Parkinson’s Disease Rigidity: Relation to Brain Connectivity and Motor Performance

Abstract

Objective: (1) To determine the brain connectivity pattern associated with clinical rigidity scores in Parkinson’s disease (PD) and (2) to determine the relation between clinically assessed rigidity and quantitative metrics of motor performance.Background: Rigidity, the resistance to passive movement, is exacerbated in PD by asking the subject to move the contralateral limb, implying that rigidity involves a distributed brain network. Rigidity mainly affects subjects when they attempt to move; yet the relation between clinical rigidity scores and quantitative aspects of motor performance are unknown.Methods: Ten clinically diagnosed PD patients (off-medication) and 10 controls were recruited to perform an fMRI squeeze-bulb tracking task that included both visually guided and internally guided features. The direct functional connectivity between anatomically defined regions of interest was assessed with Dynamic Bayesian Networks (DBNs). Tracking performance was assessed by fitting Linear Dynamical System (LDS) models to the motor performance, and was compared to the clinical rigidity scores. A cross-validated Least Absolute Shrinkage and Selection Operator (LASSO) regression method was used to determine the brain connectivity network that best predicted clinical rigidity scores.Results: The damping ratio of the LDS models significantly correlated with clinical rigidity scores (p = 0.014). An fMRI connectivity network in subcortical and primary and premotor cortical regions accurately predicted clinical rigidity scores (p < 10−5).Conclusion: A widely distributed cortical/subcortical network is associated with rigidity observed in PD patients, which reinforces the importance of altered functional connectivity in the pathophysiology of PD. PD subjects with higher rigidity scores tend to have less overshoot in their tracking performance, and damping ratio may represent a robust, quantitative marker of the motoric effects of increasing rigidity.

Motor symptoms in Parkinson’s disease: A unified framework

“…Furthermore, a later study has revealed that severity of rigidity correlated with functional connectivity between the cerebellum, the motor, temporal and occipital cortices, and the nucleus caudatus in mild-moderate PD patients OFF medication, while they were performing a motor task involving external and internal (memory) cues (Baradaran et al, 2013). To sum up, these findings suggested that rigidity is not only associated with STN firing frequency, but also with altered functioning of a widespread brain network.…”

Neuromuscular Impairments Are Associated With Impaired Head and Trunk Stability During Gait in Parkinson Fallers

“…33 Additionally, freezing of gait and balance confidence were assessed using the Freezing of Gait questionnaire 34 and the Activities-specific Balance Confidence scale, 35,36 respectively. Postural instability and gait disability (PIGD) were assessed by summing the scores for Items 13 to 15 and 27 to 30 from the UPDRS, 37 while PD subtypes 38 and a global rigidity score 39 were determined from the UPDRS using previously described methods. All assessments were completed within 1 to 2 hours of patients receiving their usual anti-parkinsonian treatment to ensure that they were optimally medicated.…”

Efeitos Da Plataforma Vibratória Sobre O Sistema Neuromusculoesquelético Em Pacientes Com Doença De Parkinson: Revisão De Literatura

“…Kaut et al 16 comprovaram que a PV possibilitou a melhora da rigidez muscular e consequentemente a melhora da marcha para execução das AVD. Baradaran et al 22 enfatizam que a rigidez está relacionada à limitação funcional em pacientes com DP. A vibração favorece a redução da rigidez devido à ativação do reflexo miotático, por meio da excitação dos neurônios motores α, possibilitando um aumento das informações proprioceptivas, provenientes do estimulo gerado pela PV.…”