Association of Specific Leg Muscle Strength and Motor Features in Parkinson's Disease.

Background: Postural instability and gait difficulties (PIGD) are a significant cause of falls, mobility loss, and lower quality of life in Parkinson's disease (PD). The connection between PD progression and diminished strength in the lower limbs has been acknowledged. However, the identification of specific muscle groups linked to PIGD and non-PIGD motor features is still unknown. Objective: To explore the relationship between the strength of specific lower limb muscle groups, along with muscle mass, and their associations with PIGD, PIGD subtypes, and non-PIGD motor features in PD. Methods: 95 PD participants underwent detailed motor and non-motor test batteries, including lower limb isometric strength testing and whole-body lean mass assessments. Correlation analysis and univariate and multivariate linear/logistic forward stepwise regression were performed to test associations between PIGD and non-PIGD motor features with normalized value (z-score) of lower limb muscle strength and measures of lean mass. Results: Multivariate regression analysis, adjusted for age, gender, and levodopa equivalent dose, revealed that hip abductor strength was significantly associated with overall PIGD motor severity ratings (p < 0.001), impaired balance (p < 0.001), and non-PIGD Parkinsonian motor features (p < 0.001). Conversely, hip extensor strength was significantly associated with falls, slow walking, and FoG motor features (p=0.016; p=0.003; p=0.020, respectively). Conclusion: We found that lower hip abductor strength was associated with PIGD and non-PIGD motor features. The association between non-PIGD motor features may suggest specific vulnerability of the hip abductors as part of a proposed brain-muscle loop hypothesis in PD. Moreover, lower hip extensor strength correlated with falls, slow walking, and FoG.

The effects of combining repetitive transcranial magnetic stimulation with task-specific training on gait performance in individuals with Parkinson's disease: A review article.

BACKGROUND: Parkinson's disease (PD) is a neurodegenerative disorder characterized by motor impairments, especially in the area of gait disturbances. Physiotherapy, with a focus on task-specific training, has demonstrated a level of efficacy as regards alleviating symptoms and enhancing functional capabilities in individuals with PD. Repetitive Transcranial Magnetic Stimulation (rTMS) has emerged as a potential therapeutic intervention for improving motor functions in individuals with PD. AIMS: This review article aims to investigate the effects of combining rTMS with task-specific training on gait performance in individuals with PD. MATERIALS AND METHODS: PubMed, Physiotherapy Evidence Database (PEDro), and Scopus were all searched for relevant studies. The focus of the search was on studies that investigated the efficacy of combining rTMS with task-specific training to improve gait performance in individuals with PD. RESULTS: Four studies were identified as fulfilling the eligibility criteria and were included in the study. The combination of rTMS with specific treadmill training and weight-bearing exercises can significantly enhance walking efficiency, including improvements in walking speed, self-mobility, and step rate. In addition, the combination of rTMS and task-specific training, such as treadmill-based training, shows promise in enhancing gait performance in individuals with PD. DISCUSSION AND CONCLUSION: High-frequency rTMS targeting the primary motor cortex (or M1) can result in improved walking speed, self-mobility, and step rate. However, limited research exists regarding low-frequency stimulation of the supplementary motor area (SMA) in individuals with gait issues. Further research is required to determine the optimal parameters of rTMS, such as strength, frequency, and duration of stimulation and it is worth considering the incorporation of additional training modalities, including cognitive exercises.

Cholinergic system correlates of postural control changes in Parkinson's disease freezers.

Postural instability and freezing of gait are the most debilitating dopamine-refractory motor impairments in advanced stages of Parkinson's disease because of increased risk of falls and poorer quality of life. Recent findings suggest an inability to efficaciously utilize vestibular information during static posturography among people with Parkinson's disease who exhibit freezing of gait, with associated changes in cholinergic system integrity as assessed by vesicular acetylcholine transporter PET. There is a lack of adequate understanding of how postural control varies as a function of available sensory information in patients with Parkinson's disease with freezing of gait. The goal of this cross-sectional study was to examine cerebral cholinergic system changes that associate with inter-sensory postural control processing features as assessed by dynamic computerized posturography and acetylcholinesterase PET. Seventy-five participants with Parkinson's disease, 16 of whom exhibited freezing of gait, underwent computerized posturography on the NeuroCom© Equitest sensory organization test platform, striatal dopamine, and acetylcholinesterase PET scanning. Findings demonstrated that patients with Parkinson's disease with freezing of gait have greater difficulty maintaining balance in the absence of reliable proprioceptive cues as compared to those without freezing of gait [ß = 0.28 (0.021, 0.54), P = 0.034], an effect that was independent of disease severity [ß = 0.16 (0.062, 0.26), P < 0.01] and age [ß = 0.092 (-0.005, 0.19), P = 0.062]. Exploratory voxel-based analysis revealed an association between postural control and right hemispheric cholinergic network related to visual-vestibular integration and self-motion perception. High anti-cholinergic burden predicted postural control impairment in a manner dependent on right hemispheric cortical cholinergic integrity [ß = 0.34 (0.065, 0.61), P < 0.01]. Our findings advance the perspective that cortical cholinergic system might play a role in supporting postural control after nigro-striatal dopaminergic losses in Parkinson's disease. Failure of cortex-dependent visual-vestibular integration may impair detection of postural instability in absence of reliable proprioceptive cues. Better understanding of how the cholinergic system plays a role in this process may augur novel treatments and therapeutic interventions to ameliorate debilitating symptoms in patients with advanced Parkinson's disease.

Composite measures of motor performance and self-efficacy are better determinants of postural instability and gait difficulties than individual clinical measures in Parkinson's disease.

BACKGROUND: Postural instability and gait difficulties (PIGD) are a significant cause of disability and loss of quality of life (QoL) in Parkinson's Disease. Most research on clinical predictors of PIGD measures have focused on individual clinical often motor performance variables, However, PIGD motor features often result in fear of falling (FoF) lowering a patient's mobility self-efficacy. The purpose of this study was to assess composite measures of motor and self-efficacy determinants PIGD motor features in PD and compare these to analysis of individual clinical metrics. METHODS: 75 PD participants underwent detailed motor and non-motor test batteries. Principal component analysis (PCA) was used to identify clusters of covarying correlates of slow walking, imbalance, falls, freezing of gait, FoG and compare these to traditional univariate analyses. RESULTS: A single PCA-derived composite measure of motor performance and self-efficacy of mobility was the most robust determinant of all PIGD motor features except for falls. In contrast, analysis of the individual clinical variables showed more limited and diverging findings, including evidence of better cognitive performance but more severe motor parkinsonian ratings in the fall group. CONCLUSION: There are robust associations between composite measures of motor performance and self-efficacy of mobility and all PIGD motor features except for falls. Univariate analysis of individual clinical measures showed limited correlates of PIGD motor features. Patient's own perception of motor performance, FoF, and QoL deserve more attention as PIGD therapeutic targets in PD.

Gait and axial postural abnormalities correlations in Parkinson's disease: A multicenter quantitative study.

INTRODUCTION: Gait and axial postural abnormalities (PA) are common and disabling symptoms of Parkinson's disease (PD). The interplay between them has been poorly explored. METHODS: A standardized protocol encompassing videos and photos for posture and gait analysis of PD patients with a clinically defined PA (MDS-UPDRS-III item 3.13 > 0) was used in 6 movement disorder centers. A comprehensive evaluation was performed to clarify the association between gait performance and the presence and severity of PA. RESULTS: 225 PD patients were enrolled: 57 had severe PA, 149 mild PA, and 19 did not meet criteria for PA, according to a recent consensus agreement on PA definition. PD patients with severe PA were significantly older (p:0.001), with longer disease duration (p:0.007), worse MDS-UPDRS-II and -III scores and axial sub-scores (p < 0.0005), higher LEDD (p:0.002) and HY stage (p < 0.0005), and a significantly lower velocity (p < 0.001) and cadence (p:0.021), if compared to mild PA patients. The multiple regression analysis evaluating gait parameters and degrees of trunk/neck flexion showed that higher degrees of lumbar anterior trunk flexion were correlated with lower step length (OR -0.244; p:0.014) and lower velocity (OR -0.005; p:0.028). CONCLUSIONS: Our results highlight the possible impact of severe anterior trunk flection on PD patients' gait, with a specific detrimental effect on gait velocity and step length. Personalized rehabilitation strategies should be elaborated based on the different features of PA, aiming to target a combined treatment of postural and specifically related gait pattern alterations.

The Efficacy of a Newly Developed Cueing Device for Gait Mobility in Parkinson's Disease.

Background: External cues are effective in improving gait in people with Parkinson's disease (PD). However, the most effective cueing method has yet to be determined. Objective: The aim of this study was to compare the immediate effects of using visual, auditory, or somatosensory cues on their own or in combination during walking compared to no cues in people with PD. Methods: This was a single blinded, randomly selected, controlled study. Twenty people with PD with an age range of 46-79 years and Hoehn and Yahr scores of 1-3 were recruited. Participants were studied under 4 cueing conditions; no cue, visual, auditory, or somatosensory cues, which were randomly selected individually or in a combination. Results: A repeated measures ANOVA with pairwise comparisons using Bonferroni correction showed that any single or combination of the cues resulted in an improvement in gait velocity and stride length compared to no cue. Some significant differences were also seen when comparing different combinations of cues, specifically stride length showed significant improvements when additional cues were added to the light cue. The statistically significant difference was set at p < 0.05. Conclusions: Walking using visual, auditory, or somatosensory cues can immediately improve gait mobility in people with PD. Any or a combination of the cues tested could be chosen depending on the ability of the individual to use that cue.

Postural abnormalities in Asian and Caucasian Parkinson's disease patients: A multicenter study.

INTRODUCTION: Postural abnormalities (PA) are disabling features of Parkinson's disease (PD). Indirect analyses suggested a higher prevalence of PA among Asian patients compared to Caucasian ones, but no direct comparisons have been performed so far. METHODS: An international, multicenter, cross-sectional study was performed in 6 European and Asian movement disorders centers with the aim to clarify differences and similarities of prevalence and characteristics of PA in Asian vs. Caucasian PD patients. Axial PA, encompassing antecollis (AC), camptocormia (CC), and Pisa syndrome (PS), and appendicular PA (appPA) were systematically searched and analysed in consecutive patients. RESULTS: 88 (27%) of 326 PD patients had PA (29.1% in Asians and 24.3% in Caucasians, p: 0.331). Prevalence of axial PA was 23.6% in Asians and 24.3% in Caucasians (p = 0.886), in spite of a longer disease duration among Caucasians, but a longer PA duration among Asians. No differences in prevalence between AC, CC, and PS were found between the two ethnicities. The prevalence of appPA was higher in Asians (p = 0.036), but the regression analysis did not confirm a significant difference related to ethnicity. Considering the whole population, male gender (OR, 4.036; 95% CI, 1.926-8.456; p < 0.005), a longer disease duration (OR, 2.61; 95% CI, 1.024-6.653; p = 0.044), and a higher axial score (OR, 1.242; 95% CI, 1.122-1.375; p < 0.0005) were the factors associated with axial PA. CONCLUSION: The prevalence of axial PA in PD patients is not influenced by ethnicity. However, Asian PD patients tend to develop PA earlier in the disease course, particularly AC.

Low frequency subthalamic stimulation and event-related potentials in Parkinson disease.

BACKGROUND: High frequency (130 Hz) subthalamic Deep-Brain-Stimulation (STN-DBS) optimally improves cardinal motor symptoms in Parkinson disease (PD). Low stimulation frequencies (60-80 Hz) improve axial symptoms in some patients and, according to preliminary evidences, may also have a beneficial effect on the cognitive component of motor planning. OBJECTIVE: To analyze the configuration of the P300 component of cortical event-related auditory potentials (ERPs), a reliable index of attentive cognitive functions, at different stimulation frequencies in STN-DBS in PD patients. METHODS: 12 PD patients underwent ERPs recordings using a standard oddball auditory paradigm with STN-DBS at 60 Hz, 80 Hz, 130 Hz, and OFF-stimulation, applied in a randomized double-blind sequence. ERPs analysis considered the peak amplitude and latency of the P300 components at midline electrode positions (Fz, Cz, Pz). RESULTS: P300 latency over Cz and Pz electrodes significantly increased with STN-DBS at 130 Hz compared to OFF-stimulation. P300 latency was also significantly increased, though to a lesser degree, over Pz electrode with stimulation at 80 Hz. No significant P300 latency modifications were detected at 60 Hz stimulation compared to OFF-stimulation condition. P300 amplitude did not change significantly for any of the stimulation conditions tested. CONCLUSIONS: Low frequency STN-DBS is associated with minor modifications of P300 latency compared to conventional stimulation at 130 Hz, possibly suggesting that 60 and 80 Hz may have less interference with attentive and cognitive processes in PD patients.

Video analysis of long-term effects of levodopa-carbidopa intestinal gel on gait and posture in advanced Parkinson's disease.

Gait and posture parameters of ten advanced Parkinson's disease (PD) patients were assessed before and after starting levodopa-carbidopa intestinal gel (LCIG) treatment by means of both objective video analysis and clinical assessment. After 3 years of treatment, gait and posture remained stable. A slower gait velocity at baseline significantly correlates with a higher axial and motor severity at follow-up. This pilot study suggests that validated video analysis software may support the clinical assessment of axial signs in PD patients who are candidates for device-aided therapies.

Long-term effect of levodopa-carbidopa intestinal gel on axial signs in Parkinson's disease.

BACKGROUND: Few studies have suggested that levodopa-carbidopa intestinal gel (LCIG) may have a benefit on Parkinson's disease (PD) axial signs. AIMS OF THE STUDY: To investigate the long-term effect of LCIG on axial signs and the related prognostic factors. METHODS: A retrospective study on 49 PD patients treated with LCIG. Axial signs as per the Unified Parkinson Disease Rating Scale axial score (AS), Hoehn and Yahr (H&Y) scale, and levodopa equivalent daily dose (LEDD) were assessed at baseline (before starting LCIG treatment) and at the last follow-up (FU). RESULTS: After 47.6 ± 30 months of treatment, total AS deteriorated while motor complications still improved, in spite of a significant LEDD/Kg increment. When adjusted for LCIG treatment duration, a higher AS and freezing of gait severity at FU were predicted by a baseline lower response to l-dopa and higher H&Y (P < 0.01) and they were related to a lower independency in activity of daily life at FU (P < 0.001). Single axial items remain stable up to one year and postural instability up to four years. CONCLUSION: Baseline disease severity and the magnitude of l-dopa response predict axial signs' severity after around four years of LCIG treatment, with consequent implication on patients' functional independence.