CLINICAL SPASTICITY ASSESSMENT USING THE MODIFIED TARDIEU SCALE DOES NOT REFLECT JOINT ANGULAR VELOCITY OR RANGE OF MOTION DURING WALKING: ASSESSMENT TOOL IMPLICATIONS

ObjectiveSpasticity assessment is often used to guide treatment decision-making. Assessment tool limitations may influence the conflicting evidence surrounding the relationship between spasticity and walking. This study investigated whether testing speeds and joint angles during a Modified Tardieu assessment matched lower-limb angular velocity and range of motion during walking.DesignObservational study.SubjectsThirty-five adults with a neurological condition and 34 assessors.MethodsThe Modified Tardieu Scale was completed. Joint angles and peak testing speed during V3 (fast) trials were compared with the same variables during walking in healthy people, at 0.40–0.59, 0.60–0.79 and 1.40–1.60 m/s. The proportion of trials in which the testing speed, start angle, and angle of muscle reaction matched the relevant joint angles and angular velocity during walking were analysed.ResultsThe Modified Tardieu Scale was completed faster than the angular velocities seen during walking in 88.7% (0.40–0.59 m/s), 78.9% (0.60– 0.79 m/s) and 56.2% (1.40–1.60 m/s) of trials. When compared with the normative dataset, 4.2%, 9.5% and 13.7% of the trials met all criteria for each respective walking speed.ConclusionWhen applied according to the standardized procedure and compared with joint angular velocity during walking, clinicians performed the Modified Tardieu Scale too quickly.LAY ABSTRACTSpasticity is an abnormal increase in muscle tightness, which is common following neurological injury. Spasticity has been shown to have a profound impact on an individual’s independence and quality of life. The main goal reported by patients in this population is to return to independent, normal walking. Yet, despite this there is a lack of consensus regarding the relationship between spasticity and walking outcomes. This may be due to a disconnect between clinical, bed-based assessment methods and how spasticity manifests during walking. This study aimed to establish how well a routine clinical assessment (the Modified Tardieu Scale) matched the speed and range of joint movement during walking. The findings suggest that, currently, clinicians performed the assessment too fast, which may lead to “false-positive” assessment findings. This may result in the identification and treatment of spasticity that is not impacting walking, leading to sub-optimal patient outcomes and significant healthcare wastage.Key words: muscle spasticity, patient outcome assessment, rehabilitation, brain injuries, gait, walking

Spasticity is a common impairment following neurological injury (1–5). The effective assessment and management of spasticity receives significant attention due to the detrimental effects it has on patient outcomes, carer burden, and quality of life (6, 7). Current spasticity guidelines recommend that only spasticity impacting function should receive intervention (8). As such, the role of a clinical assessment is to identify the presence of spasticity and decipher whether the spasticity warrants intervention, such as botulinum toxin-A (BoNT-A).Walking limitations are the most significant selfperceived, functional problem reported by individuals following neurological injury (9). A primary rehabilitation goal is often to improve walking independence, quality, speed, and endurance (10–12). In relation to spasticity, the clinician’s role is to identify whether spasticity is present, and subsequently determine if a patient’s walking may benefit from spasticity-related interventions.A definition of spasticity published by Pandyan et al. (13); “disordered sensori-motor control, resulting from an upper motor neurone lesion, presenting as intermittent or sustained involuntary activation of muscles’’, encompasses all the positive features of upper motor neurone syndrome (UMNS) under an umbrella term of spasticity. This terminology defines spasticity as a broader sensori-motor phenomenon (13), when compared with the more constrained, velocity-dependent definition published by Lance (14);”a motor disorder characterized by a velocity-dependent increase in tonic stretch reflexes (muscle tone) with exaggerated tendon jerks, resulting from hyper-excitability of the stretch reflexes, as one component of the UMNS” (14). For the purpose of this study, Lance’s definition has been used to define spasticity, since, with this definition, spasticity can be assessed as an individual construct. The Modified Tardieu Scale (MTS) is an often-recommended spasticity assessment, aligning with Lance’s (14) definition of spasticity (15–17). The MTS classifies the response of a relaxed muscle to a fast, passive stretch (V3). The assessment protocol involves a clinician moving the joint “as fast as possible” through its full range of motion (ROM) without specifying or measuring the speed of completion. The MTS is applied according to this standardized protocol regardless of the functional status or goals of the patient. For example, a household ambulator walking at ≤ 0.30 m/s is assessed at the same speed as a community ambulator walking at ≥ 0.80 m/s, whose muscles and joints are moving much faster when walking (18). This “one-size-fits” all approach does not take into account the variability in joint ROM and angular velocity (or speed of lowerlimb movement) with changes in walking speed (19). As such, the MTS may not sensitively discriminate individuals who have spasticity impacting their walking.While it is well established that interventions, such as BoNT-A, reduce spasticity at an impairment-based level, current treatment modalities for spasticity do not necessarily lead to improved walking outcomes (20–22). This may be because standardized protocols for scales such as the MTS do not reflect joint movement during walking (23–25). For example, if clinicians test at a speed that is slower than the joint angular velocity seen during walking, they may fail to identify spasticity that is affecting walking (i.e. false-negative). Conversely, if clinicians test at a speed that exceeds the joint angular velocity seen during walking, they may identify spasticity that is not impacting walking (i.e. false-positive).Matching the joint angles and testing speed of the MTS to the ROM and angular velocity seen during walking may assist in identifying patients who have spasticity impacting functional performance, leading to treatment decisions that optimize patient outcomes and healthcare resources. This study aimed to compare the joint start angle, angle of muscle reaction, and testing speed during a standardized MTS assessment of 4 major muscle groups of the lower-limb, collected in people with neurological conditions, with joint ROM and angular velocity in a healthy population walking at a range of speeds.