal glutamate release. The effect of safinamide on the glutamatergic system might present some advantages over dopamine-based therapies for PD by providing efficacy for motor (levodopa-induced dyskinesia) as well as non-motor (anxiety, mood disorders, pain) symptoms. In this article, we discuss the potential role of glutamatergic inhibition on these symptoms, using illustrative real-world examples of patients we have treated with safinamide.