Medical treatment of freezing of gait

Towards Real-Time Detection of Freezing of Gait Using Wavelet Transform on Wireless Accelerometer Data

Injuries associated with fall incidences continue to pose a significant burden to persons with Parkinson’s disease (PD) both in terms of human suffering and economic loss. Freezing of gait (FOG), which is one of the symptoms of PD, is a common cause of falls in this population. Although a significant amount of work has been performed to characterize/detect FOG using both qualitative and quantitative methods, there remains paucity of data regarding real-time detection of FOG, such as the requirements for minimum sensor nodes, sensor placement locations, and appropriate sampling period and update time. Here, the continuous wavelet transform (CWT) is employed to define an index for correctly identifying FOG. Since the CWT method uses both time and frequency components of a waveform in comparison to other methods utilizing only the frequency component, we hypothesized that using this method could lead to a significant improvement in the accuracy of FOG detection. We tested the proposed index on the data of 10 PD patients who experience FOG. Two hundred and thirty seven (237) FOG events were identified by the physiotherapists. The results show that the index could discriminate FOG in the anterior–posterior axis better than other two axes, and is robust to the update time variability. These results suggest that real time detection of FOG may be realized by using CWT of a single shank sensor with window size of 2 s and update time of 1 s (82.1% and 77.1% for the sensitivity and specificity, respectively). Although implicated, future studies should examine the utility of this method in real-time detection of FOG.

Freezing of gait is associated with increased saccade latency and variability in Parkinson's disease

OBJECTIVE

Freezing of gait (FOG) is a locomotor disturbance in Parkinson disease (PD) related to impaired motor automaticity. In this study, we investigated the impact of freezing on automaticity in the oculomotor system using an anti-saccade paradigm.

METHODS

Subjects with PD with (PD-FOG, n=13) and without (PD-NON, n=13) FOG, and healthy age-matched controls (CTRL, n=12) completed automatic pro-saccades and non-automatic anti-saccades. Primary outcomes were saccade latency, velocity, and gain.

RESULTS

PD-FOG (pro-saccade latency=271ms, anti-saccade latency=412ms) were slower to execute both types of saccades compared to PD-NON (253ms, 330ms) and CTRL (246ms, 327ms). Saccade velocity and gain variability was also increased in PD-FOG.

CONCLUSIONS

Saccade performance was affected in PD-FOG for both types of saccades, indicating differences in automaticity and control in the oculomotor system related to freezing.

SIGNIFICANCE

These results and others show that FOG impacts non-gait motor functions, suggesting global motor impairment in PD-FOG.

Partial Body Weight-Supported Treadmill Training in Patients With Parkinson Disease: Impact on Gait and Clinical Manifestation

OBJECTIVE

To evaluate the effect of conventional gait training (CGT) and partial weight-supported treadmill training (PWSTT) on gait and clinical manifestation.

DESIGN

Prospective experimental research design.

SETTING

Hospital.

PARTICIPANTS

Patients with idiopathic Parkinson disease (PD) (N=60; mean age, 58.15±8.7y) on stable dosage of dopaminomimetic drugs were randomly assigned into the 3 following groups (20 patients in each group): (1) nonexercising PD group, (2) CGT group, and (3) PWSTT group.

INTERVENTIONS

The interventions included in the study were CGT and PWSTT. The sessions of the CGT and PWSTT groups were given in patient's self-reported best on status after regular medications. The interventions were given for 30min/d, 4d/wk, for 4 weeks (16 sessions).

MAIN OUTCOME MEASURES

Clinical severity was measured by the Unified Parkinson Disease Rating Scale (UPDRS) and its subscores. Gait was measured by 2 minutes of treadmill walking and the 10-m walk test. Outcome measures were evaluated in their best on status at baseline and after the second and fourth weeks.

RESULTS

Four weeks of CGT and PWSTT gait training showed significant improvements of UPDRS scores, its subscores, and gait performance measures. Moreover, the effects of PWSTT were significantly better than CGT on most measures.

CONCLUSIONS

PWSTT is a promising intervention tool to improve the clinical and gait outcome measures in patients with PD.

Prevalence and associated features of self-reported freezing of gait in Parkinson disease: The DEEP FOG study

Freezing of Gait (FOG) is a common and disabling symptom in patients with Parkinson disease (PD). The relationship between FOG and dopaminergic medication is complex. The aim of the present study was to estimate the prevalence of self-reported FOG, its associated clinical features, and its relationship with wearing-off in a wide PD population. This is an observational multicenter study of 634 consecutive non-demented PD patients. Patients were identified either as freezers or non-freezers based on item-3 of the Freezing of Gait-Questionnaire. FOG was then classified as on, off and onoff freezing based on its relationship with wearing-off. Patients were assessed with Unified Parkinson's Disease Rating Scale, Hoehn and Yahr scale, 8-item Parkinson's disease Questionnaire, Mini-Mental State Examination. Data from 593 patients were analyzed, 325 (54.3%) were freezers of whom 200 (61.6%) experienced FOG only during off state (off-freezers), 6 (1.8%) only during on state and 119 (36.6%) either in on and off states or independently of dopaminergic response-related symptoms (onoff-freezers). Overall, freezers vs non-freezers had longer disease duration, more advanced disease and greater disability. Moreover, freezers more frequently reported wearing-off and experienced worse quality of life. Onoff-freezers vs off-freezers were older, more severely disabled, less likely to experience wearing-off, treated with lower levodopa equivalent daily dose and with poorer cognitive performance. Self-reported FOG is mainly recognizable in advanced PD and is associated with more disability and worse quality of life. Onoff-FOG may represent the result of under-treatment or rather interpretable as a distinct clinical entity.

Prediction of freezing of gait using analysis of brain effective connectivity

Freezing of gait (FOG) is a debilitating symptom of Parkinson's disease (PD), in which patients experience sudden difficulties in starting or continuing locomotion. It is described by patients as the sensation that their feet are suddenly glued to the ground. This, disturbs their balance, and hence often leads to falls. In this study, directed transfer function (DTF) and partial directed coherence (PDC) were used to calculate the effective connectivity of neural networks, as the input features for systems that can detect FOG based on a Multilayer Perceptron Neural Network, as well as means for assessing the causal relationships in neurophysiological neural networks during FOG episodes. The sensitivity, specificity and accuracy obtained in subject dependent analysis were 82%, 77%, and 78%, respectively. This is a significant improvement compared to previously used methods for detecting FOG, bringing this detection system one step closer to a final version that can be used by the patients to improve their symptoms.

[Gait disorders in Parkinson's disease]

Gait and posture disorders are frequent signs of Parkinson's disease. Authors reviewed clinical and pathophysiological results reported for these disorders as well as the methods of investigation and treatment approaches including rehabilitation measures.

Emerging therapies for gait disability and balance impairment: promises and pitfalls

Therapeutic management of gait and balance impairment during aging and neurodegeneration has long been a neglected topic. This has changed considerably during recent years, for several reasons: (1) an increasing recognition that gait and balance deficits are among the most relevant determinants of an impaired quality of life and increased mortality for affected individuals; (2) the arrival of new technology, which has allowed for new insights into the anatomy and functional (dis)integrity of gait and balance circuits; and (3) based in part on these improved insights, the development of new, more specific treatment strategies in the field of pharmacotherapy, deep brain surgery, and physiotherapy. The initial experience with these emerging treatments is encouraging, although much work remains to be done. The objective of this narrative review is to discuss several promising developments in the field of gait and balance treatment. We also address several pitfalls that can potentially hinder a fast and efficient continuation of this vital progress. Important issues that should be considered in future research include a clear differentiation between gait and balance as two distinctive targets for treatment and recognition of compensatory mechanisms as a separate target for therapeutic intervention.

Gait disorders

PURPOSE OF REVIEW

This article provides insight and reviews useful tools for the clinical assessment, understanding, and management of neurologic gait disorders.

RECENT FINDINGS

In recent years, our understanding of the physiology of human walking has steadily increased. The recognition of gait as a complex, "higher-order" form of motor behavior with prominent influence of mental processes has been an important new insight, and the clinical implications of gait disorders are increasingly being recognized. Better classification schemes, the redefinition of established entities (eg, senile gait), and new insights from research on degenerative disorders primarily affecting gait (eg, primary progressive freezing of gait) have become available.

SUMMARY

Gait disorders are directly correlated with poor quality of life and increased mortality. Because gait is very sensitive to any insult to the nervous system, its assessment should be carried out carefully in routine clinical practice. Disorders of locomotion are easily discernible to the naked eye. However, when examining gait, clinicians should bear in mind that the clinical phenotype is the net result of changes induced by the disease itself plus any compensations adopted by the patient to improve stability. This review presents a clinically oriented approach to gait disorders based on the dominant phenomenology and underlying pathophysiology, which are tightly connected. The authors conclude by proposing a practical management approach.

Randomized cross-over trial to investigate the efficacy of a two-week physiotherapy programme with repetitive exercises of cueing to reduce the severity of freezing of gait in patients with Parkinson’s disease

Objective:

To investigate the efficacy of a two-week programme of repetitive exercise with cueing and movement strategies upon freezing of gait in people with Parkinson’s disease.

Design:

Randomized cross-over trial.

Setting:

Specialist clinic for Parkinson’s disease.

Subjects:

A total of 22 patients with Parkinson’s disease and freezing while other symptoms had favorably responded to dopaminergic treatment.

Intervention:

Patients were randomized into a four-week cross-over trial, and received either treatment (Group 1) or no treatment (Group 2) during Period 1, and switched during Period 2. Treatment consisted of a two-week programme during which the patients exercised cueing, and movement strategies together with a physiotherapist.

Main measure:

The primary outcome measure was a freezing score assessed from blinded and random ratings of video recordings. The secondary outcome measure was a patient-reported freezing questionnaire. Mean differences between the treatment periods (treatment arms) were evaluated for treatment (period) effects. Sums of treatment periods were evaluated for carry-over effects.

Results:

The programme led to a significant treatment effect in the freezing score of 3.0 improvement (95% confidence interval 0.9–5.0; p < 0.01). No carry-over or period effects were detected. The questionnaire revealed a period effect, so groups were compared after Period 1, where a significant difference was found (15.0 vs. 11.7; p < 0.05).

Conclusions:

The two-week physiotherapy programme reduced the severity of freezing in patients with Parkinson’s disease.

Using gastrocnemius sEMG and plasma α-synuclein for the prediction of freezing of gait in Parkinson's disease patients

Freezing of gait (FOG) is a complicated gait disturbance in Parkinson's disease (PD) and a relevant subclinical predictor algorithm is lacking. The main purpose of this study is to explore the potential value of surface electromyograph (sEMG) and plasma α-synuclein levels as predictors of the FOG seen in PD. 21 PD patients and 15 normal controls were recruited. Motor function was evaluated using the Unified Parkinson's Disease Rating Scale (UPDRS) and Freezing of gait questionnaire (FOG-Q). Simultaneously, gait analysis was also performed using VICON capture system in PD patients and sEMG data was recorded as well. Total plasma α-synuclein was quantitatively assessed by Luminex assay in all participants. Recruited PD patients were classified into two groups: PD patients with FOG (PD+FOG) and without FOG (PD-FOG), based on clinical manifestation, the results of the FOG-Q and VICON capture system. PD+FOG patients displayed higher FOG-Q scores, decreased walking speed, smaller step length, smaller stride length and prolonged double support time compared to the PD-FOG in the gait trial. sEMG data indicated that gastrocnemius activity in PD+FOG patients was significantly reduced compared to PD-FOG patients. In addition, plasma α-synuclein levels were significantly decreased in the PD+FOG group compared to control group; however, no significant difference was found between the PD+FOG and PD-FOG groups. Our study revealed that gastrocnemius sEMG could be used to evaluate freezing gait in PD patients, while plasma α-synuclein might discriminate freezing of gait in PD patients from normal control, though no difference was found between the PD+FOG and PD-FOG groups.

Practical approach to freezing of gait in Parkinson's disease

Freezing of gait in Parkinson's disease and related disorders is common and very disabling. It usually occurs in the advanced stages, although mild forms may develop earlier. Freezing can occur on turning, in narrow spaces, immediately before reaching a destination, and in stressful situations. Dual tasking (motor or cognitive load) aggravates the problem. Freezing of gait in Parkinson's disease usually occurs in the 'off' rather than in the 'on' state. It is, therefore, not entirely drug-resistant; the first step in medical treatment is to ensure adequate dopaminergic stimulation to reduce the 'off' state. There is no good evidence for any specific drug to alleviate freezing. Visual or auditory cues are very helpful as behavioural therapy. Assistive devices, such as a wheeled walker sometimes help. Deep brain stimulation of the subthalamic nucleus may alleviate freezing in the 'off' state. Because of the complexity of freezing, individual patients need a careful assessment-particularly in relation to motor fluctuation-to optimise their treatment.

The Effect of Parkinson Drug Timing on Cardiovascular Response during Treadmill Exercise in a Person with Parkinson Disease and Freezing of Gait

PURPOSE

To examine the response of cerebral oxygenation during treadmill walking in a person with Parkinson disease (PD) who experiences freezing of gait (FOG) and to determine whether the oxygen response was related to the timing of his PD medication. Client Description: A 61-year-old man with PD performed two bouts of treadmill testing on the same day, during the on- and off-phases of his PD medication. Measures and Outcome: The client experienced two FOG episodes during the first testing session (on-phase with hypokinetic movement session). Cerebral oxygen response (measured by near-infrared spectroscopy) was stable until the FOG episodes occurred, at which point it decreased until the FOG episode was over. No electrocardiogram (ECG) changes or lightheadedness were noted; blood pressure (BP) remained stable. During the second exercise testing session (off-phase with dyskinetic movement session), the client did not experience any FOG episodes, and his cerebral oxygen response remained stable. Toward the end of the second testing session, he experienced lightheadedness and a drop in BP of approximately 30 mmHg, along with significant ST segment depression on his ECG.

IMPLICATIONS

Haemodynamic and cerebral oxygen changes occurred that were specific to the timing of the client's PD medication and to his FOG episodes. This case study shows a person with PD demonstrating decreased cerebral oxygenation during FOG, which may be based on his variable response to levodopa medication or may be attributable to as yet unidentified physiologic mechanisms.

Treatment of Parkinson's disease: what's in the non-dopaminergic pipeline?

Dopamine depletion resulting from degeneration of nigrostriatal dopaminergic neurons is the primary neurochemical basis of the motor symptoms of Parkinson's disease (PD). While dopaminergic replacement strategies are effective in ameliorating these symptoms early in the disease process, more advanced stages of PD are associated with the development of treatment-related motor complications and dopamine-resistant symptoms. Other neurotransmitter and neuromodulator systems are expressed in the basal ganglia and contribute to the extrapyramidal refinement of motor function. Furthermore, neuropathological studies suggest that they are also affected by the neurodegenerative process. These non-dopaminergic systems provide potential targets for treatment of motor fluctuations, levodopa-induced dyskinesias, and difficulty with gait and balance. This review summarizes recent advances in the clinical development of novel pharmacological approaches for treatment of PD motor symptoms. Although the non-dopaminergic pipeline has been slow to yield new drugs, further development will likely result in improved treatments for PD symptoms that are induced by or resistant to dopamine replacement.

Intravenous amantadine on freezing of gait in Parkinson's disease: a randomized controlled trial

To compare the effects of intravenous amantadine and placebo therapy on freezing of gait in patients with Parkinson's disease, this randomized, double-blind, placebo-controlled, multicenter trial compared the efficacy of 5 days intravenous amantadine and placebo treatments on freezing of gait in 42 subjects randomly allocated 2:1 to amantadine or placebo groups. Changes in freezing of gait questionnaire (FOG-Q) scores and in unified Parkinson's disease rating scale (UPDRS) scores, from baseline to immediately (V1) and 1 month (V2) after treatments, were assessed. Among the 42 patients (amantadine n = 29, placebo n = 13, a mean age 65.5 ± 9.4 years and a mean FOG-Q score 17.4 ± 3.2), 40 subjects completed treatment. There was no significant group difference on the primary outcome measure as total FOG-Q score changes at V1. However a significant beneficial effect of amantadine on freezing was seen at V2 in the UPDRS Part II freezing and FOG-Q item 3 scores, and there was significant improvement in the UPDRS Part IV total score and in the UPDRS Part II getting out of bed score in the amantadine group at both V1 and V2. There was no serious adverse event reported during the study. The intravenous amantadine therapy did not show a significant improvement on overall FOG-Q scores in patients with moderate-to-severe freezing; however, it might be beneficial by attenuating freezing severity and improving patients' mobility. To prove this finding further studies with larger sample sizes are warranted in the future.

New pharmacological options for treating advanced Parkinson's disease

BACKGROUND

Parkinson's disease (PD) affects about 1% of the over 60 population and is characterized by a combination of motor symptoms (rest tremor, bradykinesia, rigidity, postural instability, stooped posture and freezing of gait [FoG]) and non-motor symptoms (including psychiatric and cognitive disorders). Given that the loss of dopamine in the striatum is the main pathochemical hallmark of PD, pharmacological treatment of the disease has focused on restoring dopaminergic neurotransmission and thus improving motor symptoms. However, the currently licensed medications have several major limitations. Firstly, dopaminergic medications modulate all the key steps in dopamine transmission other than the most powerful determinant of extracellular dopamine levels: the activity of the presynaptic dopamine transporter. Secondly, other monoaminergic neurotransmission systems (ie noradrenergic, cholinergic and glutamatergic systems are altered in PD and may be involved in a variety of motor and non-motor symptoms. Thirdly, today's randomized clinical trials are primarily designed to assess the efficacy and safety of treatments for motor fluctuations and dyskinesia. Fourthly, there is a need for disease- modifying treatments (DMTs) that slow disease progression and reduce the occurrence of the very disabling disorders seen in late-stage PD.

OBJECTIVE

To systematically review a number of putative pharmacological options for treating the main impairments in late-stage PD (ie gait disorders, cognitive disorders and behavioural disorders such as apathy).

METHODS

We searched the PubMed database up until July 2013 with logical combinations of the following search terms: "Parkinson's disease", "gait", "cognition", "apathy", "advanced stage", "modulation", "noradrenergic", "cholinergic", "glutamatergic" and "neurotransmission".

RESULTS

In patients undergoing subthalamic nucleus stimulation, the potentiation of noradrenergic and dopaminergic transmission by methylphenidate improves gait and FoG and may relieve apathy. However, the drug failed to improve cognition in this population. Potentiation of the cholinergic system by acetylcholinesterase inhibitors (which are licensed for use in dementia) may reduce pre-dementia apathy and falls. Modulation of the glutamatergic system by an N-methyl-D-aspartate receptor antagonist did not improve gait and dementia but may have reduced axial rigidity. A number of putative DMTs have been reported.

DISCUSSION

Novel therapeutic strategies should seek to reduce the appearance of the very disabling disorders observed in late-stage PD. Dopamine and/or noradrenaline transporter inhibitors, anticholinesterase inhibitors, Peroxisome-proliferator-activated-receptor-agonists and iron chelators should at least be investigated as putative DMTs by applying a delayed-start clinical trial paradigm to a large population

CONCLUSIONS

There is a need for more randomized clinical trials of treatments for late-stage PD.

Managing palliative care in Parkinson’s disease from diagnosis to end-stage disease: what the clinician should know

SUMMARY Progression of Parkinson’s disease (PD) is followed by aggravation of both motor and non-motor symptoms, which calls for more prominent palliative care towards the end stage of the disease. These palliative services should include multidisciplinary teamwork, in addition to taking into account treatment side effects, dose readjustment, and add-on nonpharmaceutical and pharmaceutical approaches. The treatment protocols in the advanced stage of PD are quite different from the ones in the early stages. The focus is shifted from symptom relief strategies to providing the patient with comfort and support during the palliative stage. In this review, some specific palliative approaches for dealing with motor and non-motor complications of end-stage PD are provided, as well as some general knowledge on palliation.

Selegiline: a reappraisal of its role in Parkinson disease

Selegiline at the doses used in Parkinson disease is a selective irreversible monoamine oxidase type B inhibitor, which potentiates dopaminergic function in the brain, and is used as monotherapy in early Parkinson disease or in combination with levodopa in more advanced disease. A renewed interest in monoamine oxidase type B inhibitors in the treatment of Parkinson disease has emerged after recent clinical trials of agents in this class. The use of selegiline monotherapy in early Parkinson disease is supported by the results of a large well-controlled trial in 800 patients (DATATOP) and several other studies, which demonstrated a symptomatic benefit, a reduction in disability, and a delay in the need to start levodopa therapy. Administered with levodopa in studies of up to 5 years' duration in patients with more advanced disease, selegiline improved disease-related disability, reduced the end-of-dose motor fluctuations, and also led to a reduction of the dose and dose frequency of levodopa required.Selegiline was the first drug to be investigated as a possible neuroprotective agent in patients with Parkinson disease, based on preclinical studies indicating protection of dopaminergic neurons from damage. The results of the extensive body of clinical trials, including delayed and lower levodopa requirements, may indeed suggest that selegiline, in addition to conferring symptomatic benefit, may have other effects on disease progression. Selegiline is well tolerated, and initial fears of increased mortality with the drug have not been borne out by subsequent robust meta-analyses.

Review: management of Parkinson's disease

Parkinson's disease (PD) is one of the most frequent neurological diseases. Despite the modern imaging and nuclear techniques which help to diagnose it in a very early stage and lead to a better discrimination of similar diseases, PD has remained a clinical diagnosis. The increasing number of available treatment options makes the disease management often complicated even when the presence of PD seems undoubted. In addition, nonmotor symptoms and side effects of some therapies constitute some pitfalls already in the preclinical state or at the beginnings of the disease, especially with the progressive effect on patients. Therefore, this review aimed to summarize study results and depict recommended medical treatments for the most common motor and nonmotor symptoms in PD. Additionally, emerging new therapeutic options such as continuous pump therapies, eg, with apomorphine or parenteral levodopa, or the implantation of electrodes for deep brain stimulation were also considered.

Unilateral extradural motor cortex stimulation is safe and improves Parkinson disease at 1 year

BACKGROUND

The primary motor cortex, which is part of the corticobasal ganglia loops, may be an alternative option for the surgical treatment of Parkinson disease.

OBJECTIVE

To report on the 1-year safety and efficacy of unilateral extradural motor cortex stimulation in Parkinson disease.

METHODS

A quadripolar electrode strip was extradurally implanted over the motor cortex. Stimulation was continuously delivered through the electrode paddle contralateral to the most affected clinical side. Subjects were prospectively evaluated by the Unified Parkinson's Disease Rating Scale (UPDRS) and the Parkinson's Disease Quality of Life Questionnaire. In addition, an extensive cognitive and behavioral assessment and electroencephalogram recording were performed.

RESULTS

Nine patients were included in this study. No surgical complications or adverse events occurred. Moreover, no cognitive or behavioral changes were observed. Under the off-medication condition, the UPDRS III at baseline was decreased by 14.1%, 23.3%, 19.9%, and 13.2%, at 1, 3, 6, and 12 months, respectively. The motor effects were bilateral, appeared after 3 to 4 weeks of stimulation, and outlasted the stimulation itself for 3 to 4 weeks in 1 case of stimulator accidental switching off. The UPDRS IV was decreased by 40.8%, 42.1%, and 35.5% at 1, 3, and 12 months, respectively. The scores on the Parkinson's Disease Quality of Life Questionnaire were increased at months 3, 6, and 12.

CONCLUSION

Extradural motor cortex stimulation is a safe procedure. After 12 months, the patients demonstrated a moderate improvement of motor symptoms (particularly axial symptoms) and quality of life.

Postural instability in patients with Parkinson's disease. Epidemiology, pathophysiology and management

Postural instability is one of the cardinal signs in Parkinson's disease (PD). It can be present even at diagnosis, but becomes more prevalent and worsens with disease progression. It represents one of the most disabling symptoms in the advanced stages of the disease, as it is associated with increased falls and loss of independence. Clinical and posturographic studies have contributed to significant advances in unravelling the complex pathophysiology of postural instability in patients with PD, but it still remains yet to be fully clarified, partly due to the difficulty in distinguishing between the disease process and the compensatory mechanisms, but also due to the fact that non-standardized techniques are used to measure balance and postural instability. There is increasing evidence that physical therapy, especially highly challenging balance exercises, can improve postural stability and reduce the risk of falls, although the long-term effects of physical therapy interventions on postural stability need to be explored given the progressive nature of PD. Pharmacotherapy with dopaminergic medications can provide significant improvements in postural instability in early- to mid-stage PD but the effects tend to wane with time consistent with spread of the disease process to non-dopaminergic pathways in advanced PD. Donepezil has been associated with a reduced risk of falls and methylphenidate has shown potential benefit against freezing of gait, but the results are yet to be replicated in large randomized studies. Surgical treatments, including lesioning and deep brain stimulation surgery targeting the subthalamic nucleus and the globus pallidus internus, tend to only provide modest benefit for postural instability. New surgical targets such as the pedunculopontine nucleus have emerged as a potential specific therapy for postural instability and gait disorder but remain experimental.

Methylphenidate : a treatment for Parkinson's disease?

Parkinson's disease (PD) affects about 1 % of the population over the age of 60 years and is characterized by a combination of rest tremor, bradykinesia, rigidity, postural instability, stooped posture and freezing of gait (FoG). However, the clinical spectrum also spans a wide range of non-motor symptoms, such as depression, apathy, cognitive disorders, sleepiness, fatigue and pain. Given that the loss of dopamine in the striatum is the primary pathochemical hallmark in PD, pharmacological treatment of the disease has focused on restoring dopaminergic neurotransmission. The currently licensed dopaminergic treatments for PD modulate all the key steps in the dopamine transmission except the most powerful determinant of extracellular dopamine concentrations: the presynaptic dopamine transporter (DaT). Methylphenidate is a CNS stimulant that blocks the DaT and the noradrenaline (norepinephrine) transporter in the striatum and the prefrontal cortex in particular. Here, we report on and discuss the main open-label studies and randomized controlled trials on the effect of methylphenidate on severe gait disorders (e.g. the FoG) and non-motor symptoms in advanced PD. The various pharmacodynamic effects of methylphenidate mean that the drug may have significant value in the treatment of PD. However, there is a lack of randomized controlled trials in this field. Furthermore, more rigorous selection of the types and doses of the associated dopaminergic treatments is required because these parameters may profoundly influence the mechanisms of action of methylphenidate and the clinical outcomes. Pharmacogenetic tools could be of use in better defining study patients as a function of their dopaminergic metabolism and drug responsiveness.

How far do the complaints of patients with Parkinson's disease reflect motor fluctuation? Quantitative analysis using a portable gait rhythmogram

In advanced-stage Parkinson's disease (PD), motor fluctuation is a frequent and disabling problem. Assessment of motor fluctuation depends on patient's subjective self-statement. We examined whether the subjective fluctuation matched the objective motor fluctuation defined by gait disorders. Using a new device, the portable gait rhythmogram, we recorded gait cadence and acceleration continuously over the 24-hour period in 54 patients with PD and 17 normal controls, for the quantitative evaluation of motor fluctuation. The patients were asked to estimate motor fluctuation every hour. In 44 of 54 patients, changes in the cadence were associated with simultaneous changes in acceleration. We examined the subjective fluctuation in these 44 patients who were confirmed to have motor fluctuation. Nineteen (82.7%) of 23 patients who felt no fluctuation showed distinct gait disorders. During off time, they walked with marked short or bradykinetic stepping. No matching changes were observed in either the cadence or acceleration in 11 (52.4%) of 21 patients who perceived motor fluctuation. No synchronization was noted in 30 (68.2%) of the 44 patients, between the times of subjectively assessed motor fluctuation and those of quantitative analysis of gait disorder. This discrepancy suggests that the objective continuous recording of the cadence and acceleration is necessary to understand motor fluctuation.

Intravenous amantadine for freezing of gait resistant to dopaminergic therapy: a randomized, double-blind, placebo-controlled, cross-over clinical trial

BACKGROUND

Freezing of gait (FOG) is one of the most disabling symptoms in Parkinsonism. Open-label studies have suggested that intravenous (IV) amantadine is effective against FOG resistant to dopaminergic therapy in Parkinson's disease (PD). We evaluated the efficacy of IV amantadine on FOG resistant to dopaminergic therapy.

METHODOLOGY/PRINCIPAL FINDINGS

This was a randomized, double-blind, placebo-controlled, cross-over study on IV amantadine. The placebo (normal saline) and amantadine (400 mg/day) were injected for 2 days with a 52-hour washout period. The instruments for the outcome measures were the Freezing of Gait Questionnaire (FOGQ), Unified Parkinson's disease rating Scale (UPDRS), and the duration of the 4×10 m walking test. The placebo arm was compared to the amantadine arm. Ten patients were enrolled but two patients withdrew, one from each arm. The FOGQ and UPDRS scores and the duration of the 4×10 m walking test improved in both arms compared to the baseline (P<0.05 in all). However, there were no differences in these values between the amantadine arm and placebo arm (P = 0.368, P = 0.583, P = 0.206, respectively). Follow-up measures 2 weeks after discharge in an open-label study showed the beneficial effects of an amantadine tablet on FOG (FOGQ, P = 0.018; UPDRS, P = 0.012 respectively).

CONCLUSIONS/SIGNIFICANCE

This double blind, placebo-controlled study did not show the efficacy of IV amantadine on FOG when compared with the placebo. This study provides Class II evidence due to small sample size for the lack of benefit of IV amantadine on FOG resistant to dopaminergic therapy

TRIAL REGISTRATION

Clinicaltrials.gov NCT01313819.

An update on the management of juvenile and young-onset Parkinson’s disease

Early-onset Parkinson’s disease (PD) denotes onset of the disease below the age of 40 years. Patients tend to have a slower disease progression, an increased rate of dystonia, an increased rate of dyskinesias in response to L-3,4-dihydroxyphenylalanine and a lower rate of dementia compared with those in late-onset PD. Early-onset PD patients may experience more social and psychosocial conflict compared with late-onset patients and these factors would contribute to greater impairment of quality of life. Unemployment due to disability or early retirement may be causes for these conflicts. We have to take these factors into account whenever we institute drug therapy in early-onset PD. There is no randomized controlled study on early-onset PD; however, we may make a reasonable decision by considering the data on PD in general and clinical characteristics of early-onset patients. The management of motor and non-motor symptoms of early-onset PD patients is reviewed here.

Cerebral blood flow and freezing of gait in Parkinson's disease

OBJECTIVE

We investigated the relationship between freezing of gait (FOG) severity in Parkinson's disease (PD) and regional cerebral blood flow (rCBF) using single-photon emission computed tomography (SPECT) and evaluated the effect of selegiline therapy.

METHOD

We evaluated 54 patients with PD (FOG positive: 21 patients, and FOG negative: 33 patients) with N-isopropyl-p-[I-123] iodoamphetamine ((123) I-IMP) SPECT and the Unified Parkinson's Disease Rating Scale (UPDRS) part III, Mini-Mental State Examination (MMSE), and Beck Depression Inventory. [Correction added on 18 April 2012, after online publication: In the preceding statement, 55 instead of 54 patients with PD were evaluated, and FOG negative consisted of 34 instead of 33 patients] Furthermore, we examined rCBF in FOG-negative patients treated with levodopa with or without selegiline.

RESULTS

Z-values of bilateral Brodmann areas (BA) 10 and 11 and left BA32 showed significant increases in the FOG-positive group compared with the FOG-negative group. [Correction added on 18 April 2012, after online publication: In the preceding statement, Z-values was changed to Z-scores] There were significantly positive correlations between Z-values of these areas and FOG score, especially on both sides of BA11. [Correction added on 18 April 2012, after online publication: In the preceding statement, Z-values was changed to Z-scores] An increase in Z-values in bilateral BA10 and 11 and left BA32 in the levodopa-selegiline treatment group after 1 year was significantly inhibited compared with the levodopa treatment group. [Correction added on 18 April 2012, after online publication: In the preceding statement, left BA32 was changed to right BA32, and Z-values was changed to Z-scores]

CONCLUSION

There was a close relationship between FOG severity in PD and an increase in rCBF in BA 10, 11 and 32. Furthermore, selegiline's FOG prevention effect may be related to maintaining rCBF in these same areas.

Posture and locomotion coupling: a target for rehabilitation interventions in persons with Parkinson's disease

Disorders of posture, balance, and gait are debilitating motor manifestations of advancing Parkinson's disease requiring rehabilitation intervention. These problems often reflect difficulties with coupling or sequencing posture and locomotion during complex whole body movements linked with falls. Considerable progress has been made with demonstrating the effectiveness of exercise interventions for individuals with Parkinson's disease. However, gaps remain in the evidence base for specific interventions and the optimal content of exercise interventions. Using a conceptual theoretical framework and experimental findings, this perspective and review advances the viewpoint that rehabilitation interventions focused on separate or isolated components of posture, balance, or gait may limit the effectiveness of current clinical practices. It is argued that treatment effectiveness may be improved by directly targeting posture and locomotion coupling problems as causal factors contributing to balance and gait dysfunction. This approach may help advance current clinical practice and improve outcomes in rehabilitation for persons with Parkinson's disease.". . .postural activity should be regarded as a function in its own right and not merely as a component of movement. . ."James Purdon Martin.

Parkinson's disease therapeutics: new developments and challenges since the introduction of levodopa

The demonstration that dopamine loss is the key pathological feature of Parkinson's disease (PD), and the subsequent introduction of levodopa have revolutionalized the field of PD therapeutics. This review will discuss the significant progress that has been made in the development of new pharmacological and surgical tools to treat PD motor symptoms since this major breakthrough in the 1960s. However, we will also highlight some of the challenges the field of PD therapeutics has been struggling with during the past decades. The lack of neuroprotective therapies and the limited treatment strategies for the nonmotor symptoms of the disease (ie, cognitive impairments, autonomic dysfunctions, psychiatric disorders, etc.) are among the most pressing issues to be addressed in the years to come. It appears that the combination of early PD nonmotor symptoms with imaging of the nigrostriatal dopaminergic system offers a promising path toward the identification of PD biomarkers, which, once characterized, will set the stage for efficient use of neuroprotective agents that could slow down and alter the course of the disease.

The effects of gait impairment with and without freezing of gait in Parkinson's disease

OBJECTIVE

To compare the effects of gait impairment without freezing of gait (FOG) versus FOG without gait impairment in Parkinson's disease (PD) on disability and quality of life.

BACKGROUND

FOG is frequently characterized as the major cause of gait-related disability in PD. However, gait impairment may also result from other PD symptoms including slowing, motor asymmetry, gait variability, dystonia or stooped posture.

METHODS

The Unified Parkinson's Disease Rating Scale (UPDRS), Older Americans Resources and Services Disability Scale (OARS) and the SF-12 Health Status Survey were used to evaluate patients with PD. Responses to UPDRS Items #14 (Freezing) and # 29 (Gait) were used to create 4 subgroups: 1) No FOG or gait impairment, 2) FOG, no gait impairment, 3) Gait impairment, no FOG, and 4) Both FOG and gait impairment. Disease severity, disability, and quality of life were compared across the subgroups with ANOVAs, and between subgroups with t-tests.

RESULTS

916 PD patients were divided into 4 subgroups based on their gait and freezing score (#1: n = 213, #2: n = 41, #3: n = 323 and #4: n = 339). Total UPDRS progressively increased from Group 1 through Group 4 (1 = 25.2, 2 = 33.7, 3 = 39.2, 4 = 59.2; p < 0.001). Motor UPDRS also progressively increased (1 = 17.4, 2 = 19.7, 3 = 26.9, 4 = 36.5; p < 0.0001). Similarly, disability and health-related quality of life progressively increased from Group 1 through Group 4 (Total OARS: 1 = 15.3, 2 = 17.2, 3 = 18.9, 4 = 28.4; p < 0.001). Group 3 (Gait impairment, no FOG) showed greater disease severity than Group 2 (FOG, no gait impairment; Total and Motor UPDRS; p < 0.05), but the difference did not reach significance for disability or quality of life.

CONCLUSIONS

Gait impairment without FOG was associated with greater disease severity than FOG without gait impairment. The combination of gait impairment and FOG was associated with the greatest disease severity and disability. These results show differential effects of diverse features of gait impairment in PD and demonstrate the importance of gait features unrelated to freezing.

Combined STN/SNr-DBS for the treatment of refractory gait disturbances in Parkinson's disease: study protocol for a randomized controlled trial

BACKGROUND

Severe gait disturbances in idiopathic Parkinson's disease (PD) are observed in up to 80% of all patients in advanced disease stages with important impact on quality of life. There is an unmet need for further symptomatic therapeutic strategies, particularly as gait disturbances generally respond unfavourably to dopaminergic medication and conventional deep brain stimulation of the subthalamic nucleus in advanced disease stages. Recent pathophysiological research pointed to nigro-pontine networks entrained to locomotor integration. Stimulation of the pedunculopontine nucleus is currently under investigation, however, hitherto remains controversial. The substantia nigra pars reticulata (SNr)--entrained into integrative locomotor networks--is pathologically overactive in PD. High-frequent stimulation of the substantia nigra pars reticulata preferentially modulated axial symptoms and therefore is suggested as a novel therapeutic candidate target for neuromodulation of refractory gait disturbances in PD.

METHODS

12 patients with idiopathic Parkinson's disease and refractory gait disturbances under best individual subthalamic nucleus stimulation and dopaminergic medication will be enroled into this double-blind 2 × 2 cross-over clinical trial. The treatment consists of two different stimulation settings using (i) conventional stimulation of the subthalamic nucleus [STNmono] and (ii) combined stimulation of distant electrode contacts located in the subthalamic nucleus and caudal border zone of STN and substantia nigra pars reticulata [STN+SNr]. The primary outcome measure is the change of the cumulative 'axial score' (UPDRS II items '13-15' and UPRDS III items '27-31') at three weeks of constant stimulation in either condition. Secondary outcome measures include specific scores on freezing of gait, balance function, quality of life, non-motor symptoms, and neuropsychiatric symptoms. The aim of the present trial is to investigate the efficacy and safety of a three week constant combined stimulation on [STN+SNr] compared to [STNmono]. The results will clarify, whether stimulation on nigral contacts additional to subthalamic stimulation will improve therapeutic response of otherwise refractory gait disturbances in PD.

TRIAL REGISTRATION

The trial was registered with the clinical trials register of http://www.clinicaltrials.gov (NCT01355835).

Freezing of gait: moving forward on a mysterious clinical phenomenon

Freezing of gait (FoG) is a unique and disabling clinical phenomenon characterised by brief episodes of inability to step or by extremely short steps that typically occur on initiating gait or on turning while walking. Patients with FoG, which is a feature of parkinsonian syndromes, show variability in gait metrics between FoG episodes and a substantial reduction in step length with frequent trembling of the legs during FoG episodes. Physiological, functional imaging, and clinical-pathological studies point to disturbances in frontal cortical regions, the basal ganglia, and the midbrain locomotor region as the probable origins of FoG. Medications, deep brain stimulation, and rehabilitation techniques can alleviate symptoms of FoG in some patients, but these treatments lack efficacy in patients with advanced FoG. A better understanding of the phenomenon is needed to aid the development of effective therapeutic strategies.

Freezing of Gait in Parkinson Disease Is Associated With Impaired Conflict Resolution

Background. Freezing of gait (FOG) in Parkinson disease (PD) may involve executive dysfunction. This study examined whether executive functioning and attention are more affected in patients with FOG compared with those without and determined whether these processes are influenced by anti-Parkinson medication. Methods. A total of 11 PD patients with FOG, 11 without FOG, and 10 healthy control subjects, matched for age, gender, and education, participated. General motor, mental and cognitive screening tests, as well as specific neuropsychological assessment of executive functions and the Attention Network Test (ANT) were administered. The ANT was conducted in both ON and OFF phases in a counterbalanced design to determine medication-specific effects. Results. FOG showed a clear association with impairment in the executive control network for conflict resolution (inhibition of unwanted responses and impaired response selection), compared with nonfreezers and healthy controls, F(2, 28) = 5.41, P = .01. Orienting and alerting function did not differ between groups, F < 1. Other executive functions, such as abstract problem solving and mental flexibility were not associated with FOG ( P > .10). Anti-Parkinson medication did not ameliorate conflict resolution ( P > .10), although orienting attention improved with medication, F(1, 17) = 9.81, P < .01. Conclusions. This study shows an association between impaired conflict resolution and FOG, important in understanding the interplay between cognitive and motor problems, which can lead to specific rehabilitation strategies.

Insights into the neural control of locomotion from walking through doorways in Parkinson's disease

Recent evidence suggests that a network of brain areas may be involved in visually guided walking. Here we study patients with Parkinson's disease (PD) who experience 'freezing' behaviour to investigate the visual control of locomotion and the role of the basal ganglia in this system. We use a variable-width doorway to measure the scaling of motor output to visual input specifying door width. By measuring walking behaviour as participants passed through the doorway, we show that both PD and healthy control participants scaled their locomotor outputs to door width. Both groups reacted to narrower doors by walking more slowly with shorter strides. However, the changes were greater in the PD group, where walking speed dramatically decreased while approaching the doorway. Such a pattern could help explain why doorways cause freezing episodes in PD. Neither explicit perceptual judgements of door width, nor performance on motor tasks, predicted the door behaviour. On the basis of these findings, we propose that PD is associated with a visuomotor disturbance, such that responses to action-relevant visual information are exaggerated. In the PD group, dopaminergic medications improved many baseline gait variables but did not affect their sensitivity to door width, suggesting that this visuomotor effect is not mediated by the basal ganglia. This hypothesis provides a novel framework for interpreting a variety of results with PD patients.

Current strategies in the treatment of Parkinson's disease and a personalized approach to management

Parkinson's disease is a progressive, neurodegenerative disorder affecting millions of people worldwide. Given the aging population, the prevalence of the disease is expected to increase substantially. The mainstay of treatment has been dopamine replacement therapy with carbidopa, levodopa, dopamine agonists, monoamine oxidase type B inhibitors, catechol-O-methyltransferase inhibitors and amantadine. Nonmotor features, such as cognitive impairment, mood disorders, autonomic dysfunction, gastrointestinal and genitourinary dysfunction, have a substantial impact on Parkinson's disease patients and their quality of life. This review will provide an overview on medications currently available for management of both motor and nonmotor symptoms of Parkinson's disease. Focus will be placed on recent and evolving studies evaluating symptomatic and neuroprotective effects of medications, and how such studies may impact the future management of Parkinson's disease.