Robust graft survival and normalized dopaminergic innervation do not obligate recovery in a Parkinson disease patient

OBJECTIVE

The main goal of dopamine cell replacement therapy in Parkinson disease (PD) is to provide clinical benefit mediated by graft survival with nigrostriatal reinnervation. We report a dichotomy between graft structure and clinical function in a patient dying 16 years following fetal nigral grafting.

METHODS

A 55-year-old levodopa-responsive woman with PD received bilateral putaminal fetal mesencephalic grafts as part of an NIH-sponsored double-blind sham-controlled trial. The patient never experienced clinical benefit, and her course was complicated by the development of graft-related dyskinesias. Fluorodopa positron emission tomography demonstrated significant increases postgrafting bilaterally. She experienced worsening of parkinsonism with severe dyskinesias, and underwent subthalamic nucleus deep brain stimulation 8 years after grafting. She died 16 years after transplantation.

RESULTS

Postmortem analyses confirmed the diagnosis of PD and demonstrated >300,000 tyrosine hydroxylase (TH)-positive grafted cells per side with normalized striatal TH-immunoreactive fiber innervation and bidirectional synaptic connectivity. Twenty-seven percent and 17% of grafted neurons were serine 129-phosphorylated α-synuclein positive in the left and right putamen, respectively.

INTERPRETATION

These findings represent the largest number of surviving dopamine neurons and the densest and most widespread graft-mediated striatal dopamine reinnervation following a transplant procedure reported to date. Despite this, clinical recovery was not observed. Furthermore, the grafts were associated with a form of dyskinesias that resembled diphasic dyskinesia and persisted in the off-medication state. We hypothesize that the grafted cells produced a low level of dopamine sufficient to cause a levodopa-independent continuous form of diphasic dyskinesias, but insufficient to provide an antiparkinsonian benefit. ANN NEUROL 2017;81:46-57.

Sildenafil in the Treatment of Erectile Dysfunction in Parkinson's Disease

Background

Erectile dysfunction (ED) is a common nonmotor feature in patients with Parkinson's disease (PD). Data regarding the tolerability and efficacy of anti-ED medication in the PD population are limited. The aim of this work was to assess the safety and efficacy of sildenafil in treatment of ED in men with PD.

Methods

This was a double-blind, placebo-controlled, cross-over study consisting of two 4-week arms separated by a 2-week washout period. Treatment sequence (placebo-sildenafil vs. sildenafil-placebo) was randomized. Sildenafil was started at 50 mg and adjusted to 25, 50, or 100 mg after 2 weeks, depending upon side effects. The Erectile Function domain of the International Index of Erectile Function (IIEF-EF; primary outcome measure) and the Parkinson's Disease Quality of Life (secondary outcome measure) were obtained at baseline and end of each treatment period. The UPDRS was obtained at each study visit. The difference between group means was tested for statistical significance using t tests.

Results

Twenty men participated and completed both treatment arms of the study. There was one instance of headache as a side effect. There was a significant effect of sildenafil on sexual functioning as measured by the IIEF-EF domain (P < 0.0001; mean for sildenafil = 23.2 ± 7.0; mean for placebo = 12.3 ± 7.5). There were no treatment effects for quality of life (P = 0.3) or PD symptoms (P = 0.86).

Conclusions

Sildenafil was safe and improved ED in this sample of men with PD. Overall, PD symptoms and quality of life were not impacted by use of sildenafil.

Gender-, age-, and race/ethnicity-based differential item functioning analysis of the movement disorder society-sponsored revision of the Unified Parkinson's disease rating scale

OBJECTIVE

Assess MDS-UPDRS items for gender-, age-, and race/ethnicity-based differential item functioning.

BACKGROUND

Assessing differential item functioning is a core rating scale validation step. For the MDS-UPDRS, differential item functioning occurs if item-score probability among people with similar levels of parkinsonism differ according to selected covariates (gender, age, race/ethnicity). If the magnitude of differential item functioning is clinically relevant, item-score interpretation must consider influences by these covariates. Differential item functioning can be nonuniform (covariate variably influences an item-score across different levels of parkinsonism) or uniform (covariate influences an item-score consistently over all levels of parkinsonism).

METHODS

Using the MDS-UPDRS translation database of more than 5,000 PD patients from 14 languages, we tested gender-, age-, and race/ethnicity-based differential item functioning. To designate an item as having clinically relevant differential item functioning, we required statistical confirmation by 2 independent methods, along with a McFadden pseudo-R² magnitude statistic greater than "negligible."

RESULTS

Most items showed no gender-, age- or race/ethnicity-based differential item functioning. When differential item functioning was identified, the magnitude statistic was always in the "negligible" range, and the scale-level impact was minimal.

CONCLUSIONS

The absence of clinically relevant differential item functioning across all items and all parts of the MDS-UPDRS is strong evidence that the scale can be used confidently. As studies of Parkinson's disease increasingly involve multinational efforts and the MDS-UPDRS has several validated non-English translations, the findings support the scale's broad applicability in populations with varying gender, age, and race/ethnicity distributions. © 2016 International Parkinson and Movement Disorder Society.

Rating Scales for Pain in Parkinson's Disease: Critique and Recommendations

BACKGROUND

We aimed at critically appraising the clinimetric properties of existing pain scales or questionnaires and to give recommendations for their use in Parkinson's disease (PD).

METHODS

Clinimetric properties of pain scales used in PD were systematically evaluated. A scale was classified as 'recommended' if was used in PD, showed adequate clinimetric properties, and had been used by investigators other than the original developers; as 'suggested' if it was used in PD and fulfilled only one other criterion; and as 'listed' if it was used in PD but did not meet the other criteria. Only scales rating pain intensity or for syndromic classification were assessed.

RESULTS

Eleven of the 34 scales initially considered fulfilled inclusion criteria. Among the scales rating pain intensity, the "Brief Pain Inventory short form," "McGill Pain Questionnaire short and long forms," "Neuropathic Pain Symptoms Inventory," "11-point Numeric Rating Scale," "10-cm Visual Analog Scale," and "Pain-O-Meter" were "recommended with caution" because of lack of clinimetric data in PD, whereas the "King's PD Pain Scale" was "recommended." Among scales for pain syndromic classification, the "DN4" was "recommended with caution" because of lack of clinimetric data in PD; the "Leeds Assessment of Neuropathic Symptoms and Signs," "Pain-DETECT," and the "King's PD Pain Scale" were "suggested."

CONCLUSIONS

King's PD pain scale can be recommended for the assessment of pain intensity in PD. Syndromic classification of pain in PD may be achieved by the DN4, but clinimetric data in PD are needed for this scale.

MDS research criteria for prodromal Parkinson's disease

This article describes research criteria and probability methodology for the diagnosis of prodromal PD. Prodromal disease refers to the stage wherein early symptoms or signs of PD neurodegeneration are present, but classic clinical diagnosis based on fully evolved motor parkinsonism is not yet possible. Given the lack of clear neuroprotective/disease-modifying therapy for prodromal PD, these criteria were developed for research purposes only. The criteria are based upon the likelihood of prodromal disease being present with probable prodromal PD defined as ≥80% certainty. Certainty estimates rely upon calculation of an individual's risk of having prodromal PD, using a Bayesian naïve classifier. In this methodology, a previous probability of prodromal disease is delineated based upon age. Then, the probability of prodromal PD is calculated by adding diagnostic information, expressed as likelihood ratios. This diagnostic information combines estimates of background risk (from environmental risk factors and genetic findings) and results of diagnostic marker testing. In order to be included, diagnostic markers had to have prospective evidence documenting ability to predict clinical PD. They include motor and nonmotor clinical symptoms, clinical signs, and ancillary diagnostic tests. These criteria represent a first step in the formal delineation of early stages of PD and will require constant updating as more information becomes available.

MDS clinical diagnostic criteria for Parkinson's disease

This document presents the Movement Disorder Society Clinical Diagnostic Criteria for Parkinson's disease (PD). The Movement Disorder Society PD Criteria are intended for use in clinical research but also may be used to guide clinical diagnosis. The benchmark for these criteria is expert clinical diagnosis; the criteria aim to systematize the diagnostic process, to make it reproducible across centers and applicable by clinicians with less expertise in PD diagnosis. Although motor abnormalities remain central, increasing recognition has been given to nonmotor manifestations; these are incorporated into both the current criteria and particularly into separate criteria for prodromal PD. Similar to previous criteria, the Movement Disorder Society PD Criteria retain motor parkinsonism as the core feature of the disease, defined as bradykinesia plus rest tremor or rigidity. Explicit instructions for defining these cardinal features are included. After documentation of parkinsonism, determination of PD as the cause of parkinsonism relies on three categories of diagnostic features: absolute exclusion criteria (which rule out PD), red flags (which must be counterbalanced by additional supportive criteria to allow diagnosis of PD), and supportive criteria (positive features that increase confidence of the PD diagnosis). Two levels of certainty are delineated: clinically established PD (maximizing specificity at the expense of reduced sensitivity) and probable PD (which balances sensitivity and specificity). The Movement Disorder Society criteria retain elements proven valuable in previous criteria and omit aspects that are no longer justified, thereby encapsulating diagnosis according to current knowledge. As understanding of PD expands, the Movement Disorder Society criteria will need continuous revision to accommodate these advances.

A Phase 2A Trial of the Novel mGluR5-Negative Allosteric Modulator Dipraglurant for Levodopa-Induced Dyskinesia in Parkinson's Disease

BACKGROUND

The metabotropic glutamate receptor 5-negative allosteric modulator dipraglurant reduces levodopa-induced dyskinesia in the MPTP-macaque model. The objective of this study was to assess the safety, tolerability (primary objective), and efficacy (secondary objective) of dipraglurant on levodopa-induced dyskinesia in Parkinson's disease (PD).

METHODS

The study was a phase 2A double-blind, placebo-controlled, randomized (2:1), 4-week, parallel-group, multicenter dose-escalation (from 50 mg once daily to 100 mg 3 times daily) clinical trial involving 76 PD subjects with moderate to severe levodopa-induced dyskinesia. Safety and tolerability were assessed based on clinical and biological examination and adverse events recording. Secondary efficacy outcome measures included the modified Abnormal Involuntary Movement Scale, UPDRS, and diaries. Pharmacokinetics were measured at 3 visits following a single dose.

RESULTS

Fifty-two patients were exposed to dipraglurant and 24 to placebo. There were no major safety concerns. Two subjects did not complete the study because of adverse events. Most frequent adverse events included dyskinesia, dizziness, nausea, and fatigue. Dipraglurant significantly reduced peak dose dyskinesia (modified Abnormal Involuntary Movement Scale) on day 1 (50 mg, 20%; P = 0.04) and on day 14 (100 mg, 32%; P =0 .04) and across a 3-hour postdose period on day 14 (P = 0.04). There was no evidence of worsening of parkinsonism. Dipraglurant was rapidly absorbed (tmax = 1 hour). The 100-mg dose led to a mean Cmax of 1844 ng/mL on day 28.

CONCLUSIONS

Dipraglurant proved to be safe and well tolerated in its first administration to PD patients. Its efficacy in reversing levodopa-induced dyskinesia warrants further investigations in a larger number of patients. © 2016 International Parkinson and Movement Disorder Society.

Cross-Cultural Differences of the Non-Motor Symptoms Studied by the Traditional Chinese Version of the International Parkinson and Movement Disorder Society- Unified Parkinson's Disease Rating Scale

BACKGROUND

Given the importance of ethnic differences in the evaluation of various aspects of symptoms in patients with Parkinson's disease (PD), we present the formal procedure for completing the traditional Chinese translation of the International and Parkinson and Movement Disorder Society/UPDRS (MDS-UPDRS) and highlight the discrepancy in nonmotor symptoms (NMS) between patients in Eastern and Western countries.

METHODS

A total of 350 native Chinese-speaking PD patients were recruited from multiple hospitals in Eastern countries; they completed the MDS-UPDRS. The translation process was executed and factor analysis was performed to determine the structure of the scale. Chi-squared and t tests were used to compare frequency and severity of PD symptoms between the Chinese-speaking and English-speaking groups (n = 876).

RESULTS

NMS and motor symptoms were more severe in the Western population (Part I: t₍₁₂₀₅₎ = 5.36, P < 0.0001; and Part III: t₍₁₂₀₅₎ = 7.64, P < 0.0001); however, the prevalence of cognitive dysfunction and impairments in activities of daily living were more frequent in the Eastern patients. The comparative fit index was 0.93 or greater, and the exploratory factor analysis revealed compatible results between the translated scale and the original version.

CONCLUSION

The traditional Chinese version of the MDS-UPDRS can be designated as an official translation of the original scale, and it is now available for use. Moreover, NMS in PD constitute a major issue worldwide, and the pattern of NMS among the Chinese population is more marked in terms of cognition-based symptoms and activities of daily living.

Clinimetric testing of the comprehensive cervical dystonia rating scale

INTRODUCTION

The aim of this study was to test the clinimetric properties of the Comprehensive Cervical Dystonia Rating Scale. This is a modular scale with modifications of the Toronto Western Spasmodic Torticollis Rating Scale (composed of three subscales assessing motor severity, disability, and pain) now referred to as the revised Toronto Western Spasmodic Torticollis Scale-2; a newly developed psychiatric screening instrument; and the Cervical Dystonia Impact Profile-58 as a quality of life measure.

METHODS

Ten dystonia experts rated subjects with cervical dystonia using the comprehensive scale. Clinimetric techniques assessed each module of the scale for reliability, item correlation, and factor structure.

RESULTS

There were 208 cervical dystonia patients (73% women; age, 59 ± 10 years; duration, 15 ± 12 years). Internal consistency of the motor severity subscale was acceptable (Cronbach's alpha = 0.57). Item to total correlations showed that elimination of items with low correlations (<0.20) increased alpha to 0.71. Internal consistency estimates for the subscales for disability and pain were 0.88 and 0.95, respectively. The psychiatric screening scale had a Cronbach's alpha of 0.84 and satisfactory item to total correlations. When the subscales of the Toronto Western Spasmodic Torticollis Scale-2 were combined with the psychiatric screening scale, Cronbach's alpha was 0.88, and construct validity assessment demonstrated four rational factors: motor; disability; pain; and psychiatric disorders. The Cervical Dystonia Impact Profile-58 had an alpha of 0.98 and its construction was validated through a confirmatory factor analysis.

CONCLUSIONS

The modules of the Comprehensive Cervical Dystonia Rating Scale are internally consistent with a logical factor structure.

Parkinson's disease-related fatigue: A case definition and recommendations for clinical research

Fatigue is one of the most common and disabling symptoms in Parkinson's disease (PD). Since fatigue was first described as a common feature of PD 20 years ago, little progress has been made in understanding its causes or treatment. Importantly, PD patients attending the 2013 World Parkinson Congress voted fatigue as the leading symptom in need of further research. In response, the Parkinson Disease Foundation and ProjectSpark assembled an international team of experts to create recommendations for clinical research to advance this field. The working group identified several areas in which shared standards would improve research quality and foster progress including terminology, diagnostic criteria, and measurement. Terminology needs to (1) clearly distinguish fatigue from related phenomena (eg, sleepiness, apathy, depression); (2) differentiate subjective fatigue complaints from objective performance fatigability; and (3) specify domains affected by fatigue and causal factors. We propose diagnostic criteria for PD-related fatigue to guide participant selection for clinical trials and add rigor to mechanistic studies. Recommendations are made for measurement of subjective fatigue complaints, performance fatigability, and neurophysiologic changes. We also suggest areas in which future research is needed to address methodological issues and validate or optimize current practices. Many limitations in current PD-related fatigue research may be addressed by improving methodological standards, many of which are already being successfully applied in clinical fatigue research in other medical conditions (eg, cancer, multiple sclerosis). © 2016 International Parkinson and Movement Disorder Society.

Genetic and Clinical Predictors of Deep Brain Stimulation in Young-Onset Parkinson's Disease

OBJECTIVE

In a cohort of patients with young-onset Parkinson's disease (PD), the authors assessed (1) the prevalence of genetic mutations in those who enrolled in deep brain stimulation (DBS) programs compared with those who did not enroll DBS programs and (2) specific genetic and clinical predictors of DBS enrollment.

METHODS

Subjects were participants from 3 sites (Columbia University, Rush University, and the University of Pennsylvania) in the Consortium on Risk for Early Onset Parkinson's Disease (CORE-PD) who had an age at onset < 51 years. The analyses presented here focus on glucocerebrosidase (GBA), leucine-rich repeat kinase 2 (LRRK2), and parkin (PRKN) mutation carriers. Mutation carrier status, demographic data, and disease characteristics in individuals who did and did not enroll in DBS were analyzed. The association between mutation status and DBS placement was assessed in logistic regression models.

RESULTS

Patients who had PD with either GBA, LRRK2, or PRKN mutations were more common in the DBS group (n = 99) compared with the non-DBS group (n = 684; 26.5% vs. 16.8%, respectively; P = 0.02). In a multivariate logistic regression model, GBA mutation status (odds ratio, 2.1; 95% confidence interval, 1.0-4.3; P = 0.05) was associated with DBS surgery enrollment. However, when dyskinesia was included in the multivariate logistic regression model, dyskinesia had a strong association with DBS placement (odds ratio, 3.8; 95% confidence interval, 1.9-7.3; P < 0.0001), whereas the association between GBA mutation status and DBS placement did not persist (P = 0.25).

CONCLUSIONS

DBS populations are enriched with genetic mutation carriers. The effect of genetic mutation carriers on DBS outcomes warrants further exploration.

Fatigue in Parkinson's disease: report from a mutidisciplinary symposium

Fatigue is a severe problem for many people living with Parkinson's disease (PD). Best estimates suggest that more than 50% of patients experience this debilitating symptom. Little is known about its etiology or treatment, making the understanding of fatigue a true unmet need. As part of the Parkinson's Disease Foundation Community Choice Research Program, patients, caregivers, and scientists attended a symposium on fatigue on 16 and 17 October 2014. We present a summary of that meeting, reviewing what is known about the diagnosis and treatment of fatigue, its physiology, and what we might learn from multiple sclerosis (MS), depression, and cancer-disorders in which fatigue figures prominently too. We conclude with focused recommendations to enhance our understanding and treatment of this prominent problem in PD.

Charcot, hysteria, and simulated disorders

Jean-Martin Charcot (1825-1893) was the 19th-century's premier international neurologist. One of his areas of focused interest was the neurologic disorder, hysteria, a condition with distinctive neurologic signs, but no established structural lesions identified at autopsy. Charcot considered hysteria as a physiologic disorder that affected specific neuroanatomic areas of the brain comparable to the same areas that were damaged by structural neurologic disorders provoking the same or similar signs. He considered hysteria primarily a hereditary disorder, but environmental factors including physical and emotional stress served as provoking factors. Charcot drew the strict distinction between hysteria and consciously simulated neurologic disorders, although he was keenly aware that the two disorders could occur in the same patients or be difficult to distinguish at times. He developed specific experimental techniques to separate hysteria from simulation. His studies of hysteria and simulation offer a basis for studies of functional neurologic disorders applicable to the 21st century.

Failing as doorman and disc jockey at the same time: Amygdalar dysfunction in Parkinson's disease

In Braak's model of ascending degeneration in Parkinson's disease (PD), involvement of the amygdala occurs simultaneously with substantia nigra degeneration. However, the clinical manifestations of amygdalar involvement in PD have not been fully delineated. Considered a multitask manager, the amygdala is a densely connected "hub," coordinating and integrating tasks ranging from prompt, multisensorial emotion recognition to adequate emotional responses and emotional tuning of memories. Although phylogenetically predisposed to handle fear, the amygdala handles both aversive and positive emotional inputs. In PD, neuropathological and in vivo studies suggest primarily amygdalar hypofunction. However, as dopamine acts as an inverted U-shaped amygdalar modulator, medication-induced hyperactivity of the amygdala can occur. We propose that amygdalar (network) dysfunction contributes to reduced recognition of negative emotional face expressions, impaired theory of mind, reactive hypomimia, and impaired decision making. Similarly, impulse control disorders in predisposed individuals, hallucinations, anxiety, and panic attacks may be related to amygdalar dysfunction. When available, we discuss amygdala-independent trigger mechanisms of these symptoms. Although dopaminergic agents have mostly an activation effect on amygdalar function, adaptive and compensatory network changes may occur as well, but these have not been sufficiently explored. In conclusion, our model of amygdalar involvement brings together several elements of Parkinson's disease phenomenology heretofore left unexplained and provides a framework for testable hypotheses in patients during life and in autopsy analyses.

Using cognitive pretesting in scale development for Parkinson's disease: the Movement Disorder Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS) example

BACKGROUND

Cognitive pretesting, a qualitative step in scale development, precedes field testing and assesses the difficulty of instrument completion for examiners and respondents. Cognitive pretesting assesses respondent interest, attention span, discomfort, and comprehension, and highlights problems with the logical structure of questions/response options that can affect understanding. In the past this approach was not consistently used in the development or revision of movement disorders scales.

METHODS

We applied qualitative cognitive pretesting using testing guides in development of the Movement Disorder Society-sponsored revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS). The guides were based on qualitative techniques, verbal probing and "think-aloud" interviewing, to identify problems with the scale from the patient and rater perspectives. English-speaking Parkinson's disease patients and movement disorders specialists (raters) from multiple specialty clinics in the United States, Western Europe and Canada used the MDS-UPDRS and completed the testing guides.

RESULTS

Two rounds of cognitive pretesting were necessary before proceeding to field testing of the revised scale to assess clinimetric properties. Scale revisions based on cognitive pretesting included changes in phrasing, simplification of some questions, and addition of a reassuring statement explaining that not all PD patients experience the symptoms described in the questions.

CONCLUSIONS

The strategy of incorporating cognitive pretesting into scale development and revision provides a model for other movement disorders scales. Cognitive pretesting is being used in translating the MDS-UPDRS into multiple languages to improve comprehension and acceptance and in the development of a new Unified Dyskinesia Rating Scale for Parkinson's disease patients.

The Core Assessment Program for Surgical Interventional Therapies in Parkinson's Disease (CAPSIT-PD): Tolerability of Preoperative Neuropsychological Testing for Deep Brain Stimulation in Parkinson's Disease

Objective

We examined tolerability of preoperative neuropsychological testing (the Core Assessment Program for Surgical Interventional Therapies in Parkinson's Disease [CAPSIT-PD] protocol) for DBS. We also examined factors that may influence tolerability, including fatigue, global cognitive function, depression, and patient-based characteristics.

Methods

In this retrospective study, we reviewed preoperative neuropsychological testing results from 35 patients who were scheduled to undergo DBS. We examined the overall tolerability of the full battery and the tolerability of each test. We placed attention on a test's placement in the fixed order of the battery to measure whether there was a clustering of poorly tolerated tests toward the end of the battery as an indication of fatigue. Spearman's rank correlation was used to determine the relationship between tolerability and (1) global cognitive function, (2) depression, and (3) patient-based characteristics.

Results

Fourteen subjects (40%) were able to tolerate the full battery and completed all 10 tests. The domains that were least tolerated pertained to executive function and procedural memory. There was a consistent time-based tolerability pattern that was observed. There was a significant correlation between tolerability and global cognitive function (ρ = 0.344; P = 0.043), but not depression (P = 0.197). There was a significant correlation between tolerability and age (ρ = -0.491; P = 0.003) and disease duration (ρ = -0.442; P = 0.008), but not UPDRS-III scores (P = 0.284).

Conclusion

Our results have shown limited tolerability of the full neuropsychological battery as outlined by the CAPSIT-PD protocol. We suggest the consideration of updating the neuropsychological assessment used in the CAPSIT-PD protocol.

Gene delivery of neurturin to putamen and substantia nigra in Parkinson disease: A double-blind, randomized, controlled trial

OBJECTIVE

A 12-month double-blind sham-surgery-controlled trial assessing adeno-associated virus type 2 (AAV2)-neurturin injected into the putamen bilaterally failed to meet its primary endpoint, but showed positive results for the primary endpoint in the subgroup of subjects followed for 18 months and for several secondary endpoints. Analysis of postmortem tissue suggested impaired axonal transport of neurturin from putamen to substantia nigra. In the present study, we tested the safety and efficacy of AAV2-neurturin delivered to putamen and substantia nigra.

METHODS

We performed a 15- to 24-month, multicenter, double-blind trial in patients with advanced Parkinson disease (PD) who were randomly assigned to receive bilateral AAV2-neurturin injected bilaterally into the substantia nigra (2.0 × 10(11) vector genomes) and putamen (1.0 × 10(12) vector genomes) or sham surgery. The primary endpoint was change from baseline to final visit performed at the time the last enrolled subject completed the 15-month evaluation in the motor subscore of the Unified Parkinson's Disease Rating Scale in the practically defined off state.

RESULTS

Fifty-one patients were enrolled in the trial. There was no significant difference between groups in the primary endpoint (change from baseline: AAV2-neurturin, -7.0 ± 9.92; sham, -5.2 ± 10.01; p = 0.515) or in most secondary endpoints. Two subjects had cerebral hemorrhages with transient symptoms. No clinically meaningful adverse events were attributed to AAV2-neurturin.

INTERPRETATION

AAV2-neurturin delivery to the putamen and substantia nigra bilaterally in PD was not superior to sham surgery. The procedure was well tolerated, and there were no clinically significant adverse events related to AAV2-neurturin.

Handling missing values in the MDS-UPDRS

This study was undertaken to define the number of missing values permissible to render valid total scores for each Movement Disorder Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS) part. To handle missing values, imputation strategies serve as guidelines to reject an incomplete rating or create a surrogate score. We tested a rigorous, scale-specific, data-based approach to handling missing values for the MDS-UPDRS. From two large MDS-UPDRS datasets, we sequentially deleted item scores, either consistently (same items) or randomly (different items) across all subjects. Lin's Concordance Correlation Coefficient (CCC) compared scores calculated without missing values with prorated scores based on sequentially increasing missing values. The maximal number of missing values retaining a CCC greater than 0.95 determined the threshold for rendering a valid prorated score. A second confirmatory sample was selected from the MDS-UPDRS international translation program. To provide valid part scores applicable across all Hoehn and Yahr (H&Y) stages when the same items are consistently missing, one missing item from Part I, one from Part II, three from Part III, but none from Part IV can be allowed. To provide valid part scores applicable across all H&Y stages when random item entries are missing, one missing item from Part I, two from Part II, seven from Part III, but none from Part IV can be allowed. All cutoff values were confirmed in the validation sample. These analyses are useful for constructing valid surrogate part scores for MDS-UPDRS when missing items fall within the identified threshold and give scientific justification for rejecting partially completed ratings that fall below the threshold.

Initial management of Parkinson's disease

Parkinson's disease is one of the most common neurodegenerative disorders seen in the United States and United Kingdom. The disease is characterised by two processes-cellular degeneration and the resulting biochemical deficiency of dopamine. Although these processes are inter-related, they are approached separately in the clinical setting. Currently, no proven neuroprotective or disease modifying treatment is available for Parkinson's disease. Several agents can be used to treat the motor symptoms associated with dopamine deficiency, and it is important to choose wisely when starting treatment. Drugs can have mild, moderate, or high potency, and the patient's goals, comorbidities, and the short and long term implications of choosing a specific agent should be taken into account when selecting the appropriate agent. Non-motor symptoms, such as depression, fatigue, and disorders of sleep and wakefulness, also need to be evaluated and treated. Research is under way to deliver dopaminergic therapy more effectively, but studies aimed at slowing or stopping disease progression have not shown promise.