Asymmetry and freezing of gait in parkinsonian patients

It has been hypothesized that freezing of gait (FOG) in parkinsonian patients (PD) might be triggered by a breakdown in the normal symmetry of gait. In this study, we evaluated the relationship between asymmetry of gait and FOG and the effects of intensive treadmill treatment on asymmetry. We studied 30 patients with (FOG+) and 30 without (FOG?) freezing in “on” stage. Patients underwent a 4-week rehabilitation treatment using a treadmill with auditory and visual cues and were evaluated at enrolment and at the end of rehabilitation. Outcome measures were gait speed, stride length, asymmetry of gait, Six-minute walking test (6MWT), Unified Parkinson’s Disease Rating Scale (UPDRS) II–III, Berg Balance Scale, Timed Up and Go Test, comfortable-fast gait speeds, freezing of gait questionnaire (FOGQ). At enrolment, no differences in gait parameters were observed between the two groups, which differed only in UPDRS_II and BBS. Both FOG+ and FOG? patients spent more time on the left foot (time on left/time on right foot 1.37, p = 0.002, 1.18, p = 0.016, respectively). Rehabilitation determined a homogeneous improvement in both groups of patients for all variables except UPDRS_II and balance, for which a better improvement was observed in FOG+ patients. The improvement in FOGQ in FOG+ patients was significantly correlated to the improvement in asymmetry of gait (Spearman R = 0.46, p = 0.013). Our data support a direct involvement of the asymmetry of gait in the development of FOG in PD. Treadmill training is effective in improving gait and balance in PD FOG+ patients and this might be related to a reduction of asymmetric gait.     

Anal sphincter EMG in the diagnosis of parkinsonian syndromes

Winge K, Jennum P, Lokkegaard A, Werdelin L. Anal sphincter EMG in the diagnosis of parkinsonian syndromes.
Acta Neurol Scand: 2010: 121: 198–203.
© 2009 The Authors Journal compilation © 2009 Blackwell Munksgaard. Background – The role of electromyography (EMG) recorded from the external anal sphincter (EAS) in the diagnosis of atypical parkinsonian syndromes is a matter for continuous debate. Most studies addressing this issue are retrospective. Methods – In this study, we prospectively investigated six patients with Parkinson’s Disease (IPD), 14 patients with multiple system atrophy (MSA) and eight with progressive supranuclear palsy (PSP) using EMG of the EAS, motor‐evoked potential (MEP) to the EAS and EMG of m. gastrocnemius and nerve conduction velocity measured at the sural nerve. Patients were followed up for 2 years to secure correct diagnosis. Results – The mean duration of motor unit potentials (MUPs) recorded from the EAS was significantly longer in patients with MSA and PSP compared with MUPs recorded from patients with PD (P < 0.005 for both). There were no signs of diffuse loss of motor neurons or peripheral neuropathy. MEP revealed signs of supranuclear affection in patients with MSA, whereas in patients with PSP the mechanism is a focal loss of motor neurons in Onuf’s nucleus. Conclusion – Abnormal EMG of the EAS is strongly suggestive of atypical parkinsonism and the pathophysiology may be different in patients with MSA and PSP.     

Long-term EMG recordings differentiate between parkinsonian and essential tremor

The differential diagnosis of tremor is mainly based on clinical criteria.Nevertheless, these criteria are in some cases not sufficient to differentiate between different tremor forms. Long-term EMG has proven to be a valid and reliable method for the quantification of pathological tremors. The aim of the study was to develop a long-term EMG-based automated analysis procedure that separates parkinsonian tremor from essential tremor. Using longterm EMG tremor was recorded in 45 consecutive patients, 26 with Parkinson's disease (PD) and 19 with essential tremor (ET). Eight tremor parameters were generated automatically. By stepwise backward regression a subset of these criteria was extracted to achieve an automated classification of the tremor by a mathematical model. The obtained model was then tested on a new group of 13 patients in early stages of the disease. Significant differences between groups were found for tremor occurrence, tremor asymmetry, mean tremor frequency and standard deviation of phase of antagonistic muscles. Due to data overlap a classification of the two tremor forms was not possible based on a single tremor parameter. Using logistic regression, a linear formula based on the three parameters tremor occurrence, mean tremor frequency and standard deviation of phase was established and predicted the correct diagnosis in 93% of patients. The validation of the model on the new group of patients in early stages of the tremor disease yielded a correct diagnosis in 100% of cases. We conclude that long-term EMG recording allows a rater-independent classification of parkinsonian versus essential tremor.     

Effect of bilateral subthalamic nucleus stimulation on parkinsonian gait

Clinical reports show that bilateral subthalamic nucleus (STN) stimulation is effective in improving parkinsonian gait. Quantitative analysis of the efficacy of STN stimulation on gait is of interest and can be carried out using a commercially available stride analyser. Ten parkinsonian patients (5 men, 5 women) with a mean age of 55.8, SD 9.6 years were included in our study. They had a mean duration of Parkinson's disease (PD) of 13.3, SD 4.5 years and a motor examination score (part III of the Unified Parkinson's Disease Rating Scale) (UPDRS) of 43, SD 13 in off-stimulation off-drug condition. All the patients had bilateral chronic STN stimulation which had started from 3 to 36 months before the study. Patients were evaluated in off-drug and on-drug conditions both with and without stimulation. We analysed the principal gait measures: velocity, cadence, stride length, gait cycle, duration of single and double limb support. The clinical parkinsonian signs were evaluated with the part III of the UPDRS. In the off-drug condition, STN stimulation significantly (p < 0.05) improved velocity and stride length. The effect was similar to that of levodopa. When STN stimulation was switched on at the best of the levodopa induced effect, no further improvement was observed. The UPDRS motor score was significantly (p < 0.001) decreased after both stimulation and levodopa. In conclusion, STN stimulation is effective on parkinsonian gait.     

Effects of bilateral subthalamic nucleus stimulation on parkinsonian gait.

Gait analysis was carried out to assess the effects of L-dopa and bilateral subthalamic nucleus stimulation on gait velocity, cadence, stride length, and gait kinematics in nine patients with PD. Substantial effects of bilateral subthalamic nucleus stimulation on gait, with an increase in gait velocity and stride length comparable to that of a suprathreshold L-dopa dose, were found. Interestingly, stride length was more improved by L-dopa and cadence more by subthalamic nucleus stimulation. In two patients with freezing during the "on" period, subthalamic nucleus stimulation failed to reduce this symptom effectively.     

Automated gait analysis in bilateral parkinsonian rats and the role of L-DOPA therapy

Gait disturbances and postural instability represent major sources of morbidity in Parkinson's disease (PD), and respond poorly to current treatment options. Some aspects of gait disturbances can be observed in rodent models of PD; however, knowledge regarding the stability of rodent gait patterns over time is lacking. Here we investigated the temporal constancy and reproducibility of gait patterns in neurologically intact and bilaterally 6-hydroxydopamine (6-OHDA) lesioned rats, by using an automated quantitative gait analysis method (CatWalk). The bilateral neurotoxin injections into the medial forebrain bundle resulted in an average dopamine (DA) loss of 70% in striatum, which corresponds to the DA levels observed in moderate-mid stage human PD. Rats were tested weekly during one month, and we found that in intact rats all parameters investigated remained constant over multiple tests. The 6-OHDA lesioned rats were impaired in several aspects of gait, such as stride length, swing speed, stance duration, step cycle duration, and base of support. However the stance and step cycle deficits were transient, the performance of 6-OHDA lesioned rats were indistinguishable from control rats by the last test session with regard to these parameters. Finally, we found that administration of a single dose of levodopa (l-DOPA) to the 6-OHDA lesioned rats could counteract all but one observed deficits. Based on these findings we conclude that the gait pattern of intact rats is highly reproducible, 6-OHDA lesioned rats display impairments in gait, and l-DOPA can counteract most deficits seen in this model of experimental PD.     

Vitamin B12 supplementation improves heart rate variability in healthy elderly Indian subjects

The vestibular system plays an important role in control of arterial pressure (AP) upon head-up tilt (HUT). To examine this role in human subjects, we previously compared changes in AP with and without high-amplitude galvanic vestibular stimulation (GVS), which is considered to obscure vestibular input. In contrast, regarding sensory function in skin and muscle, it has been documented that low-amplitude electrical stimulation improves both sensitivity and response. In the present study, we examined whether GVS of smaller amplitude improves AP control upon HUT. GVS was applied at the amplitude of the somatosensory threshold (0.3-0.8 mA), 0.1 mA over the threshold, and 0.1 and 0.2 mA below the threshold during HUT. AP decreased at the onset of HUT compared with that in the supine position in 15 of 25 subjects without GVS (-12±2 mmHg), but applying GVS at 0.1 mA below the somatosensory threshold diminished the decrease (0.3±0.7 mmHg). The APs of another 10 subjects were maintained or decreased by less than 5 mmHg without GVS at the onset of HUT (4±2 mmHg), but applying GVS at the amplitude of 0.1 mA below the somatosensory threshold further increased the AP (12±2 mmHg). GVS at the other amplitudes did not result in AP changes in either group. Thus, subsensory weak GVS enhances AP control at the onset of HUT.     

Concentric needle EMG versus macro EMG I. Relation in healthy subjects.

OBJECTIVES: The relation between motor unit action potentials (MUAPs) recorded via a macro needle electrode (MA-MUAP, MA-EMG) and MUAPs recorded via a concentric needle electrode (CN-MUAP, CN-EMG) is under debate. In particular it is not known to what degree CN-MUAP variables reflect the electrical properties of a motor unit. METHODS: CN-EMGs and MA-EMGs of the right brachial biceps muscle were recorded from 40 healthy subjects (23 women and 17 men) aged 17-83 years and CN-MUAP and MA-MUAP variables were cross-correlated. RESULTS: CN-MUAP duration was positively and significantly correlated with CN-MUAP area (r=0.52), rate of polyphasia (r=0.45), MA-MUAP amplitude (r=0.47) and MA-MUAP area (r=0.45). CN-MUAP amplitude was positively and significantly correlated with the rate of polyphasia (r=0.39) and the fibre density (r=0.45). CONCLUSIONS: CN-MUAP duration appropriately reflects the motor unit's electrical activity and may substitute MA-MUAP area and amplitude.     

Factor structure of parkinsonian signs in the community-dwelling elderly.

Parkinsonian signs are present in 40% of older people. Factor analysis of the motor section of the Unified Parkinson's Disease Rating Scale (UPDRS) in patients with Parkinson's disease (PD) has identified several principal domains, including rigidity, axial function, and rest tremor. We hypothesized that if Parkinsonian signs in the elderly were due to basal ganglia dysfunction that this same constellation of factors (rigidity, axial function, rest tremor) would emerge in a factor analysis. We carried out factor analysis, using the principal component method with orthogonal (varimax) rotation, on motor UPDRS scores in community-dwelling elderly without PD. A modified (10-item) version of the motor portion of the UPDRS was administered to 1,339 older adults living in the Washington Heights-Inwood community and it was found that Parkinsonian signs were present in 537 (40.1%). Three factors (rigidity, axial function. and rest tremor) were obtained from the factor analysis and, together, explained 67.4% of the variance. A second factor analysis was carried out excluding the 26 participants with rest tremor, and two factors (rigidity, axial function) emerged. These data support the view that Parkinsonian signs in older adults might be due to basal ganglia dysfunction, a possibility that requires further exploration.     

Quantification of dynamic EMG patterns during gait in children with cerebral palsy

Our goal was to simplify the representation and interpretation of surface electromyographic (EMG) activity during gait to develop a clinical method for evaluating gait disabilities in children with cerebral palsy (CP). EMG was recorded from four muscles of a lower extremity. Gait cycles were tracked from one force-sensing resistor signal that was recorded synchronously with EMG. The method is based on the comparison of a patient's dynamic EMG envelope shapes and the normative gait-related patterns (norms). Developed norms were based on EMG data obtained in 10 healthy children. Due to newly introduced techniques for time and amplitude normalization, norms were developed regardless of differences in subject age, gender, basic gait parameters and the EMG measurement process. The proposed gait metric quantifies the similarity between a patient's gait-related patterns and norms by a single global value suitable for gait analysis in general, including a detailed analysis using the 10 partial values. The gait metric was experimentally validated with a control group of healthy children and a group of children with CP with different degrees of motor deficits. Gait metric values obtained in children from the control group are high for all muscles, which means that gait-related patterns are close to norms, whereas in children with CP the higher the degree of motor deficit, the lower the gait metric values. The method could be a very useful clinical tool for the recognition and tracking of motor disorders of the lower extremities in children with CP as well as many other neuromotor pathologies.     

Macro EMG in healthy subjects of different ages.

The findings of the recently developed technique of Macro EMG in healthy subjects of different ages are described. The characteristics of the Macro motor unit potential which probably reflects the relative size of the whole motor unit are presented together with suggested normal data for the three muscles studied. An increase in size of the Macro motor unit potential was found with age, particularly after the age of 60 years. Possible factors determining the Macro EMG signal and the age related changes are discussed.     

Mild parkinsonian signs and plasma homocysteine concentration in community-dwelling elderly individuals

OBJECTIVE: To determine whether plasma homocysteine (Hcy) concentration is associated with mild parkinsonian signs (MPS) in community-dwelling elderly individuals. DESIGN: Cross-sectional analyses of a population-based cohort study. SETTING: Washington Heights-Inwood, New York. Patients Persons without dementia 65 years and older. Main Outcome Measure Participants underwent an abbreviated motor portion of the Unified Parkinson's Disease Rating Scale. Each participant was assigned an MPS score (range, 0-40). The Hcy concentration was measured from plasma. All analyses were cross-sectional. RESULTS: There were 369 participants (mean +/- SD age, 77.8 +/- 6.0 years; mean +/- SD MPS score, 1.51 +/- 2.55; mean +/- SD plasma Hcy concentration, 17.3 +/- 6.5 mumol/L). Mean +/- SD MPS scores in plasma Hcy concentration quintiles were as follows: lowest quintile, 1.15 +/- 1.77; second quintile, 1.18 +/- 1.88; third quintile, 1.64 +/- 2.93; fourth quintile, 1.45 +/- 2.17; and highest quintile, 2.12 +/- 3.49 (84.3% higher than 1.15) (P = .02). In an unadjusted linear regression model, plasma Hcy concentration was associated with log MPS score (dependent variable) (P = .008). In a linear regression model that adjusted for confounding variables, plasma Hcy concentration was associated with log MPS score (P = .04). CONCLUSIONS: These data indicate that MPS are associated with higher plasma Hcy concentrations. Prospective neuroimaging as well as clinical-pathological studies would further our understanding of several mechanisms that could underlie the observed association.     

History of vascular disease and mild parkinsonian signs in community-dwelling elderly individuals

BACKGROUND: Mild parkinsonian signs (MPS) are commonly found during the clinical examination of older people. These signs could reflect the accumulation of vascular pathological changes in the brain. If the etiology were vascular, one could hypothesize that individuals with MPS would be more likely to have systemic vascular disease than would their counterparts without these signs. OBJECTIVES: To examine whether MPS are associated with a history of vascular disease and whether certain MPS (rigidity, changes in axial function) are more strongly associated with a history of vascular disease than are other MPS (tremor). METHODS: Evaluation of older people without dementia in Washington Heights-Inwood, northern Manhattan, NY. The presence of vascular diseases was assessed with a structured health interview. RESULTS: Mild parkinsonian signs were present in 375 (16.4%) of 2286 participants without dementia. Diabetes mellitus, heart disease, peripheral vascular disease, and stroke were more prevalent in participants with MPS than without MPS, whereas nonvascular diseases (cancer, thyroid disease) were not. In a logistic regression analysis that adjusted for age, sex, education, and depressive symptoms, the number of vascular diseases was associated with MPS (odds ratio, 1.31 [95% confidence interval, 1.18-1.46]; P<.001). The combination of diabetes mellitus and heart disease increased the odds of MPS by 70% and the combination of these with stroke increased the odds by 332%. CONCLUSIONS: The presence of MPS in elderly individuals might reflect, in part, the accumulation of vascular pathological changes in the basal ganglia or white matter regions caused by preventable vascular diseases. Prospective and pathological studies are needed to further explore this finding.     

The efficacy of quantitative gait analysis by the GAITRite system in evaluation of parkinsonian bradykinesia

The aim of this study was to assess whether the GAITRite gait analysis system an effective tool in evaluating parkinsonian bradykinesia. In their best ON and worst OFF states, 13 parkinsonian patients were asked to perform walking trail at their fastest velocity, and to submit to traditional timed tests. Significant correlations existed between OFF-ON improvement in gait parameters and in UPDRS III score (r(2)=0.59-0.78) except cadence. Among the gait parameters, stride length is the most effective indicator of timed test and UPDRS III score improvements. The GAITRite system is an efficient, yet effective device in evaluating parkinsonian bradykinesia and can be used as a substitute for the traditional timed test.     

Mild parkinsonian signs in a community-dwelling elderly population sample in Japan

Mild parkinsonian signs (MPS) may represent the mild end of a disease spectrum that spans from normal aging to neurodegenerative diseases. We conducted a population-based study in a rural island town in western Japan, Ama-cho. Participants included 1129 subjects, aged 60 years and older, residing in the town. Participants were classified according to a modified Unified Parkinson's Disease Rating Scale (mUPDRS) score. MPS was determined to be present if any of the following conditions were met: (1) two or more mUPDRS ratings=1 [MPS-mild]; (2) one mUPDRS rating≥2; or (3) mUPDRS rest tremor rating≥1; [(2) and (3): MPS-severe]. Subjects wore a uniaxial accelerometer (Actiwatch), resulting in the measurement of actigraphic activity counts (AC). Of the 804 participants with complete data, 178 subjects (22.1%) were classified as demonstrating MPS. AC was significantly lower in the MPS-severe group compared with both the CTL and the MPS-mild groups. Diagnostic sensitivity for MPS-severe became 100% when we adopted a cutoff point of low physical activity, as measured by actigraphy, combined with the presence of subjective depression. We established the prevalence of MPS in a community-dwelling elderly population sample in Japan. Actigraphy may be a useful objective tool for screening MPS-severe.     

A new method of quantitative analysis of parkinsonian gait: report of 6 patients

A simple quantitative method of gait analysis in parkinsonism is presented. In this method, spatial and temporal parameters (stride length and duration, stance duration and double support duration) and cinematic parameters (velocity) were evaluated. A pilot trial performed in 6 patients highlighted the pathological aspect of the parkinsonian gait as compared to the gait of healthy elderly subjects. A significant degradation (reduced speed, diminished stride length, short duration of the double support stage) was noted, even when parkinsonians were compared with the oldest of the control subjects.