Amplitude- and velocity-dependency of rigidity measured at the wrist in Parkinson’s disease

Abstract

Objective Quantify the effects of increased amplitude and rate of muscle stretch on parkinsonian rigidity. Methods Eighteen subjects with Parkinson’s disease participated in this study. Subjects’ tested hand was passively displaced through 60° and 90° ranges of wrist flexion and extension at velocities of 50°/s and 280°/s in both treated and untreated conditions. Joint angular position, resistance torque, and surface electromyography (EMG) of the wrist flexors and extensors were recorded. Rigidity was quantified by normalized work scores and normalized angular impulses for flexion and extension, separately. Reflex responses of stretched and shortened muscles were quantified by mean EMG and EMG ratio. A series of ANOVAs was performed to determine the effect of amplitude, velocity and medication on selected variables. Results Both work scores and angular impulses revealed that the larger displacement amplitude and the higher velocity were associated with significantly greater rigidity, increased EMG ratio and mean EMG of stretched muscles. Dopaminergic medication was not associated with a reduction in rigidity. Conclusions Parkinsonian rigidity is modulated by the amplitude and rate of muscle stretch. Significance These findings shed light on the biomechanical underpinnings and physiological characteristics of rigidity and may inform clinical rigidity assessment in Parkinson’s disease.

Antagonist muscle co-activation during straight walking and its relation to kinematics: Insight from young, elderly and Parkinson's disease

“…Therefore, we normalized EMG activity taking as reference peak amplitude during baseline gait. This is in line with works avoiding the use of maximal voluntary contraction (MVC) for normalizing EMG-activity in elder or PD in different movements, including gait (Caliandro et al, 2011;Murley et al, 2010;Peterson and Martin, 2010;Powell et al, 2011). The coactivation index (CAI)was calculated following the equation described by Winter (1990), for which a minimum of 16 strides were analyzed in each subject, which were identified through footswitches recordings ( Fig.…”

Quantitative Measurement of Rigidity in Parkinson’s Disease: A Systematic Review

“…Eighteen studies were included, which are summarized in Table 4. Eight examined the wrist joint [40][41][42][43][44][45][46], 6 examined the elbow [47][48][49][50][51][52], and 1 examined thumb [47], knee [53], cervical spine [54], and trunk [55]. The case-control design was the most frequent design used, even though 18.75% used a case series design.…”

“…Studies that evaluated the rigidity in the wrist [40,43,44,46] determined that the ideal range for the detection of rigidity is between 60 • and 90 • , with the wider ranges being more sensitive. Likewise, contradicting the classic definition of rigidity, it has been demonstrated through the included studies that rigidity, in addition to suffering variations along the articular range, is dependent on the speed at which the stretching is performed [40,42,44].…”

“…No consensus has been reached about the possible relationship between the severity of PD and the stretch reflex due to the diversity of results obtained in these studies [41,45,47]. Likewise, there are large discrepancies in relation to the influence of dopaminergic medication on rigidity [45,46,50].…”

“…The joint amplitude used in the rigidity test also determines the results of the rigidity [21,40,42,44,46]. In the wrist, the ideal range for rigidity detection is between 60 • and 90 • , with the wider ranges being more sensitive.…”