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There has been a growing appreciation for freezing of gait as a disabling symptom that causes a significant burden in Parkinson's disease. Previous research has highlighted some of the key components that underlie the phenomenon, but these reductionist approaches have yet to lead to a paradigm shift resulting in the development of novel treatment strategies. Addressing this issue will require greater integration of multi-modal data with complex computational modeling, but there are a number of critical aspects that need to be considered before embarking on such an approach. This paper highlights where the field needs to address current gaps and shortcomings including the standardization of definitions and measurement, phenomenology and pathophysiology, as well as considering what available data exist and how future studies should be constructed to achieve the greatest potential to better understand and treat this devastating symptom. ispartof: TRANSLATIONAL NEURODEGENERATION vol:11 issue:1 ispartof: location:England status: published

Copyright © 2021 The Authors. Freezing of gait (FOG) can severely compromise daily functioning in people with Parkinson’s disease. Inability to initiate a step from FOG is likely underpinned, at least in part, by a deficient preparatory weight-shift. Conscious attempts to weight-shift in preparation to step can improve success of initiating forward steps following FOG. However, FOG often occurs during turning, where weight-shifting is more complex and risk of falling is higher. We explored the effectiveness of a dance-based (‘cha-cha’) weight-shifting strategy to re-initiate stepping following FOG during turning. Results suggest that this simple movement strategy can enhance turning steps following FOG, without compromising safety. Parkinson's UK project grant (K-1604).

Despite increasing evidence for, and heightened awareness of, the importance of exercise in Parkinson’s disease, many patients remain sedentary. This tendency to lead an inactive lifestyle has various underlying reasons, including the presence of gait and balance impairments that complicate the patients’ ability to perform sports activities. This case report illustrates that a personally tailored approach may be required in these patients, supported, if needed, by the use of compensation strategies or novel technological advances. LAY ABSTRACTExercise is important for people with Parkinson’s disease. However, the presence of walking problems due to the condition may complicate patients’ ability to perform sports activities. This case report illustrates that a personally tailored approach is needed in such cases. This may include the use of novel technological advances (such as a special walker).

Objectives This study examined if people with Parkinson’s and freezing of gait pathology (FoG) could be trained to increase preparatory weight-shift amplitude, and facilitate step initiation during FoG. Methods Thirty-five people with Parkinson’s and FoG attempted to initiate forward walking from a stationary position caused by a freeze (n = 17, FoG-F) or voluntarily stop (n = 18, FoG-NF) in a Baseline condition and two conditions where an increased weight-shift amplitude was trained via: (i) explicit verbal instruction, and (ii) implicit movement analogies. Results At Baseline, weight-shift amplitudes were smaller during: (i) unsuccessful, compared to successful step initiations (FoG-F group), and (ii) successful step initiations in the FoG-F group compared to FoG-NF. Both Verbal and Analogy training resulted in significant increases in weight-shift amplitude in both groups, and a corresponding pronounced reduction in unsuccessful attempts to initiate stepping (FoG-F group). Conclusions Hypometric preparatory weight-shifting is associated with failure to initiate forward stepping in people with Parkinson’s and FoG. However, impaired weight-shift characteristics are modifiable through conscious strategies. This current study provides a novel and critical evaluation of preparatory weight-shift amplitudes during FoG events. The intervention described represents an attractive ‘rescue’ strategy and should be further scrutinised regarding limitations posed by physical and cognitive deficits.

Background Freezing of gait is a highly disabling symptom in persons with Parkinson's disease (PwP). Despite its episodic character, freezing can be reliably evaluated using the FOG score. The description of the minimal clinically relevant change is a requirement for a meaningful interpretation of its results. Objective To determine the minimal clinically relevant change of the FOG score. Methods We evaluated video recordings of a standardized freezing-evoking gait parkour, i.e., the FOG score just before and 30 minutes after the intake of a regular levodopa dose in a randomized blinded fashion. The minimal clinically relevant response was considered a value of one or more on a 7-step Likert-type response scale [-3; +3] that served as the anchor. The minimal clinically relevant change was determined by ROC analysis. Results 37 PwP (Hoehn & Yahr stages 2.5-4, 27 male, 10 female) were aged 68.2 years on average (range 45-80). Mean disease duration was 12.9 years (2-29 years). Minimum FOG score was 0 and Maximum FOG score was 29. Mean FOG scores before medication were 10.6, and 11.1 after medication intake, with changes ranging from -14.7 to +16.7. The minimal clinically relevant change (MCRC) for improvement based on expert clinician rating was three scale points with a sensitivity of 0.67 and a specificity of 0.96. Conclusions The FOG score is recognized as a useful clinical instrument for the evaluation of freezing in the clinical setting. Knowledge of the MCRC should help to define responses to interventions that are discernible and meaningful to the expert physician and to the patient.

Individuals with Parkinson’s disease (PD) experience rhythm disorders in a number of motor tasks, such as (i) oral diadochokinesis, (ii) finger tapping, and (iii) gait. These common motor deficits may be signs of “general dysrhythmia”, a central disorder spanning across effectors and tasks, and potentially sharing the same neural substrate. However, to date, little is known about the relationship between rhythm impairments across domains and effectors. To test this hypothesis, we assessed whether rhythmic disturbances in three different domains (i.e., orofacial, manual, and gait) can be related in PD. Moreover, we investigated whether rhythmic motor performance across these domains can be predicted by rhythm perception, a measure of central rhythmic processing not confounded with motor output. Twenty-two PD patients (mean age: 69.5 ± 5.44) participated in the study. They underwent neurological and neuropsychological assessments, and they performed three rhythmic motor tasks. For oral diadochokinesia, participants had to repeatedly produce a trisyllable pseudoword. For gait, they walked along a computerized walkway. For the manual task, patients had to repeatedly produce finger taps. The first two rhythmic motor tasks were unpaced, and the manual tapping task was performed both without a pacing stimulus and musically paced. Rhythm perception was also tested. We observed that rhythmic variability of motor performances (inter-syllable, inter-tap, and inter-stride time error) was related between the three functions. Moreover, rhythmic performance was predicted by rhythm perception abilities, as demonstrated with a logistic regression model. Hence, rhythm impairments in different motor domains are found to be related in PD and may be underpinned by a common impaired central rhythm mechanism, revealed by a deficit in rhythm perception. These results may provide a novel perspective on how interpret the effects of rhythm-based interventions in PD, within and across motor domains.

Evaluating freezing of gait (FOG) and quantifying its severity in patients with Parkinson’s disease (PD) is challenging; objective assessment is not sufficiently established. We aimed to improve the ability to objectively evaluate FOG severity by investigating the value of measuring the duration of the test and its components. Seventy-one patients with PD and FOG completed a previously validated FOG-provoking test. The test was performed under three conditions: (1) usual, single task; (2) dual task (walking while carrying a tray); and (3) triple task (walking while holding a tray and subtracting 7 s). FOG and festination were scored using standard procedures. We evaluated effect sizes based on both the original scoring and the test duration for the motor–cognitive cost and before and after anti-Parkinsonian medication intake. Additionally, video recording of the test and total time frozen were measured. As expected, the original test score and the test duration increased across the three conditions of the task and were higher in OFF than in the ON-medication state (p

Gait festination is one of the most characteristic gait disturbances in patients with Parkinson’s disease or atypical parkinsonism. Although festination is common and disabling, it has received little attention in the literature, and different definitions exist. Here, we argue that there are actually two phenotypes of festination. The first phenotype entails a primary locomotion disturbance, due to the so-called sequence effect: a progressive shortening of step length, accompanied by a compensatory increase in cadence. This phenotype strongly relates to freezing of gait with alternating trembling of the leg. The second phenotype results from a postural control problem (forward leaning of the trunk) combined with a balance control deficit (inappropriately small balance-correcting steps). In this viewpoint, we elaborate on the possible pathophysiological substrate of these two phenotypes of festination and discuss their management in daily clinical practice. Electronic supplementary material The online version of this article (10.1007/s00415-018-9146-7) contains supplementary material, which is available to authorized users.

Background Deep brain stimulation (DBS) is an established and effective treatment for Parkinson's disease (PD). After surgery, a number of extensive programming sessions are performed to define the most optimal stimulation parameters. Programming sessions mainly rely only on neurologist's experience. As a result, patients often undergo inconsistent and inefficient stimulation changes, as well as unnecessary visits. Objective/hypothesis We reviewed the literature on initial and follow-up DBS programming procedures and integrated our current practice at Toronto Western Hospital (TWH) to develop standardized DBS programming protocols. We propose four algorithms including the initial programming and specific algorithms tailored to symptoms experienced by patients following DBS: speech disturbances, stimulation-induced dyskinesia and gait impairment. Methods We conducted a literature search of PubMed from inception to July 2014 with the keywords “deep brain stimulation”, “festination”, “freezing”, “initial programming”, “Parkinson's disease”, “postural instability”, “speech disturbances”, and “stimulation induced dyskinesia”. Seventy papers were considered for this review. Results Based on the literature review and our experience at TWH, we refined four algorithms for: (1) the initial programming stage, and management of symptoms following DBS, particularly addressing (2) speech disturbances, (3) stimulation-induced dyskinesia, and (4) gait impairment. Conclusions We propose four algorithms tailored to an individualized approach to managing symptoms associated with DBS and disease progression in patients with PD. We encourage established as well as new DBS centers to test the clinical usefulness of these algorithms in supplementing the current standards of care.

To investigate the occurrence and clinical associations of festination in Chinese patients with Parkinson's disease (PD).A total of 480 PD patients were recruited in this cross-sectional study. Assessments scales included the Unified PD Rating Scale (UPDRS) part III, PD Questionnaire-39 (PDQ-39), Non-Motor Symptoms Scale (NMSS), Mini-Mental State Examination (MMSE), frontal assessment battery (FAB), Montreal Cognitive Assessment (MoCA), Hamilton Depression Scale (HAMD) and Hamilton Anxiety Scale (HAMA).One hundred and forty PD patients (29.2%) reported festination. Festination occurred more frequently in patients with lower limbs as the site of onset and patients with longer disease duration or higher Hoehn and Yahr (HY) stage (P0.05). The mean age, levodopa and entacapone use, incidences of motor complications, falls and freezing of gait, and the scores for the UPDRS part III, NMSS, HAMD and HAMA were higher in patients with festination than those without festination (P0.05). There were no differences in the scores for the PDQ-39, MMSE, FAB and MoCA between the patients with and without festination. The binary logistic regression model indicated that UPDRS part III, lower limbs as the site of onset, freezing of gait and falls were associated with festination.Festination is a relatively common disabling symptom in Chinese PD patients. Patients with lower limbs as the site of onset and more severe disability were more likely to experience festination. Festination in PD is not related to non-motor symptoms and cognitive dysfunction.

Parkinson disease (PD) patients have turning impairments that may increase fall risk. Clinics lack specialized kinematic equipment used in gait and turn analysis and require a simple method to evaluate fall risk and advise patients in turning strategy selection.To enhance understanding of PD turning strategies and determine if turning can be assessed using a video-recording and categorization method, we compared 180-degree and 90-degree turns as a function of medication status and dual-tasking (DT).21 PD participants (HY stage 1-3) in PD-ON and PD-OFF medication states and 16 controls completed 180-degree and 90-degree turn-tasks with and without DT. Video-recordings of tasks permitted classification of 180-degree turns into Few-Step turns (FST) vs. Multi-Step turns (MST) and 90-degree turns into Step vs. Spin-turns. FST were further sub-classified into Twisting vs. Sideways turns and MST into Backward, Festination, Forward or Wheeling turns. Percentages of subtypes were analyzed across groups by task.IN 180-degree tasks, there was an effect of group: FST vs. MST F(2,55) = 9.578, p .001. PD participants in the off-medication state (PD-OFF) produced significantly more MST with a larger number of different turning subtypes vs. controls or PD on medication (PD-ON). In 90-degree tasks, controls significantly increased their proportion of Step-turns while DT (p .001), an adaptation not observed in PD-ON or PD-OFF.PD turning impairments may stem from an inability to select a unified turning strategy and to adapt to the turning environment, which may be exacerbated in PD-OFF. Video-analysis may prove beneficial in predicting a clinical course for PD patients by revealing features of turning dysfunction.

The rhythm of the internal clock is considered to be determined by the basal ganglia, with some studies suggesting slower internal clock in Parkinson’s disease (PD). However, patients may also show motor hastening when they walk (festination) or are engaged in repetitive tapping, indicating faster ticking of the internal clock. Is the internal clock slower or faster in PD? The purpose of this study was to answer this question, i.e., how fast and slow a rhythm they can synchronize with, especially with reference to the limit of sensorimotor synchronization or temporal integration, representing the threshold of slower pace they can entrain into their motor actions, which is known to lie between 2 and 3 s in normal subjects but not yet studied in PD. We employed a synchronized tapping task that required subjects to tap the key in synchrony with repetitive tones at fixed interstimulus intervals (ISI) between 200 and 4800 ms. Twenty normal subjects and sixteen PD patients were enrolled, who were classified into early and advanced PD groups by UPDRS-III (early: 15 or less, advanced: more than 15). The ISI at which the response changes from synchronizing with the tones to lagging behind them was considered to be the limit of temporal integration. Early PD patients responded ahead of the tones (negative asynchrony), which became more apparent with repeated tapping. This suggested “faster” ticking clock even in the presence of the pacing tones. In normal subjects, the limit of temporal integration was around 2–3 s: below this, subjects could synchronize with the tones, while above it they had difficulty in synchronization. In early PD patients, the limit of temporal integration was significantly longer than in normal subjects, pointing to their enhanced ability to synchronize also with slower paces of tones, but advanced PD patients had significantly shortened limits, suggesting that advanced patients lost this ability. In conclusion, the limit of temporal integration is initially longer but gets shorter as the disease progresses. It can be explained by the hastening of the internal clock at the earlier stages of PD, followed by the loss of temporal integration.

Objective To explore the clinical predictors of freezing of gait (FOG) in Chinese patients with Parkinson's disease (PD). Methods This study included 225 patients with PD who completed a three‐year follow‐up visit. The end‐point was the presence of FOG (freezers), which was assessed during the follow‐up visit. Group comparisons were conducted, followed by a further forward binary logistic regression analysis. Results Eighty‐five patients with PD (38%) had developed FOG at the end of study. At baseline, freezers exhibited higher age, longer disease duration, higher scores in Unified PD Rating Scale (UPDRS) III and Hamilton Depression/Anxiety Rating Scale, lower Frontal Assessment Battery (FAB) score, higher subscores (e.g., “urgency”) and frequencies (e.g., “hallucinations”) in Non‐Motor Symptoms Scale, higher annual changes in MoCA, UPDRS III and FAB scores, and higher incidences of festination and falls than nonfreezers (p

The genetic basis of festination, a common motor symptom in Parkinson’s disease (PD), remains unclear. Since polymorphism in the alpha-synuclein (SNCA) gene is associated with PD phenotype, we examined whether such polymorphism is also associated with festination. SNCA polymorphisms rs11931074 and rs894278 were genotyped in a consecutive series of 258 patients with PD, of whom 122 (47.3%) suffered festination. Univariate analysis revealed significant differences in genotype and minor allele frequencies at rs11931074 or rs894278 between patients with festination and those without it (all p<0.05). Based on logistic regression, a GG or GT genotype at rs11931074 was associated with higher risk of festination among patients with PD (OR 2.077, 95% CI 1.111–3.883, p=0.022), as was the TT genotype at rs894278 (OR 2.271, 95% CI 1.246–4.139, p=0.007). Therefore, we conclude that festination is associated with polymorphism at rs11931074 or rs894278 among patients with PD.

Freezing of gait (FOG) is a clinically defined phenomenon of Parkinson's disease (PD). Recent evidence suggests that subtle FOG episodes can be elicited in a gait laboratory using suddenly appearing obstacles during treadmill walking. We evaluated which quantitative gait parameters identify such subtle FOG episodes. We included 10 PD patients with FOG, 10 PD patients without FOG, and 10 controls. Subjects walked on a motorized treadmill while avoiding unexpectedly appearing obstacles. Treadmill walking was videotaped, and FOG episodes were identified by two independent experts. Gait was also analyzed using detailed kinematics. Knee joint signals were processed using time-frequency analysis with combinations of sliding fast Fourier transform and wavelets transform. Twenty FOG episodes occurred during treadmill walking in 5 patients (all with clinically certified FOG), predominantly in relation to obstacle avoidance. FOG was brief when it occurred just before or after obstacle crossing and was characterized by short, rapid steps. Frequency analysis showed a typical qualitative pattern: before the FOG episode an increase in dominant frequency in the 0 to 3 Hz band (festination), followed by decreased power in 0 to 3 Hz band and an increased power in the 3 to 8 Hz band during the FOG episode. This pattern led to an increased FOG index as a qualitative measure. These approaches detected even very brief FOG with acceptable sensitivity (75-83%) and specificity (>95%). We conclude that time-frequency analysis is an appropriate approach to detect brief and subtle FOG episodes. Future work will need to decide whether this approach can support or even replace expert clinical opinion.

Gait festination (FE) can cause serious disability in Parkinson's disease (PD) patients. It is argued that the center of pressure position (COP) and body center of mass (COM) are possibly implicated in FE pathogenesis. The relationship between them remains unclear. The goal of this study was to determine spatiotemporal relationships between COM and COP in PD and to explore whether FE arises as a consequence of lack of physiological link between COP and COM during step stride. Twenty patients with idiopathic PD, in OFF state and 17-age-matched control subjects completed a 10-m walking protocol. PD patients were divided in two groups: those with FE and those without (NF). COM position, excursion, and its relationship with COP, as well as other kinematic parameters were analyzed. COM displacement along the horizontal and vertical plane was significantly lower in FE patients as was the maximum position on the movement direction axis compared with controls or NF patients. Significant difference in minimal COM position in FE patients was also observed. The percentage of stride time during which COM was situated ahead of COP along the movement axis in FE patients was significantly greater than for controls or NF patients. This would seem to indicate that FE patients are constantly attempting to align COP to COM, causing FE. The explanation might be that FE arises as a postural strategy to align COP within the area of COM displacement. Findings illustrate a putative role for postural strategies in the treatment of FE.

ZusammenfassungMotorische Blockaden während des Gehens sind als eine episodisch auftretende Störung der Ganginitiierung und des Lokomotionserhalts bei Parkinsonsyndromen und zentralen Gangstörungen definiert. Phänomenologisch werden Festination, trembling-in-place und total akinesia als Freezing-Formen unterschieden. Fünf differente Gangsituationen wurden als klassische Provokatoren für Freezing-Episoden benannt. Um eine Testung durch einen Beobachter klinisch einfach und aussagekräftig durchführen zu können, haben wir ein neues Testinstrument, den Freezing-ofgait-Score (FOG-Score) entwickelt, der im klinischen Alltag erprobt wird. Freezing bei Parkinsonpatienten ist meist dopasensitiv, kann aber auch im On-Zustand des Patienten auftreten und ist dann schwer zu therapieren.Wir diskutieren standardisierte Therapieschemata für Patienten mit On-Freezing, die wir an unserem Zentrum entwickelt haben.

Recent studies suggest that depression and anxiety in patients with Parkinson´s disease may predispose them to freezing. Although festination is also frequent, the association with emotional disorders has not been examined. The aim of the authors was to clarify the association between freezing and festination with anxiety, depressive disorders, and emotional distress. The authors examined a consecutive series of 95 patients with Parkinson´s disease using comprehensive psychiatric assessments and a new instrument specifically designed to assess the severity of freezing, festination, and emotional distress (Motor Blocks and Festination Scale). All patients were assessed with the Motor Blocks and Festination Scale, the Mini International Neuropsychiatric Interview, and scales to measure the severity of mood and anxiety disorders. A linear regression analysis showed that both motor blocks and festination were significantly associated with emotional distress and deficits on activities of daily living. Conversely, there was no significant association between motor blocks or festination and generalized anxiety disorder, panic disorder, agoraphobia, social phobia, or depression. Motor blocks and festination are significantly associated with emotional distress, but no significant associations were found with anxiety or affective disorders. Fil: Starkstein, Sergio. University of Western Australia; Australia Fil: Dragovic, Milan. University of Western Australia; Australia Fil: Brockman, Simone. University of Western Australia; Australia Fil: Wilson, Mark. University of Western Australia; Australia Fil: Bruno, Veronica Andrea. Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Merello, Marcelo Jorge. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia; Argentina

Various walk supporting systems have been devised and developed. However, they have not been designed for supporting or evaluating the gait of parkinsonian patients, and not much consideration has been given to gait disturbances of parkinsonian patients. In this study : (a) We prepared a tentative model of walk supporting and monitoring system in consideration of typical symptoms of parkinsonism. (b) We conducted gait rehabilitation in a parkinsonian patient using the walk supporting and monitoring system and confirmed (i) the occurrence of frozen gait during walking, (ii) brachybasia, (iii) the absence of anterior tilting of the posture, pulsion symptom, and festination, and (iv) occurrence of hesitation to start walking. Therefore, typical symptoms of parkinsonism can be detected by the use of this system. (c) The medical staff can evaluate the state of recovery of patients on the basis of the data obtained from this system and use them for purposes such as guidance of rehabilitation.

International audience; Freezing of gait (FOG) and festination are common symptoms in Parkinson Disease. They affect gait pattern and are associated to fall risks. We aim at early detection of FOG and festination episodes in order to trigger FES assistance. In this paper we present preliminary experimental results of FOG and festination detection including frequency analysis and gait parameters changes. The proposed solution is based on one wireless inertial sensor placed on the patient shank.

Besides the continuous motor impairments that characterize Parkinson’s disease (PD), patients are frequently troubled by sudden paroxysmal arrests or brief episodes of movement breakdown, referred to as ‘freezing’. Freezing of gait (FOG) is common in advanced PD and typically occurs in walking conditions that challenge dynamic motor-cognitive control. Mounting evidence suggests that episodic motor phenomena during repetitive upper limb (e.g. writing), lower limb (e.g. foot tapping) and speech sequences resemble FOG and may share some underlying neural mechanisms. However, the precise association between gait and non-gait freezing phenomena remains controversial. This review aimed to clarify this association based on literature on non-gait freezing published between 2000 and 2013. We focused on clinical and epidemiological features of the episodes and their relevance to current influential models of FOG, including recent neuroimaging studies that used a non-gait freezing paradigm as a proxy for FOG. Although not capturing the full complexity of FOG, the neurobehavioral insights obtained with non-gait freezing paradigms will contribute to an increased understanding of disturbed brain-behavior output in PD. publisher: Elsevier articletitle: Freezing beyond gait in Parkinson's disease: A review of current neurobehavioral evidence journaltitle: Neuroscience & Biobehavioral Reviews articlelink: http://dx.doi.org/10.1016/j.neubiorev.2014.04.010 content_type: article copyright: Copyright © 2014 Elsevier Ltd. All rights reserved. ispartof: Neuroscience and Biobehavioral Reviews vol:43 pages:213-227 ispartof: location:United States status: published

International audience; Freezing of gait (FOG) is a common symptom in Parkinsonism, which affects the gait pattern and is associated to a fall risk. Automatized FOG episode detection would allow systematic assessment of patient state and objective evaluation of the clinical effects of treatments. Techniques have been proposed in the literature to identify FOG episodes based on the frequency properties of inertial sensor signals. Our objective here is to adapt and extend these FOG detectors in order to include other associated gait pattern changes, like festination. The proposed approach is based on a single wireless inertial sensor placed on the patient's lower limbs. The preliminary experimental results show that existing frequency-based freezing detectors are not sufficient to detect all FOG and festination episodes and that the observation of some gait parameters such as stride length and cadence are valuable inputs to anticipate the occurrence of upcoming FOG events.

Besides the continuous motor impairments that characterize Parkinson's disease (PD), patients are frequently troubled by sudden paroxysmal arrests or brief episodes of movement breakdown, referred to as 'freezing'. Freezing of gait (FOG) is common in advanced PD and typically occurs in walking conditions that challenge dynamic motor-cognitive control. Mounting evidence suggests that episodic motor phenomena during repetitive upper limb (e.g. writing), lower limb (e.g. foot tapping) and speech sequences resemble FOG and may share some underlying neural mechanisms. However, the precise association between gait and non-gait freezing phenomena remains controversial. This review aimed to clarify this association based on literature on non-gait freezing published between 2000 and 2013. We focused on clinical and epidemiological features of the episodes and their relevance to current influential models of FOG, including recent neuroimaging studies that used a non-gait freezing paradigm as a proxy for FOG. Although not capturing the full complexity of FOG, the neurobehavioral insights obtained with non-gait freezing paradigms will contribute to an increased understanding of disturbed brain-behavior output in PD.

Oral levodopa has been proposed to be one of the more effective medications to alleviate freezing of gait, but there is limited data on its efficacy. We evaluated the gait phenomenology of 20 Parkinson's disease patients with freezing of gait before and 60 min after a standardized levodopa dose using a rating scale based on the assumption that festination and akinetic freezing share a common pathophysiology. Levodopa abolished festination and freezing in 20% of patients (p 0.0001), and reduced the freezing sum score from a median of 15 (IQR 6.75-27.5) to 3.5 (1-11.25), p 0.001) in all but one of the remainder. Pre-dose ratings correlated with post-dose ratings, in that those patients with lower pre-dose item-scores also showed lower post-dose outcome scores. Levodopa's effect on both festination and akinetic freezing was linear, thereby supporting the concept that festination and freezing are variants on a continuity of episodic gait disorders in PD.

Degeneration of dopamine neurons in the substantia nigra and intracellular deposition of Lewy body inclusions are the pathologic hallmarks of Parkinson disease (PD). Depletion of dopamine and other neurotransmitters results in motor (rest tremor, bradykinesia, and rigidity) and nonmotor (cognitive impairment, sleep disorders, fatigue, and depression) symptoms.

Parkinson’s disease (PD) is characterised by difficulty with the timing of movements. Data collected using the synchronization-continuation paradigm, an established motor timing paradigm, have produced varying results but with most studies finding impairment. Some of this inconsistency comes from variation in the medication state tested, in the inter-stimulus intervals (ISI) selected, and in changeable focus on either the synchronization (tapping in time with a tone) or continuation (maintaining the rhythm in the absence of the tone) phase. We sought to re-visit the paradigm by testing across four groups of participants: healthy controls, medication naïve de novo PD patients, and treated PD patients both ‘on’ and ‘off’ dopaminergic medication. Four finger tapping intervals (ISI) were used: 250ms, 500ms, 1000ms and 2000ms. Categorical predictors (group, ISI, and phase) were used to predict accuracy and variability using a linear mixed model. Accuracy was defined as the relative error of a tap, and variability as the deviation of the participant’s tap from group predicted relative error. Our primary finding is that the treated PD group (PD patients ‘on’ and ‘off’ dopaminergic therapy) showed a significantly different pattern of accuracy compared to the de novo group and the healthy controls at the 250ms interval. At this interval, the treated PD patients performed ‘ahead’ of the beat whilst the other groups performed ‘behind’ the beat. We speculate that this ‘hastening’ relates to the clinical phenomenon of motor festination. Across all groups, variability was smallest for both phases at the 500 ms interval, suggesting an innate preference for finger tapping within this range. Tapping variability for the two phases became increasingly divergent at the longer intervals, with worse performance in the continuation phase. The data suggest that patients with PD can be best discriminated from healthy controls on measures of motor timing accuracy, rather than variability.

Gait disturbances occur frequently in advanced Parkinson's disease (PD) including slow gait, postural changes, festination and freezing of gait. We have reviewed descriptions of gait abnormalities in PD from classic predopa-literature and compared them with those found in contemporary references. Several components of gait disturbances associated with shaking palsy were very well known in classic literature. James Parkinson, Charcot, Gowers and Wilson described slowness of gait, postural changes, loss of postural reflexes and festination; according to James Parkinson, festination was a pathognomonic element in shaking palsy. In contrast, freezing of gait was rarely mentioned in historic literature save for anecdotal reports (Buzzard 1888). Freezing of gait was fully noticed after the chronic use of levodopa (Barbeau and Ambani). In this historical review, we analyze the concept, identification and evolution of gait disturbances in PD through the time.

Freezing of gait (FOG) is defined as an episodic inability to generate effective stepping in the absence of any known cause, other than parkinsonism or high-level gait disorders. Substantial effort has been made to describe the clinical and kinematic characteristics of patients with FOG. In our review, we highlight the distinctive features of FOG in Parkinson’s disease (PD) and apply the knowledge of its pathophysiology in PD to other clinical situations and conditions. It is possible that FOG in PD represents the ultimate break in the frontal lobe–basal ganglia–cerebellar–brainstem network that controls gait. Dysrhythmic and discoordinated gait with abnormal scaling of stride length, as well as gait festination, likely is the primary and continuous abnormality of “the gait network” in PD, and FOG represents its extreme and complete but transient disruption.

Freezing of gait (FOG) is a common and disabling feature of Parkinson's disease, with unexpected episodes during which patients experience an inability to start walking or to continue moving forward. We present a practical algorithm to ascertain the diagnosis. Treatment may be challenging, but several pharmacological and physiotherapeutic options exist.