Modeling of cerebellar transcranial electrical stimulation effects on hand tremor in Parkinson's disease.

Introduction: Parkinson's disease (PD) is a neurodegenerative disorder with different motor and neurocognitive symptoms. Tremor is a well-known symptom of this disease. Increasing evidence suggested that the cerebellum may substantially contribute to tremors as a clinical symptom of PD. However, the theoretical foundations behind these observations are not yet fully understood. Methods: In this study, a computational model is proposed to consider the role of the cerebellum and to show the effectiveness of cerebellar transcranial alternating current stimulation (tACS) on the rest tremor in participants with PD. The proposed model consists of the cortex, cerebellum, spinal circuit-muscular system (SC-MS), and basal ganglia blocks as the most critical parts of the brain, which are involved in generating rest tremors. The cortex, cerebellum, and SC-MS blocks were modeled using Van der Pol oscillators that interacted through synchronization procedures. Basal ganglia are considered as a regulator of the coupling weights defined between oscillators. In order to evaluate the global behavior of the model, we applied tACS on the cerebellum of fifteen PD patients for 15 min at each patient's peak frequency of their rest tremors. A tri-axial accelerometer recorded rest tremors before, during, and after the tACS. Results and Discussion: The simulation of the model provides a suggestion for the possible role of the cerebellum on rest tremors and how cerebellar tACS can affect these tremors. Results of human experiments also showed that the online and offline effects of cerebellar tACS could lead to the reduction of rest tremors significantly by about %76 and %68, respectively. Our findings suggest that the cerebellar tACS could serve as a reliable, therapeutic technique to suppress the PD tremor.

Dilemma in Parkinson's Treatment; Levodopa Monotherapy May be the Best Choice.

INTRODUCTION: Several treatment strategies have been claimed for Parkinson's disease (PD) so far. However, there remains controversies over the best possible treatment. The aim of this study is to compare Levodopa monotherapy versus Pramipexole in combination with Levodopa L in patients with PD with regards to the efficacy and side effects. METHODS: Patients being treated with levodopa alone and Pramipexole add-on therapy to Levodopa were enrolled in the study. Factors regarding efficacy and side effects were assessed and analyzed between both groups by appropriate tests. RESULTS: 176 Patients were enrolled in the study. Results showed significant higher total MDS-UPDRS (worse total disease severity score) among patients being treated with Pramipexole add-on therapy which was particularly higher in parts 1 (Mentation, behavior and mood), 2 (Activity of daily living) and 3 (Motor examination) (P-values < 0.05). Psychosis global score with significantly higher frequency of hallucination and depression, statistically higher in combination therapy group compared to Levodopa monotherapy group (P-value < 0.05). Patients in the Pramipexole add-on group reported lower scores of Health-related quality of life (HRQoL) (P-value < 0.05). Significant correlation was between disease duration and psychosis score among Levodopa monotherapy group (P-value < 0.05). CONCLUSIONS: Compared to Levodopa monotherapy, Add-on therapy with Pramipexole shows less efficiency yet more side effects. This indicates that single administration of Levodopa still remains the best available treatment for Parkinson's disease.

The effects of spaced transcranial Direct Current Stimulation combined with conventional dysphagia therapy in Parkinson's disease: A case report.

Parkinson's disease (PD) is a neurodegenerative disease of the central nervous system that is characterized by a set of motor and non-motor symptoms. Impaired swallowing or dysphagia is one relatively common motor symptom in patients with PD. We investigated whether neuroplasticity induction by spaced transcranial Direct Current Stimulation (tDCS) combined with conventional swallowing therapy leads to long-lasting effects on swallowing ability in patients with PD. We present a case of a 61-year-old male PD patient with dysphagia. Conventional Swallowing Therapy (CDT) combined with tDCS (bilateral anodal, 1 mA, 20 min, 10 online sessions, twice daily with a 20 min interval in between for five days over two weeks) was applied over the pharyngeal motor cortex. Our findings suggest that anodal tDCS combined with CDT is feasible, safe, and well-tolerated, and leads to a clinically relevant improvement of swallowing functions.

Effect of eccentric-based rehabilitation on hand tremor intensity in Parkinson disease.

BACKGROUND AND PURPOSE: Hand tremor is a disturbing yet sometimes resistant symptom in persons with Parkinson disease (PD). Although many exercise regimens for these people have gained attention in recent years, the effect of resistance training and especially eccentric training on parkinsonian tremor is still uncertain. This study was conducted to investigate the precise effect of upper limb eccentric training on hand tremor in PD. METHODS: In this randomized controlled trial, a consecutive sample of 21 persons with PD recruited from general hospitals went through 6 weeks of upper limb pure eccentric training as the intervention group (n = 11) or no additional exercise during this period as the control group (n = 10). Resting and postural tremor amplitudes were measured with the cellphone-based accelerometer. RESULTS: Comparing hand tremor amplitudes before and after the trial showed a significant reduction in resting tremor amplitude in the intervention group after exercise sessions (p < 0.05) while detecting no changes in the control group during 6 weeks of study. Meanwhile, postural tremor amplitude remained unchanged in both groups.

The effects of anxiety and external attentional focus on postural control in patients with Parkinson's disease.

BACKGROUND: Although anxiety is a common non-motor outcome of Parkinson's disease (PD) affecting 40% of patients, little attention has been paid so far to its effects on balance impairment and postural control. Improvement of postural control through focusing on the environment (i.e. external focus) has been reported, but the role of anxiety, as a confounding variable, remains unclear. OBJECTIVES: This study aimed to investigate the influence of anxiety and attentional focus instruction on the standing postural control of PD patients. METHODS: Thirty-four patients with PD (17 with high anxiety (HA-PD) and 17 with low anxiety (LA-PD)), as well as 17 gender- and age-matched healthy control subjects (HC) participated in the study. Postural control was evaluated using a combination of two levels of postural difficulty (standing on a rigid force plate surface with open eyes (RO) and standing on a foam surface with open eyes (FO)), as well as three attentional focus instructions (internal, external and no focus). RESULTS: Only the HA-PD group demonstrated significant postural control impairment as compared to the control, as indicated by significantly greater postural sway measures. Moreover, external focus significantly reduced postural sway in all participants especially during the FO condition. CONCLUSION: The results of the current study provide evidence that anxiety influences balance control and postural stability in patients with PD, particularly those with high levels of anxiety. The results also confirmed that external focus is a potential strategy that significantly improves the postural control of these patients. Further investigation of clinical applicability is warranted towards developing effective therapeutic and rehabilitative treatment plans.