Impaired Postural Reflexes Research Articles

FUNCTIONAL STATUS AMONG PATIENTS WITH STAGE III PARKINSON’S DISEASE

Aims Of Study: The purpose of the study was to assess the functional capabilities of patients with Stage III Parkinson's disease (PD). Functional status of PD patients declines due to impaired postural reflexes and characteristic loss of balance which became evident at Stage III thus activities of daily living (ADLs) are compromised as the severity of the disease increases. Methodology: Descriptive case series was conducted on stage III PD patients (n=64). Patients with age ranges from 45 to 75 years were recruited and patients with other neurological issues were excluded. They were assessed using a Functional independence measure scale having reliability 0.95. Results: Out of 64 patients, 75% required minimal assistance and 9.4% required supervision while performing the ADLs. Whereas, 81% of patients need 2 hours of personal care assistance according to burden of care. Limitations & Future Implications: Only functional status of PD patient is determined no exercise regime or intervention were incorporated to assess their impact on the PD patient functional activities. Thus, future studies should be carried out to find the correlation between aerobic exercises and their impact on PD patient level of functional independence. Originality: Information added was all taken from databases and reduced to similarity index and was not submitted to any other journal. Conclusion: Stage III Parkinson’s disease patient required minimal level of assistance while performing tasks of daily living. However, majority of these patients required 2 hours of personal care assistance on average per day to compete with daily living.

A Man with Rapid Speech and Handwriting.

Video 1 Video showing abnormal speech, handwriting, partial supranuclear gaze palsy, and impaired postural reflexes. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Investigation of The Relationship between The Pesticide Fluopyram and Parkinson’s disease

Parkinson's disease (PD) is a neurodegenerative disease defined as a shaky stroke. It is clinically characterized by; resting tremor, cogwheel rigidity, bradykinesia, and postural reflex impairment. It is also pathologically characterized by Lewy bodies (LBs) and formed by the loss of dopaminergic neurons in the Substantia nigra pars compacta (SNpc) region of the brain and the accumulation of AlphaSynuclein (α-Syn) proteins. Pesticides are the hugest risk factor of PD. They cause the formation of PD by using different mechanisms. They also permanently disrupt the function of the electron transport complex (ETC) located in the mitochondria. Researches show that the pesticide Rotenone (ROT) causes PD in vivo and in vitro conditions by inhibiting mitochondrial complex I and causing oxidative stress. Fluopyram (Flu) is a frequently used pesticide that causes mitochondrial toxicity like ROT. When literature is searched, it makes one think about a connection with PD. it seems that there is no available study on Flu and PD. Flu is one of the fungicides utilized in Isparta city at a high rate for all planting types. The Flu is a mitochondrial complex II inhibitor. The inhibition of mitochondrial complexes is the main pathway in the PD mechanism, therefore complex II inhibitor pesticide may lead to the same result. In this context, we created a Parkinson's model in mice with ROT and compare the result of Flu with this ROT to be sure whether that lead to Parkinson's or not. Swiss albino male and female mice were the testing animals of our study. Positive control (ROT Parkinson model, 1 mg/kg/day), negative control (Solvent only, DMSO), and Flu (0.5,1 and 2 mg/kg/day) were administrated to mice daily doses subcutaneously (SC). The experiment got completed after 21 days. Motor Function Test, Histochemical and Immunohistochemical Studies, Comet assay, and quantitative real-time PCR (qRT-PCR) were utilized in the study as well. In our results, no statistically significant changes were observable in animal weights in all groups. In the motor function test, a significant decrease in the ROT group was observable, On the other hand, a significant decrease was detected specifically in the Flu value which was applied at high doses. When the brain tissues that belong to the ROT and Flu tested groups got examined, all-important structural changes such as LBs got observed in the SN. When brain tissues belonging to ROT and Flu groups were examined in α-Syn immunohistochemical staining, more positive markings were observable. When the brain tissues belonging to the ROT and Flu groups were examined in Tyrosine hydroxylase (TH) immunohistochemical staining, fewer positive markings were observed. ROT has been found to cause DNA damage in blood and brain tissues. It has been determined that groups with Flu applied in the brain do not have DNA damage. ROT was observed to increase SNCA mRNA expression levels while decreasing TH and DJ-1 mRNA expression levels. Comparing the Flu and ROT results, SNCA mRNA expression levels increased but were not significant. With the detection of decreased TH and DJ-1 mRNA expression levels, the difference was shown in our ROT results. In conclusion, The study results have proved that in mice Flu's induce of PD phenotype depends on Flu doses. It is recommended to do more research with Flu especially in high doses and with different methods

Early-Onset Parkinsonism and Early-Onset Parkinson's Disease: A Population-Based Study (2010-2015).

Early-onset Parkinson's disease (EOPD), occurring between ages 40 and 55, carries social, societal, and personal consequences and may progress, with fewer comorbidities than typical, later-onset disease. To examine the incidence and survival of EOPD and other Parkinsonism occurring before age 55 in the population-based cohort of residents in seven Minnesota counties. A movement-disorder specialist reviewed all the medical records in a 2010-2015 Parkinsonism-incident cohort to confirm diagnosis and subtypes. We identified 27 patients diagnosed at ≤ 50 years with incident Parkinsonism 2010-15:11 (41%) cases of EOPD, 13 (48%) drug-induced Parkinsonism, and 3 (11%) other Parkinsonism; we also identified 69 incident cases of Parkinsonism ≤ 55 years, of which 28 (41%) were EOPD, 28 (41%) DIP, and 13 (19%) other Parkinsonism. Overall incidence for Parkinsonism ≤ 50 years was 1.98/100,000 person-years, and for EOPD was 0.81/100,000 person-years. In patients ≤ 55 years, Parkinsonism incidence was 5.05/100,000 person-years: in EOPD, 2.05/100,000 person-years. Levodopa-induced dyskinesia was present in 45%of EOPD (both ≤ 50 years and ≤ 55 years). Onset of cardinal motor symptoms was proximate to the diagnosis of EOPD, except for impaired postural reflexes, which occurred later in the course of EOPD. Among the 69 Parkinsonism cases ≤ 55 years, 9 (13%; all male) were deceased (only 1 case of EOPD). Men had a higher mortality risk compared to women (p = 0.049). The incidence of EOPD ≤ 50 years was 0.81/100,000 person-years (1.98 in Parkinsonism all type); prior to ≤ 55 years was 2.05/100,000 person-years (5.05 in Parkinsonism all type) with higher incidence in men than women. Men with Parkinsonism, all type, had higher mortality compared to women.

Impact of the COVID-19 Pandemic on Parkinson's Disease and Movement Disorders.

Impact of the COVID-19 Pandemic on Parkinson's Disease and Movement Disorders.

Survival and Progression in Synucleinopathy Phenotypes With Parkinsonism: A Population-Based Study

ObjectiveTo compare survival by the presenting parkinsonism symptoms at diagnosis among patients with incident clinically diagnosed synucleinopathies. Patients and MethodsUsing the Rochester Epidemiology Project medical records–linkage system, we identified all persons residing in Olmsted County, Minnesota, who received a diagnostic code of parkinsonism from January 1, 1991, through December 31, 2010. A movement disorder specialist reviewed the complete medical records of each individual to confirm the presence of parkinsonism, determine the type of synucleinopathy, and identify the onset dates of each cardinal symptom (tremor at rest, bradykinesia, rigidity, and impaired postural reflexes). We determined the median time from age at diagnosis to death or censoring (June 30, 2015) for each presenting symptom and the age- and sex-adjusted risk of death. ResultsFrom 1991 through 2010, a total of 433 individuals had a synucleinopathy diagnosed (301 [69.5%], Parkinson disease; 68 [15.7%], dementia with Lewy bodies; 52 [12.0%], Parkinson disease dementia; and 12 [2.8%], multiple systems atrophy with parkinsonism). Overall, the risk of death in the tremor-predominant group was less than that in the bradykinesia/rigidity-only group (hazard ratio [HR], 0.59; 95% CI, 0.40-0.87; P=.007). Similarly, risk of death in the bradykinesia/rigidity-only group was significantly greater than in the tremor-predominant group (HR, 1.75; 95% CI, 1.23-2.51; P=.002) and compared with tremor before bradykinesia (HR, 1.75; 95% CI, 1.24-2.47; P=.001). ConclusionPatients with tremor as a presenting symptom have longer survival. In contrast, the presence of bradykinesia/rigidity as a presenting symptom correlates with reduced survival across all types of synucleinopathies.

An Instrumented Pull Test to Characterize Postural Responses.

Impairment of postural reflexes, termed postural instability, is a common and disabling deficit in Parkinson's disease. To assess postural reflexes, clinicians typically employ the pull test to grade corrective responses to a backward perturbation at the shoulders. However, the pull test is prone to issues with reliability and scaling (score/4). Here, we present an instrumented version of the pull test to more precisely quantify postural responses. Akin to the clinical test, pulls are manually administered except pull force is also recorded. Displacements of the trunk and feet are captured by a semi-portable motion tracking system. Raw data represent distance traveled (in millimeter units), making subsequent interpretation and analysis intuitive. The instrumented pull test also detects variabilities influencing pull test administration, such as pull force, thereby identifying and quantifying potential confounds that can be accounted for by statistical techniques. The instrumented pull test could have application in studies seeking to capture early abnormalities in postural responses, track postural instability over time, and detect responses to therapy.

Falls in the elderly.

The falls frequently occurring as a result of impaired postural reflexes, due to degenerative changes that accompany the aging process, have a great impact on quality of life in the elderly. Falls and the fear of falling can trigger restraints and limits to freedom, ultimately leading to definitive care from professional or other. In nursing homes, security regulations often predominate over any other consideration and become a source of suffering and oppression. Pharmacological or "medical" management of this condition is effective in only a small proportion of elderly individuals. In the vast majority of cases, preventive measures and daily activity management programs need to be implemented to avoid the partial or complete loss of personal freedom, though these highly depend on the available individual economic resource. Doctors, namely neurologists operating in public services of the territory, have to face difficult medical, human and ethical problems. This article reviews this issue in the light of personal experience and by the analysis of several case reports.

Association of SNCA in late-onset Parkinson’s disease with 22q11.2 deletion

Parkinson’s disease (PD) is a neurodegenerative, age-related type of movement disorder, which occurs due to two pathological hallmarks such as the degeneration of the dopamine and Lewy body formation. The clinical manifestations of PD are tremor, bradykinesia, rigidity and impairment of postural reflexes. The incidence is about 17 per 100,000 person-years but in India, studies have been based on population deter- mining the exact evidence and prevalence of PD. The intend of the study was to identify the chromosomal aberrations and mutational analysis in SNCA (α-synuclein) gene in 19 late-onset of PD using GTG banding and PCR-RFLP techniques. The resulted polymorphism was observed with a protein change p.Ala53Glu (A53E) whereas the chromosomal abnormalities were observed in chromosome 22 with a deletion in 22q11.2. Therefore, these findings shows that the chromosomal aberrations and mutation in SNCA are rare in late-onset cases of PD hence, this is the foremost report in Coimbatore population and a unique study from the researches done earlier.

Non Motor Symptoms In Patients With parkinson's Disease In Baghdad Hospitals

Background:Parkinson’disease(PD) is a neurodegenerative disorder of the central nervous system characterized by resting tremor, bradykinesia, cogwheel rigidity, and impairment of postural reflexes; the frequency of PD increases with aging.Clinically Parkinson's disease characterized by two groups of symptoms: motor and non-motor symptoms.Non-motor symptoms can be categorized as autonomic, cognitive/psychiatric (may include depression, dementia, anxiety, hallucinations), sensory and rapid eye movements (REM) sleep behavior disorder (RBD).
 Objectives:The objectives of this study are to find out the frequency of the non-motor symptoms of idiopathic Parkinson disease in a group of patients in Baghdad hospitals.
 Type of the study:A cross sectional study with analytic elements,
 Methods: It was conducted in movement disorders clinic in neuroscience hospital, outpatient clinic at Baghdad teaching hospital and AL-Kadhumain teaching hospital during the period between the 1st. of December 2013 through July 2014. One hundred and two patients diagnosed as idiopathic Parkinson disease by a consultant neurologist..
 Results:The study found that the mean age of patients with Idiopathic Parkinson disease was 60 years. Among them, two thirds of patients (68/102) were males, and 55 % (56/102) of patients were in advanced stage of the disease. The study also mentioned the percentage of non-motor symptoms of Idiopathic Parkinson disease and they ranged from the most frequent symptom[constipation(80%)] to the least frequent[bowel incontinence(16%)].Also the study shows the distribution of symptoms according to gender and the study found no significant difference between males and females. The study finds that there is no significant difference in symptoms development along the period of disease progression except for bowel incontinence [30.4 % (14/46) in early disease progression compared to 3.6 %( 2/56) in advanced disease] and sexual interest [34.8 %( 16/46) in early disease progression compared to3.6 (2/56) in advanced disease].
 Conclusions:Non motor symptoms of Parkinson disease is so frequent and represent a major burden on patients' quality of life and the study recommends a more concentration on them in the future

Infusion treatments and deep brain stimulation in Parkinson's Disease: The role of nursing

Parkinson's Disease (PD) represents one of the most common neurodegenerative disorders in the elderly. PD is caused by a loss of dopaminergic cells in the substantia nigra pars compacta. The motor cardinal signs include a resting tremor, bradykinesia, rigidity and postural reflex impairment. Although levodopa represents the gold standard also in the advanced stage of the disease, over the years most patients develop disabling motor fluctuations, dyskinesias, and non-motor complications, which are difficult to manage. At this stage, more complex treatment approaches, such as infusion therapies (subcutaneous apomorphine and intraduodenal levodopa) and deep brain stimulation of the subthalamic nucleus or the globus pallidus internus should be considered. All three procedures require careful selection and good compliance of candidate patients. In particular, infusional therapies need adequate training both of caregivers and nursing staff in order to assist clinicians in the management of patients in the complicated stages of disease.

About existence of overmedication in patients with depressive symptoms and the appearance of un-induced movement disorder

Overmedication and the combined use of various antidepressants while increasingly seen in daily clinical practice. The drug-induced Parkinsonism, often presented as tremor, rigidity, bradykinesia and impaired postural reflexes. The syndrome is caused by multiple drug drugs can be classified into high risk, intermediate and low. This case is a 75-year-old woman diagnosed with recurrent depressive disorder, which after several adjustments in medication for depressive symptoms with poor response to treatment. It is referred by her family doctor to the neurologist at the onset of tremors in limbs, dyskinesia orolinguales, rigidity and bradykinesia. After studies to rule out organic neurology disease, is derived psychiatry for changing inducing drugs parkinsonism. The last scheduled treatment was: Mirtazapine 15 mg/day, quetiapine 25 mg/day, Clonazepam 2 mg/day, paroxetine 40 mg/day, Sulpiride 50–150 mg daily. After confirming parkinsonism signs, psychiatry proceeds to changing pharmacology, with slow decline until suspension of antipsychotics, paroxetine by venlafexina change, and also change of antihypertensive (captopril). After review at 2 months it is seen signs of improvement parkinsonism, appreciating the mental patient improvement with decreased physical discomfort and keeping the improvement in the last review (4 month) with venlafaxine 150 mg/day, Lorazepam 1 mg casual. The prevalence of drug-induced Parkinson's can go from 15 to 32% of the population. Risk factors identified are: advanced age, family predisposition, doses and drug power inductor, female gender and the presence of brain atrophy. The main objective should be to prevent the onset of Parkinson drug, to monitor patients that may be at higher risk of developing it.Disclosure of interestThe authors have not supplied their declaration of competing interest.

Concomitant progressive supranuclear palsy and chronic traumatic encephalopathy in a boxer

We report the case of a 75-year-old ex-professional boxer who developed diplopia and eye movement abnormalities in his 60’s followed by memory impairment, low mood and recurrent falls. Examination shortly before death revealed hypomimia, dysarthria, vertical supranuclear gaze palsy and impaired postural reflexes. Pathological examination demonstrated 4-repeat tau neuronal and glial lesions, including tufted astrocytes, consistent with a diagnosis of progressive supranuclear palsy. In addition, neurofibrillary tangles composed of mixed 3-repeat and 4-repeat tau and astrocytic tangles in a distribution highly suggestive of chronic traumatic encephalopathy were observed together with limbic TDP-43 pathology. Possible mechanisms for the co-occurrence of these two tau pathologies are discussed.

Rehabilitation Procedures Aimed at Decreasing Motor Symptoms in Parkinson’s Disease

Parkinson's disease (PD) is the second most common degenerative disease of the nervous system, whose incidence increases with age. Despite increasing progress in the treatment of PD, resulting from development of diagnostic methods and experimental research into the understanding of the essence of this disease, an increase in the severity of disability is still observed with the passing time. Physiotherapy is one of the non-pharmacological methods, which through its complexity, phases and regularity is aimed at preventing early physical disability as well as permanent disability. Maintaining independence as long as possible, functional self-reliance and social usefulness are the main targets. Facing a real risk of PD incidence, the aim of the work was to present rehabilitation strategy in reducing the severity of motor symptoms like; tremor, rigidity, bradykinesia and impaired postural reflexes. Therapeutic activities are aimed at working out a strategy to cope with trembling while in rigidity, emphasis is not laid on eliminating rigidity but on reducing the negative impact of increased muscle tension and slowing down of mobility. The goal of rehabilitation is to assure optimal use of stored patterns for automatic movements and acquired ones, using control signals in disorders of postural reflexes on the implementation of rehabilitation when there are still no severe difficulties in performing daily activities. The conclusion that may be drawn is that physical therapy tailored to the severity of individual symptoms of motion, allows for improving the functionality and quality of life of people with PD.

A novel transgenic rat model for spinocerebellar ataxia type 17 recapitulates neuropathological changes and supplies in vivo imaging biomarkers.

Spinocerebellar ataxia 17 (SCA17) is an autosomal-dominant, late-onset neurodegenerative disorder caused by an expanded polyglutamine (polyQ) repeat in the TATA-box-binding protein (TBP). To further investigate this devastating disease, we sought to create a first transgenic rat model for SCA17 that carries a full human cDNA fragment of the TBP gene with 64 CAA/CAG repeats (TBPQ64). In line with previous observations in mouse models for SCA17, TBPQ64 rats show a severe neurological phenotype including ataxia, impairment of postural reflexes, and hyperactivity in early stages followed by reduced activity, loss of body weight, and early death. Neuropathologically, the severe phenotype of SCA17 rats was associated with neuronal loss, particularly in the cerebellum. Degeneration of Purkinje, basket, and stellate cells, changes in the morphology of the dendrites, nuclear TBP-positive immunoreactivity, and axonal torpedos were readily found by light and electron microscopy. While some of these changes are well recapitulated in existing mouse models for SCA17, we provide evidence that some crucial characteristics of SCA17 are better mirrored in TBPQ64 rats. Thus, this SCA17 model represents a valuable tool to pursue experimentation and therapeutic approaches that may be difficult or impossible to perform with SCA17 transgenic mice. We show for the first time positron emission tomography (PET) and diffusion tensor imaging (DTI) data of a SCA animal model that replicate recent PET studies in human SCA17 patients. Our results also confirm that DTI are potentially useful correlates of neuropathological changes in TBPQ64 rats and raise hope that DTI imaging could provide a biomarker for SCA17 patients.

Дифференциальная диагностика болезни Паркинсона и мультисистемной атрофии

Целью нашей работы было выделение и описание ключевых дифференциально-диагностических признаков и критериев мультисистемной атрофии и болезни Паркинсона с целью улучшения диагностики и дифференциальной диагностики этих заболеваний. Обследовано 205 больных с идиопатической болезнью Паркинсона и 17 больных мультисистемной атрофией. Тяжесть заболевания в группе больных мультисистемной атрофией была значительно выше, чем у пациентов с болезнью Паркинсона. Падения, застывания при ходьбе, нарушения глотания, вегетативные расстройства, интеллектуальные нарушения и депрессия встречались достоверно чаще в группе больных мультисистемной атрофией по сравнению с группой больных паркинсонизмом. В отличие от болезни Паркинсона, при которой в подавляющем большинстве случаев (97,84 %) наблюдался отличный, хороший или умеренный эффект противопаркинсонических препаратов, у большинства больных мультисистемной атрофией (73,33 %) наблюдался только незначительный терапевтический эффект. Быстро прогрессирующие вегетативные расстройства (не связанные с какой-либо сопутствующей патологией), развившиеся незадолго (1–2 года) до появления паркинсонизма, а также начало заболевания с нарушения постуральных рефлексов могут быть одними из дифференциальных признаков мультисистемной атрофии.

Familial Aggregation of Essential Tremor and Parkinson's Disease (PD4.004)

Objective: To inspect the co-occurrence of essential tremor (ET) and Parkinson9s disease (PD) in families and evaluate their clinical and genetic characteristics. Background ET and PD are two separate entities and both disorders are common. Thus their coexistence could be due to chance effect. However, their presence within the same family suggests potential overlap in genetic predisposition. There are also reports suggesting the possibility of a pathogenic link between these two conditions. Design/Methods: We reviewed the Mayo Clinic Florida Familial Movement Disorder database for ET and PD cases with blood samples collected. We isolated families with members diagnosed with ET, PD or both conditions within the same individual. We also performed mutation analysis of all known pathogenic mutations in the LRRK2 gene within these familial cases. Results: We identified 286 ET and 1033 PD cases from our database. We found 131 families with members affected by both ET and PD. There were 37 families having 43 individuals afflicted with both conditions. On examination postural and kinetic tremor affecting hands, voice, head or combination of these was seen. Cardinal symptoms of PD were also found, including resting tremor, bradykinesia, rigidity, and impaired postural reflexes. In 37 cases, 23 individuals showed signs of ET preceding the onset of PD whereas four cases were diagnosed with PD prior to ET. Five patients were diagnosed with ET and PD simultaneously and information was not available for 11 other individuals. Genetic tests revealed that all samples were negative for known LRRK2 pathogenic mutations. Conclusions: We plan to investigate these families using further genetic approaches in order to learn about the molecular genetic makeup of ET and PD. Supported by: ZKW is partially supported by the NIH/NINDS 1RC2NS070276, NS057567, P50 NS072187-01S2, Mayo Clinic Florida (MCF) Research Committee CR program (MCF #90052030), Dystonia Medical Research Foundation, and the gift from Carl Edward Bolch, Jr., and Susan Bass Bolch (MCF #90052031/PAU #90052). SF is partially supported by MCF Research Committee CR program (MCF #90052030). Disclosure: Dr. Fujioka has nothing to disclose. Dr. Hanna AL-Shaikh has nothing to disclose. Dr. Sundal has nothing to disclose. Dr. Strongosky has nothing to disclose. Dr. Ross has nothing to disclose. Dr. Wszolek has received personal compensation in an editorial capacity for Parkinsonism and Realted Disorders and European Journal of Neurology.

Magnetic resonance imaging in pantothenate kinase-2-associated neurodegeneration

Pantothenate kinase-2-associated neurodegeneration (PKAN) is a rare autosomal recessive pediatric neurodegenerative disorder characterized by rigidity, dystonia, impaired postural reflexes, and progressive dementia. On T2-weighted magnetic resonance imaging images, marked low signal intensity is seen in the globus pallidus. This low signal intensity surrounds a central region of high signal intensity in the anteromedial globus pallidus, giving an eye-of-the-tiger appearance.

Parkinsonism: heterogeneity of a common neurological syndrome

Parkinsonism refers to a neurological syndrome embracing bradykinesia, muscle rigidity, tremor at rest and impaired postural reflexes, and involving a broad differential diagnosis. Having ruled out secondary causes (most importantly drugs), distinguishing levodopa-responsive idiopathic parkinson's disease (PD) from chiefly treatment-resistant and hence atypical parkinsonism is essential. Recent clinico-pathological studies using data-driven approaches have refined the traditional classifications of parkinsonism by identifying a spectrum of subtypes with different prognoses. For example, progressive supranuclear palsy (PSP), characterised by early vertical gaze limitation and falls, probably has a milder variant with predominant parkinsonism (PSP-P) which may respond quite well to levodopa before converting to the classical disease, relabelled Richardson syndrome (PSP-RS). Analysis of PD subcategories has shown that tremor-dominant forms are probably less benign than was hitherto thought and that in mild cases dystonia should rather be considered. In addition, life expectancy in early onset PD may be shortened. Despite the clinical and pathological overlap of the various subtypes, appreciating the heterogeneity of parkinsonism also includes identifying non-motor features such as early autonomous or cognitive problems which are potentially amenable to pharmacological treatment. Not least, non-motor symptoms, along with postural instability, render the patient particularly vulnerable to side effects, and hence avoiding unnecessary treatment is equally important in the management of parkinsonian disorders.

A Classification of Postural Sway Patterns During Upright Stance in Healthy Adults and Patients with Parkinson’s Disease

The intermittent control during human quiet upright stance is a new hypothesis which claims that the active neural feedback control generating the ankle muscle torque is switched off and on intermittently at appropriate timings. The intermittent strategy is capable of providing compliant posture while ensuring robust stability. Contrastingly, impairment of postural reflexes in patients with Parkinson’s disease (PD) causes postural instability. Here we hypothesize that the instability in PD patients might be due to a loss of appropriate intermittent activations in the feedback muscle torque during stance. In order to provide evidence for this hypothesis, we characterized stochastic postural sway patterns measured as changes in center of pressure (CoP) and activities of ankle muscles during quiet stance in healthy young and elderly subjects as well as PD patients. To this end, sway patterns and associated ankle muscle activities were quantified by several indices including the CoP sway area, scaling factors of double-power-law power spectra of the sway, as well as levels and patterns of the muscle activations. Hierarchical cluster analysis was performed to suggest that the sway patterns could be classified into two major types. The first type consisted mainly of sway and muscle activation patterns from healthy subjects and some PD patients with the mild level of severity, and they showed features indicating the intermittent control. The second type, consisting mainly of PD patients with relatively severe levels of motor symptoms, was accompanied with non-intermittent but tonic muscle activities and sway areas either smaller or larger than those in the first type. Moreover, the major two types were further classified into several subtypes with distinguishable characteristics. Results suggested that a loss of the intermittent activations in the ankle muscles could be a cause of the postural instability for a population of PD patients.